The document summarizes key aspects of human gait, including the gait cycle, phases of stance and swing, joint motions, muscle functions, shock absorption, energy conservation, and analysis methods. The gait cycle consists of stance and swing phases, with stance further divided into initial contact, loading response, mid stance, terminal stance, and preswing. Key motions include plantarflexion during loading response, dorsiflexion during single support, and plantarflexion at toe-off. Muscles like the quadriceps and hamstrings function to control knee motion and absorb shock during gait. Analysis methods examine motion, forces, electromyography, work, and energy expenditure to evaluate gait.
Discus throwing performances and medical classification of wheelchair athlete...Ciro Winckler
CHOW, J. W.; MINDOCK, L. A. Discus throwing performances and medical classification of wheelchair athletes. Medicine and Science in Sports and Exercise, v. 31, n. 9, p. 1272-1279, 1999.
Discus throwing performances and medical classification of wheelchair athlete...Ciro Winckler
CHOW, J. W.; MINDOCK, L. A. Discus throwing performances and medical classification of wheelchair athletes. Medicine and Science in Sports and Exercise, v. 31, n. 9, p. 1272-1279, 1999.
Crimson Publishers- The Effect of Medial Hamstring Weakness on Soft Tissue Lo...CrimsonPublishers-SBB
Anterior cruciate ligament (ACL) reconstructions are frequently performed in the United States of America. The medial hamstrings graft has been shown to produce lower rates of osteoarthritis (OA) than the patellar tendon graft. The goal of this study was to determine how altering medial hamstring strength during surgery affects soft tissue loading, and hence the joint’s proclivity towards OA. Muscle-actuated forward dynamic simulations of running were performed for normal muscle strength and decreased medial hamstring strength. The results show weakening the medial hamstrings caused an overall decrease in total hamstrings force by 7%, in total quadriceps force by 35%, and in cartilage contact force by 6%. This decreased force may be protective against long-term OA.
Comparison between Hamstring Lengthening Tendon and Hamstring Tendon Transfer...Service_supportAssignment
Cerebral Palsy (CP) is defined as a non-progressive brain lesion and has many disorders that may affect both movement and posture (Bobath 1991). Spastic cerebral palsy influence 70% of child population with CP and happen when white matter tracks damage between the cortex and the spinal cord. Moreover, a main problem for children with spastic CP is their feet and leg muscles, which might shorten or tighten around certain joints (Bjorklund 2006). C
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.
John Orchard
Adjunct Associate Professor, Sydney Medical School, University of Sydney.
-
Hamstrings are most susceptible to injury during the late stance phase of sprinting
Os resultados atuais indicaram que a ocorrência de lesões de isquiotibiais podem estar associadas a uma mudança hierárquica na distribuição da atividade metabólica dentro do complexo muscular do isquiotibial após o trabalho excêntrico em que o Semitendinoso provavelmente deveria tomar a parte principal, seguido pelo BÍceps Femural e Semimembranoso. Quando o BF aumenta sua contribuição e é ativado em uma extensão proporcionalmente maior, o risco de sofrer uma lesão do isquiotibial pode aumentar substancialmente.
Crimson Publishers- The Effect of Medial Hamstring Weakness on Soft Tissue Lo...CrimsonPublishers-SBB
Anterior cruciate ligament (ACL) reconstructions are frequently performed in the United States of America. The medial hamstrings graft has been shown to produce lower rates of osteoarthritis (OA) than the patellar tendon graft. The goal of this study was to determine how altering medial hamstring strength during surgery affects soft tissue loading, and hence the joint’s proclivity towards OA. Muscle-actuated forward dynamic simulations of running were performed for normal muscle strength and decreased medial hamstring strength. The results show weakening the medial hamstrings caused an overall decrease in total hamstrings force by 7%, in total quadriceps force by 35%, and in cartilage contact force by 6%. This decreased force may be protective against long-term OA.
Comparison between Hamstring Lengthening Tendon and Hamstring Tendon Transfer...Service_supportAssignment
Cerebral Palsy (CP) is defined as a non-progressive brain lesion and has many disorders that may affect both movement and posture (Bobath 1991). Spastic cerebral palsy influence 70% of child population with CP and happen when white matter tracks damage between the cortex and the spinal cord. Moreover, a main problem for children with spastic CP is their feet and leg muscles, which might shorten or tighten around certain joints (Bjorklund 2006). C
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.
John Orchard
Adjunct Associate Professor, Sydney Medical School, University of Sydney.
