By Dan Hutchison, MS, ATC, CSCS
Improving power in sport activities has been manipulated using various training tools from traditional strength training, to contraptions and devices placing the individual in a position to be ‘resisted’ in his/her movement. Plyometrics have been implemented to complement traditional weight lifting practices by adding a ‘speed-strength’ component. Bodyweight has been consistently used across the spectrum of athletic enhancement programs to elicit this power for the improvement of running, jumping and throwing skills.
As mentioned in a previous performance blog, Fundamental Plyometric Training, the fundamental approach to integrating plyometrics starts with basic movements in all standard directions – forward, lateral and diagonal. Once these basic directional movements are established, complex applications can be added and progressed to enhance performance. The “complex applications” in this case will involve adding variable resistance to these basic movements to enhance athletic performance.
Variable resistance applies load to the body through the properties of rubber tubing. As the cord or band is extended, the elasticity of the device gets heavier, thus forcing the joint to apply an increasing load throughout the entire range of motion. In theory, this increased loading throughout the range of motion should enhance muscle stimulation, and provide improved strength gains at joint positions that may not have experienced this stimulation through traditional weight training. This theory should hold true for plyometric applications as well, especially when the ‘fundamentals’ have been established.
Cord-loaded plyometric movements should initially be applied with forces pulling the individual/athlete directly down to the ground. Horizontal pulling, via anterior or posterior loading, is part of the progression but should only be used after vertical loads have been applied, and sufficient body control and speed have been established. The percent load occurring early in the application should optimally be between 5%-15% of bodyweight, mainly to provide an effective muscle stimulus and to not hinder the ‘fast’ movement principles. This small stimulus applied to basic directional movements – forward, lateral and diagonal – will cause incremental power adaptations and the chance of injury is significantly reduced. Essentially, this load creates more bodyweight forcing the muscles to adapt to not only the load, but also to maintaining that load through a high level of velocity. Newton’s Third Law states that for every action there is an equal and opposite reaction. If we can provide an increased load to a specific action, we should receive an opposing reaction with a load that forces the body to react with more strength and power. In scientific terms, the stretch-shortening cycle is exploited during cord-loaded plyometric movement which intensifies the muscular response, thereby creating more power to improve vertical and horizontal displacement of the body.
Key Points on Resistance Applications for Plyometrics:
- Establish fundamental plyometric movements in all standard directions – forward, lateral and diagonal – prior to progressing to variable resistance applications.
- When variable resistance is added to plyometric movements, start with a direct vertical load using between 5%-15% of the individuals bodyweight as the cord-loaded resistance.
- Directional movement should be objectively measured to establish a baseline assessment, with advancements occurring through an increase in vertical load, an anterior or posterior load, or through an increased distance covered during the drill.
Chu, D.A. and Myer, G.D. (2013). Plyometrics: Dynamic Strength and Explosive Power. Human Kinetics.
Hrysomallis, C. (2012). The effectiveness of resisted movement training on sprinting and jumping performance. The Journal of Strength and Conditioning Research, 26(1), 299-306.
Hutchison, D. (2015). Perform-X Training Systems Education Manual.
Saeterbakken, A.H., Andersen, V., Kolnes, M.K., and Fimland, M.S. (2014). Effects of replacing free weights with elastic band resistance in squats on muscle trunk activation.