Muscle Mechanics Chapter 17 KINE 3301 Biomechanics of Human
Movement
Slide 2
Instrumentation used to study muscle force- velocity and
force-length relationship.
Slide 3
Length changes to an individual sarcomere during an isometric
contraction. The sarcomere directly underneath the end-plate will
be the first to develop tension which causes the sarcomeres to the
right and left to lengthen.
Slide 4
Sarcomere Force Length Relationship
Slide 5
Force Length in Normal Joint Range of Motion
Slide 6
Force Velocity Relationship (P + a) V = b (Po P)
Slide 7
Efficiency of Eccentric & Concentric Exericse Bernard
Abbott, Brenda Bigland-Ritchie, JJ Woods Loiselle D S et al. J Appl
Physiol 2010;108:1465-1471 2010 by American Physiological
Society
Slide 8
DOMS Damage to Muscle Following Eccentric Contractions
Slide 9
Stretch Shorten Cycle 1.Stored elastic energy (tendon,
cross-bridge, and titin). 2.Eccentric phase elicits a stretch
reflex. 3.Eccentric phase pre-loads the muscle, so the concentric
phase begins at a higher force. 4.Two joint muscles (rectus
femoris, gastrocnemius) transfers energy and allows the muscle to
work at a lower velocity and a higher force. The stretch shorten
cycle is defined as an eccentric contraction followed by an
immediate concentric contraction. Additional work is performed
during the concentric phase of a stretch shorten cycle. This extra
work is attributed to:
Slide 10
Stretch Shorten Cycle The area under the force length curve is
equal to the work done.
Slide 11
Effects of Increasing the velocity of stretch on the concentric
work done for the concentric phase. 1974 by American Physiological
Society Adapted from: Cavagna and Citterio. J Appl Physiol 1974;
239:1-14.
Slide 12
Slide 13
Three Component Muscle Model Describes the mechanical response
of muscle. Contractile Component (CC) models active cross-bridges.
Dashpot models muscle viscosity. Series Elastic Component (SEC)
models elastic structures in series (tendon, passive cross-
bridges, titin). The SEC explains extra work done in
stretch-shorten and EMD. Parallel Elastic Component (PEC) models
passive elastic structures (passive cross- bridges, connective
tissue: endomysium, perimysium, epimysium, titin, desmin.