-
Hamstrings are most susceptible to injury during the late stance phase of sprinting
Os resultados atuais indicaram que a ocorrência de lesões de isquiotibiais podem estar associadas a uma mudança hierárquica na distribuição da atividade metabólica dentro do complexo muscular do isquiotibial após o trabalho excêntrico em que o Semitendinoso provavelmente deveria tomar a parte principal, seguido pelo BÍceps Femural e Semimembranoso. Quando o BF aumenta sua contribuição e é ativado em uma extensão proporcionalmente maior, o risco de sofrer uma lesão do isquiotibial pode aumentar substancialmente.
Real Estate Investing - How to run real estate compsSteve Liang
Real Estate comps - Fundamental knowledge in coming up with real estate valuation, including Fair market value (as is value) and after repair value (ARV).
For additional webinars: www.mlsdealfinder.com/education
www.fastCMA.com
www.mlsdealfinder.com
Gait_Biomechanics, Analysis and AbnormalitiesVivek Ramanandi
Biomechanics, Analysis, and Abnormalities in Gait. Oriented for Second-year students of Undergraduate Physiotherapy studies. Details of kinetic and kinematic analysis of gait.
Mechanics of the human hamstring muscles during sprintingFernando Farias
As peak musculotendon
force and strain for BF
LH
, ST, and SM occurred around the same time during terminal swing, it is suggested that this period in the
stride cycle may be when the biarticular hamstrings are at greatest injury risk. On this basis, hamstring injury prevention or rehabilitation
programs should preferentially target strengthening exercises that involve eccentric contractions performed with high loads at longer
musculotendon lengths.
Evaluation and Selection of Footware for the RunnerKevin Christie
Every athlete seeks out equipment to maximize his/her sport performance and minimize risk of injury. The two primary equipment variables in the runner’s tool box are running shoes and orthoses. Runners repeatedly subject their bodies to stresses that are equal to two to three times their body weight [1,2] for a huge number of cycles each time that they participate in their sport. Few runners are structurally ideal; this results in a range of compensations that contribute to inefficiencies and, potentially, injury. The purpose of this article is to educate clinicians regarding the basic evaluation of the patient to assess appropriate shoe wear and to recognize when over- the-counter or custom orthosis intervention is necessary. To do this effectively, a basic understanding of foot and ankle mechanics is essential.
International Journal of Computational Engineering Research(IJCER)ijceronline
International Journal of Computational Engineering Research(IJCER) is an intentional online Journal in English monthly publishing journal. This Journal publish original research work that contributes significantly to further the scientific knowledge in engineering and Technology.
Clin Sports Med 23 (2004) 531–544Biomechanics and developmen.docxbartholomeocoombs
Clin Sports Med 23 (2004) 531–544
Biomechanics and development of the elbow in
the young throwing athlete
Mark R. Hutchinson, MD*, Shawn Wynn, MD
Sports Medicine and Human Performance Center, Department of Orthopaedics,
University of Illinois at Chicago, 270 MSB, M/C 844, 835 South Wolcott, Chicago, IL 60612, USA
Biomechanics is a complex study of function and demands, including struc-
ture, motor power and acceleration, and angular forces and loads. Regarding the
elbow, the study of biomechanics includes: the flexion/extension motion;
pronation/supination motion; motor power and acceleration related to the biceps,
brachialis, triceps, brachioradialis, supinator, and pronator teres muscles; struc-
tural shapes and interactions of the distal humerus/proximal radius/proximal ulna;
and the forces related to a variety of demands, ranging from lifting to throwing.
The biomechanics of throwing is particularly complex, and relies not only on the
function of an isolated segment such as the elbow, but on the performance and
function of an entire kinetic chain of segments, including the foot-ground surface,
hip and core power and rotation, scapular mobility and stability, shoulder motion
and function, and hand and wrist position at ball release. The throwing motion
has been studied in youth, adolescent, and adult pitchers at all levels of com-
petition [1–14]; however, most biomechanical studies have been performed
on the skeletally mature athlete, with closed physes, with years of throwing
experience, and usually involved in competition at some level. There is less
biomechanical information available on the developing child at different stages of
growth, physeal age, and throwing levels.
The complexity of the study of biomechanics is magnified in the skeletally
immature athlete, due to the dynamic changes occurring during the devel-
opmental phases of youth. The forces and torques of throwing with open physes
have been associated with adaptational changes in the growing bone. As long
bones lengthen with physeal growth, moment arms are altered, changing any
force calculation. The maturing neuromuscular system is progressing with in-
0278-5919/04/$ – see front matter D 2004 Elsevier Inc. All rights reserved.
doi:10.1016/j.csm.2004.06.005
* Corresponding author.
