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Training for speed and power in sport and fitness
Training for speed and power in sport and fitness

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3.1 Power training: physiology and mechanics

An image of a person bounding up steps
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

Timing: 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 [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)]

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

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

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

  1. Eccentric

  2. Amortisation

  3. Concentric

  • a.First

  • b.Third

  • c.Second

The correct answers are:
  • 1 = a
  • 2 = c
  • 3 = b

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