Isotonic and isometric contraction in sporting actions

Overview

Isotonic, concentric, eccentric and isometric contractions, analysed in squats, press-ups, a bicep curl, a scrum, a high jump take-off and a tennis forehand.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is an isotonic contraction?

   Model answer

   An isotonic contraction is one in which the muscle changes length while under tension. Isotonic contractions can be concentric or eccentric.

2. 2

   Define a concentric contraction.

   Model answer

   A concentric contraction is one in which the muscle shortens under tension.

3. 3

   Define an eccentric contraction.

   Model answer

   An eccentric contraction is one in which the muscle lengthens under tension. The muscle acts as a brake, controlling the movement.

4. 4

   What is an isometric contraction?

   Model answer

   An isometric contraction is one in which the muscle is under tension but its length does not change. The joint stays still.

5. 5

   Which type of contraction do the quadriceps perform as a basketball player lands from a jump?

   Model answer

   The quadriceps contract eccentrically. The knee flexes under control as the quadriceps lengthen to absorb the landing.

6. 6

   Analyse the knee in the downward phase of a squat.

   Model answer

   The joint action is knee flexion. The quadriceps are the agonist, contracting eccentrically, and the hamstrings are the antagonist.

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