E-mail address: [email protected] (M.R. Hutchinson).
M.R. Hutchinson, S. Wynn / Clin Sports Med 23 (2004) 531–544532
creased muscle mass and power. The pace of muscular maturation mirrors, but is
not directly correlated to, advancing maturity of the neurologic system that
controls coordination, proprioception, quickness, and control. Each segment of
the kinetic chain matures at a different pace, requiring the young thrower to make
continuous, subconscious modifications to account for the changes and still
successfully perform the task or demand. Indeed, although young throwers may
develop the normal sequence of throwing—including windup, cocking, accel-
er.
The neck - or cervical spinal column - is a collaborated network of nerves, bones, joints, as well as muscular tissues guided by the brain and also the spinal cord. It is created for toughness, stability, and nerve communication.
Groin discomfort as well as tenderness establishes from a selection of reasons including athletic and non-athletic injuries in addition to inner physiological elements.
Forgotten in the complexity of attempting to identify. Groin discomfort is tendon laxity. Damaged, torn ligaments that cause instability. Consequently, physicians experienced in ligament reference patterns should be gotten in touch with in cases of groin discomfort.
New York DNS & Physical Therapy center is the first one in the niche to practise Dynamic Neuromuscular Stabilization therapy method in New York. Its professional medicine employees have more than 18 years of experience.
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Factory Supply Best Quality Pmk Oil CAS 28578–16–7 PMK Powder in Stockrebeccabio
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Hot Selling Organic intermediates
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...
Gait analysis
1. Fundamentals
Gait cycle
Walking is the most convenient way to travel short distances. Free joint mobility
andappropriate muscle force increases walking efficiency. As the body moves
forward, one limbtypically provides support while the other limb is advanced in
preparation for its role asthe support limb. The gait cycle (GC) in its simplest form is
comprised of stance andswing phases. The stance phase further is subdivided into 3
segments, including initial double stance, single limb stance, and terminal double
limb stance.
Each double stance period accounts for 10% of the GC, while single stance
typicallyrepresents 40% (60% total). The 2 limbs typically do not share the load
equally duringdouble stance periods. The swing phase for this same limb is the
remaining 40% of the GC.Ipsilateral swing temporally corresponds to single stance
by the contralateral limb.Slight variations occur in the percentage of stance and
swing related to gait velocity.Duration of each aspect of stance decreases as walking
velocity increases. The transitionfrom walking to running is marked by elimination of
double support period( s).
A stride is the equivalent of a GC. The duration of a stride is the interval
betweensequential initial floor contacts by the same limb. A step is recognized as the
intervalbetween sequential floor contacts by ipsilateral and contralateral limbs. Two
steps makeup each GC, which is roughly symmetric in normal individuals.
GC phasing
A consistent sequence of motions is performed at each of the lower extremity joints
duringlocomotion. Each stride contains 8 relevant phases. Stance is comprised of 5
gait phases(ie, initial contact, loading response, mid stance, terminal stance,
preswing), with theremaining 3 phases occurring during swing.
The first 2 gait phases (0-10% GC) occur during initial double support. These
phasesinclude initial contact and the loading response. Initial contact often is
referred to asheel strike. While this term is appropriate in normal gait, many patients
achieve heelcontact later in the GC, if at all. The joint motion during this phase
allows the transferof weight onto the new stance phase leg while attenuating shock,
preserving gait velocity,and maintaining stability.
Swing phase by the contralateral limb corresponds with single support by the
ipsilaterallimb to support body weight in the sagittal and coronal planes. The first half
of singlesupport is termed mid stance (10-30% GC) and is involved with progression
of the bodycenter of mass over the support foot. This trend continues through
2. terminal stance (30-50%GC). This phase includes heel rise of the support foot and
terminates with contralateralfoot contact. [1] The final stance element, preswing
(50-60% GC), is related functionallymore to the swing phase that follows than to the
preceding stance phase events. Preswingbegins with terminal double support and
ends with toe-off of the ipsilateral limb.
Three unique phases characterize swing, including initial swing (60-73% GC), mid
swing(73-87% GC), and terminal swing (87-100% GC). The swing phase achieves
foot clearance andadvancing of the trailing limb.
Shock absorption
Shock absorption and energy conservation are important aspects of efficient gait.
