# 3.1 Power training: physiology and mechanics

Figure 5

When a muscle is stretched rapidly, the neuromuscular system responds by initiating a concentric muscle contraction to prevent the muscle from being stretched too far and becoming damaged. This is known as the stretch-reflex system. In plyometrics, this means that if a rapid eccentric loading phase is performed before a concentric contraction, a greater and more powerful concentric muscle action will occur. This ‘pre-stretch’ action is known as the stretch shortening cycle and is explained further in Activity 4.

## Activity 4 Plyometric mechanics and physiology

Allow 40 minutes for this activity

Watch Video 4, on the stretch-shortening cycle, at the link below. Focus on the section between the start and 02:55. Once you’ve watched Video 4, do the related tasks below.

Video 4: The stretch-shortening cycle

1. Use the drop-down menus to select the correct missing word.

View document

2. Put the three phases of the stretch-shortening cycle in the order they are performed.

Eccentric

First

Amortisation

Second

Concentric

Third

Using the following two lists, match each numbered item with the correct letter.

1. Eccentric

2. Amortisation

3. Concentric

1. 1

   First

2. 2

   Second

3. 3

   Third

The correct answers are:

- 1 =
- 2 =
- 3 =

Now that you have an understanding of how plyometric training works, in the next section you will investigate some examples of plyometric training.

OpenLearn - Training for speed and power in sport and fitness
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