1) The study assessed the influence of vastus muscle activity on patellar kinematics in subjects with and without patellofemoral pain.
2) Electromyography was used to measure vastus muscle activity and kinematic magnetic resonance imaging was used to measure patellar displacement and tilt.
3) Increased vastus medialis longus muscle activity was associated with greater lateral patellar displacement at 27 degrees of knee flexion in subjects. Increased vastus medialis muscle activity was also associated with abnormal patellar kinematics in some positions of knee flexion in subjects.
This study aimed to compare the ratio of vastus medialis obliquus to vastus lateralis muscle activity (VMO:VL ratio) between healthy subjects and those with patellofemoral pain (PFP) during different types of quadriceps muscle contractions. The study found that patients with PFP had significantly lower VMO:VL ratios compared to healthy subjects. Additionally, isotonic exercises elicited more favorable muscle activation patterns than isometric exercises for PFP patients. This suggests PFP may be associated with abnormal vastus muscle activation that certain exercises could help address.
The effect of patellar taping on the onset of vm and vl muscle activity in pe...FUAD HAZIME
This study investigated the effect of patellar taping on the timing of vastus medialis obliquus (VMO) and vastus lateralis (VL) muscle activity in 14 females with patellofemoral pain syndrome. Without taping, there was no difference in onset timing between the VMO and VL during stair tasks. With taping, the VMO activated earlier relative to the VL during stair tasks. Taping may alter patella tracking and warrants further research to determine if this is beneficial for patellofemoral pain.
Are patellofemoral pain and qs muscle torque associated with locomotor functionFUAD HAZIME
The study examined the influence of patellofemoral pain (PFP) and quadriceps femoris muscle weakness on gait variables. Nineteen females with PFP and 19 controls underwent gait analysis during various activities and isometric knee extension testing. Compared to controls, those with PFP walked slower due to shorter stride length and slower cadence. Increased knee extension torque correlated with improved gait, while PFP was not associated with locomotor function. Weak quadriceps strength, not pain, appeared to influence gait limitations in those with PFP.
This document describes a study that used a dual spinal cord lesion paradigm in cats to investigate spinal locomotor plasticity after partial spinal cord injury (SCI). The paradigm involved first performing a hemisection at thoracic level T10, followed by a complete spinalization at T13 three weeks later. The findings showed that major changes occurred in the spinal locomotor circuitry between the two lesions. This suggests that plastic changes at the spinal cord level could contribute to recovery of locomotion after partial SCI. The dual lesion paradigm provides insights into how the spinal cord circuitry adapts following incomplete SCI when some descending pathways remain intact.
This dissertation investigated differences in muscle coactivation in the lumbopelvic region between individuals with different pelvic mobility patterns during the active straight leg raise test. Twenty-five participants were divided into two groups based on their pelvic movement during a hip abduction and external rotation test: a reciprocal group with coordinated pelvic movement and a unilateral group with asymmetric movement. Surface electromyography was used to measure and compare muscle coactivation in abdominal, back, gluteal and hamstring muscles between the groups during the leg raise test. The results showed the reciprocal group had significantly greater coactivation in the internal obliques, gluteus maximus and biceps femoris compared to the unilateral group. Conversely, the unilateral
1) The study examined electromyographic (EMG) activity in the anterior, middle, and posterior subdivisions of gluteus medius (GM) muscle during three weight-bearing exercises: wall squat, pelvic drop, and wall press.
2) The results showed significant differences in activation levels between the three GM subdivisions and between the three exercises.
3) The wall press produced the highest activation overall and was most effective at activating the posterior GM subdivision, which typically displays higher activation than the other two subdivisions.
This study aimed to determine which exercises best activate the gluteus medius and superior portion of the gluteus maximus muscles while minimizing activation of the tensor fascia lata muscle. Researchers used fine-wire electromyography to measure muscle activity in the gluteus medius, gluteus maximus, and tensor fascia lata muscles during 11 different exercises in 20 healthy subjects. They found that the clam exercise, sidestepping, unilateral bridging, and quadruped hip extension activated the gluteal muscles significantly more than the tensor fascia lata muscle.
This study aimed to compare the ratio of vastus medialis obliquus to vastus lateralis muscle activity (VMO:VL ratio) between healthy subjects and those with patellofemoral pain (PFP) during different types of quadriceps muscle contractions. The study found that patients with PFP had significantly lower VMO:VL ratios compared to healthy subjects. Additionally, isotonic exercises elicited more favorable muscle activation patterns than isometric exercises for PFP patients. This suggests PFP may be associated with abnormal vastus muscle activation that certain exercises could help address.
The effect of patellar taping on the onset of vm and vl muscle activity in pe...FUAD HAZIME
This study investigated the effect of patellar taping on the timing of vastus medialis obliquus (VMO) and vastus lateralis (VL) muscle activity in 14 females with patellofemoral pain syndrome. Without taping, there was no difference in onset timing between the VMO and VL during stair tasks. With taping, the VMO activated earlier relative to the VL during stair tasks. Taping may alter patella tracking and warrants further research to determine if this is beneficial for patellofemoral pain.
Are patellofemoral pain and qs muscle torque associated with locomotor functionFUAD HAZIME
The study examined the influence of patellofemoral pain (PFP) and quadriceps femoris muscle weakness on gait variables. Nineteen females with PFP and 19 controls underwent gait analysis during various activities and isometric knee extension testing. Compared to controls, those with PFP walked slower due to shorter stride length and slower cadence. Increased knee extension torque correlated with improved gait, while PFP was not associated with locomotor function. Weak quadriceps strength, not pain, appeared to influence gait limitations in those with PFP.
This document describes a study that used a dual spinal cord lesion paradigm in cats to investigate spinal locomotor plasticity after partial spinal cord injury (SCI). The paradigm involved first performing a hemisection at thoracic level T10, followed by a complete spinalization at T13 three weeks later. The findings showed that major changes occurred in the spinal locomotor circuitry between the two lesions. This suggests that plastic changes at the spinal cord level could contribute to recovery of locomotion after partial SCI. The dual lesion paradigm provides insights into how the spinal cord circuitry adapts following incomplete SCI when some descending pathways remain intact.
This dissertation investigated differences in muscle coactivation in the lumbopelvic region between individuals with different pelvic mobility patterns during the active straight leg raise test. Twenty-five participants were divided into two groups based on their pelvic movement during a hip abduction and external rotation test: a reciprocal group with coordinated pelvic movement and a unilateral group with asymmetric movement. Surface electromyography was used to measure and compare muscle coactivation in abdominal, back, gluteal and hamstring muscles between the groups during the leg raise test. The results showed the reciprocal group had significantly greater coactivation in the internal obliques, gluteus maximus and biceps femoris compared to the unilateral group. Conversely, the unilateral
1) The study examined electromyographic (EMG) activity in the anterior, middle, and posterior subdivisions of gluteus medius (GM) muscle during three weight-bearing exercises: wall squat, pelvic drop, and wall press.
2) The results showed significant differences in activation levels between the three GM subdivisions and between the three exercises.
3) The wall press produced the highest activation overall and was most effective at activating the posterior GM subdivision, which typically displays higher activation than the other two subdivisions.
This study aimed to determine which exercises best activate the gluteus medius and superior portion of the gluteus maximus muscles while minimizing activation of the tensor fascia lata muscle. Researchers used fine-wire electromyography to measure muscle activity in the gluteus medius, gluteus maximus, and tensor fascia lata muscles during 11 different exercises in 20 healthy subjects. They found that the clam exercise, sidestepping, unilateral bridging, and quadruped hip extension activated the gluteal muscles significantly more than the tensor fascia lata muscle.
This study examined ankle muscle activity in faster and slower basketball players during a reactive cutting task. Eighteen male basketball players completed the Y-shaped agility test while electromyography measured activity of ankle muscles. Faster players were quicker in both preferred and non-preferred cuts. For the preferred cut, only the peroneus longus on the inside cut leg showed significantly greater activity in faster players. Otherwise, ankle muscle activity did not generally differentiate faster from slower players. While ankle function is important for cutting, strength training should target all ankle muscles to support cutting demands.
This randomized controlled trial examined the effects of two modified posterior shoulder stretching exercises (PSSEs) on shoulder mobility, pain, and dysfunction in patients with subacromial impingement syndrome (SIS). 67 patients with SIS and internal rotation deficit were assigned to receive either a modified cross-body stretch, modified sleeper stretch, or a control treatment of modalities and exercises without PSSEs. Both stretching groups demonstrated greater improvements in pain with activity, internal rotation range of motion, function, and disability compared to the control group. However, there was no significant difference between the two stretching groups. All treatments led to improvements in pain, shoulder mobility, function, and disability.
Laudner kajiyama the relationship between anterior gh laxity and propriocepti...Satoshi Kajiyama
This study examined the relationship between anterior glenohumeral laxity and proprioception in 30 asymptomatic collegiate baseball players. Anterior glenohumeral laxity was measured using an arthrometer and proprioception was assessed by measuring active joint position sense at various shoulder rotations. Linear regression analyses showed no relationship between anterior laxity and proprioception at 30 degrees of internal and external rotation. However, there was a moderate positive relationship between anterior laxity and proprioception at 75 degrees of external rotation, suggesting that proprioception decreases as anterior laxity increases at this position.
This document lists 20 research publications by S. Tashman and various co-authors on topics related to biomechanics, gait analysis, prosthetics, orthotics, and spinal cord injury rehabilitation. The publications report on studies involving pre- and postoperative gait analysis in patients with cerebral palsy, evaluation of prosthetic components, modeling of paraplegic ambulation, investigation of brain and cervical spine injuries, measurement of in vivo joint kinematics, and development of hybrid orthotic systems.
Knee strenght after total knee arthroplastyFUAD HAZIME
1) Knee strength was measured in 52 healthy control knees and 32 knees more than 2 years after total knee arthroplasty (TKA).
2) On average, isometric extension peak torque values in TKA patients were reduced by up to 30.7% compared to controls. Isometric flexion peak torque values in TKA patients were on average 32.2% lower than controls.
3) Relatively greater quadriceps strength in TKA patients was associated with better Knee Society Functional Scores, while a higher hamstring to quadriceps ratio was associated with worse scores. Older and more overweight TKA patients also had lower strength.
