emd (electeromechanical delay)

Company Name - Business Info www.companypage.com, [email protected]

Presentor:S.Mahboube.Razavi

Supervisor: Dr. Amiri khorasani

http://www.companypage.com/


EMD

Electromechanical Delay



1

Start:Definition

Discussion

2

Why?

3

Affecting Factors

4End:

Questions

5

Table of Contents



Force-Velocity Relationship

Length-Tension Relationship

Electromechanical Delay

Stretch-Shortening Cycle

Factors Affecting Muscular Force Generation



An indirect indicator of force development delay is

electromechanical delay (EMD), the time period between the first signs of

the electrical activity of the muscle (determined by electromyography, or

EMG) and the first signs of its mechanical action, such as

movement onset or the start of the force increase.

1: Difinition1 2

30-60 ms



The importance of EMD

It has been suggested that EMD measurement is essential to a proper understanding of the role and coordination of muscles in a movement and the relationship between EMG activity and body segment motion

EMD values are substantially important during practical evaluation of muscular function, especially during evaluation of the strength

and endurance of muscles in professional sports.

Is used to assess muscle function in healthy and pathological subjects



The EMD consists of electrical, chemical and mechanical processes

1: Conduction of the action potential along the T-tubule system

2: Release of calcium by the sarcoplasmic reticulum (SR)

3: Cross-bridge formation between actin and myosin filaments, thus developing tension in the contractile component (CC)

4: Stretching of the series elastic component (SEC) by CC

38.9%

60.9%



There is inverse proportionality between

EMD and musculotendinous stiffness

1EMD FStiffness

In human, electromechanical delay (EMD) has often been hypothesized to account more for musculo-tendinous stiffness than for the propagation velocity of action

potential along the muscle-fibres and the time course of the excitation-contraction coupling process



This difference was relatedto differences in the rate of change of length of

the series elastic element of the muscle

EMDFor

Kinds of contraction

IsometricConcentricEccentric

49.4 ms 59.3 ms55.4 ms

The EMD determined for the biceps brachii during eccentric action was 38 ± 13 ms (at the slow joint angular velocity) and 28 ±11 ms (at the faster velocity), whereas EMD

during concentric action was 41 ±13 ms and was independent of joint velocity



Loading rate high rates of force development cause tendons

to behave with greater stiffness then SSC motions involving high eccentric loads should

result in shorter EMD In eccentric contraction lower loading rates

should result in longer EMD

High loading rates appear to alter muscle-tendon interaction, which affects EMD, and high loading rates may cause force enhancement



Fiber Type fast twitch EMD

slow twitch EMD

Age Age EMD

Temperature & Fatigue Temperature Fatigue EMD



Exercise for slow fiber

Endurance training EMD

plyometric training EMD

stretching EMD



The effect of passive stretching on EMD

EMD

EMD changes resulting from passive stretching of plantar flexors, showed that 20 minutes of passive stretching

increases EMD, which suggests that stretching, may have lengthened the muscle’s elastic component, thus

contributing to a “less stiff” force transfer from the contractile component to the bone. These authors suggest

that stretching may have caused more slack in the musculotendinous system, which may have weakened the contractile component by requiring more time (increased

EMD) to produce external force.



Reference

Vladimir_Zatsiorsky,_Boris_Prilutsky]_Biomechanic

ROBERT W. NORMAN and PAAVO V. KOMI ,Electromechanical delay in skeletal muscle under normal movement conditions

Lilian Lacourpaille, Franc¸ois Hug*, Antoine Nordez, Influence of Passive Muscle Tension onElectromechanical Delay in Humans

Charlotte M. Waugh, The Effects of Age- and Training-Related Changes in Tendon Stiffness on Muscular Force Production and Neuro-Motor Control during Childhood Lilian Lacourpaille1 et al,ELECTROMECHANICAL DELAY AND ITS MECHANISMS ARE NOT IMPAIRED FOLLOWING ECCENTRIC EXERCISE

Grosset Jean-Francois ,ELECTROMECHANICAL DELAY AND STIFFNESS OF THE TRICEPS SURAE PRESENT CORRELATED ADAPTATIONS TO TRAINING



Reference

Emiliano Cè et al, Reliability of the Electromechanical Delay Components Assessment during the Relaxation Phase

S. Utku Yavuz , Effect of gender, age, fatigue and contraction level on electromechanical delayRodney J Snow , Effects of muscle fatigue and temperature on electromechanical delay

Antoine Nordez , Electromechanical delay revisited using very high frame rate ultrasound

P. R. Cavanagh I and P. V. Komi 2 , Electromechanieal Delay in Human Skeletal Muscle Under Concentric and Eccentric Contractions



QUESTIONS

?



THANK YOU!


emd (electeromechanical delay)

Education