ACE Personal Trainer Practice Exam

During which phase of plyometric exercise is power development most crucial?

1. Eccentric phase

2. Concentric phase

3. Amortization phase

4. Rest phase

The correct answer is: Amortization phase

In plyometric exercise, the phase where power development is most crucial is the amortization phase. During this phase, the transition occurs between the eccentric and concentric phases. Specifically, the amortization phase refers to the short isometric hold that follows the eccentric loading of the muscle and precedes the explosive concentric contraction. The critical aspect of the amortization phase is that it's where the body needs to quickly convert the stored elastic energy from the eccentric loading into a powerful concentric contraction. The faster a person can transition through this phase, the greater the potential for power output during the subsequent contraction. The key to effective plyometrics is minimizing the duration of this phase, thus maximizing the utilization of stored energy and enhancing overall performance. In contrast, the eccentric phase involves lengthening the muscle under tension, which is essential for energy storage, while the concentric phase represents the subsequent shortening and explosive movement. The rest phase is important for recovery but does not directly contribute to power development during the exercise itself. Understanding the importance of each phase helps trainers design effective plyometric training programs aimed at improving explosive strength and athletic performance.