This document summarizes an experiment that examined the effects of direct and indirect stimulation on a frog gastrocnemius muscle. It found that:
1) Direct stimulation of the muscle required a higher threshold voltage than indirect stimulation of the nerve to induce contraction.
2) Onset and peak latencies were shorter when stimulating the muscle directly compared to stimulating the nerve indirectly.
3) Both direct and indirect prolonged stimulation induced muscle fatigue, with an 83-85% reduction in contractile force over 30 seconds.
Three applications of mechanical vibration to the quadriceps muscle for 10 minutes each over three consecutive days improved body balance in subjects who underwent ACL reconstruction, as shown by decreased length of trace, mean speed of shifts, and ellipse area when standing on the operated leg up to 90 days later. While leg force did not differ between treated and untreated groups, treated subjects showed greater confidence standing on the operated leg, suggesting vibration facilitated proprioceptive learning. The long-lasting effects may be due to conditioning of the neural network controlling the muscle and joint from association of voluntary contraction during vibration.
How to use Electrical Stimulation for Faster Hand Recovery After Stroke? by M...Techcare Innovation
Electrical Stimulation (ES) has been proven to help in upper limb recovery after stroke. Its benefits include strengthening weak muscles, increasing range of motion, reducing spasticity, and etc.
However, its benefits are limited in actual application due to lack of knowledge and experience in many patients.
In this sharing session, Ms. Yvonne will share practical recommendations with the clinical support evidence that can help to translate into actual practice and application for hand recovery of stroke patients. It is suitable for stroke patients, caregivers, physiotherapists, occupational therapists, doctors, nurses, and etc.
This study aimed to investigate the neuromotor effects of transverse friction massage (TFM) on the quadriceps femoris tendon using surface electromyography, force sensors, and ultrafast ultrasound. Fourteen healthy males received TFM on their quadriceps tendon while fifteen controls rested. Signals were recorded before and after TFM/resting to analyze time delays related to excitation-contraction coupling, force transmission, and electromechanical delay during voluntary contractions. Results showed TFM increased the time of excitation-contraction coupling and electromechanical delay, while decreasing time of force transmission, suggesting TFM influences neuro-motor mechanisms and changes muscle and tendon stiffness. The study provides insight into how TFM applied
1) Musculoskeletal pain can cause changes in motor activity and control, including both increases and decreases in muscle activity.
2) Experimental evidence shows that nociception affects motor function through changes in muscle activity, neuronal control mechanisms, proprioception, and local muscle morphology.
3) Various models have been proposed to explain motor responses to pain, including the vicious cycle model and pain adaptation model, but these do not fully capture the complex scenario seen clinically, particularly in chronic pain.
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.
Three applications of mechanical vibration to the quadriceps muscle for 10 minutes each over three consecutive days improved body balance in subjects who underwent ACL reconstruction, as shown by decreased length of trace, mean speed of shifts, and ellipse area when standing on the operated leg up to 90 days later. While leg force did not differ between treated and untreated groups, treated subjects showed greater confidence standing on the operated leg, suggesting vibration facilitated proprioceptive learning. The long-lasting effects may be due to conditioning of the neural network controlling the muscle and joint from association of voluntary contraction during vibration.
How to use Electrical Stimulation for Faster Hand Recovery After Stroke? by M...Techcare Innovation
Electrical Stimulation (ES) has been proven to help in upper limb recovery after stroke. Its benefits include strengthening weak muscles, increasing range of motion, reducing spasticity, and etc.
However, its benefits are limited in actual application due to lack of knowledge and experience in many patients.
In this sharing session, Ms. Yvonne will share practical recommendations with the clinical support evidence that can help to translate into actual practice and application for hand recovery of stroke patients. It is suitable for stroke patients, caregivers, physiotherapists, occupational therapists, doctors, nurses, and etc.
This study aimed to investigate the neuromotor effects of transverse friction massage (TFM) on the quadriceps femoris tendon using surface electromyography, force sensors, and ultrafast ultrasound. Fourteen healthy males received TFM on their quadriceps tendon while fifteen controls rested. Signals were recorded before and after TFM/resting to analyze time delays related to excitation-contraction coupling, force transmission, and electromechanical delay during voluntary contractions. Results showed TFM increased the time of excitation-contraction coupling and electromechanical delay, while decreasing time of force transmission, suggesting TFM influences neuro-motor mechanisms and changes muscle and tendon stiffness. The study provides insight into how TFM applied
1) Musculoskeletal pain can cause changes in motor activity and control, including both increases and decreases in muscle activity.
2) Experimental evidence shows that nociception affects motor function through changes in muscle activity, neuronal control mechanisms, proprioception, and local muscle morphology.
3) Various models have been proposed to explain motor responses to pain, including the vicious cycle model and pain adaptation model, but these do not fully capture the complex scenario seen clinically, particularly in chronic pain.
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 document summarizes a presentation given by David López Sánchez on spinal osteopathic manipulative therapy. It provides an overview of osteopathic philosophy which views the body as a single unified system. It describes assessment techniques for somatic dysfunction including asymmetry and tissue changes. Mechanisms of spinal manipulation are discussed such as restoring range of motion and reducing nociception. The document concludes that osteopathy aims to optimize health and stimulate self-regulation rather than simply treat diseases.
The document discusses the multifidus muscle and its importance for spinal stability and motor control. It provides details on its anatomy and function, explaining how weakness or dysfunction of the multifidus can contribute to spinal issues. The document also discusses approaches to strengthening the multifidus through specific stabilization exercises and motor learning principles to help patients regain control and function.
This document discusses muscle plasticity, which refers to the ability of skeletal muscle to adapt structurally and functionally in response to environmental changes such as increased or decreased activity levels. It provides definitions and history of the concept. It describes the effects of chronic low frequency electrical stimulation on muscles, including fiber type transformations, increased mitochondria and vascularization, and changes to contractile properties. Over time periods of hours to weeks, stimulated muscles demonstrate metabolic and structural adaptations that increase their fatigue resistance and transform them from fast-twitch to slow-twitch phenotypes. Several studies are summarized that investigate muscle adaptations to long-term stimulation in animals and humans.
Nerve Gliding Exercises - Excursion and Valuable Indications for TherapySarah Arnold
This document discusses nerve gliding exercises and their benefits for therapy. It describes how nerve glides can help increase nerve mobility and blood flow. Specific nerve glides are presented for common nerve entrapment syndromes like cubital tunnel syndrome (ulnar nerve) and carpal tunnel syndrome (median nerve). The document emphasizes performing glides symptom-free and using sliding techniques over tensioning. Nerve glides are recommended to prevent nerve adhesions after injuries or surgery.