Alteredjoint motion or absent muscle forces may increase joint reaction (contact)
forces and leadsubsequently to additional pathology. In early stance, nearly 60% of
one's body weight isloaded abruptly (less than 20 milliseconds) onto the ipsilateral
limb. This abrupt impactis attenuated at each of the lower extremity joints. Loading
response plantar flexion ispassive, substantially restrained by eccentric work of
pretibial muscles. The absorptivework by pretibial muscles delays forefoot contact
until late in the initial double supportperiod (7-8% GC).
At initial contact, external (ground reaction) forces applied to the contact foot
producea tendency toward knee flexion. Repositioning the knee (recurvatum)
increases kneemechanical stability, but at the cost of increased contact forces and
shock generation. Abalance between knee stability and shock absorption is achieved
by eccentric quadricepscontractions during loading response. The impact of loading
is minimized at the hip duringsingle support through hip abductor muscle contraction.
Energy conservation
Ambulation always is associated with metabolic costs. These costs are relatively
minor innormal adults performing free speed level walking. The self-selected walking
speed innormal adults closely matches the velocity that minimizes metabolic work.
This associationdoes not apply with gait pathology. Walking velocity, energy cost per
time, and energycost per distance are considerations when the patient is making
choices about walkingversus wheelchair mobility. Gait velocity typically decreases
with all neuromuscularpathology, and the reduction is related to the magnitude of the
pathology. Energy cost perunit of time may not change substantially, even with
severe involvement. Energy cost perunit of time is maintained by decreasing walking
velocity considerably. Energy cost perunit of time does not change markedly
following stroke, as compared to changes associatedwith aging; however, the energy
requirement per distance traveled is more than 3 timesnormal.
3. In this same population, wheelchair use cuts energy cost per distance in half
anddecreases cost per minute slightly, while preserving ambulation velocity. Similar
trendsare observed when examining various energy cost parameters in individuals
with spinal cordinjury, myelomeningocele, and increasing levels of amputation.
Energy cost to travel aprescribed distance increases (greater than 500% increase in
myelomeningocele withbilateral knee-ankle-foot orthoses), while oxygen cost per
minute is maintained bydecreasing walking velocity substantially. Often the critical
factor in selecting awheelchair for mobility is the energy requirement to traverse a
given distance. Mostindividuals self-select wheelchair mobility when cost per
distance exceeds 300% of normalvalues.
Methods Of Analysis
Most commonly, observational gait analysis is appropriate to characterize most
gaitpathologies. This approach is sufficient to note gross abnormalities in walking;
however,as walking complexity increases with organic pathology, objective analysis
becomesnecessary. The measurement systems that follow may be used individually
or collectively.The choice of method is based on clinical need, financial
considerations, and staffing atthe specific laboratory. Typically, motion and force
data are compiled simultaneously.
Motion
Instrumented motion analysis is a logical extension of observational gait analysis.
Thelevel of complexity involved in examining 3 joints each in 2 limbs is such that
fewindividuals can perform this task consistently. Measurement of human motion is
complex.Although most gait motion occurs in the sagittal plane, subtle rotations in
the otherplanes are clinically important. Analysis of motion in the sagittal plane is
confounded ifthat motion does not lie within the plane recorded by a single camera.
Rotations of thelimb are attenuated when the limb is internally or externally rotated
with respect to thecamera's plane. Three-dimensional motion analysis overcomes
this drawback.
Position of joint centers of rotation is estimated by markers placed on the skin
surface.Markers may be enhanced with passive markers or active light-emitting
diodes. Motion ofthe limb segments about the joint centers is recorded. At least 3
markers are required perlimb segment, and the position of each marker is recorded
using multiple cameras. Acalibration system is used to translate film to real-life
dimensions. Angular position ofeach segment may be determined for each percent
GC interval. Angular velocity andacceleration of the limb segments are obtained by
mathematical differentiation andsmoothing of limb position data. Motion data may be
combined with analysis of externalforces that act on the body.
4. An alternative technique to quantify motion is through use of electrogoniometers.
Atriaxial electrogoniometer has parallelograms and potentiometers for the
sagittal,coronal, and transverse planes. Electrogoniometers have several limitations,
but theadvantages of this method include convenience, ease of use, immediate
availability ofdata, and decreased expense when compared to video acquisition
techniques.
External forces
Calculation of joint moments (torque) and reaction forces between segments is
dependent onknowledge of the inertial components of the respective segments
(kinematics), bodysegment parameters, and external forces (kinetics) that affect the
body.
The magnitude and distribution of segment masses with respect to joint axes are
obtainedfrom cadaveric data or mathematical modeling of limb segments. The
contact (groundreaction) force applied at the distal segment is measured with a force
platform. This thinplate typically measures forces and moments in 3 dimensions
about the foot center ofpressure. Oscillation of the center of pressure may be
obtained in the same manner.