—Kyphosis and lordosis changes might be related to back extensor weakness and osteoporosis. The purpose of this study was to find out the correlations between thoracic kyphosis, lumbar lordosis with back extensor strength (BES) and bone mineral density (BMD). Methods: Thoracic kyphosis, lumbar lordosis, maximal isometric strength of the back extensors and BMD of the lumbar vertebral were evaluated in 47 elderly (50-75 years old)women. BMD of the lumbar vertebral was measured using Dual-Energy X-Ray Absorptiometry (DEXA) and kyphosis and lordosis degree were assayed using a flexible ruler. The maximal isometric strength of the back extensors was measured using an isometric manual muscle tester (MMT). Data were analyzed using ANOVA and independent t-test at p≤0.05 level of acceptance. Results: A significant reverse correlation was shown between BES and kyphosis (p=0.044, r=-0.30). No significant correlation were found between BES and lordosis degree, nor between lumbar vertebral BMD and, both, kyphosis and lordosis degrees. However, there was a significant difference in BES between three groups with various degree of kyphosis (p≤ 0.05). Conclusion: It can be concluded that the severity of thoracic kyphosis may be influenced by BES. So, stronger back extensor can prevent thoracic kyphosis despite decreased BMD.
This document contains assessment findings and proposed training program for a 25-year old client with anterior pelvic tilt, leg length discrepancy, foot hyperpronation, and limited range of motion. Static and functional assessments identified impairments including excessive foot pronation, weak gluteal muscles, and anterior pelvic tilt. The proposed training focuses on self-myofascial release, static stretching, isolated strengthening, and integration exercises for the feet, hips, and core to address imbalances and improve posture. Regular participation in the program was limited by the client's work commitments.
Surplus value of hip adduction in leg press exercise in patients with patello...FUAD HAZIME
1) This randomized controlled trial examined the effects of incorporating hip adduction into leg press exercise (LPHA group) compared to leg press exercise alone (LP group) and a no exercise control group for patients with patellofemoral pain syndrome (PFPS).
2) 89 patients with PFPS were randomly assigned to one of the three groups and underwent either LPHA, LP, or no exercise over 8 weeks. Outcome measures included pain, function, and vastus medialis oblique (VMO) muscle morphology.
3) Both exercise groups experienced significant improvements in pain, function and VMO size after treatment compared to the control group, but there were no differences between the LPHA and LP groups
Effect of Kinesiology Tape on Cycling PerformanceRockTape
A study was conducted to determine if Rocktape could improve athletic endurance performance in cyclists. 5 elite cyclists rode a 24-mile course with and without Rocktape, and their performance was measured. Athletes who wore Rocktape performed 2-6% better than when they did not wear Rocktape, based on measures of wattage, time and distance. The study had limitations as it was funded and conducted by Rocktape and lacked a control group, but provides preliminary low-level evidence that Rocktape may improve endurance performance in cyclists.
If you have ever treated runners, having them stop or modify activity during rehabilita- tion is nearly impossible. As someone who specializes in the treatment of endurance
athletes, I am always looking for an edge
to return them to activity as soon as possible.
EMG of the Transverse Abdominus and Multifidus During Pilates ExercisesGrandFinalTechnologies
This study evaluated the intensity of muscle activation in the transverse abdominis and multifidus muscles during four Pilates exercises using electromyography. Eight healthy women performed exercises including shoulder bridges, leg circles, and scissors. The results found that shoulder bridges and variations extending the right or left leg produced greater co-activation of the transverse abdominis and multifidus muscles compared to other exercises. Therefore, these exercises are most effective for rehabilitating lumbar spine stability through activation of the core muscles.
This study examined muscle activation patterns in the lower extremities during different squat techniques. 28 healthy subjects performed squats with neutral alignment (control), intentional frontal plane malalignment (medial knee displacement), and sagittal plane malalignment (anterior knee displacement). Electromyography was used to measure muscle activation in the quadriceps, hamstrings, and gastrocnemius. Results showed altered muscle activation patterns during the malaligned squats, with decreased quadriceps activation during medial knee displacement and changes in quadriceps and hamstring activation timing during anterior knee displacement compared to the control squat. The study provides information on how muscle activation changes with different squat alignments.
Nikos Malliaropoulos - Rehabilitation of hamstring injuries MuscleTech Network
Nikos Malliaropoulos
Director of the Athletics National Sports Medicine Centre Thessaloniki Greece. Consultant SEM Physician Barts and The London Clinical Senior Lecturer QMUL CSEM.
-
The rehabilitation of Hamstring injuries - Can we be more injury specific?
(6th MuscleTech Network Workshop)
14th October, Barcelona
This document discusses return to sport criteria and rehabilitation protocols for acute hamstring strains, noting that criteria should include measures of strength, range of motion, neuromuscular control and readiness, and that eccentric strengthening can help prevent reinjury for chronic or recurrent strains. Guidelines are proposed focusing on a progressive agility program without stretching to regain strength and function before clearing for full sport activity.
This document describes a study that investigated the reliability of different electromyography (EMG) normalization methods for cycling analyses. The study tested 25 male cyclists and examined four lower leg muscles. Participants performed isometric maximum voluntary contractions (IMVC) on a dynamometer and submaximal and maximum cycling trials. The study found that different normalization methods produced significantly different EMG amplitude reference values and that the peak dynamic amplitude (PDA) method demonstrated the highest reliability for all muscles. Therefore, the study supports the use of the PDA method for EMG normalization in cycling analyses.
Resistance training can lead to improvements in strength and reverse some effects of aging in older adults. The study found increases in maximal torque of 9-37% after resistance training in adults aged 65-81. These gains were due to increases in neural drive to muscles without changes in co-activation of antagonist muscles. Resistance training also increased muscle size and altered muscle architecture, including longer fascicles and greater pennation angles. Tendon stiffness and modulus increased by 65-69% after training as well, indicating reversal of aging effects on tendons. In conclusion, resistance training can help mitigate many musculoskeletal changes associated with aging.
The document examines back muscle activity during three traditional mat Pilates exercises - swimming, single leg kick with static prone back extension, and double leg kick - through surface electromyography of healthy adult females. The study found that swimming increased lumbar extensor muscle activity the most at 29% on average compared to the other two exercises. Double leg kicking produced significantly more back muscle activation than single leg kicking. Overall, back muscle activation during the exercises ranged from 15-61% of participants' maximum voluntary isometric contraction levels.
This study aimed to detect the electromechanical delay (EMD) and its components during voluntary isometric contractions of the quadriceps femoris muscle. The researchers measured time delays between the onsets of EMG-MMG, EMG-US, MMG-FORCE, US-FORCE, and EMG-FORCE signals. They found ultrasonography (US) provided more reliable detection of muscle fiber motion onset compared to mechanomyography (MMG). The study concluded synchronization of US with EMG and force sensors can reveal reliable results about EMD and its components during voluntary muscle contractions by detecting fiber motion onset from a certain muscle depth.
This research report studied the influence of the depth of the trochlear groove on patellar kinematics in subjects with and without patellofemoral pain (PFP). 23 women with PFP and 12 women without PFP underwent kinematic magnetic resonance imaging during resisted knee extension. The depth of the trochlear groove was found to correlate with increased lateral patellar tilt and displacement at certain flexion angles in subjects with PFP. Shallower trochlear grooves were predictive of abnormal patellar tracking patterns. The results indicate that bony structure influences patellar kinematics and is an important determinant of patellar alignment, especially near full extension.
1) The study examined whether individuals with patella alta experience higher patellofemoral joint stress during walking compared to pain-free controls.
2) Magnetic resonance images and gait analysis were used to calculate subject-specific knee biomechanics and patellofemoral joint stress during normal and fast walking speeds.
3) During fast walking, individuals with patella alta had significantly less patellofemoral joint contact area and significantly higher joint stress compared to controls, due to reductions in contact area while joint reaction forces were similar between groups.
This study examined ankle muscle activity in faster and slower basketball players during a reactive cutting task. Eighteen male basketball players completed the Y-shaped agility test while electromyography measured activity of ankle muscles. Faster players were quicker in both preferred and non-preferred cuts. For the preferred cut, only the peroneus longus on the inside cut leg showed significantly greater activity in faster players. Otherwise, ankle muscle activity did not generally differentiate faster from slower players. While ankle function is important for cutting, strength training should target all ankle muscles to support cutting demands.
This randomized controlled trial examined the effects of two modified posterior shoulder stretching exercises (PSSEs) on shoulder mobility, pain, and dysfunction in patients with subacromial impingement syndrome (SIS). 67 patients with SIS and internal rotation deficit were assigned to receive either a modified cross-body stretch, modified sleeper stretch, or a control treatment of modalities and exercises without PSSEs. Both stretching groups demonstrated greater improvements in pain with activity, internal rotation range of motion, function, and disability compared to the control group. However, there was no significant difference between the two stretching groups. All treatments led to improvements in pain, shoulder mobility, function, and disability.
Laudner kajiyama the relationship between anterior gh laxity and propriocepti...Satoshi Kajiyama
This study examined the relationship between anterior glenohumeral laxity and proprioception in 30 asymptomatic collegiate baseball players. Anterior glenohumeral laxity was measured using an arthrometer and proprioception was assessed by measuring active joint position sense at various shoulder rotations. Linear regression analyses showed no relationship between anterior laxity and proprioception at 30 degrees of internal and external rotation. However, there was a moderate positive relationship between anterior laxity and proprioception at 75 degrees of external rotation, suggesting that proprioception decreases as anterior laxity increases at this position.
This document lists 20 research publications by S. Tashman and various co-authors on topics related to biomechanics, gait analysis, prosthetics, orthotics, and spinal cord injury rehabilitation. The publications report on studies involving pre- and postoperative gait analysis in patients with cerebral palsy, evaluation of prosthetic components, modeling of paraplegic ambulation, investigation of brain and cervical spine injuries, measurement of in vivo joint kinematics, and development of hybrid orthotic systems.
Knee strenght after total knee arthroplastyFUAD HAZIME
1) Knee strength was measured in 52 healthy control knees and 32 knees more than 2 years after total knee arthroplasty (TKA).
2) On average, isometric extension peak torque values in TKA patients were reduced by up to 30.7% compared to controls. Isometric flexion peak torque values in TKA patients were on average 32.2% lower than controls.
3) Relatively greater quadriceps strength in TKA patients was associated with better Knee Society Functional Scores, while a higher hamstring to quadriceps ratio was associated with worse scores. Older and more overweight TKA patients also had lower strength.