The professor David Lopez, PT and DC expose about the theorical basis of manual therapy in Osteopathy for extremities. In a short approach inted demonstrate the differences and similarities with other manual therapy concepts
Experimental Muscle Mechanics in Aging and DiseaseInsideScientific
The focus of this webinar is on the mechanisms underlying muscle impairment associated with aging and age-related diseases. This research evaluates the regulation of muscle contraction at the motor protein, single muscle fiber, and whole muscle levels using in vitro, in situ and in vivo methods in experimental and clinical settings. Specifically, Dr. Qaisar is interested in the contribution(s) of muscle SR stress and calcium dysregulation to loss of muscle mass and strength. Reduced calcium uptake by muscle SR plays a pivotal role in muscle impairment in aging while boosting SR calcium uptake with pharmacological activators can partially restore muscle mass and strength. Matt shares a technical overview of the experimental equipment used in this research. He discusses the design, component functionality, and the applications that can be explored with this system. He also shares some valuable insights into the parameters that can be measured and the data that can be produced with various experimental designs.
Key Learning Objectives
- Contractile dysfunction in sarcopenia involves alterations at motor protein, single fibers and whole muscle levels in rodent models of aging and elderly humans
- Loss of calcium regulation by muscle SR plays a pivotal role in muscle atrophy and weakness associated with sarcopenia
- Age-associated comorbidities such as COPD and Parkinson’s disease accelerated the sarcopenia phenotype in humans
- Circulating biomarkers such as CAF22 can be useful predictors of muscle mass and strength in accelerated sarcopenia
19 rbeb relationship between peak and mean amplitudes v29n2Nathanael Amparo
The document describes a study that investigated the relationship between peak and mean amplitudes of stimulator output voltage during functional electrical stimulation (FES) of the knee. Ten healthy volunteers and ten spinal cord injured volunteers participated. Four different FES profiles were tested to determine which produced the lowest peak and mean amplitudes needed to extend the knee from 90 to 40 degrees. The results showed that higher amplitudes were required for spinal cord injured volunteers compared to healthy volunteers. The profile with 100 microsecond pulses at 50 Hz produced the lowest mean amplitudes for both groups.
This document discusses neurodynamic testing and neural mobilization. It begins by outlining the objectives of determining neurodynamic restrictions, evaluating neurodynamics through testing, and selecting neural mobilizations based on test findings. It then reviews neural anatomy, neurodynamics, types of neural injury, and examples of common neurodynamic tests. The document concludes by summarizing evidence that neural mobilization can reduce pain, improve flexibility and range of motion, and enhance performance.
The document discusses neuropathodynamics and neuromobilization techniques. It covers:
- Flexion and extension of the spine and their effects on neural tissues, producing tension and sliding.
- Lateral flexion and its effects of increasing tension on the convex side and reducing tension on the concave side.
- Various mechanical interface and neural dysfunctions that can occur.
- Objectives, clinical tests, and techniques used in neuromobilization to restore normal neuromechanical function.
- Contraindications for neuromobilization include acute injuries or infections of the nervous system.
- Different levels of neurodynamic testing based on symptoms and neurological status.
1) The study measured the longitudinal excursion and strain in the median and ulnar nerves during different types of nerve gliding exercises commonly used to treat carpal tunnel syndrome and cubital tunnel syndrome.
2) It found that "sliding techniques" which involve alternating movements at two joints resulted in substantially larger nerve excursion with much smaller increases in nerve strain, compared to "tensioning techniques" which simply elongate the nerve bed.
3) The findings demonstrate that different nerve gliding techniques have different mechanical effects on the peripheral nervous system, and may influence neuropathological processes differently. Clinicians should consider these effects when selecting exercises for conservative or post-operative treatment of common neuropathies.
pediatric electrodiagnostic for cerebral palsy,
A diagnosis of CP is often made based on MRI, delay of motor milestones and the presence of gait abnormalities in young children
Although the initial brain injury is non-progressive, the musculoskeletal impairments and functional limitations associated with CP are progressive
Three main classes of CP include spastic, dyskinetic and ataxic
This slide explains the technique of assessing soft tissue manually. the slide show also, describes about the different palpatory methods to assess it as described by janda
This document provides an overview of spasticity, including:
- Definitions and descriptions of spasticity and the underlying pathophysiology.
- Common causes of spasticity like cerebral palsy, stroke, multiple sclerosis, and spinal cord injury.
- Methods for assessing spasticity severity, including the Ashworth scale and pendulum tests.
- Goals and approaches for managing spasticity, which may involve eliminating triggers, non-pharmacological interventions, medications, and occasionally surgery.
This study investigated whether short-term strength training induces task-specific neuroplasticity at the spinal or supraspinal level. Subjects performed 4 sessions of either explosive or sustained knee extensions. H-reflexes and motor evoked potentials (MEPs) were measured before and after training during the onset of both tasks. After training, H-reflexes remained unchanged but MEP areas decreased during the onset of the trained task only, suggesting training-induced task-specific neuroplasticity occurred at the supraspinal level to improve corticospinal efficiency for the trained task.
This document provides an overview of neuromuscular electrical stimulation (NMES). It discusses how NMES works by sending electrical impulses to nerves that cause muscle contraction. NMES can increase strength, range of motion, and offset disuse effects. The document outlines different electrical waveforms, stimulus parameters, and applications of NMES for conditions like stroke, spinal cord injury, and more. Precautions and contraindications are also reviewed.
PhD Dissertation Defense - Melissa Mazzo - Estimates of neural drive and the ...Melissa Mazzo
A brief background on motor unit physiology and some of the findings from my PhD research projects involving quantification of the neural command to the calf muscles and adjustments in neural drive in response to stretching.
This letter discusses a study that examined the false positive rates of two neurodynamic tests - the upper limb neural tension test and seated slump test. The author takes issue with how the study defined a positive test result, as being based solely on structural differentiation, rather than also considering symptoms, bilateral comparisons, and other clinical information. The author argues this led to an underestimation of the false positive rate in healthy subjects. The response from the original study authors defends their methodology and definitions, noting they aimed to isolate the validity of the individual tests. Both discuss the need for further research on the diagnostic validity of neurodynamic tests.
This document provides an overview of peripheral nerve anatomy and physiology, mechanisms of nerve injury, and neurodynamic testing and treatment approaches. Key points include:
- The perineurium creates a closed compartment around nerve fibers and positive endoneural pressure can cause edema to spread longitudinally.
- Nerve injuries can range from neuropraxia to neurotemesis depending on the severity of the ischemic insult such as compression, elongation, or disruption.
- Neurodynamic testing involves assessing nerve mechanics and sensitivity through passive and active movements while monitoring for barriers, pain responses, and altered symptoms. Treatment aims to improve nerve gliding and decrease intraneural pressures.
Beyond Isometric Twitch: Utilizing lengthening, shortening and isotonic contr...InsideScientific
An important webinar for muscle researchers discussing characterization of complete muscle function by combining lengthening, shortening and isotonic contraction tests with traditional isometric twitch and tetanus measurements.