Moments and power
Integration of external force, center of pressure, unique body segment parameters,
andmotion data yields information on joint moments, joint power, and reaction forces
betweensegments using standard inverse dynamics techniques. The role of muscle
groups is inferredfrom the magnitude and sign of the moments and power at the
respective lower extremityjoints.
Dynamic electromyography
Muscle action can not be measured directly. The electromyogram (EMG) allows
indirectmeasurement of muscle activity. While single motor units are analyzed
routinely inclinical electrodiagnostic studies, this level of analysis is not performed as
part of aroutine gait analysis. A typical kinesiologic (dynamic) EMG represents the
activity ofmultiple motor units. The stochastic nature of the waveform confounds
simple analysis. Theinterference pattern recorded demonstrates both mechanisms
used to increase force outputand increase in the number and in the firing rate of
motor units.
Kinesiologic EMG contains important information about the timing and relative
intensity ofthe signal. Timing of the signal is straightforward. Muscle electrical activity
precedesforce generation by 40-120 milliseconds. This electromechanical delay is
5. associated withcompliance of the tendon at the onset of the EMG signal and
continued binding of actin-myosin crossbridges after termination of neural drive
related to delays in calciumresequestration.
Muscle force can not be estimated directly from the relative intensity of the signal.
Alinear relationship between EMG intensity and force output has been demonstrated
only inisometric contractions. Presentation of the quantified EMG may be in absolute
values(volts) or as a percentage of some normalized standard. Absolute voltage
does notrepresent clinically significant effort, as the electrode type and placement
substantiallyaffect signal magnitude. Normalization of muscle force output allows for
comparisonsacross muscles related to relative intensity. Gait EMG is expressed as a
percentage ofmaximum muscle contraction. Another technique is to express gait
EMG output as apercentage of gait maximum. This latter technique often must be
used in persons who cannot give a maximum voluntary contraction as a result of
decreased neural control. Adisadvantage is that peak values of weak and strong
muscle forces are defined as 100%.
Mechanical and metabolic efficiency
Mechanical work is the integral of force and velocity over time and the product of
jointpower and joint angular velocity. Mechanical work includes changes in the
mechanicalenergy of the body links; energy expenditure for mechanical movement
as the sum of thepositive values, including general center of mass energy changes
(external work); and changes in energy in the links in their movement relative to the
center of mass (internalwork).
Limb movement requires energy for muscle contraction. Mechanical work does not
equalmetabolic work in most instances. For example, mechanical work in a cyclic
motion withconstant average speed (without dissipation of energy) is equal to 0 since
the mechanicalenergy of the system has not changed (net 0 paradox). Metabolic
energy is required formechanical movement in this case. Energy metabolism is
another means of assessing the costof locomotion.
Energy expenditure may be determined by indirect calorimetry; however, in most
recentliterature, the O2 gas volume is reported without conversion to calories. The
volume ofoxygen consumption per body weight enables intersubject comparisons
and providesinformation on overall gait performance. Measurement of oxygen
consumption (metabolicenergy expenditure, VO2) generally is reported under
standard conditions of temperature (0° C), pressure (760 mm Hg), and dry conditions
(no water vapor). After 2-3 minutes ofexercise at a constant submaximal workload,
the rate of oxygen consumption reaches a levelsufficient to meet tissue demand for
oxygen. Parameters of physical work (cardiac output,heart rate, and respiratory rate)
reach a steady state. Energy consumption for theactivity at this time is reflected by
6. the rate of oxygen consumption. The O2 ratedetermines the intensity and duration
the exercise can be performed.
The rate of oxygen consumption is lowest at comfortable walking speeds in normal
adults(approximately one third of maximal aerobic capacity). Slight increases in
energy demandsare demonstrated at slower walking speeds; more substantial
increases are observed aswalking speed increases above the upper limits of normal.
Energy expenditure at eachwalking speed is not related to whether the patient is
male or female.
Ankle/Foot
The arcs of motion at the ankle are relatively small; yet, they are essential for
shockabsorption and progression of the body's center of mass. The ankle plantar
flexesthroughout loading response. Dorsiflexion begins with single support, as the
tibia rotatesforward over the fixed foot. Rapid plantar flexion begins at terminal
double support, withmaximum plantar flexor position of 30 ° attained at toe-off. This
action marks theinitiation of swing with dorsiflexion throughout the 3 swing-phase
segments.