—Kyphosis and lordosis changes might be related to back extensor weakness and osteoporosis. The purpose of this study was to find out the correlations between thoracic kyphosis, lumbar lordosis with back extensor strength (BES) and bone mineral density (BMD). Methods: Thoracic kyphosis, lumbar lordosis, maximal isometric strength of the back extensors and BMD of the lumbar vertebral were evaluated in 47 elderly (50-75 years old)women. BMD of the lumbar vertebral was measured using Dual-Energy X-Ray Absorptiometry (DEXA) and kyphosis and lordosis degree were assayed using a flexible ruler. The maximal isometric strength of the back extensors was measured using an isometric manual muscle tester (MMT). Data were analyzed using ANOVA and independent t-test at p≤0.05 level of acceptance. Results: A significant reverse correlation was shown between BES and kyphosis (p=0.044, r=-0.30). No significant correlation were found between BES and lordosis degree, nor between lumbar vertebral BMD and, both, kyphosis and lordosis degrees. However, there was a significant difference in BES between three groups with various degree of kyphosis (p≤ 0.05). Conclusion: It can be concluded that the severity of thoracic kyphosis may be influenced by BES. So, stronger back extensor can prevent thoracic kyphosis despite decreased BMD.
This document contains assessment findings and proposed training program for a 25-year old client with anterior pelvic tilt, leg length discrepancy, foot hyperpronation, and limited range of motion. Static and functional assessments identified impairments including excessive foot pronation, weak gluteal muscles, and anterior pelvic tilt. The proposed training focuses on self-myofascial release, static stretching, isolated strengthening, and integration exercises for the feet, hips, and core to address imbalances and improve posture. Regular participation in the program was limited by the client's work commitments.
Surplus value of hip adduction in leg press exercise in patients with patello...FUAD HAZIME
1) This randomized controlled trial examined the effects of incorporating hip adduction into leg press exercise (LPHA group) compared to leg press exercise alone (LP group) and a no exercise control group for patients with patellofemoral pain syndrome (PFPS).
2) 89 patients with PFPS were randomly assigned to one of the three groups and underwent either LPHA, LP, or no exercise over 8 weeks. Outcome measures included pain, function, and vastus medialis oblique (VMO) muscle morphology.
3) Both exercise groups experienced significant improvements in pain, function and VMO size after treatment compared to the control group, but there were no differences between the LPHA and LP groups
Effect of Kinesiology Tape on Cycling PerformanceRockTape
A study was conducted to determine if Rocktape could improve athletic endurance performance in cyclists. 5 elite cyclists rode a 24-mile course with and without Rocktape, and their performance was measured. Athletes who wore Rocktape performed 2-6% better than when they did not wear Rocktape, based on measures of wattage, time and distance. The study had limitations as it was funded and conducted by Rocktape and lacked a control group, but provides preliminary low-level evidence that Rocktape may improve endurance performance in cyclists.
If you have ever treated runners, having them stop or modify activity during rehabilita- tion is nearly impossible. As someone who specializes in the treatment of endurance
athletes, I am always looking for an edge
to return them to activity as soon as possible.
EMG of the Transverse Abdominus and Multifidus During Pilates ExercisesGrandFinalTechnologies
This study evaluated the intensity of muscle activation in the transverse abdominis and multifidus muscles during four Pilates exercises using electromyography. Eight healthy women performed exercises including shoulder bridges, leg circles, and scissors. The results found that shoulder bridges and variations extending the right or left leg produced greater co-activation of the transverse abdominis and multifidus muscles compared to other exercises. Therefore, these exercises are most effective for rehabilitating lumbar spine stability through activation of the core muscles.
This study examined muscle activation patterns in the lower extremities during different squat techniques. 28 healthy subjects performed squats with neutral alignment (control), intentional frontal plane malalignment (medial knee displacement), and sagittal plane malalignment (anterior knee displacement). Electromyography was used to measure muscle activation in the quadriceps, hamstrings, and gastrocnemius. Results showed altered muscle activation patterns during the malaligned squats, with decreased quadriceps activation during medial knee displacement and changes in quadriceps and hamstring activation timing during anterior knee displacement compared to the control squat. The study provides information on how muscle activation changes with different squat alignments.
Nikos Malliaropoulos - Rehabilitation of hamstring injuries MuscleTech Network
Nikos Malliaropoulos
Director of the Athletics National Sports Medicine Centre Thessaloniki Greece. Consultant SEM Physician Barts and The London Clinical Senior Lecturer QMUL CSEM.
-
The rehabilitation of Hamstring injuries - Can we be more injury specific?
(6th MuscleTech Network Workshop)
14th October, Barcelona
This document discusses return to sport criteria and rehabilitation protocols for acute hamstring strains, noting that criteria should include measures of strength, range of motion, neuromuscular control and readiness, and that eccentric strengthening can help prevent reinjury for chronic or recurrent strains. Guidelines are proposed focusing on a progressive agility program without stretching to regain strength and function before clearing for full sport activity.
This document describes a study that investigated the reliability of different electromyography (EMG) normalization methods for cycling analyses. The study tested 25 male cyclists and examined four lower leg muscles. Participants performed isometric maximum voluntary contractions (IMVC) on a dynamometer and submaximal and maximum cycling trials. The study found that different normalization methods produced significantly different EMG amplitude reference values and that the peak dynamic amplitude (PDA) method demonstrated the highest reliability for all muscles. Therefore, the study supports the use of the PDA method for EMG normalization in cycling analyses.
Resistance training can lead to improvements in strength and reverse some effects of aging in older adults. The study found increases in maximal torque of 9-37% after resistance training in adults aged 65-81. These gains were due to increases in neural drive to muscles without changes in co-activation of antagonist muscles. Resistance training also increased muscle size and altered muscle architecture, including longer fascicles and greater pennation angles. Tendon stiffness and modulus increased by 65-69% after training as well, indicating reversal of aging effects on tendons. In conclusion, resistance training can help mitigate many musculoskeletal changes associated with aging.
The document examines back muscle activity during three traditional mat Pilates exercises - swimming, single leg kick with static prone back extension, and double leg kick - through surface electromyography of healthy adult females. The study found that swimming increased lumbar extensor muscle activity the most at 29% on average compared to the other two exercises. Double leg kicking produced significantly more back muscle activation than single leg kicking. Overall, back muscle activation during the exercises ranged from 15-61% of participants' maximum voluntary isometric contraction levels.
This study aimed to detect the electromechanical delay (EMD) and its components during voluntary isometric contractions of the quadriceps femoris muscle. The researchers measured time delays between the onsets of EMG-MMG, EMG-US, MMG-FORCE, US-FORCE, and EMG-FORCE signals. They found ultrasonography (US) provided more reliable detection of muscle fiber motion onset compared to mechanomyography (MMG). The study concluded synchronization of US with EMG and force sensors can reveal reliable results about EMD and its components during voluntary muscle contractions by detecting fiber motion onset from a certain muscle depth.
This research report studied the influence of the depth of the trochlear groove on patellar kinematics in subjects with and without patellofemoral pain (PFP). 23 women with PFP and 12 women without PFP underwent kinematic magnetic resonance imaging during resisted knee extension. The depth of the trochlear groove was found to correlate with increased lateral patellar tilt and displacement at certain flexion angles in subjects with PFP. Shallower trochlear grooves were predictive of abnormal patellar tracking patterns. The results indicate that bony structure influences patellar kinematics and is an important determinant of patellar alignment, especially near full extension.
1) The study examined whether individuals with patella alta experience higher patellofemoral joint stress during walking compared to pain-free controls.
2) Magnetic resonance images and gait analysis were used to calculate subject-specific knee biomechanics and patellofemoral joint stress during normal and fast walking speeds.
3) During fast walking, individuals with patella alta had significantly less patellofemoral joint contact area and significantly higher joint stress compared to controls, due to reductions in contact area while joint reaction forces were similar between groups.
Effect of Sit To Sit And Activity On Forward Bending TestApeksha Besekar
Sit-to-stand activity was found to be an effective pre-stretching tool to improve flexibility of the lower back, hamstrings, and Achilles tendon muscles based on this study of 50 females. Participants were divided into two groups that performed either 10 or 20 repetitions of sit-to-stand activity. Both groups had statistically significant improvements in flexibility as measured by increased forward bending distance and decreased muscle tightness. However, there was no significant difference found between the two groups, suggesting that 10 and 20 repetitions were equally effective. The study concluded that sit-to-stand activity provides warm-up and increases flexibility through mechanisms of reciprocal inhibition and autogenic inhibition.
The hamstring muscle group is the most frequently injured, representing
approximately 12 to 24% of all athletic injuries.1,2 These injuries may be due to
disproportionate training performed for the quadriceps,3 with hamstring strains
occurring more frequently in those who demonstrated hamstring weakness, and
lower hamstring-to-quadriceps strength ratios.2 Thus, hamstring strength is impor-
tant for athletic performance and injury prevention in a variety of sports.
This document summarizes a presentation on foot and ankle pathologies and rehabilitation. The objectives are to understand biomechanics related to injuries, clinical concepts in rehabilitation, literature on dysfunctions and treatments, and how to apply evidence. Common conditions discussed include anterior impingement, Achilles tendinitis, posterior tibialis dysfunction, ankle sprains, and peroneal tendinitis. The importance of examining regional interdependence and impairments in distant areas that may contribute to problems is emphasized. Evidence is presented for various treatments related to specific conditions.
Correlation between conventional clinical tests and a new movement assessment...Stavros Litsos
Correlation between conventional clinical tests and a new movement assessment battery - Bachelor thesis
Despite the complexity of movements performed in sports, physical examination is today done by conventional tests that evaluate joints and muscles individually (e.g. Smith press test, Figure1). Our study used a new movement assessment battery of 20 reach tests, which incorporates the complexity and diversity of natural human movements, taking into consideration that joints are interdependent in a movement and that the planes and sequences of a movement change during its performance. The purpose of this study was to determine whether or not there is a correlation between conventional mobility tests and the new assessment battery.
Já conheces a PNF? Neste artigo irás verificar as amplas possibilidades do conceito PNF, nomeadamente no caso de uma paciente com queixas ao nível do ombro.
This document summarizes a conceptual model of the spinal stabilizing system consisting of three interconnected subsystems: passive (vertebrae, discs, ligaments), active (spinal muscles), and neural (nerves and central nervous system). It describes how the subsystems normally function in a coordinated manner to provide spinal stability. A dysfunction in any subsystem can lead to compensation attempts by the others to maintain stability, but may result in long-term adaptation or injury if compensation is insufficient. The model proposes that the neural subsystem monitors passive tissue deformation to determine stability requirements and directs the active subsystem's muscle tensions accordingly.