Quantifying muscle function continues to be an important part of any research where muscle is being directly or indirectly studied. However, a broad survey of literature reveals research remains heavily skewed towards isometric twitch and tetanus testing, which may not necessarily provide the most physiologically relevant data to the researcher. This webinar intends to discuss the subject of complete characterization of muscle and how scientists can combine a number of functional tests in their experimental design to better reveal scientific findings relating to muscle dynamics.
In this webinar, sponsored by Aurora Scientific, experts will show how to increase your experimental toolbox to create protocols that utilize lengthening, shortening and isotonic contractions, in addition to the more common isometric tests. Attendees will also learn when best to implement these new protocols to obtain the most complete data possible.
Stoichiometric control via periods of open-circuit during electrodepositionArkansas State University
Electrodeposition can enable stoichiometric control of deposited samples through variation of electroplating potential. We demonstrate an in-situ technique for deposit analysis and stoichiometric control by interspersing periods of open-circuit during deposition. Opening the circuit in an organic Cu-In-S plating bath allows greater incorporation of Cu, In, and/or S into deposited films, based upon the open-circuit voltage the film/electrolyte interface is allowed to achieve. With the same deposition potential, samples can be made to vary from highly Cu-rich to highly In-rich through selection of an appropriate open-circuit voltage limit.
1. A 42-year-old Thai man presented to the emergency room with right knee pain after falling off his motorcycle when hit by a bicycle.
2. Physical examination revealed swelling, deformity, and limited range of motion of the right knee with intact sensation and good blood flow. X-rays showed a closed fracture of the right tibial plateau.
3. The patient was admitted for pain control, antibiotics, and planned surgery to repair the closed fracture of the right tibial plateau via open reduction and internal fixation.
This document discusses patella and tibial plateau fractures. It describes the anatomy and mechanisms of injury for each. For patella fractures, it outlines types including undisplaced transverse, displaced transverse, comminuted, and vertical fractures. Clinical features and treatment options are provided for each type, including closed reduction, open reduction and internal fixation, and partial/total patellectomy. For tibial plateau fractures, the Schatzker classification system is described along with clinical features and treatment depending on fracture type, including closed treatment, open reduction and internal fixation. Complications of each injury are also mentioned.
This document summarizes a presentation given by David López Sánchez on spinal osteopathic manipulative therapy. It provides an overview of osteopathic philosophy which views the body as a single unified system. It describes assessment techniques for somatic dysfunction including asymmetry and tissue changes. Mechanisms of spinal manipulation are discussed such as restoring range of motion and reducing nociception. The document concludes that osteopathy aims to optimize health and stimulate self-regulation rather than simply treat diseases.
The document discusses the multifidus muscle and its importance for spinal stability and motor control. It provides details on its anatomy and function, explaining how weakness or dysfunction of the multifidus can contribute to spinal issues. The document also discusses approaches to strengthening the multifidus through specific stabilization exercises and motor learning principles to help patients regain control and function.
This document discusses muscle plasticity, which refers to the ability of skeletal muscle to adapt structurally and functionally in response to environmental changes such as increased or decreased activity levels. It provides definitions and history of the concept. It describes the effects of chronic low frequency electrical stimulation on muscles, including fiber type transformations, increased mitochondria and vascularization, and changes to contractile properties. Over time periods of hours to weeks, stimulated muscles demonstrate metabolic and structural adaptations that increase their fatigue resistance and transform them from fast-twitch to slow-twitch phenotypes. Several studies are summarized that investigate muscle adaptations to long-term stimulation in animals and humans.
Nerve Gliding Exercises - Excursion and Valuable Indications for TherapySarah Arnold
This document discusses nerve gliding exercises and their benefits for therapy. It describes how nerve glides can help increase nerve mobility and blood flow. Specific nerve glides are presented for common nerve entrapment syndromes like cubital tunnel syndrome (ulnar nerve) and carpal tunnel syndrome (median nerve). The document emphasizes performing glides symptom-free and using sliding techniques over tensioning. Nerve glides are recommended to prevent nerve adhesions after injuries or surgery.
The professor David Lopez, PT and DC expose about the theorical basis of manual therapy in Osteopathy for extremities. In a short approach inted demonstrate the differences and similarities with other manual therapy concepts
Experimental Muscle Mechanics in Aging and DiseaseInsideScientific
The focus of this webinar is on the mechanisms underlying muscle impairment associated with aging and age-related diseases. This research evaluates the regulation of muscle contraction at the motor protein, single muscle fiber, and whole muscle levels using in vitro, in situ and in vivo methods in experimental and clinical settings. Specifically, Dr. Qaisar is interested in the contribution(s) of muscle SR stress and calcium dysregulation to loss of muscle mass and strength. Reduced calcium uptake by muscle SR plays a pivotal role in muscle impairment in aging while boosting SR calcium uptake with pharmacological activators can partially restore muscle mass and strength. Matt shares a technical overview of the experimental equipment used in this research. He discusses the design, component functionality, and the applications that can be explored with this system. He also shares some valuable insights into the parameters that can be measured and the data that can be produced with various experimental designs.
Key Learning Objectives
- Contractile dysfunction in sarcopenia involves alterations at motor protein, single fibers and whole muscle levels in rodent models of aging and elderly humans
- Loss of calcium regulation by muscle SR plays a pivotal role in muscle atrophy and weakness associated with sarcopenia
- Age-associated comorbidities such as COPD and Parkinson’s disease accelerated the sarcopenia phenotype in humans
- Circulating biomarkers such as CAF22 can be useful predictors of muscle mass and strength in accelerated sarcopenia
19 rbeb relationship between peak and mean amplitudes v29n2Nathanael Amparo
The document describes a study that investigated the relationship between peak and mean amplitudes of stimulator output voltage during functional electrical stimulation (FES) of the knee. Ten healthy volunteers and ten spinal cord injured volunteers participated. Four different FES profiles were tested to determine which produced the lowest peak and mean amplitudes needed to extend the knee from 90 to 40 degrees. The results showed that higher amplitudes were required for spinal cord injured volunteers compared to healthy volunteers. The profile with 100 microsecond pulses at 50 Hz produced the lowest mean amplitudes for both groups.
This document discusses neurodynamic testing and neural mobilization. It begins by outlining the objectives of determining neurodynamic restrictions, evaluating neurodynamics through testing, and selecting neural mobilizations based on test findings. It then reviews neural anatomy, neurodynamics, types of neural injury, and examples of common neurodynamic tests. The document concludes by summarizing evidence that neural mobilization can reduce pain, improve flexibility and range of motion, and enhance performance.
The document discusses neuropathodynamics and neuromobilization techniques. It covers:
- Flexion and extension of the spine and their effects on neural tissues, producing tension and sliding.
- Lateral flexion and its effects of increasing tension on the convex side and reducing tension on the concave side.
- Various mechanical interface and neural dysfunctions that can occur.
- Objectives, clinical tests, and techniques used in neuromobilization to restore normal neuromechanical function.
- Contraindications for neuromobilization include acute injuries or infections of the nervous system.
- Different levels of neurodynamic testing based on symptoms and neurological status.
