Week 2 Study Questions

Question 1

1. How are the roles of the biceps brachii, triceps brachii and posterior deltoid best described during a standing dumbbell curl? (Which act as prime movers, stabilisers, true or helping synergists?).

Answer 1

Prime mover - biceps
Synergist - Triceps
Stabilisers - posterior deltoid

Question 2

Define true and helping synergy and give examples, other than those already supplied to you in the lecture notes, of each

Answer 2

helping synergy: When two muscles contract together to create one movement.

true synergy , in which a different muscle contracts to stop the secondary action of another muscle.

example of a true synergy, for the hamstrings to produce hip extension without knee flexion, a knee extensor must act with the hamstrings in a true synergy

• helping synergy example, iliacus, psoas major, and rectus femoris all can act to flex the hip joint

Question 3

What pattern of muscle activity occurs in a free weight squat? (Which muscles are active and what are these muscle’s actions at each stage of the lift?).

Answer 3

peak quadriceps activity occurs at 80 – 90 degrees

Lowering phase: hip extensors – gluteus maximus, semimembranosus, semitendinosis and biceps femoris

Standing phase: same hip extensors as lowering phase. Knee extensors rectus femoris, vastus medialis, vastus intermedius and vastus lateralis – contract and straighten your knee joints. At ur ankle ur gastrocnemius and solues

Question 4

Define the stretch-shorten cycle and explain its performance benefits (see the model answer below after attempting you own!)

Answer 4

The stretch-shorten cycle involves eccentric actions (active lengthening) that immediately precede concentric (shortening) actions. The prior eccentric action stretches the series elastic component of muscles which store elastic potential energy that can be utilized in the concentric action. This makes the concentric action stronger (it increases force), faster (it increases muscle shortening rate) and therefore more powerful. The eccentric action also makes the subsequent concentric action more efficient (it saves energy) in comparison with a concentric action performed with no prior eccentric activation.

Question 5

Other than cycling and swimming name another water sport that involves cyclical active shortening of antagonistic muscle groups.

Answer 5

Water polo