Motor control at the ankle is understood most easily by commencing with swing
phase muscleactivity. Ankle dorsiflexors undergo brief eccentric contraction in
preswing, followedshortly by concentric contraction at the initiation of swing. This
contraction sequenceincreases mechanical efficiency and assures foot clearance.
Continued pretibial muscleisometric contraction through swing maintains this neutral
or slightly dorsiflexedposture. Subsequent loading response is notable for eccentric
contraction of the pretibialmuscles to control plantar flexion. A brief period of
co-contraction of ankle plantarflexors and dorsiflexors occurs at the transition from
initial stance double support tosingle support. This co-contraction interval increases
limb stability and may smooth thetransition from double to single support.
The orientation of the ankle and subtalar axes couples loading response dorsiflexion
witheversion. Both are attenuated by eccentric contraction of the ankle inverters
(ie,posterior tibialis). The plantar flexors begin force generation in single support,
withpeak activity late in terminal stance and preswing. The absorptive power
demonstrated insingle support is related to their role in restraining forward tibial
rotation. The timingof the triceps surae and perimalleolar muscles is similar to that of
the triceps surae(gastrocnemius plus soleus) that supplies most of the ankle plantar
flexor moment. Theankle then is plantar flexed vigorously during preswing.
The role of the calf muscles during preswing is controversial. Some authors describe
thisgait phase as push-off and suggest that muscle force by the ipsilateral calf
activelypropels the limb (and body center of mass) forward. An alternative model is
proposed byPerry, who states that the ipsilateral limb makes no active contribution to
the push-off.A third model is that active plantar flexion occurs at the ankle (positive
7. power) and doesnot serve to propel the body forward (no increase in walking
velocity), but, instead,functions as part of a closed kinetic chain to initiate knee and
hip flexion inpreparation for swing. This phenomenon may account for the increased
knee and hip powerrequirements in individuals who do not plantar flex actively in
preswing (ie, transtibialamputees).
Knee
Most knee motion is limited to the sagittal plane. The knee travels from slight
kneeflexion at initial contact (5 ° )to nearly 20 ° of flexion by the end of loading
response.The knee then extends( net flexion )through single support, with peak
stance phaseextension at 40% GC. At the conclusion of terminal stance and
preswing, knee flexion israpid, continuing through initial swing until peak knee flexion
(60 ° )occurs. This trendthen is reversed, with knee extension continuing through
terminal swing. Peak kneeextension occurs slightly before the end of the swing
phase, with minor flexion occurringin preparation for the subsequent stance phase.
The role of knee muscles, like that of ankle muscles, is understood most easily if
onebegins the analysis as the limb is in swing. In early swing phase, knee flexion
ispassive, resulting from active plantar flexion and hip flexion. During swing, motion
atthe hip changes from flexion to extension, with the knee passively extended as a
result ofthis change of hip joint direction. All 3 hamstrings (long head of the biceps
femoris,semimembranosus, semitendinosus) are active in mid-to-late swing to
decelerate theextending knee. The quadriceps is also active in terminal swing. This
co-contraction ofknee flexors and extensors prepares the limb for weight acceptance
that follows shortly.The quadriceps continues to be active in loading support. The
eccentric activity of thesemuscles attenuates the shock of weight acceptance, while
preventing excess knee flexion (<20 °). Both the hamstring and quadriceps muscles
are quiescent during mid stance whilethe knee is extended passively. The role of the
remaining quadriceps muscle is different.The rectus femoris is active electrically for
only a brief period corresponding withpreswing and initial swing. Although this
muscle crosses and extends the knee, its role ingait is to assist in flexion at the hip
as swing commences.
Hip
The gluteus maximus timing and relative intensity are similar to those demonstrated
by theother hip extensors (eg, hamstrings). During late swing, the gluteus maximus
functions toreverse hip flexion to extension. The gluteus maximus, generally the
body's singlestrongest muscle, resists external forces from loading response that
would flex the hipexcessively (eg, jack-knifing). A similar EMG profile and role are
demonstrated by theadductor magnus. Unlike in the knee and ankle, there is a
8. substantial amount of frontalplane motion at the hip. During single support, the mass
of the torso tends to rotate thebody about the stance limb hip joint axis (eg,
contralateral lateral tilt). Typically,this motion is limited by eccentric activity of the
gluteus medius, gluteus minimus, and,to a lesser extent, the tensor fascia lata.
Weakness
Insufficient force output by muscles may result from disuse, primary muscle disease,
orneurologic impairment. Substitution of impaired motor function frequently is
possible, andreduction of walking velocity further reduces demand on muscles.