1) The study measured the longitudinal excursion and strain in the median and ulnar nerves during different types of nerve gliding exercises commonly used to treat carpal tunnel syndrome and cubital tunnel syndrome.
2) It found that "sliding techniques" which involve alternating movements at two joints resulted in substantially larger nerve excursion with much smaller increases in nerve strain, compared to "tensioning techniques" which simply elongate the nerve bed.
3) The findings demonstrate that different nerve gliding techniques have different mechanical effects on the peripheral nervous system, and may influence neuropathological processes differently. Clinicians should consider these effects when selecting exercises for conservative or post-operative treatment of common neuropathies.
pediatric electrodiagnostic for cerebral palsy,
A diagnosis of CP is often made based on MRI, delay of motor milestones and the presence of gait abnormalities in young children
Although the initial brain injury is non-progressive, the musculoskeletal impairments and functional limitations associated with CP are progressive
Three main classes of CP include spastic, dyskinetic and ataxic
This slide explains the technique of assessing soft tissue manually. the slide show also, describes about the different palpatory methods to assess it as described by janda
This document provides an overview of spasticity, including:
- Definitions and descriptions of spasticity and the underlying pathophysiology.
- Common causes of spasticity like cerebral palsy, stroke, multiple sclerosis, and spinal cord injury.
- Methods for assessing spasticity severity, including the Ashworth scale and pendulum tests.
- Goals and approaches for managing spasticity, which may involve eliminating triggers, non-pharmacological interventions, medications, and occasionally surgery.
This study investigated whether short-term strength training induces task-specific neuroplasticity at the spinal or supraspinal level. Subjects performed 4 sessions of either explosive or sustained knee extensions. H-reflexes and motor evoked potentials (MEPs) were measured before and after training during the onset of both tasks. After training, H-reflexes remained unchanged but MEP areas decreased during the onset of the trained task only, suggesting training-induced task-specific neuroplasticity occurred at the supraspinal level to improve corticospinal efficiency for the trained task.
This document provides an overview of neuromuscular electrical stimulation (NMES). It discusses how NMES works by sending electrical impulses to nerves that cause muscle contraction. NMES can increase strength, range of motion, and offset disuse effects. The document outlines different electrical waveforms, stimulus parameters, and applications of NMES for conditions like stroke, spinal cord injury, and more. Precautions and contraindications are also reviewed.
PhD Dissertation Defense - Melissa Mazzo - Estimates of neural drive and the ...Melissa Mazzo
A brief background on motor unit physiology and some of the findings from my PhD research projects involving quantification of the neural command to the calf muscles and adjustments in neural drive in response to stretching.
This letter discusses a study that examined the false positive rates of two neurodynamic tests - the upper limb neural tension test and seated slump test. The author takes issue with how the study defined a positive test result, as being based solely on structural differentiation, rather than also considering symptoms, bilateral comparisons, and other clinical information. The author argues this led to an underestimation of the false positive rate in healthy subjects. The response from the original study authors defends their methodology and definitions, noting they aimed to isolate the validity of the individual tests. Both discuss the need for further research on the diagnostic validity of neurodynamic tests.
This document provides an overview of peripheral nerve anatomy and physiology, mechanisms of nerve injury, and neurodynamic testing and treatment approaches. Key points include:
- The perineurium creates a closed compartment around nerve fibers and positive endoneural pressure can cause edema to spread longitudinally.
- Nerve injuries can range from neuropraxia to neurotemesis depending on the severity of the ischemic insult such as compression, elongation, or disruption.
- Neurodynamic testing involves assessing nerve mechanics and sensitivity through passive and active movements while monitoring for barriers, pain responses, and altered symptoms. Treatment aims to improve nerve gliding and decrease intraneural pressures.
Beyond Isometric Twitch: Utilizing lengthening, shortening and isotonic contr...InsideScientific
An important webinar for muscle researchers discussing characterization of complete muscle function by combining lengthening, shortening and isotonic contraction tests with traditional isometric twitch and tetanus measurements.
Quantifying muscle function continues to be an important part of any research where muscle is being directly or indirectly studied. However, a broad survey of literature reveals research remains heavily skewed towards isometric twitch and tetanus testing, which may not necessarily provide the most physiologically relevant data to the researcher. This webinar intends to discuss the subject of complete characterization of muscle and how scientists can combine a number of functional tests in their experimental design to better reveal scientific findings relating to muscle dynamics.
In this webinar, sponsored by Aurora Scientific, experts will show how to increase your experimental toolbox to create protocols that utilize lengthening, shortening and isotonic contractions, in addition to the more common isometric tests. Attendees will also learn when best to implement these new protocols to obtain the most complete data possible.
Stoichiometric control via periods of open-circuit during electrodepositionArkansas State University
Electrodeposition can enable stoichiometric control of deposited samples through variation of electroplating potential. We demonstrate an in-situ technique for deposit analysis and stoichiometric control by interspersing periods of open-circuit during deposition. Opening the circuit in an organic Cu-In-S plating bath allows greater incorporation of Cu, In, and/or S into deposited films, based upon the open-circuit voltage the film/electrolyte interface is allowed to achieve. With the same deposition potential, samples can be made to vary from highly Cu-rich to highly In-rich through selection of an appropriate open-circuit voltage limit.
1. A 42-year-old Thai man presented to the emergency room with right knee pain after falling off his motorcycle when hit by a bicycle.
2. Physical examination revealed swelling, deformity, and limited range of motion of the right knee with intact sensation and good blood flow. X-rays showed a closed fracture of the right tibial plateau.
3. The patient was admitted for pain control, antibiotics, and planned surgery to repair the closed fracture of the right tibial plateau via open reduction and internal fixation.
This document discusses patella and tibial plateau fractures. It describes the anatomy and mechanisms of injury for each. For patella fractures, it outlines types including undisplaced transverse, displaced transverse, comminuted, and vertical fractures. Clinical features and treatment options are provided for each type, including closed reduction, open reduction and internal fixation, and partial/total patellectomy. For tibial plateau fractures, the Schatzker classification system is described along with clinical features and treatment depending on fracture type, including closed treatment, open reduction and internal fixation. Complications of each injury are also mentioned.
This document provides an overview of radiation detectors. It discusses why radiation detection is important, how radiation interacts with matter, common types of detectors like ionization chambers, proportional counters, and GM counters, and how detectors work to detect different types of radiation. Specific examples are given around using an ion chamber survey meter to detect x-rays. Key factors around detector selection, specifications, and operating principles are summarized.
India has several major physical features that define its geography. These include the Himalayan mountains in the north, the northern plains formed by major river systems below the mountains, the peninsular plateau that makes up most of central and southern India, the Indian desert in the northwest, and the coastal plains along the eastern and western shores. India is also home to the island groups of Lakshadweep off the western coast and the Andaman and Nicobar Islands in the bay of Bengal.
