Written by John Corr, Personal trainer and one of the owners at fitnessworxgym!
Plyometric exercises are used to increase explosive power, by means of the stretch-shortening cycle (SSC). A SSC is a rapid coupling between an eccentric and concentric muscle action.
Plyometric training is highly effective, with the advantage of requiring reduced physical space, time, and equipment to complete the training sessions.
Although commonly accepted as an effective training method, studies have not established optimum plyometric training design i.e. volume, frequency etc for explosive strength enhancement.
The landing surface where plyometric training takes place has been poorly studied.
A study published in the Journal of Strength & Conditioning Research October 2013 investigated plyometric volume and training surface and their effects on explosive strength. The findings are summarised as follows;
High training volume led to a significant increase in explosive performance requiring fast SSC actions compared with what was observed after a moderate training volume.
Plyometric training performed on a hard training surface (high impact reaction force), with a moderate training volume, increased explosive performance requiring fast SSC actions, maximal dynamic strength, and training efficiency.
After 7 weeks of plyometric training, performance enhancements in actions requiring maximal strength and fast SSC were dependent on the training surface and training volume.
The hardness of the training surface used during plyometric training has an effect on training adaptations. When a reduced volume of plyometric training is combined with a relatively hard training surface, it may represent an optimal stimulus to induce significant neuromuscular adaptations.
The study found, over a 7 week period of plyometric training, using only Drop jump exercises in non-trained adolescent males, only high plyometric training volume (240 jumps per week) induced a significant increase in sprint performance. Also, only a hard plyometric training surface induced an increase in maximal dynamic strength performance. Although both, a high plyometric training volume and a hard training surface had an effect on Drop jump performance, only the hard training surface induced an increase in fast SSC muscle action after high drop jump height and proves to be highly efficient to induce performance adaptations.
The study shows that different plyometric training volumes and surfaces are associated with different explosive strength adaptations. The data is convincing in its conclusion that moderate plyometric training volume i.e. 60 jumps per session or 120 jumps per week, would not induce an increase in sprint performance, instead, a high plyometric training volume of 120 jumps per session or 240 jumps per week, would be necessary to induce an increase in acceleration sprint i.e. 20m.
The study indicates that when moderate volume is used during plyometric training, a hard training surface would be needed if adaptations in fast SSC muscle actions, or reactive strength, are an important objective of training.
The data suggests that, compared to a high plyometric training volume completed on a soft surface (athletic mat), using a moderate plyometric training volume on a hard surface (wood gymnasium floor) would double the efficiency of adaptations in reactive strength. In others words, a high volume of training would not be necessary to induce reactive strength adaptations when a hard landing surface is used.
Its important here to stress that these results do not support the notion of “more is better”. Using a harder surface, and lower plyometric training volume, significant (and time saving) explosive strength adaptations can be achieved.
Concern has often been expressed by researchers with regard to the training surface used during plyometric training because of its speculated high harm or injury risk. To the best of my knowledge, when controlled (monitored/supervised) plyometric training takes place, no significant injuries have been reported. In fact, plyometric training had been advocated as a preventive injury strategy and even as a rehabilitation tool.
Learning to jump and to land
It is advisable to follow a progression when it comes to teaching jumps and subsequently plyometric training. I would advise starting with relatively uncomplicated single effort jumps, with emphasis on landing technique, monitoring ankles, knees, hips and torso. Athletes should learn to land softly and in a stable athletic ready position before being progressed to more complex types of jumps and/or plyometric exercises.