Chapter 9: Plyometrics, Speed, Agility, and Quickness Training Principles
Plyometric Exercises
What are Plyometric Exercises?
Plyometric exercises are a type of training that was developed initially to address the gap between strength training and speed training with activity that involve explosive types of activities such as sprinting activities, jumping activities, etc.10 There are several strategies at play that help with the development of plyometric training that include the utilization of the stretch reflex, the stretch-shortening cycle, and neural adaptations that occur during increased central nervous system activation due to the eccentric and concentric components of plyometrics.
The Stretch-Shortening Cycle
The stretch-shortening cycle refers to the preparatory movement that places a stretch on a muscle before the movement occurs. During the stretch-shortening cycle there are three distinct stages:
- Eccentric movement
- Amortization
- Concentric movement
During the eccentric movement the muscles at play are stretched while they are loading which is sometimes referred to as the countermovement. The amortization stage is the transition moment between the eccentric and concentric movement where the change of movement direction occurs. The concentric movement is when the muscles utilized in the primary movement shorten as they contract. In order for a plyometric activity to be optimized and successful, the timing of the movement is essential. If there is any delay in the timing of any of these stages individually there will be a collective disfunction in the overall success of the movement as any stored or potential energy is lost in the delayed movement. The timing of these phases will have external variables that may influence the optimization of performance including added weight or drop heights.
The Role of Strength and Power
Strength is a key component of effective plyometric programming and development. Developing strength prior to progressing into plyometrics exercise is essential for creating maximal loading and force during the eccentric movement stage and the concentric movement stage. Continuing to develop strength can also help to provide further benefits to explosive power in plyometric activities. While developing strength can help to promote power improvements, fewer benefits are seen in the opposite strategy with regard to strength improvements being seen with exclusively power focused training development.
Additional Resources
Heinecke, Marc. Literature Review: Neuromuscular Response to Plyometric Training. International Journal of Strength and Conditioning: 2021. https://journal.iusca.org/index.php/Journal/article/view/53/116