This document summarizes an experiment studying the effect of applying a high voltage DC current to a jet fuel stream. The researchers observed that applying voltage caused the liquid stream to break up into droplets that repelled each other along the jet axis, creating a more uniform distribution. It also found the stream would wander about the vertical flow axis when voltage was applied. Future work will aim to quantify surface charge density, measure droplet motion, and perform simulations to better understand the physics involved.
This thesis examines alloy anode materials for sodium-ion batteries. Chapter 1 provides an introduction to sodium-ion batteries and hard carbon anodes. Chapter 2 describes the experimental methods used, including X-ray diffraction theory and techniques, electrochemical testing methods, and electrode fabrication. Chapter 3 discusses optimization of sodium-ion coin cells using different separator combinations. Chapter 4 evaluates the electrochemical alloying of sodium with silicon, tin, lead, and bismuth through galvanostatic cycling and in-situ X-ray diffraction. Chapter 5 investigates sodium insertion in a tin-cobalt-carbon nanocomposite.
The document summarizes key aspects of cardiac anatomy, electrophysiology, and the cardiac cycle. It discusses the pacemaker potential in the sinoatrial and atrioventricular nodes, the myocardial action potential, and the phases of the cardiac cycle. It also reviews how to examine heart sounds, common heart sounds and murmurs, and provides two case examples.
The document discusses action potentials and their propagation in excitable tissues. It begins by stating the objectives of understanding the mechanisms of action potential production and propagation. It then lists the main contents that will be covered, including the definition of action potential, its typical stages in large myelinated nerve fibers, the ion channels involved, propagation, and different types of action potentials. The document provides detailed explanations and diagrams of these topics. It emphasizes that action potentials are rapid changes in membrane potential that transmit signals through tissues via the coordinated opening and closing of sodium and potassium ion channels.
India has a variety of physical features due to its formation from different geological periods and the movement of tectonic plates. The major physical divisions of India are the Himalayan Mountains, Northern Plains, Peninsular Plateau, Indian Desert, Coastal Plains, and Islands. The Himalayas were formed by the collision of the Indian plate with Eurasia, and include India's highest peaks. The Northern Plains were formed by deposition of sediment from Himalayan rivers. The Peninsular Plateau is one of Earth's oldest landmasses.
Anti-arrhythmic drugs can be used to terminate or prevent arrhythmias. They work by blocking ion channels involved in cardiac action potentials. Class 1 drugs block sodium channels, prolonging the action potential. Class 1A drugs like procainamide and quinidine prolong the action potential. Class 1B drug lidocaine has rapid sodium channel blocking kinetics. Class 2 drugs like esmolol are beta blockers that reduce automaticity. Class 3 drugs like amiodarone and dofetilide block potassium channels, prolonging the action potential. Calcium channel blockers like verapamil are Class 4 drugs that suppress arrhythmias by blocking calcium channels, especially in the SA and AV nodes. Choice of drug depends
India has several physical features including mountains, rivers, plains, and plateaus. The Himalayas and Hindu Kush mountains lie to the north. Major rivers include the Ganges and Indus. The large and fertile Indo-Gangetic Plain spans northern and eastern India. South India's Deccan Plateau rises up to 1 km high. Coastal areas include the Eastern and Western Coastal Plains. Islands include the Lakshadweep and Andaman and Nicobar Islands.
A SHORT REVIEW ON ALUMINIUM ANODIZING: AN ECO-FRIENDLY METAL FINISHING PROCESSJournal For Research
Protection of aluminium alloys is most commonly done by forming anodic films. Anodic films can also be formed on metals like titanium, zinc, magnesium, niobium, and tantalum. Aluminium alloy parts are anodized to greatly increase the thickness of the natural oxide layer for corrosion resistance. A thin aluminium oxide film, that seals the aluminium from further oxidation when it is exposed to air. The anodizing process increases the thickness of the oxidized surface. Anodizing is accomplished by immersing the aluminium into an acid electrolyte bath and passing an electric current through the medium. In an anodizing cell, the aluminium work piece is made the anode by connecting it to the positive terminal of a dc power supply and the cathode is connected to the negative terminal of the dc source. Sealing is needed to seal the pores in oxide layer to prevent further corrosion. Oxide layer on the anodized aluminium has a highly ordered, porous structure that allows for secondary processes such as dyeing, printing and sealing. Nanowires and nanotubes can be made by using the pores in the oxide layer as templates.
Anodizing is an electrochemical process that converts the metal surface of aluminum to aluminum oxide. It produces a coating that is very durable, corrosion resistant, and maintains the metallic appearance of the aluminum. The anodizing process involves racking parts for processing, cleaning, etching, anodizing in an acid bath using electricity, coloring or sealing the pores, and testing to quality check the coating. Anodized aluminum has advantages like durability, low maintenance, and an environmentally friendly process.
Protection des métaux contre la corrosionCHTAOU Karim
Cette présentation présentent tout d’abord les principaux types de la corrosion et il présente une description détaillée des trois grandes méthodes, préventives et curatives, utilisées en anticorrosion.
This lecture describes the process of anodic oxidation of aluminium, which is one of the most unique and commonly used surface treatment techniques for aluminium; it illustrates the weathering behaviour of anodized surfaces. Some familiarity with the subject matter covered in TALAT This lectures 5101- 5104 is assumed.
The document discusses the Peninsular Plateau of India. It is located south of the Northern Plains and was formed by the breaking of the Gondwana landmass, making it one of India's oldest landforms. The plateau consists of the Central Highlands in the north and the Deccan Plateau further south. The Central Highlands include regions like the Malwa, Bundelkhand, Baghelkhand and Chotanagpur plateaus. The Deccan Plateau is bounded by the Western and Eastern Ghats and contains the Deccan Traps in the northwest. The plateau is rich in minerals and supports agriculture.
2 Brain activation and exhaustion - Kilty et al 2011-annotated.pdfJorgeSilva638591
1) The study investigated how communication between the mid/anterior insular cortex and motor cortex changes during a fatiguing cycling exercise using electroencephalography (EEG).
2) Results showed that lagged phase synchronization, a measure of intracortical communication, significantly increased between the mid/anterior insular cortex and motor cortex at the end of the fatiguing cycling exercise compared to the beginning.
3) Lagged phase synchronization returned to baseline levels during a recovery cycling period after subjects stopped exercising, indicating the increased communication was specific to the fatigued state.
Reduced Short- and Long-Latency Afferent Inhibition Following Acute Muscle Pa...Antonio Martinez
Corticomotor output is reduced in re-
sponse to acute muscle pain, yet the mechanisms
that underpin this effect remain unclear. Here the au-
thors investigate the effect of acute muscle pain on
short-latency afferent inhibition, long-latency afferent
inhibition, and long-interval intra-cortical inhibition to
determine whether these mechanisms could plausibly
contribute to reduced motor output in pain.
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.