Muscle force requirementsare trivial in normal individuals. Less than 25% of normal
strength (manual muscle testgrade 3+/ 5) is needed for locomotion. In cases of
disease, with decreased maximum muscleforce, functional reserve is lost.
Endurance is compromised, and community-levelambulation may not be possible.
Selective loss of muscles (or muscle groups) isdemonstrated by characteristic gait
patterns. In each case, orthotic management istargeted at preventing excessive
motion.
Uncompensated calf weakness results in diminished midstance control of the
forwardlyrotating tibia. Substitution for calf weakness is difficult. The increased
amount and rateof dorsiflexion increases the functional demands on the quadriceps
to maintain limbstability. Alternatively, tibial advancement is curtailed with resultant
genu recurvatum,decreasing the work of the quadriceps. Unfortunately, this gait
alteration frequentlyinitiates knee joint pathology. Other compensatory maneuvers
include reducing stepvelocity and step length.
The consequence of pretibial muscle weakness is increased plantar flexion. With
mildweakness, foot slap occurs during loading response. With more extensive
dorsiflexionweakness, foot drop and toe drag are observed during swing phase.
Compensation is achievedthrough circumduction of the ipsilateral limb, increased
ipsilateral knee plus hipflexion, and hip hiking of the contralateral limb. Each of these
tendencies assists inswing-phase toe clearance. Of these compensations,
circumduction is the most energyefficient and most commonly observed technique
for dorsiflexor insufficiency.
Quadriceps weakness diminishes knee control, and deficits in stance are most
pronounced.External forces tend to hyperflex the knee, and a variety of
compensations are employed topreserve stability in weight bearing. Compensations
begin prior to weight acceptance (lateswing) and continue through that limb's support
activity. Late swing hip flexion leads topassive knee extension through momentum
transfer. Stance phase increased knee flexion isattenuated by hip extension and
premature plantar flexion. Alternatively, externalrotation of the affected limb orients
the external force vector medial to the joint axis,minimizing the tendency toward
knee flexion.
9. Isolated hamstring weakness is an uncommon gait deficit. Isolated hip flexor
weakness isuncommon. Clinical presentation includes decreased walking velocity or
decreased hip rangeof motion. Reduction of hip extensor forces, which may be
secondary to paralysis or musclelengthening, leads to increases in anterior pelvic tilt
during stance.
Hip adductor weakness results in pelvic instability during stance. External forces
(ie,torso mass) lead to frontal plane rotation about the ipsilateral hip joint.
Thiscontralateral tilt normally is resisted by eccentric contraction of ipsilateral
hipabductors (ie, gluteus medius, minimus). Shifting the torso over the ipsilateral hip
jointin mid stance (Trendelenburg gait) minimizes the force required by the hip
abductors. Thisgait pattern, which limits contact forces between femur and
acetabulum, also is observedin hip joint pathology.
Spasticity
Spasticity results from lesions of the CNS. The primary lesion may be in the brain
orspinal cord, although multiple lesions along the neuraxis also are possible.
Spasticitymay involve the upper and lower extremities. Although arm swing does
have some effect ongait and is altered with spasticity, discussion of gait alterations
resulting from upperextremity spasticity is beyond the scope of this analysis. In the
lower extremity, a fewcommon patterns emerge, including the equinovarus foot,
valgus foot, striatal toe, stiff(extended) knee, flexed knee, adducted thighs, and
flexed hip.
Equinovarus is the most common spasticity-related pathology seen in the lower
extremity.Toe curling (clawing) may coexist. Contact is at the forefoot, with weight
acceptancealong the lateral aspect of the foot. Skin breakdown along the lateral
border of the footmay be an associated problem.
Equinovarus posturing limits single support dorsiflexion, prevents forward
progression ofthe tibia, and leads to a hyperextension thrust of the knee and
restrained forwardtranslation of the body's center of mass. This abnormality
compromises stability bydecreasing the base of support and may prevent functional
ambulation. Swing phase footclearance is compromised. Muscles that may
contribute to this disorder include tibialisposterior, tibialis anterior, long toe flexors,
medial and lateral gastrocnemius, soleus,extensor hallucis longus, and peroneus
longus. Conservative management includesadministration of neurolytic and
chemodenervation agents. Tendon lengthening decreasesforce output with no
change in neural drive.
Valgus foot results from inappropriate contraction of peroneal and triceps surae
muscles.Stance phase stability is compromised by an abnormal base of support.