The study examined the effects of calf muscle stretching in weight-bearing and non-weight-bearing positions. It found that non-weight-bearing stretching significantly increased muscle fascicle length and Achilles tendon length compared to weight-bearing stretching. Weight-bearing positioning limits the muscle's ability to relax fully and elongate due to forces from the body weight. Non-weight-bearing stretching allows for greater lengthening of both the muscle and tendon tissues. The results suggest non-weight-bearing calf stretching may provide greater benefits for improving ankle mobility.
Voluntary activation and decreased force production of the qs after total kne...FUAD HAZIME
1) Patients who had undergone total knee arthroplasty (TKA) 3-4 weeks prior had significantly lower quadriceps force (64% lower) and greater voluntary activation deficits (26% vs 6%) compared to older adults without knee pathology.
2) Age did not correlate with quadriceps activation for TKA patients, and knee pain only explained a small amount of variability in force production.
3) Voluntary activation deficits in TKA patients accounted for a large portion (r^2=0.65) of the variability in their knee extension force production.
This study examined differences in strength and activation timing of the ankle dorsiflexors and evertors between individuals with functionally unstable ankles and uninjured controls using a stretch-shortening cycle protocol. 30 subjects (15 with unilateral ankle instability and 15 controls) performed concentric contractions of the ankle muscles at two speeds on an isokinetic dynamometer. The study found no significant differences in peak torque normalized to body weight or time to peak torque between the groups. This suggests that differences in strength and muscle activation timing during the stretch-shortening cycle do not exist between those with and without ankle instability.
Application of fascial manipulation technique in chronic shoulder painAdam Glowacz MCSP
This pilot study examines the application of the Fascial Manipulation technique in 28 patients with chronic shoulder pain. The technique involves deep kneading of fascial points along myofascial sequences to reduce pain. Patients underwent 3 treatment sessions and reported pain levels before, after, and 3 months post-treatment using a visual analogue scale. Results suggest the technique may effectively reduce pain in chronic shoulder dysfunctions. The study also discusses the anatomical basis of fascial continuity and the biomechanical model of the Fascial Manipulation technique.
- The study examined the effects of gastrocnemius (calf muscle) fatigue on ankle joint kinetics during the squat jump in 5 trained male basketball players.
- Participants performed squat jumps before and after a calf raise protocol to induce gastrocnemius fatigue. Kinematic and kinetic data of the foot segment was analyzed.
- Results showed no significant difference in foot segment power between pre- and post-fatigue jumps, indicating that bi-articular muscle fatigue did not reduce segmental kinetics.
- The conclusion is that the gastrocnemius acts to transfer energy between segments rather than generate work, so its fatigue did not decrease ankle joint power during the squat jump.
Effect of hamstring stretching and neural mobilization.pptxEnglishSSC
The document reviews several studies on the effectiveness of hamstring stretching, neural mobilization, and radial extracorporeal shock wave therapy for treating low back pain with radiculopathy. One randomized controlled trial found that neural mobilization combined with lumbar stabilization exercises and radial extracorporeal shock wave therapy was more effective for chronic low back pain with radiculopathy than lumbar stabilization exercises and radial extracorporeal shock wave therapy alone. Another study found that hamstring stretching can significantly improve hamstring flexibility and pelvic mobility in patients with low back pain. A third study demonstrated that hamstring stretching and neural mobilization can be effective therapies for reducing pain in patients with radicular lower back pain.
Core stability is a complex issue with many myths and misconceptions. There are several beliefs that are refuted by current evidence:
1) Certain core muscles like transversus abdominis are not uniquely important for spinal stability.
2) Weak abdominal muscles do not necessarily lead to back pain.
3) Strengthening core muscles does not reliably reduce back pain more than general exercises.
4) A strong core will not necessarily prevent injury more than other forms of exercise. Core stability exercises provide benefits similar to general exercises and are not uniquely effective for back pain.
This document summarizes a study that analyzed muscle coordination during rectilinear and curvilinear walking using muscle synergies extracted from electromyography (EMG) data. EMG signals were recorded from 15 muscles in the leg and trunk from 13 healthy subjects walking straight and along circular trajectories in both directions. Muscle synergies were identified using non-negative matrix factorization and compared across conditions. Results showed cadence decreased and stance phase duration increased in curvilinear walking compared to straight. Abdominal and adductor muscles had high variability and were excluded. Synergies accounted for muscle coordination in different walking conditions.
1. The document discusses the use of EMG to guide and evaluate lumbar spine manual therapy. Several studies have used real-time EMG to monitor paraspinal muscle activity during manual therapy techniques.
2. One study found increased spinal stiffness and positive neuromuscular responses during thrust techniques compared to those with less back pain. Another found increased paraspinal muscle strength immediately following spinal manipulation.
3. A third study observed paraspinal EMG patterns mimicking stretching responses during myofascial treatments, relating clinical effectiveness to tonic muscle reactions detected by EMG.
O documento descreve princípios e propriedades da água, incluindo densidade relativa, flutuação, resistência do fluido e pressão hidrostática. A densidade relativa determina se um objeto flutuará ou afundará, e a flutuação ocorre devido à força de empuxo de Arquimedes igual ao volume de fluido deslocado. A pressão hidrostática é exercida igualmente em todas as áreas de um corpo imerso e é proporcional à profundidade e densidade do fluido.
O documento discute o uso do ultra som, explicando que é uma onda mecânica que se propaga através do movimento de moléculas em um meio. Ele também descreve os efeitos físicos térmicos e não térmicos do ultra som no corpo, incluindo aumento de temperatura, cavitação, correntes acústicas e ondas estacionárias. Além disso, discute a escolha apropriada da frequência, intensidade, meio acoplador e outros parâmetros para aplicação segura e eficaz do ultra som terapêutico
1) The document discusses issues with relying solely on statistical significance (p-values) to determine clinical significance. While p-values indicate if results could be due to chance, they do not provide information on the size of the treatment effect or its clinical meaningfulness.
2) Effect sizes and confidence intervals provide a measure of the magnitude of the treatment effect but do not necessarily indicate clinical significance on their own.
3) The document argues that clinical significance should be determined based on external standards from patients and clinicians regarding what would constitute a meaningful improvement, rather than solely on statistical measures.
A randomised, placebo controlled trial of low level laser therapy for activat...FUAD HAZIME
This randomized controlled trial investigated whether low-level laser therapy (LLLT) has an anti-inflammatory effect on activated Achilles tendinitis. Seven patients with bilateral Achilles tendinitis received either active LLLT or placebo LLLT on their two tendons. Prostaglandin E2 (PGE2) concentrations, measured via microdialysis, were significantly reduced after active LLLT compared to placebo and pre-treatment levels, indicating LLLT's anti-inflammatory effect. Pressure pain threshold also increased more after active LLLT than placebo LLLT. The study demonstrates that LLLT can reduce inflammation and pain in activated Achilles tendinitis.
Systematic review and meta analysis comparing land and aquatic exercise for p...FUAD HAZIME
This systematic review and meta-analysis compares the effects of aquatic exercise and land-based exercise on function, mobility, and other health outcomes for people with hip or knee arthritis. The review included 10 randomized controlled trials and found no significant differences in outcomes between the two exercise methods based on meta-analysis. However, the exercise programs varied considerably between trials and were poorly reported. The review identifies a need for further research comparing participant preferences for aquatic versus land-based exercise.
Preoperative physical therapy in primary total knee arthroplastyFUAD HAZIME
This study evaluated the effects of preoperative physical therapy in patients undergoing primary total knee arthroplasty. 10 patients completed 6 weeks of physical therapy before surgery while 10 control patients did not receive preoperative therapy. Both groups were tested before and after surgery and compared. The study found that preoperative physical therapy resulted in modest gains in knee flexion strength but no difference in extension strength or other short-term outcomes like function, range of motion, or muscle size. Therefore, the study did not support the routine use of preoperative physical therapy for knee replacement surgery.
Predictive risk factors for stif knees in total knee arthroplastyFUAD HAZIME
This study reviewed 1216 primary total knee arthroplasties (TKAs) to identify predictors of stiffness, defined as flexion less than 90 degrees one year after surgery. The incidence of stiffness was 3.7% (45 cases). These stiff cases were matched to 45 controls with flexion over 90 degrees. Predictors of stiffness included lower preoperative and intraoperative flexion. There was no correlation with medical comorbidities like diabetes. Lower preoperative and postoperative patellar height ratios also correlated with stiffness. Attention to surgical technique and rehabilitation may help reduce stiffness risk.
Management of extensor mechanism deficit as a consequence of patellar tendon ...FUAD HAZIME
This article describes a new surgical technique for reconstructing the extensor mechanism in patients who have experienced patellar tendon loss following total knee arthroplasty. The technique involves using an allograft consisting of the patella, patellar tendon, and tibial tubercle. The allograft is secured with the host patella by creating a trough in the host patella and fitting the allograft patella into it, allowing for bone-to-bone healing. The results were promising, with no patients experiencing more than a 10 degree extensor lag at final follow-up. This technique aims to provide a more stable reconstruction compared to previous techniques by promoting direct bone healing rather than relying solely on soft tissue healing.
In hospital complications after total joint arthroplastyFUAD HAZIME
The study prospectively collected data on systemic and local complications from 15,383 joint arthroplasty procedures performed over 6 years. There were 486 major systemic complications, most commonly pulmonary embolism (152 cases), tachyarrhythmia (92), and acute myocardial infarction (36). There were also 109 major local complications, including 16 vascular injuries and 29 peripheral nerve injuries. The incidence of complications was higher after knee arthroplasty, bilateral procedures, and revision surgery. This study provides baseline data on the range and frequency of potential in-hospital complications following elective joint arthroplasty.
Full thicness burn formation after the use of electrical stimulation for reha...FUAD HAZIME
1) A patient developed a full-thickness burn on his proximal tibia after undergoing a unicompartmental knee arthroplasty and receiving electrical stimulation therapy during physical rehabilitation.
2) The burn occurred when interferential current electrodes were placed directly over the patient's metal tibial implant.
3) It is believed the current increased local skin temperature unnoticed by the patient due to lack of sensation in the area.
4) To avoid similar complications, it is recommended to avoid placing electrodes directly over metal implants or insensate skin areas during electrical stimulation therapy.