The document discusses shockwave therapy for musculoskeletal injuries in horses. It provides an overview of shockwave therapy including the mechanism of action, various generators used, and clinical applications for conditions like tendonitis, osteoarthritis, and fractures. Several research studies on shockwave therapy are also summarized that showed improvements in lameness, range of motion, and force plate measurements for conditions like stifle lameness and hip osteoarthritis in dogs receiving shockwave therapy.
The document summarizes a study that investigated the effects of applying vibratory stimulation to the quadriceps muscle of subjects who underwent anterior cruciate ligament (ACL) reconstruction surgery. The study found that applying short periods of vibration for a few consecutive days led to improved balance and equilibrium over longer periods of time, as measured by various parameters, compared to a control group. While leg force was not significantly different between groups, the treated subjects showed a preference for standing on the operated leg, indicating the vibration helped them regain confidence in using that leg for balance. The long-lasting positive effects are believed to be due to improvements in proprioceptive control and learning in the central nervous system.
This case study looked at using an intelligent stretcher robot to reduce tremors in the forearms and hands of two subjects with Parkinson's disease. Electromyography sensors were used to measure muscle activity in the extensor carpi radialis longus and flexor carpi radialis muscles. For both subjects, tremors were found to be present in both muscles and induced when the muscles were in a shortening state, such as during movement. The stretcher robot was able to reduce tremors by stretching the muscles and increasing damping. For the second subject, angle and damping changes were also able to reduce tremors without consistent results. The study suggests intelligent stretching may help reduce tremors but more research is needed on different patients.
This study investigated changes in sensory and electromyography (EMG) measurements over different regions of the quadriceps muscle before and after eccentric exercise intended to induce delayed-onset muscle soreness (DOMS). Surface EMG signals and pressure pain thresholds were measured at 15 locations on the quadriceps during sustained isometric contractions and at rest. After eccentric exercise, time to failure during contractions, EMG amplitude, and pain thresholds all decreased significantly and were lowest in the distal region of the quadriceps. This suggests DOMS manifestations vary by muscle region, likely due to differences in fiber morphology and architecture. The distal quadriceps may be more susceptible to further injury after eccentric exercise.
1) The article reviews recent research on the non-thermal effects of therapeutic ultrasound at the cellular and molecular levels.
2) Studies show that non-thermal ultrasound can modify cell functions like membrane properties, proliferation, and inflammatory protein production.
3) The frequency resonance hypothesis proposes that ultrasound energy absorption by proteins can cause conformational shifts, altering protein activity, or dissociate multimolecular complexes to disrupt their functions. This may explain ultrasound's non-thermal molecular and cellular effects.
This document summarizes an experimental study that evaluated prolonging nerve grafts using bioengineered muscle-in-vein scaffolds with a 'window-vein' method. The study used 30 rats divided into 3 groups: direct nerve coaptation; grafting with 2 x 1.5 cm muscle-in-vein grafts sutured together; and a single 3 cm muscle-in-vein graft using the 'window-vein' method with electromagnetic stimulation. Histological and functional analyses at 12 weeks found similar regeneration in the direct coaptation and 'window-vein' groups, but poorer results in the sutured graft group. The researchers concluded that the 'window-vein'
The lab experiment tested the muscle reaction of a psoas muscle fiber to three different solutions by measuring the fiber size before and after adding each solution. The fiber size did not change with any of the solutions, not supporting the hypothesis that ATP solution would cause muscle contraction. The purpose was to determine if the solutions would cause contraction. The introduction provided background on muscle contraction and the role of ATP.
This study examined the effects of altering pre-exercise muscle temperature on muscle damage from eccentric exercise. Subjects received either a microwave treatment to increase muscle temperature or an icing treatment to decrease it before performing eccentric exercises with one arm. A control arm performed the exercises without treatment. Measures of muscle damage like strength loss and soreness increased significantly after exercise but were not significantly different between treatment and control arms. Neither warming nor cooling the muscle before exercise appeared to influence the magnitude of exercise-induced muscle damage.
This study investigated how localized muscle fatigue of the ankle plantarflexors affects spatial electromyography (EMG) patterns in the medial gastrocnemius muscle during walking and running. The researchers recorded high-density EMG from the medial gastrocnemius before and after subjects performed a calf raise task to induce fatigue. They found that after fatigue, peak EMG activity decreased but mean power frequency increased during locomotion. Additionally, the location of peak EMG shifted proximally compared to the pre-fatigue location, suggesting altered motor unit recruitment to distribute muscle loads. Despite these EMG changes, lower limb biomechanics were similar before and after fatigue.
Non-uniform electromyographic activity during fatigue and recovery of the vas...Nosrat hedayatpour
The aim of the study was to investigate EMG signal features
during fatigue and recovery at three locations of the vastus
medialis and lateralis muscles.
This presentation discusses current management of spinal cord injuries and includes the following: It defines spinal cord injuries and discusses epidemiology, types, and potential outcomes. It then covers causes, importance of awareness and immediate management, physiotherapy goals and techniques. New developments are also summarized, including electrical stimulation, restoring respiratory function, epidural stimulation, stem cells, brain-computer interfaces, and robotic assisted therapy.
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.
Electrical stimulation is used both diagnostically and therapeutically for muscles and nerves. Diagnostic tests measure the rheobase, chronaxie, and create strength-duration curves to determine if a muscle is innervated, denervated, or partially denervated. Therapeutically, neuromuscular electrical stimulation is used to prevent muscle atrophy and decrease spasms by causing asynchronous muscle contractions, though it must be supplemented with voluntary strength training. The optimal stimulation parameters vary but generally include a pulse duration of 300-400 microseconds, frequency of 20-100 Hz, and a duty cycle sufficient to generate force without causing fatigue.
INFLUENCE OF GENDER ON MUSCLE ACTIVITY PATTERNS DURING NORMAL AND FAST WALKING ijbesjournal
Electromyography (EMG) signals are often described as electrical manifestation of neuromuscular
activation associated with the muscles. These signals are commonly utilized as principal input signals to
control several prosthetic devices such as prosthetic hands, arm, lower limbs, and exoskeleton robots as
well as in designing of rehabilitation and assistive devices. It is well proven that EMG signals vary among
subjects and gender is one of the major factors that play a significant role in this variation. This study
detects the possible gender differences by measuring changes in the EMG activity during different phases
of human walking by acquiring the surface EMG signals from Gluteus Maximus, Hamstrings (biceps
femoris), Quadriceps (rectus femoris) and Soleus muscles of the leg with the healthy subjects walking
barefoot at two paces-normal and fast. The statistical analysis of the results showed no gender differences
at normal speed of walking but when speed of walking changed; it showed clear differences in the
behavior of these muscles. The results from this study would aid in designing closed loop control strategy
for designing a smart functional electrical stimulator (FES) which is the larger goal of this research.
