Muscular Contractions

Question 1

What is a dynamic (isotonic) contraction?

Answer 1

Muscle changes length

Question 2

What is a static contraction?

Answer 2

Muscle remains the same length

Question 3

What is an isometric muscle contraction?

Answer 3

(Static)
> Muscle length does not change
> Increased tension, no movement
e.g. Plank - Bicep brachii
Wall sit - Quadricep group

Question 4

What is a concentric muscle contraction?

Answer 4

(Dynamic, isotonic)
> Muscle contracts and shortens under tension
e.g. Upwards phase of a bicep curl - Bicep brachii

Question 5

What is an eccentric muscle contraction?

Answer 5

(Dynamic, isotonic)
> Muscle lengthens under tension
> Acts as a break to control movement
e.g. Lowering phase of a bicep curl -
Bicep brachii

Question 6

What is the stretch shortening cycle?

Answer 6

(Muscle action)

> Active muscle lengthening (eccentric contraction), followed immediately by shortening of the same muscle (concentric contraction)

(Eccentric - Isometric - Concentric)

> When stretching occurs rapidly, stored elastic energy in the muscle fibres produce a powerful concentric contraction

Question 7

What is the eccentric phase of the stretch shortening cycle?

Answer 7

(Loading phase)
> Muscle lengthening phase, preloads energy in the muscle

e.g. Lengthening of the quadricep group during lowering squat phase

Question 8

What is the amortisation phase of the stretch shortening cycle?

Answer 8

(Transition phase)
> Transition phase between eccentric and concentric contractions (quick to maximise use of stored energy)

e.g. short motionless moment during a squat

Question 9

What is the concentric phase of the stretch shortening cycle?

Answer 9

(Unleashing phase)
> Unleashing stored energy by contracting muscles previously lengthened

e.g. contraction of quadricep group during jump of the squat jump