Factors affecting length of stay and need for rehabilitation after hip and kn...FUAD HAZIME
This study examined factors that predict the length of stay in the hospital and the need for rehabilitation after hip or knee arthroplasty. The records of 125 patients who underwent elective hip or knee replacement surgery in 1995 at Albany Medical Center were reviewed. The average length of stay was 6.4 days. Younger age significantly correlated with longer hospital stay. Older age and diabetes significantly correlated with the need for inpatient rehabilitation after surgery.
Effectiveness of pt artro systematic review and metanalysisFUAD HAZIME
This systematic review evaluated the effectiveness of physiotherapy exercise after knee arthroplasty for osteoarthritis. The review included 6 randomized controlled trials that compared physiotherapy exercise interventions to usual care or different exercise interventions after discharge. The review found small to moderate benefits of functional exercise for function, range of motion, and quality of life 3-4 months after surgery. However, benefits were no longer evident at 1 year, suggesting no long term benefit of physiotherapy exercise after knee arthroplasty.
Effectiveness of physiotherapy exercise after knee arthroplasty for oa.FUAD HAZIME
This systematic review evaluated the effectiveness of physiotherapy exercise after knee arthroplasty for osteoarthritis. The review included 6 randomized controlled trials that compared physiotherapy exercise interventions to usual care or different exercise interventions after discharge. The review found small to moderate benefits of functional exercise for function, range of motion, and quality of life 3-4 months after surgery. However, benefits were no longer evident at 1 year, suggesting no long term benefit of physiotherapy exercise after knee arthroplasty.
Effectiveness of cpm and conventional physical therapy after total knee arthr...FUAD HAZIME
This randomized clinical trial compared the effectiveness of 3 in-hospital rehabilitation programs following primary total knee arthroplasty (TKA): 1) conventional physical therapy alone, 2) conventional physical therapy with 35 minutes of continuous passive motion (CPM) daily, and 3) conventional physical therapy with 2 hours of CPM daily. Outcome measures included range of motion, functional ability, and length of stay. The results showed no significant differences between the groups for any outcomes, suggesting that adding CPM to conventional physical therapy provided no additional benefits after primary TKA.
The study compared the effectiveness of electrical stimulation (ES) versus voluntary exercise (VE) for strengthening thigh musculature after anterior cruciate ligament (ACL) reconstructive surgery. Twenty patients were randomly assigned to either an ES or VE group and completed a 3-week training regimen. Results showed that patients in the ES group achieved significantly higher percentages of knee extension and flexion torque compared to patients in the VE group, indicating ES was more effective for strengthening thigh muscles early in postoperative rehabilitation.
Does shortened length of hospital stay affect total knee arthroplasty rehabil...FUAD HAZIME
The study compared rehabilitation outcomes for patients who participated in a hospital joint arthroplasty program designed to decrease length of stay ("Joint Camp") to outcomes for patients before the program was implemented. The program reduced average length of stay by 1.3 days but resulted in decreased range of motion at discharge. No significant differences were found between the groups at 3, 6, and 12 month follow ups for range of motion or Knee Society scores, suggesting primary knee arthroplasty rehabilitation outcomes were not compromised by the reduced hospital stay.
Does a standard outpatient physiotherapy regime improve the range of knee mot...FUAD HAZIME
This study investigated whether a standard outpatient physiotherapy regime improved range of knee motion after primary total knee arthroplasty (TKA). 150 patients were randomly assigned to either receive 6 weeks of outpatient physiotherapy after TKA (Group A) or no outpatient physiotherapy (Group B). Range of motion measurements found that while Group A achieved greater flexion than Group B, the difference was not statistically significant. The study concluded that outpatient physiotherapy does not improve range of knee motion after primary TKA.
Determinants of function knee arthroplastyFUAD HAZIME
This research study examined 276 patients who received a primary total knee arthroplasty (TKA) to identify preoperative factors that predict functional status after surgery. Data on demographics, medical history, and knee function were collected before and 6 months after surgery. The results found that lower baseline function, use of a walking device, shorter walking distance, and more comorbid health conditions predicted poorer functional outcomes 6 months after TKA. Patients with more preoperative dysfunction may require more intensive physical therapy to achieve functional gains similar to less impaired patients.
Cryotherapy for postoperative pain relief following knee arthroplastyFUAD HAZIME
This study investigated the effects of cryotherapy on postoperative pain relief following knee arthroplasty. 90 patients were randomly assigned to have thermal pads applied to their incisions set to temperatures of 50°, 60°, or 70°F for 72 hours after surgery. The amount of morphine administered via patient-controlled analgesia pumps and the number of attempts to receive morphine were analyzed. There were no significant differences found between the temperature groups, sexes, sides operated on, ages, weights, or diagnoses in terms of morphine administered or attempts. Cryotherapy provided no additional pain relief compared to room temperature pads following knee arthroplasty.
Comparison of the effects of exercise in water and on land on the rehabilitat...FUAD HAZIME
1. The study compared the effects of rehabilitation exercises performed in water versus on land for patients who had undergone ACL reconstruction surgery.
2. Patients were randomly assigned to either a traditional land-based rehabilitation group or a pool rehabilitation group that performed identical exercises in water.
3. Outcome measures included range of motion, muscle strength, joint effusion, laxity, and functional scores, which were assessed at various intervals over the 8-week rehabilitation period.
4. Preliminary results found higher functional scores in the water group, less joint effusion, and similar results between groups for other outcomes. The study aimed to determine if water-based exercises provided benefits over traditional land exercises following ACL reconstruction.
Main Java[All of the Base Concepts}.docxadhitya5119
This is part 1 of my Java Learning Journey. This Contains Custom methods, classes, constructors, packages, multithreading , try- catch block, finally block and more.
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
How to Add Chatter in the odoo 17 ERP ModuleCeline George
In Odoo, the chatter is like a chat tool that helps you work together on records. You can leave notes and track things, making it easier to talk with your team and partners. Inside chatter, all communication history, activity, and changes will be displayed.
Thinking of getting a dog? Be aware that breeds like Pit Bulls, Rottweilers, and German Shepherds can be loyal and dangerous. Proper training and socialization are crucial to preventing aggressive behaviors. Ensure safety by understanding their needs and always supervising interactions. Stay safe, and enjoy your furry friends!
Assessment and Planning in Educational technology.pptxKavitha Krishnan
In an education system, it is understood that assessment is only for the students, but on the other hand, the Assessment of teachers is also an important aspect of the education system that ensures teachers are providing high-quality instruction to students. The assessment process can be used to provide feedback and support for professional development, to inform decisions about teacher retention or promotion, or to evaluate teacher effectiveness for accountability purposes.
Assessment and Planning in Educational technology.pptx
Patellar kinematics, Part I
1. Research Report
Patellar Kinematics, Part I:
The Influence of Vastus Muscle
Activity in Subjects With and Without
Patellofemoral Pain
Background and Purpose. Reduced motor unit activity of the vastus
medialis muscle relative to the vastus lateralis muscle has been impli-
cated as a cause of lateral patellar subluxation. The purpose of this
study was to assess the influence of vastus muscle motor unit activity on
patellar kinematics. Subjects. Twenty-three women (mean age 26.8
years, SD 8.5, range 14 – 46) with a diagnosis of patellofemoral pain
and 12 women (mean age 29.1 years, SD 5.0, range 24 –38) without
patellofemoral pain participated. Only female subjects were studied
because of potential biomechanical differences between sexes.
Methods. Patellar kinematics (kinematic magnetic resonance imaging)
and vastus muscle electromyographic (EMG) activity using indwelling
electrodes were measured during resisted knee extension. Measure-
ments of medial and lateral patellar displacement and tilt obtained
from magnetic resonance images were correlated with normalized
vastus lateralis:vastus medialis oblique muscle and vastus lateralis:vastus
medialis longus muscle EMG ratios at 45, 36, 27, 18, 9, and 0 degrees
of knee flexion using a stepwise regression procedure. Results. The
vastus lateralis:vastus medialis longus muscle EMG ratio contributed to
the prediction of lateral patellar displacement at 27 degrees of knee
flexion (r -.48), with increased vastus medialis longus muscle activity
being associated with greater lateral patellar displacement. A similar
inverse relationship was evident with lateral patellar tilt at 36, 27, 18,
and 9 degrees of knee flexion. Conclusion and Discussion. These
results suggest that increased motor unit activity of the vastus medialis
muscle appears to be associated with abnormal patellar kinematics in
women, but it is not necessarily a cause of abnormal patellar kinemat-
ics. [Powers CM. Patellar kinematics, part I: the influence of vastus
muscle activity in subjects with and without patellofemoral pain. Phys
Ther. 2000;80:956 –964.]
Key Words: Electromyography, Magnetic resonance imaging, Patellar kinematics, Patellofemoral joint,
Quadriceps femoris muscle.
Christopher M Powers
956 Physical Therapy . Volume 80 . Number 10 . October 2000
2. P
atellar instability is commonly thought to be importantly, whether it is predictive of abnormal patello-
the result of unequal activity of the various femoral joint function.
components of the quadriceps femoris mus-
cle.1–5 More specifically, lateral patellar sublux- With the advent of kinematic magnetic resonance imag-
ation has been attributed to reduced motor unit activity ing (KMRI), quantification of patellar kinematics
of the vastus medialis muscle.6 – 8 Lieb and Perry9 sepa- throughout an arc of resisted knee extension is possi-
rated the vastus medialis muscle of cadavers into 2 ble.16,17 This diagnostic technique has a distinct advan-
functional components based on fiber orientation, with tage over imaging procedures that do not allow for knee
the proximal longitudinal fibers being termed the vastus movement because contributions of the extensor mech-
medialis longus muscle (VML) and the distal oblique anism to patellofemoral joint kinematics can be
fibers being designated the vastus medialis oblique mus- assessed.18
cle (VMO). As a result of its more horizontal fiber
orientation, they considered the VMO to be the primary The purpose of this investigation was to assess the
medial stabilizer of the patella. This premise has formed influence of vastus muscle activity (as determined
the theoretical basis for exercises for patellofemoral pain through EMG) on patellar tracking patterns in subjects
(PFP) because improving VMO force is thought by some with and without PFP. I hypothesized that lateral dis-
authors3,10,11 to be essential in overcoming the lateral placement and lateral tilting of the patella would be
pull of the much larger vastus lateralis muscle (VL). associated decreased vastus medialis muscle activity rel-
ative to the VL.