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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. Effects of Direct Stimulation, Indirect Stimulation, and Fatigue in Frog Nerve and
Muscle
By
Anastasia O. Belyakova
Systems Physiology Lab 357
Section 5
2. Abstract
Studying physiological effects of the body with animal experimentation has
progressed the knowledge and understanding humans have on bodily functions. The
purpose of this experiment was to examine different kinds of muscle stimulation in the
Northern Leopard Frog, and compare muscle activation characteristics by direct muscular
stimulation, indirect nerve stimulation, latency period and fatigue effects in the
gastrocnemius muscle. The frogs were anesthetized and dissected leaving the leg,
followed by a surgical procedure to isolate and remove the gastrocnemius muscle –
careful not to damage the sciatic nerve. Once the muscle was removed, it was maintained
in room temperature Ringer’s solution and then positioned onto the force transducer
followed by series of tests with varying electrical stimuli.
In the first part of the experiment, the threshold voltage to induce action potential
by direct stimulation of the muscle was found to be approximately 450mV with a peak at
1800mV, as compared to a much lower threshold during indirect stimulation of the nerve
– at about 35mV, with a peak at 160mV. The plateau voltages were found to be 675mV
for the muscle and 52.5mV in the nerve. In the second part of the experiment, the onset
and peak twitch latency in the muscle and nerve were compared. In the nerve, the onset
latency was at 13.5ms while the peak reached 54ms, while in the muscle they were
12.5ms and 50ms, respectively. In the third experiment, fatigue of the muscle was
examined, and it was found that maximum contraction of muscle by direct super
excitation decreased from 25.847mV to 4.461mV (exertion force loss of 83 per cent),
while in the nerve it decreased from 32.279mV to 4.821mV (force loss of 85 per cent).
3. The results of these experiments determined that excitation of the muscle yields
different results when an electrode is stimulating the muscle directly and the nerve
indirectly. The first experiment determined that the threshold, peak, and overall voltage
range of stimulation is a lot higher for direct stimulation than for the indirect stimulation,
while the second experiment showed that the onset and peak latencies were higher in the
nerve than in the muscle. The final experiment illustrated the effects of prolonged
stimulation of the muscle and compared the force exertions throughout the duration of
direct and indirect stimuli. From these experiments, a comprehensive understanding of
the way that muscles and the nervous system work together to produce movement was
achieved; such experiments would further understanding in what may prevent the
physical functioning of the body, and push medicine further in treating physically
limiting conditions.
Introduction
While the study of physiology is not a young science, the understanding of the
morphology and functionality of systems within the organism is. It was not until
technological advancements within the last century did scientists begin to see the inside
of a living organism, as opposed to exploring the body post-mortem. In 1980,
neuromuscular morphology was studied in Japan, and early imaging techniques by
scanning electron microscopy allowed scientists to visualize the structure of the
neuromuscular junction – as well as establish comparisons among various animal species
(Desaki & Uehara, 1980). It was proved that structure between species differed, but the
reactions to stimuli essentially were the same. From this point forward, methods of
muscle stimulation and studies continued to progress.
4. The understanding of the neuromuscular junction advanced from imaging to
stimulation techniques. By the twenty-first century, nerve-clamping electrodes that place
the nerve within the tube set up were created – which is useful in stimulating nerves of
various lengths and examining the effects of toxins that may affect contraction by
inhibiting acetylcholine (Hilmas et al., 2010). Indirect muscle stimulation allows testing
the functionality of the nerve and muscle response, which would be useful in
comprehension of factors affecting physically compromised patients.
In order to determine issues in physical injuries, studies in healthy subjects have
been conducted. Experimentation with electrical impulses has gained advancements in
neuromuscular knowledge by comparing voluntary muscular contractions to electrically
induced ones (Ward & Shkuratova, 2002). This study explored the increase of muscle
force in young Russian athletes as well as older individuals: to test whether muscular
output gains were better affected by muscular growth, electrical stimuli, or both. The
finding that a combination of the two yielded the best results supports the benefits of
electrical stimuli in producing stronger muscular output, which in turn could also
challenge the effects of muscle fatigue during prolonged exercise.
In these experiments, basic neuromuscular functions were explored. Using
electrodes to induce direct and indirect stimulation of the muscle showed the differences
between stimulation voltages required to activate the nerve, and the muscle itself, for a
contraction. Contrasting values for latency as well as muscular reaction to fatigue
explains what is happening within the neuromuscular junction, which leads to the
conclusion that establishing the differences in nerve and muscle stimulation is the key to
aiding physically impaired individuals with future advancements in technology.
5. Understanding the effects of voltages on the muscle or the nerve has resulted in the field
of creation of robotic limbs, which could dramatically improve with more studies into the
future.
Methods
The Northern Leopard Frog was used in this experiment, placed in a jar of
isoflurane to anesthetize it. After 10-15 minutes the frog achieved deep anesthesia,
evidenced by lack of pain response to pulling its toes. The frog was removed from the jar,
pithed at the neck through the spinal cord using standard techniques approved by the
Rutgers University Laboratory Animal Science veterinarians (RU, LAS). Then the leg
was removed and pinned down to the board for surgery.
First, the skin was detached from the muscular tissues of the leg. While keeping
the muscle moist with room temperature Ringer’s solution, a hole was punctured between
the Achilles tendon and the tibia with a glass rod in order to prevent any overstimulation
of the muscle and nerve to be exposed. A surgical silk suture of approximate length 10-
15cm and a hook at one end was tied tightly around the bottom of the tendon to prepare it
for direct stimulation experiments. Then a cut with surgical scissors was made at the
bottom of the Achilles tendon, detaching it from the bone. Next, the optimal muscle
length was measured and found to be 3.0cm long, and then surgical scissors were used to
cut the tibia below the kneecap. After the muscle was freed from the lower leg, a glass
rod was used to expose the sciatic nerve, and further separate it from upper leg muscle
tissues so that another suture could be tied around the end of the nerve for indirect
stimulation experimentation. Finally, the thigh muscle and femur were cut off the leg
above the kneecap, leaving the knee along with the gastrocnemius muscle and sciatic
6. nerve extracted. While the frog leg rested in room temperature Ringer’s solution, the
force transducer was zeroed and calibrated.
The force transducer was zeroed and calibrated before attaching the frog muscle
and running tests. This was done by recording 5 seconds of data by the ECG with no
weight attached. Then the transducer was calibrated with a 1.0g weight, and the software
measured a 0.010N force. The weight was taken off the force transducer, the muscle was
placed to have two electrodes stimulating it from the top of the apparatus, the bottom two
electrodes were stimulating the sciatic nerve. All results were recorded by Lab Tutor
software.
In the first experiment, the resting potential was recorded. The threshold of the
nerve was determined by increasing the administered voltage by increments of +5mV,
until a response occurred. From there, additional increments of +25mV were
administered until the peak was reached. A similar format of stimulation was done for the
muscle, starting at 300mV stimulation additional increments of +50mV lead to the
threshold and peak voltages.
From the recorded data in the first experiment, the onset and peak latency of
direct and indirect stimulation were measured. To find the onset latency, a marker was
positioned at the baseline of the action potential at the moment the shock was
administered, and ranged to the point where contraction began and an action potential
occurred. Similarly, the peak latency was measured from the same initial marker at the
administration of the stimulus, to the peak of the action potential.
