movement analysis 1/27

static contraction

isometric

dynamic contraction

isokinetic, isotonic

eccentric contraction

generates the greatest muscle tension

key component of functional movement, e.g. deceleration

implications for high injury risk, e.g. strains

2 key considerations for which muscle is working

movement dynamics and force dynamics

movement dynamics

what joint is moving (primary joint of motion )?

any secondary joint of motion?

effect of gravity or external resistance?

force dynamics

what type of contraction is occurring?

muscle lengthening or shortening?

muscle action algorithm scenario A

gravity overpowers muscle torque and resistance overpowers muscle torque→muscle yields and lengthens

→deceleration force→eccentric contraction

muscle action algorithm scenario B

muscle torque overpowers gravity, muscle torque overpowers resistance→muscle dominates and shortens

→acceleration force→concentric contraction

muscle action algorithm scenario C

force counterbalances→isometric contraction

movement dynamics considerations

direction of motion of a limb does not always dictate which muscle group is active

active muscle group may become inactive depending on the direction of force (muscle action can switch from agonist to antagonist)

acceleration force by PT and pt, pt wins →

concentric assisted active exercise

acceleration force by pt, pt wins →

concentric “free” active exercise

acceleration force by PT, pt yield →

eccentric resisted active exercise

deceleration force by PT, pt wins →

concentric resisted active exercise

push up analysis

up: shoulder flexors concentric RAEx, elbow extensors concentric RAEx, shoulder adductors concentric RAEx, scapula protractors concentric RAEx

down: shoulder flexors eccentric RAEx, elbow extensors eccentric RAEx, shoulder adductors eccentric RAEx, scapula protractors eccentric RAEx

lombards paradox

self contradiction

squats

tend to impact distal quadriceps fibers more

can significantly improve quadriceps power

leg (knee) extension

tends to impact proximal quadriceps fibers more

generates a greater torque and hypertrophy in rectus femoris