Despite the large emphasis on the VMO in the treatment
of PFP, assessment of VMO force production in vivo is Method
not possible. In lieu of this limitation, electromyography
(EMG) has been used to establish the activity patterns of Subjects
the vastus muscles with the rationale that decreased Twenty-three women with a diagnosis of PFP and 12
activity of the VMO relative to the VL is indicative of women without PFP participated in this study. Only
compromised medial patellar stability. Numerous female subjects were studied because of potential biome-
researchers7,8,12–15 have compared the EMG activity of chanical differences between sexes. Both groups were
the VMO with that of the VL. There is no general similar in age, height, and weight (Tab. 1). Age, height,
consensus, however, as to whether reduced motor unit and weight were found to be normally distributed within
activity of the VMO exists in people with PFP or, more each group and when data from both groups were
CM Powers, PT, PhD, is Director, Musculoskeletal Biomechanics Research Laboratory, and Assistant Professor, Department of Biokinesiology and
Physical Therapy, University of Southern California, 1540 E Alcazar St, CHP-155, Los Angeles, CA 90033 (USA) (powers@hsc.usc.edu).
Dr Powers provided concept/research design, writing, data collection and analysis, subjects, project management, and fund procurement.
This study was approved for human subjects by the Los Amigos Research and Education Institute Inc of Rancho Los Amigos Medical Center,
Downey, Calif.
This study was partially funded by a grant from the Foundation for Physical Therapy.
This article was submitted November 5, 1998, and was accepted May 29, 2000.
Physical Therapy . Volume 80 . Number 10 . October 2000 Powers . 957
3. Table 1.
Subject Characteristics
Subjects With Patellofemoral Pain Subjects Without Patellofemoral Pain
(n 23) (n 12)
X SD Range X SD Range Pa
Age (y) 26.8 8.5 14–46 29.1 5.0 24–38 .38
Height (cm) 165.6 7.2 151.3–177.1 168.4 8.0 153.6–183.5 .29
Weight (kg) 62.2 9.1 42.0–82.7 61.2 8.0 48.7–74.1 .76
a
Probability values based on independent t tests.
combined. No attempt was made to match each subject and a 7-mm section thickness with an interslice spacing
specifically for age, height, and weight, as there is no of 0.5 mm.16 Acquisition time was 6 seconds to obtain 6
evidence in the literature to suggest that individuals of images (ie, 1 image per second).
different ages, heights, and weights will demonstrate
differences in patellar kinematics. All imaging was performed using a specially constructed,
nonferromagnetic positioning device† that permitted
The subjects with PFP were patients of the Southern bilateral knee extension against resistance (in the prone
California Orthopaedic Institute who were deemed to be position) from 45 degrees of flexion to full extension
appropriate candidates by the treating physician. Prior (Fig. 1). The device was designed to allow uninhibited
to participation, all subjects with PFP were screened to movement of the patellofemoral joint and natural rota-
rule out ligamentous instability, internal derangement, tion of the lower extremities. I believe that these design
and patellar tendinitis. Each subject’s pain originated features are important because patellar tracking may be
from the patellofemoral joint, and only patients with influenced by tibial rotation.20
histories relating to nontraumatic events were accepted.
In addition, pain had to be readily reproducible with at Resistance was provided through a pulley system with a
least 2 of the following activities: stair ascent or descent, constant 30.5-cm lever arm. The design of the device was
squatting, kneeling, prolonged sitting, or isometric such that the application of the force was always perpen-
quadriceps femoris muscle contraction.2,19 Subjects were dicular to the tibia to ensure a constant (isotonic) torque
excluded from the study if they reported previous knee throughout the entire range of motion.16 Weights con-
surgery or a history compatible with acute traumatic structed of nonmagnetic, 316L series stainless steel‡
patellar dislocation. supplied the resistive force for this maneuver. These
plates were placed on a movable carriage that was
Individuals comprising the comparison group were attached to the pulley apparatus (Fig. 1).
recruited by word of mouth and were either employees
of Rancho Los Amigos Medical Center (Downey, Calif) Electromyography. Indwelling, fine-wire electrodes
or students from the University of Southern California. were used to record the intensity of vastus muscle
Subjects had to have no history or diagnosis of knee activity. The electrodes were bipolar in configuration
pathology or trauma and they had to be free of any and were made of nylon-insulated 50- m wire (nickel-
current knee pain. In addition, these subjects did not chromium alloy). The wires were passed through the
report pain with any of the activities listed earlier. cannula of a 25-gauge hypodermic needle with the distal
ends staggered and folded over the needle tip as
Instrumentation described by Basmajian and DeLuca.21
Kinematic magnetic resonance imaging. Kinematic mag- After insertion into the muscle, the wires were secured to
netic resonance imaging (KMRI) of the patellofemoral a plate that also contained a ground electrode and the
joint was assessed with the transmit and receive quadra- signals were fed directly into a differential amplifier/FM
ture body coil of a 1.5T magnetic resonance system* radio transmitter unit.§ The differential amplifier had a
using a fast-spoiled GRASS pulse sequence.16 Axial-plane common mode rejection ratio of 60 dB. The EMG
imaging was performed using the following parameters: signals were then telemetered from the transmitter to
time to repeat 6.5 milliseconds, time to echo 2.1 the receiver unit where the signal was band-pass filtered
milliseconds, number of excitations 1.0, matrix size
256 128, field of view 38 cm, flip angle 30 degrees,
†
Captain Plastic, PO Box 27493, Seattle, WA 98125.
‡
Esco Corp, 6415 E Corvette St, Los Angeles, CA 90242.
§
* General Electric Medical Systems, 3200 N Grandview Ave, Waukesha, WI 54601. Biosentry Telemetry Inc, 20270 Earl St, Torrance, CA 90503.
958 . Powers Physical Therapy . Volume 80 . Number 10 . October 2000
4. imaging at 45, 36, 27, 18, 9, and 0 degrees of knee
flexion. Approximation of this rate was made by the
principal investigator (CMP) with the use of a stopwatch.
Once the subject was able to reproduce the desired rate
of motion in a smooth and even manner, imaging
commenced. Subjects were instructed to initiate exten-
sion upon verbal command and continue until full
extension had been reached. Imaging was done at 3
different image planes to assess the entire excursion of
the patella in relation to the trochlear groove (ie, 3 slices
were obtained for each angle of knee flexion). These
procedures were repeated if the rate of knee extension
was too fast or too slow, or not performed in a smooth
manner. In addition, assessment was repeated if 6 ade-
Figure 1.
Subject set-up on the nonferromagnetic positioning device used for
quate images were not obtained. An adequate image was
imaging. A pulley system consisting of a one foot lever arm (back- one in which the medial and lateral borders of the
ground) and a movable carriage (foreground) allowed resisted knee midsection of the patella, the trochlear groove, and the
extension from 45 degrees to full extension. This device was designed to posterior femoral condyles were well defined. Visualiza-
permit uninhibited movement of the patella and natural rotation of the tion of these landmarks was necessary for subsequent
lower extremity. Velcro straps were used to secure the subject’s thigh
and tibia to the apparatus. Reprinted by permission of Lippincott
analysis.
Williams & Wilkins from Powers CM, Shellock FG, Beering TV, et al.
Effect of bracing on patellar kinematics in patients with patellofemoral Electromyography. Following KMRI, all subjects under-
joint pain. Med Sci Sports Exerc. 1999;31:1714 –1720. went EMG analysis at the Pathokinesiology Laboratory,
Rancho Los Amigos Medical Center. This analysis typi-
(150 –1,000 Hz) and amplified to a gain of 1,000. The cally occurred within 24 hours of the KMRI evaluation.
raw signal was sampled and digitized by a DEC 11/23
data acquisition computer. Each analog channel was Sterilized, fine-wire electrodes were inserted into the
sampled at 2,500 Hz. mid-belly of the VMO, VML, and VL, with electrode
placement being confirmed by mild electrical stimula-
Procedure tion. To allow for comparison of EMG intensity between
This study involved 2 different testing sessions: KMRI to subjects and muscles and to control for the variability of
determine patellar kinematics and EMG evaluation to electrode placement, EMG data were normalized to the
assess the vastus muscle activity pattern. The EMG and EMG data acquired during a maximal isometric knee
KMRI data could not be collected simultaneously in our extension effort. This was done on a LIDO dynamome-
study due to magnetic interference. Prior to testing, all ter** with the subject seated and the knee flexed to 60
procedures were explained to each subject and written degrees. This position was used because women without
informed consent was obtained. musculoskeletal impairment are thought to generate the
greatest extensor torque in this position and because this
Kinematic magnetic resonance imaging. All imaging was position is supposed to provide greater patellar stabili-
performed at Tower Imaging Center in west Los Ange- zation within the trochlear groove.2,19 It would appear,
les, Calif. Subjects were placed prone on the position- therefore, that positioning subjects in 60 degrees of knee
ing device with care taken to allow for natural lower- flexion would minimize quadriceps femoris muscle inhi-
extremity rotation. After this position was achieved, bition resulting from the pain associated with patellar
Velcro straps# were used to secure the subjects’ thigh instability.
and tibia to the positioning device. Resistance on the
device was then set at 15% of body weight. Vastus muscle activity then was recorded during active
knee extension using the positioning device described
After familiarization with the knee extension apparatus, previously for the KMRI. Procedures for subject position-
subjects were instructed to practice extending their ing, setting of the device resistance, and familiarization
knees at a rate of approximately 9°/s. This rate ensured practice were identical to those reported earlier. To
6 evenly spaced images throughout the 45-degree arc of ensure the same rate of knee extension during KMRI,
motion (including the 45° position) and permitted signals from an electric goniometer positioned at the
axis of rotation of the knee were fed into an oscilloscope
Digital Equipment Corp, 146 Main St, Maynard, MA 01754-2571.
#
Velcro USA Inc, PO Box 5218, 406 Brown Ave, Manchester, NH 03108. ** Loredan Biomedical Corp, PO Box 1154, Davis, CA 95617.
Physical Therapy . Volume 80 . Number 10 . October 2000 Powers . 959
5. Figure 4.
Method used to assess patellar tilt. Patellar tilt was defined as the angle
formed by lines joining the maximum width of the patella (AB) and the
posterior femoral condyles (BC). All tilt measurements were reported in
degrees. Reprinted by permission of Lippincott Williams & Wilkins from
Figure 2. Powers CM, Shellock FG, Beering TV, et al. Effect of bracing on patellar
Experimental set-up used to assess vastus muscle activity using the kinematics in patients with patellofemoral joint pain. Med Sci Sports
magnetic resonance imaging positioning device. Subject positioning Exerc. 1999;31:1714 –1720.
and resistance were the same as reported for kinematic magnetic
resonance imaging (KMRI). In order to ensure the same rate of knee
extension during the KMRI assessment, electrical signals from an electric Following the knee extension trials, the maximal isomet-
goniometer positioned at the axis of rotation of the knee were fed into an ric muscle test on the LIDO dynamometer was repeated,
oscilloscope to provide visual feedback (background).
with the maximal EMG activity being recorded. This was
done in an effort to ensure that the intramuscular
electrodes had not been displaced during the testing
procedure. At no time during the course of this study
was electrode displacement observed.