7. All throughout experimentation the muscle specimen was washed with room
temperature Ringer’s solution. In the third experiment, the ECG shock was administered
with constant voltage duration of 30 seconds to stimulate the muscle and test its capacity
for fatigue. The first part of the experiment tested the indirect prolonged stimulation of
the nerve, followed by a two-minute rest to let the muscle recover, and then direct
stimulation of fatigue was administered. After all testing was completed, the muscle
specimen was untied and detached from the force transducer apparatus, the surgical silk
sutures were cut off and washed, and the frog leg was disposed of following the REHS
guidelines into a brown bag.
Results
Figure 1: Twitch Response
This graph shows the threshold and peak voltages of the nerve and the muscle, thereby
showing direct and indirect stimulation ranges that produce muscle contractions.
Figure 1 illustrates direct and indirect stimulation of the muscle: from the threshold
voltage when action potential is first experienced, to the plateau – when the contractile
8. force no longer increases. When stimulating the nerve, the threshold voltage is
determined to be at 35mV, and contractile force rises until approximately 8.92 – 9.114N
at 160mV administration, where the plateau is reached. This is a much smaller voltage
range in comparison to direct muscle stimulation: the threshold being at 450mV, reaching
a plateau around 1650 – 1800mV, producing contractile forces at 12.782 – 13.033N.
Table 1: Latency Onset and Peak Latency in Nerve and Muscle
This table shows the comparison of time frames in milliseconds for the onset of latency,
as well as the peak in latency for the nerve and the muscle.
Onset (ms) Peak (ms)
Nerve 13.5 54.0
Muscle 12.5 50.0
Table 1 compares and contrasts the latency onset and peaks of direct and indirect
stimulation. It is evident that the onset of latency for the muscle (12.5ms) takes less time
than for the nerve (13.5ms), confirmed by the peak latencies: which were 50.0ms and
54.0ms respectively. This proves that stimulating the muscle directly causes a faster
contraction of the muscle than indirectly stimulating the nerve.
Figure 2: Fatigue in Nerve and Muscle
Figure 2 shows the change in force that is exerted during the administration of a 30
second prolonged stimulus to the muscle via direct and indirect stimulation.
9. Figure 2 demonstrates the effect of muscle stimulation for duration of 30 seconds. The
voltage was administrated, and the muscle exerted a contractile force demonstrating
fatigue. When stimulating the nerve, there is a consistent drop in the force the muscle
exerts throughout the duration of the stimulus. The initial contractile force via the nerve
was 32.279N, which dropped to 4.821N – losing 85% of muscle exertion. A similar
observation can be made for the muscle, which had an initial contractile force of 25.847N
and diminished to 4.461N – losing 83% of exertion power. The contractile force for
indirect stimulation was significantly lower than for indirect stimulation, due running a
direct stimulation after the first 30 second long duration, where the muscle was allowed
to rest for a few minutes. Upon the second 30-second direct stimulation, the muscle had
already been fatigued and therefore produced a lower initial muscle contractile force.
Discussion
In order to understand what is wrong with something, it is crucial to understand
the result when it functions properly. Any movement in the body is controlled by
10. electrical impulses that travel from the central nervous system and affect the muscle,
forcing it to contract. When the brain sends an electrical signal to initiate movement, the
signal travels down the axon of the terminal somatic motor neuron, which has several
branches that each attach to a muscle fiber. When the electrical impulse reaches threshold
voltage of the motor neuron, it causes the neuron depolarize and produce an action
potential. Acetylcholine is released into the synaptic cleft and attach to the postsynaptic
receptors of the muscle – which then also experiences an action potential, inducing a
contraction (Silverthorn, 2012). This is the sequence of activation of muscle contraction
via indirect stimulation of the nerve, however direct stimulation of the muscle yields
several changes.
In a direct stimulation, it is seen that there are voltage differences that will cause
an action potential sequence for contraction. The first experiment showed that it takes a
much higher voltage to directly stimulate contraction than to activate the nerve to
produce the same result. The typical resting potential of a motor neuron is -70mV, and if
the neuron is depolarized to -50mV an action potential results (Birkill et al.). However,
each presynaptic terminal of a motor neuron affects one fiber of muscle, so stimulation of
the entire muscle would require a high voltage in order to depolarize the muscle to cause
a contraction.
When testing latency in the second experiment, it was discovered that the onset
and peak of latencies were shorter for the muscle than for the nerve. This is due to the
mechanism behind eliciting a contraction. When stimulating the nerve, it takes a fraction
of a second longer because acetylcholine needs to be released into the synaptic cleft, and
then sodium ions need to depolarize the muscle membrane in order to activate the DHP
11. receptor to release calcium ions out of the sarcoplasmic reticulum. The calcium ions
induce contraction between the actin and myosin filaments (Silverthorn). When
stimulating the muscle directly, although it requires a higher voltage, the muscle itself
gets depolarized and contraction is immediately induced. The difference in eliciting the
contractions is the distance the electrical signal must travel – it takes longer for the action
potential to travel from the nerve to the muscle than from within the muscle itself.
In the third experiment, direct and indirect administration of prolonged voltage
stimulus induced muscle fatigue. Muscular fatigue is the decrease in the contractile force
of the muscle for the duration of a stimulus rather than the inability to perform a task
(Enoka & Duchateau, 2008) as was established in the experiment as well. Both direct and
indirect electrical prolonged forced contractions showed an 83 – 85 per cent loss of
contractile force within that time. It was also evident that the initial contractile force was
diminished by 20 per cent since the first experimentation of a prolonged stimulus, which
proves that muscle contractile force decreases with each round of exertion. This explains
why an individual gets more tired with each repeat of an exercise.
Citations:
1. Birkill, C., Van Rensburg, R., & Raath, R. (n.d.). Electrophysiology and Nerve
Stimulators. South African Journal of Regional Anaesthetics.
2. Desaki, J., & Uehara, Y. (1980). The overall morphology of neuromuscular
junctions as revealed by scanning electron microscopy. Journal of
Neurocytology, (10), 101-110.
3. Enoka, R., & Duchateau, J. (2007). Muscle Fatigue: What, Why And How It
Influences Muscle Function.The Journal of Physiology, (586), 11-23.
12. 4. Hilmas, C., Scherer, J., & Williams, P. (2010). A Nerve Clamp Electrode Design
For Indirect Stimulation Of Skeletal Muscle. Biotechniques, 49, 739-744.
5. Silverthorn, D. (2012). Chapter 12: Muscles. In Human Physiology: An Integrated
Approach (6th ed., pp. 410-413). Austin, TX: Benjamin-Cummings Publishing
Company.
6. Ward, A., & Shkuratova, N. (2002). Russian Electrical Stimulation: The Early
Experiments. Physical Therapy, 82(10), 1019-1030.