This condition alsomay lead to genu valgum stresses and resultant pathology to
medial knee joint structures.
10. Persistent great toe hyperextension (hitchhiker toe) is not uncommon. Selection
offootwear is complicated. The usual offender is the extensor hallucis longus (EHL)
muscle.This pathology often is managed successfully with motor point block of the
EHL muscle.Diagnostic blocks often are helpful if co-contraction by the flexor hallucis
longus issuggested.
Stiff knee, a frequent complication of stroke, is a severe hindrance during
swing.Overactivity by iliopsoas, gluteus maximus, quadriceps, and hamstrings (as
hip extensors)is a possible contributor to this condition. Functional deficits include
increasedeffective limb length, with circumduction, contralateral vaulting, or hiking of
the pelvisrequired for foot clearance. Energy consumption is increased, typically in
patients withlittle functional reserve. Kinesiologic EMG analysis may be required to
identify thecontributing muscle( s) from the extensive aforementioned list.
Crouched gait is marked by excessive knee flexion in both swing and stance.
Limbadvancement is attenuated as part of this crouch pattern. Both hamstring and
quadricepsmuscles may be involved. Kinesiologic EMG may demonstrate prolonged
activity of the medialhamstrings. Knee flexion contracture is common. Excessive hip
flexion may interfere withmultiple activities of daily living and may contribute to knee
flexion deformity. Again,excessive hip flexion may interfere with limb advancement in
swing, as well as decreasedadvancement of the center of mass over the flexed
support limb. Initial treatment of bothexcessive knee and hip flexion is controversial.
Therapeutic interventions include motorpoint blocks, chemoneurolysis, tendon
lengthening, tendon transfers, and muscle release.
Thigh adduction (ie, scissoring) may interfere with daily activities, as well as withgait.
Limb advancement is curtailed by severe hip adduction. Balance may be impaired as
aresult of a narrowing of the base of support. Muscles that potentially contribute to
gaitscissoring include the adductor longus and brevis, adductor magnus, and
gracilis. Lessfrequently, the iliopsoas and pectineus are contributors. Diagnostic
obturator nerve blockhelps establish whether contracture is present.
A study by MacWilliams et al found that among patients who underwent a
hamstring-lengthening procedure, those whose surgeon followed or agreed with a
gait analysis--derived surgical recommendation had a 3.6-fold greater chance of a
positive outcome.
Contractures
Plantar flexor contracture of 15 ° is most common. This joint position minimizes
jointcapsule tensile forces. Contracture may be rigid or elastic. Only the ankle
orientation atinitial contact and mid swing is altered with elastic contractures. Despite
that fact,limb advancement may be slowed, because of the viscoelastic nature of
tissues. A rigid 15° contracture is associated with early foot flat and lack of early
stance phase tibialadvancement. Decreased toe clearance and foot drag are swing
11. phase consequences.Dorsiflexion contractures are rare, although sometimes they
are observed in lumbar-levelmyelomeningocele (present anterior tibialis and absent
triceps surae).
Knee joint contractures are typically at 30 ° of flexion. This position correlates withthe
resting position of the swollen knee. Only initial swing is affected by thisposturing.
Step length is shortened as a result of decreased knee extension in terminalswing,
and metabolic demands are increased. Knee extension contractures (ie,
capsulescarring) diminish limb advancement in early swing phase.
Hip flexor contractures result from shortening of hip flexor muscles or the joint
capsule.A tight iliotibial band is a variant of this disorder. Each results in increased
forwardpelvic tilt. Loss of hip joint flexion due to hip extensor contracture is
infrequent.
Pain
Pain does not inhibit normal motion directly; however, deformity and weakness may
resultfrom the person's attempts to attenuate pain through gait modifications. The
positions ofmaximal joint capsule and ligamentous laxity typically are adopted.
Generally, jointreaction forces are magnified with increases in muscle forces
crossing the joint, andincreased joint contact force is associated with increased
discomfort. One mechanism forreduction of joint pain is to limit the muscle force
output at the painful joint. Thisprotective response leads to muscle atrophy and
weakness.
Sensory loss
Impaired proprioception inhibits walking because of diminished information about the
limbsegment positions in space. When sensory loss predominates (intact motor
control), initialcontact may be emphasized. Superimposed motor losses diminish the
individual's ability tomake rapid substitution efforts, resulting in decrements in
walking velocity andstability.
Orthotics and assistive devices
Studies have indicated that when required, an ankle-foot orthosis (AFO) and/or
crutchesmay improve energy requirements and some kinematic properties of gait in
children withspina bifida.
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