Data Management
Kinematic magnetic resonance imaging. Prior to analy-
sis, all images were screened to ascertain the midsection
of the patella (maximum patellar width) at each angle of
knee flexion. Once this was determined, measurements
for these images were obtained. Only images containing
a midpatella slice were analyzed.
To accurately assess patellofemoral joint relationships at
the various degrees of knee flexion, measures that were
independent of the shape of the patella and the anterior
Figure 3. femoral condyles were used.16 This was done to avoid
Method used to measure medial and lateral displacement using the
bisect offset measurement. This was determined by drawing a line measurement variability resulting from the continually
connecting the posterior femoral condyles (AB) and then projecting a changing contour of these structures when viewed at
perpendicular line anteriorly through the deepest portion of the trochlear different angles of knee flexion and to allow assessment
groove (CD) to a point where it bisected the patellar width line (EF) (left). of patellar orientation when the intercondylar groove
To obtain data when the trochlear groove was flattened, the perpendic-
ular line was projected anteriorly from the bisection of the posterior
was not well visualized. All measurements were made
condylar line (right). The bisect offset was reported as the percentage of with a custom-made, computer-assisted program and
patellar width lateral to the midline. Reprinted by permission of Lippin- included assessment of medial and lateral patellar dis-
cott Williams & Wilkins from Powers CM, Shellock FG, Beering TV, et al. placement, medial and lateral patellar tilt, and the sulcus
Effect of bracing on patellar kinematics in patients with patellofemoral angle.
joint pain. Med Sci Sports Exerc. 1999;31:1714 –1720.
Medial and lateral patellar displacement were deter-
mined by the “bisect offset” measurement as described
to provide visual feedback (Fig. 2). Once the requested by Stanford et al22 and modified by Brossmann et al.23
rate of knee extension could be consistently achieved, 6 The bisect offset was measured by drawing a line con-
seconds of EMG activity was recorded while performing necting the posterior femoral condyles and then project-
this maneuver. Data were collected during 5 trials. ing a perpendicular line anteriorly through the deepest
point (apex) of the trochlear groove (Fig. 3). This line
960 . Powers Physical Therapy . Volume 80 . Number 10 . October 2000
6. intersected with the patellar width line, which connected Table 2.
Electromyography Trial Ratio Reliability: Intraclass Correlation
the widest points of the patella. The perpendicular line
Coefficients (ICC 1)25 (Averaged Across All Angles of Knee Flexion)a
was projected anteriorly from the bisection of the poste-
rior condylar line to obtain data when the trochlear
No. of Averaged
groove was flattened (Fig. 3).16 All bisect offset data Measurements VL:VMO VL:VML
represented the extent of the patella lying lateral to the
projected perpendicular line and were expressed as a 1 .47 .54
percentage of patellar width. 2 .48 .62
3 .61 .64
4 .62 .61
Medial and lateral patellar tilt were measured using a 5 .59 .63
modification of the technique described by Sasaki and a
VL vastus lateralis muscle, VMO vastus medialis oblique muscle,
Yagi.24 The patellar tilt angle was reported as the angle VML vastus medialis longus muscle.
formed by the lines joining the maximum width of the
patella and the line joining the posterior femoral con-
dyles (Fig. 4). All tilt measurements were reported in
Reliability of the EMG measurements (VL:VMO and
degrees.
VL:VML ratios) and MRI measurements (bisect offset
and patellar tilt) was assessed using ICCs. Multiple
Electromyography. Digitally acquired EMG data were
one-way analyses of variance (ANOVAs) for repeated
full-wave rectified and integrated over 0.25-second inter-
measures were used to compare EMG ratios between
vals. Intensities were reported as a percentage of the
sessions at each designated angle of knee flexion. The
EMG data collected during the maximum isometric
mean squares between subjects and the mean squares
muscle test.
within subjects were substituted into the ICC 1 equa-
tion described by Bartko.25 This analysis was repeated for
Intensity of VL, VMO, and VML contraction was assessed
each measurement to obtain correlation coefficients for
at points in the range of motion that corresponded to
each of the number of averaged values (ie, ICCs were
the angular position at which the magnetic resonance
calculated for the data obtained by averaging 2 measure-
images were obtained. These data were further analyzed
ments for both sessions and were compared with ICCs
to obtain VL:VMO and VL:VML ratios.
calculated for data obtained by averaging 3, 4, and 5
measurements). I determined that averaging data
Reliability of KMRI and EMG data. Because MRI and
obtained from 3 EMG trials produced the most consis-
EMG data were not collected simultaneously, I believed
tent results (Tab. 2). Overall, moderate reliability in
that it was particularly important to assess reliability of
obtaining the VL:VMO and VL:VML ratios was evident
these measures in order to compare data between testing
across all angles of knee flexion (ICC values of .61 and
sessions. In addition, determination of the number of
.64, respectively).
trials to be averaged for consistent data was necessary. To
assess the reproducibility of the measurements, 7 sub-
To determine whether EMG ratios varied between
jects without PFP underwent repeated testing. All repeat
groups or angles of knee flexion, a 2 6 (group
testing took place within 24 hours of the initial testing
angle) ANOVA for repeated measures on one variable
session, using the same procedures outlined earlier. The
(angle) was performed. This analysis was performed for
day-to-day reliability of KMRI data, assessed using the
each EMG ratio. Main effects were reported if there were
procedures and measurements described earlier, was
no interactions. If an interaction was found, the individ-
previously reported to have intraclass correlation coeffi-
ual main effects were analyzed separately.
cients (ICCs) ranging from .79 to .85.16 Intraobserver
measurement error was determined to be 3.4% for the
A regression analysis was performed to determine
bisect offset measurement and 2.9 degrees for patellar tilt.
whether the VL:VMO ratio or the VL:VML ratio was
predictive of patellar tilt or displacement. This analysis
Data Analysis
was repeated for patellar tilt and displacement at each
All statistical procedures were performed with BMDP
angle of knee flexion. Because the presence of PFP
statistical software.†† Prior to analysis, descriptive statis-
could potentially influence the relationship between the
tics were calculated for all variables, and normality of
variables, I deemed it necessary to account for this factor
distribution was assessed using the Wilk-Shapiro test.
by including the grouping variable in all regression
Based on the analysis of distribution, all data were
equations. This type of analysis was used in an effort to
analyzed using parametric tests. All significance levels
ensure that an overall relationship between the EMG
were set at P .05.
ratios and patellar kinematics could be ascertained
regardless of a diagnosis of PFP.
††
SPSS Inc, 444 N Michigan Ave, Chicago, IL 60611.
Physical Therapy . Volume 80 . Number 10 . October 2000 Powers . 961
7. Figure 5. Figure 6.
Comparison of the vastus lateralis:vastus medialis oblique muscle (VL: Comparison of the vastus lateralis:vastus medialis longus muscle (VL:
VMO) electromyographic ratio between the subjects with patellofemoral VML) electromyographic ratio between the subjects with patellofemoral
pain (PFP) and the subjects without PFP from 45 to 0 degrees of knee pain (PFP) and the subjects without PFP from 45 to 0 degrees of knee
flexion. Error bars indicate one standard deviation. flexion. Error bars indicate one standard deviation.
Table 3. and the subjects without PFP (no group effect or inter-
Pearson Correlation Coefficients for Bisect Offset (After Controlling for action) (Fig. 6). When averaged across all angles of knee
Group) flexion, the mean VL:VML ratio for the subjects with PFP
was .78 compared with .94 for the subjects without PFP.
Knee Flexion Angle (°)
Independent
Variablea 45 36 27 18 9 0 Patellar Kinematics
For results and discussion concerning the comparison of
VL:VMO ratio .03 .10 .04 .14 .23 .13
VL:VML ratio .02 .22 .48b .25 .31 .30
patellar kinematic data between groups, the reader is
referred to the article by Powers titled “Patellar Kinemat-
a
VL vastus lateralis muscle, VMO vastus medialis oblique muscle, ics, Part II: The Influence of the Depth of the Trochlear
VML vastus medialis longus muscle.
b
Significant predictor of bisect offset (P .05). Groove in Subjects With and Without Patellofemoral
Pain” in this issue.
Table 4. Relationship Between EMG Ratios and Patellar Kinematics
Pearson Correlation Coefficients for Patellar Tilt (After Controlling for
In general, the Pearson correlation coefficients ranged
Group)
from .48 to .37 for both bisect offset (Tab. 3) and
patellar tilt (Tab. 4). The VL:VML ratio was found to be
Knee Flexion Angle (°)
Independent the only predictor of patellar tilt at 36 degrees (r .40,
Variablea 45 36 27 18 9 0 R2 .16), 27 degrees (r .48, R2 .24; Fig. 7), 18
VL:VMO ratio .06 .14 .17 .02 .22 .13 degrees (r .42, R2 .18), and 9 degrees of flexion
2
VL:VML ratio .23 .40b .48b .42b .45b .37 (r .45, R .20). Similarly, the only EMG predictor of
a
VL vastus lateralis muscle, VMO vastus medialis oblique muscle,
the bisect offset measurement was the VL:VML ratio at
VML vastus medialis longus muscle. 27 degrees of flexion (r .48), which accounted for
b
Significant predictor of patellar tilt (P .05). 24% (R2) of the variability (Fig. 8).
Discussion
Results The EMG data obtained from the comparison group
were relatively consistent, with the VL:VMO and
Electromyography VL:VML ratios averaging 1.17 and 0.94, respectively,
There was no difference in the VL:VMO ratio between across all knee flexion angles. This finding is consistent
the subjects with PFP and the subjects without PFP (no with those of previous studies7,19,26 in which the activity
group effect or interaction) (Fig. 5). When averaged of the VMO relative to the VL in subjects without pain is
across all knee flexion angles, the mean VL:VMO ratio approximately 1:1. The EMG data obtained from the
was 1.85 for the subjects with PFP compared with 1.17 for subjects with PFP, however, showed much greater vari-
the subjects without PFP. Similarly, there was no differ- ability. The lack of statistical significance in the VL:VMO
ence in the VL:VML ratio between the subjects with PFP and VL:VML EMG ratios between groups may have been
962 . Powers Physical Therapy . Volume 80 . Number 10 . October 2000
8. Figure 7. Figure 8.
Relationship between the vastus lateralis:vastus medialis longus muscle Relationship between the vastus lateralis:vastus medialis longus muscle
(VL:VML) electromyographic (EMG) ratio and patellar tilt for the subjects (VL:VML) electromyographic (EMG) ratio and bisect offset (percentage
with patellofemoral pain (PFP) and the subjects without PFP at 27 of patella lateral to midline) for the subjects with patellofemoral pain
degrees of knee flexion (r .48; F 10.9; df 2,33; P .05). (PFP) and the subjects without PFP at 27 degrees of knee flexion
(r .48; F 4.6; df 2,33; P .05).
the result of a type II statistical error due to the high
variability of the subjects with PFP throughout the range flexion. In contrast, the VL:VML ratio was a predictor of
of motion, variability that was 2 to 3 times greater than patellar tilt at 36, 27, 18, and 9 degrees of flexion, as well
for the comparison group. A post hoc power analysis as of bisect offset at 27 degrees of flexion. All correla-
revealed that the number of subjects in each group was tions involving the VL:VML ratios were negative, how-
adequate to test the null hypothesis (no group effect), as ever, indicating an inverse relationship between EMG
the statistical power to detect a 60% change was found to activity and patellar motion. For example, subjects with
be greater than 0.90. lower VL:VML ratios (increased VML activity relative to
the VL) were found to have greater degrees of lateral
The EMG ratio data obtained from the subjects with PFP patellar displacement and tilt, whereas subjects with
suggests that the motor unit activity of the VML and that higher VL:VML ratios (decreased VML activity relative to
of the VMO were different during the knee extension the VL) had less severe abnormalities. These results do
maneuver. This difference was reflected by the observa- not support the original hypothesis that decreased activ-
tion that the VL:VML ratio remained consistent ity of the vastus medialis muscle is a cause of patellar
throughout knee extension, whereas the activity of the malalignment. To the contrary, increased motor unit
VMO (with respect to the VL) became more pro- activity of the vastus medialis muscle appeared to be in
nounced at terminal knee extension. This pattern of response to meeting the increased demand of providing
EMG activity may be related to the fact that the VML is patellar stability. The fact that VML activity was increas-
primarily a knee extensor (as a result of a more longitu- ing as the patella demonstrated greater malalignment
dinal fiber orientation), whereas the VMO is much less was suggestive of an active, but inadequate, effort to
efficient in this role because of its oblique fiber arrange- center the patella within the trochlear groove.
ment.9 Because knee extension was the primary move-
ment performed, I believe it is logical that the VML A premise behind the use of EMG biofeedback to
would be recruited more readily to accomplish this task. evaluate VMO activity is, in my opinion, that diminished
However, the fact that the EMG activity of the VMO VMO EMG activity is indicative of abnormal patello-
became more pronounced at the end-range of extension femoral joint function. The finding that VMO activity
emphasizes the function of this structure in providing could not be shown to be predictive of patellar kinemat-
medial patellar stability, as it is at this point in the range ics illustrates the limitations associated with the use of
of movement where maximum lateral displacement typ- EMG ratios as indictors of patellofemoral joint pathome-
ically occurs.2 Differences in the observed EMG activity chanics. Although normalized EMG data are useful in
of these 2 portions of the vastus medialis muscle com- measuring relative levels of activity between muscles
pared with the VL suggests that this muscle may have (ie, intensity of effort), such information is not indicative
varied roles with respect to patellofemoral joint of muscular strength or “muscular balance,” as is com-
mechanics. monly assumed.27 Without considering factors such as
muscle length, cross-sectional area, and angle of inser-
Regression analysis of the EMG and KMRI variables tion of the various muscle fibers, it would appear that
revealed that the VL:VMO EMG ratio was not predictive EMG has limited use in determining the effective muscle
of patellar motion at any point in the range of knee force.27
Physical Therapy . Volume 80 . Number 10 . October 2000 Powers . 963
9. The correlation coefficients in this study had R2 values 7 Souza DR, Gross MT. Comparison of vastus medialis obliquus:vastus
that were small (ranging from .16 to .24), indicating that lateralis muscle integrated electromyographic ratios between healthy
subjects and patients with patellofemoral pain. Phys Ther. 1991;71:
only a small percentage of the variance in patellar 310 –316.
kinematics could be explained by the EMG ratios.
8 Wise HH, Fiebert IM, Kates JL. EMG biofeedback as treatment for
Although the inherent variability in EMG data combined
patellofemoral pain syndrome. J Orthop Sports Phys Ther. 1984;6:95–103.
with inability to precisely control the speed of knee
extension could have contributed to the low r values, 9 Lieb FJ, Perry J. Quadriceps function: an anatomical and mechanical
study using amputated limbs. J Bone Joint Surg Am. 1968;50:1535–1548.
further research should be directed toward identifying
additional factors that can improve the predictability of 10 LeVeau BF, Rogers C. Selective training of the vastus medialis
muscle using EMG biofeedback. Phys Ther. 1980;60:1410 –1415.
patellofemoral joint kinematics.
11 McConnell J. The management of chondromalacia patellae: a long
As a result of the limitations imposed by the size of the term solution. Australian Journal of Physiotherapy. 1986;32:215–223.
MRI bore, the loading condition used in this study 12 Boucher JP, King MA, Lefebvre R, Pepin A. Quadriceps femoris
(non–weight bearing) was not consistent with the load- muscle activity in patellofemoral pain syndrome. Am J Sports Med.
1992;20:527–532.
ing condition that would be evident with running or
climbing stairs or with our inability to take all of our 13 MacIntyre DL, Robertson DG. Quadriceps muscle activity in women
measurements simultaneously (EMG and KMRI). runners with and without patellofemoral pain syndrome. Arch Phys Med
Rehabil. 1992;73:10 –14.
Although there have been no studies that have exam-
ined the differences in patellar tracking patterns 14 Moller BN, Krebs B, Tidemand-Dal C, Aaris K. Isometric contrac-
between weight-bearing and non–weight-bearing activi- tions in the patellofemoral pain syndrome: an electromyographic
study. Arch Orthop Trauma Surg. 1986;105:24 –27.
ties, an argument can be made that the non–weight-
bearing knee extension maneuver does not simulate 15 Wild JJ Jr, Franklin TD, Woods GW. Patellar pain and quadriceps
rehabilitation: an EMG study. Am J Sports Med. 1982;10:12–15.
most functional tasks. Therefore, care must be taken in
interpreting the results of this study until differences in 16 Powers CM, Shellock FG, Pfaff M. Quantification of patellar track-
patellar kinematics can be established between various ing using kinematic MRI. J Magn Reson Imaging. 1998;8:724 –732.
loading conditions. 17 Shellock FG, Mink JH, Deutsch AL, Pressman BD. Kinematic
magnetic resonance imaging of the joints: techniques and clinical
applications. J Magn Reson Imaging. 1991;7:104 –135.
Conclusion
The results of this study showed an inverse relationship 18 Shellock FG, Mink JH, Deutsch AL, Foo TK. Kinematic MR imaging
between the VL:VML EMG ratio and lateral patellar tilt of the patellofemoral joint: comparison of passive positioning and
active movement techniques. Radiology. 1992;184:574 –577.
at 36, 27, 18, and 9 degrees of knee flexion and lateral
patellar displacement at 27 degrees of knee flexion. 19 Powers CM, Landel R, Perry J. Timing and intensity of vastus muscle
activity during functional activities in subjects with and without patel-
Although increased activity of the vastus medialis muscle lofemoral pain. Phys Ther. 1996;76:946 –955.
relative to the VL may be a response to patellar malalign-
20 van Kampen A, Huiskes R. The three-dimensional tracking pattern
ment, decreased activity does not appear to be associated
of the human patella. J Orthop Res. 1990;8:372–382.
with abnormal patellar tracking. The premise that lateral
patellar displacement and tilt are the result of dimin- 21 Basmajian JV, DeLuca CJ. Muscles Alive: Their Functions Revealed by
Electromyography. 5th ed. Baltimore, Md: Williams & Wilkins; 1985.
ished activity of the vastus medialis muscle is not sup-
ported by this study. 22 Stanford W, Phelan J, Kathol MH, et al. Patellofemoral joint
motion: evaluation by ultrafast computed tomography. Skeletal Radiol.
1988;17:487– 492.
References
1 Fox TA. Dysplasia of the quadriceps mechanism: hypoplasia of the 23 Brossmann J, Muhle C, Schroder C, et al. Patellar tracking patterns
vastus medialis muscle as related to the hypermobile patella syndrome. during active and passive knee extension: evaluation with motion-
Surg Clin North Am. 1975;55:199 –226. triggered cine MR imaging. Radiology. 1993;187:205–212.
2 Fulkerson JP, Hungerford DS. Disorders of the Patellofemoral Joint. 2nd 24 Sasaki T, Yagi T. Subluxation of the patella: investigation by
ed. Baltimore, Md: Williams & Wilkins; 1990. computerized tomography. Int Orthop. 1986;10:115–120.
3 Hanten WP, Schulthies SS. Exercise effect on electromyographic 25 Bartko JJ. On various intraclass correlation reliability coefficients.
activity of the vastus medialis oblique and vastus lateralis muscles. Phys Psychol Bull. 1976;83:762–765.
Ther. 1990;70:561–565. 26 Cerny K. Vastus medialis oblique/vastus lateralis muscle activity
4 Hughston JC. Subluxation of the patella. J Bone Joint Surg Am. ratios for selected exercises in persons with and without patellofemoral
1968;50:1003–1026. pain syndrome. Phys Ther. 1995;75:672– 683.
5 Paulos L, Rusche K, Johnson C, Noyes FR. Patellar malalignment: a 27 Portney L. Electromyography and nerve conduction tests.
treatment rationale. Phys Ther. 1980;60:1624 –1632. In: O’Sullivan SB, Schmitz TJ, eds. Physical Rehabilitation: Assessment and
Treatment. 2nd ed. Philadelphia, Pa: FA Davis Co; 1988:159 –194.
6 Mariani PP, Caruso I. An electromyographic investigation of sublux-
ation of the patella. J Bone Joint Surg Br. 1979;61:169 –171.
964 . Powers Physical Therapy . Volume 80 . Number 10 . October 2000