You want to jump higher, you got to get stronger. That much we know. Or maybe we don’t. In any case, jump technique doesn’t actually get you very far according to the best study on the subject. Most of the difference in vertical jump ability between athletes is a result of strength and power differences, and only to a small degree technique (Vanezis, 2005).
So that means you need to train, but how much? There has actually been a fair amount of study of how much plyometric training is enough and how much is too much. Remember,
The objective of plyometrics is to generate the greatest amount of force in the shortest amount of time…. Plyometrics trains the nervous system and metabolic pathways to increase explosiveness, giving the athlete an extra push to move higher and faster (Griner, 2003).
Beyond a certain amount of training, though, you just can’t push hard enough anymore and explode to maximum effect. So you need to be fit enough to handle a minimum volume, but there’s no point in exercising beyond a certain point because the amount of benefit starts to trail off.
The biggest study of plyometric jumping programs determined with respect training volume that the most effective jump program would have these characteristics:
- More than 10 weeks. Change doesn’t happen instantly and even programs of seven weeks seemed to not allow enough time for serious gains in vertical jump.
- More than 20 sessions. In other words, twice a week or more. Another recent study found that four sessions per week did lead to more benefit than two sessions, but not a lot more. So that implies that one should not do jump training for more than four sessions. So your program should include at least two plyometric sessions per week, but not more than four sessions.
- More than 50 jumps per session. It doesn’t sound like much. After all, you can do 50 jumping jacks in way less than a minute. But remember, your plyometric program focusses on maximum effort jumps. So if you’re not fit, you may not be able to give 50 or 100 truly explosive jumps in a session. So this implies a basic fitness level so that you can do 50 or more good jumps per session.
- More is not better. Training beyond your capacity to maintain max force and thus max quality may not really do much good. In other words, doubling the work suggested here will not mean doubling the results. At a certain point, it may be decreasing results. One study looked specifically at programs that included one day, 2 days and 4 days per week of plyometric training. The researchers found a substantial difference in vertical jump and sprint times between the one day per week and two day per week groups. But, "the magnitude of increases in the vertical jump was the same for both the 14S [2 days/week] and 28S [4 days/week] training groups, despite the fact that the average number of jumps accomplished in 14S (840 jumps) was 50% of that performed in the 28S (1680 jumps)."
So when developing your program, you need to do a certain number of jumps to get decent improvement in vertical leap or sprint times, but you also need to focus on workout quality rather than quantity.
- Athanosios Vanezis and Adrian Lees, "A biomechanical analysis of good and poor performers of the vertical jump,", Ergonomics, vol. 48:11–14 (15 Sept – 15 Nov 2005), pp. 1594–1603. Specifically, they say "The performance technique appears to be a less important factor, although there is evidence to suggest that it plays a small role."
- Brenda G. Griner et alia, "Plyometrics, or Jump Training for Dancers," The Sport Journal, summer 2003, vol. 6:3.
- Eduardo Saéz-Saez de Villarreal et alia, "Determining variables of plyometric training for improving vertical jump height performance: a meta-analysis," Journal of Strength and Conditioning Research, 2009, vol. 23:2, pp. 495-506.
- Eduardo Saez-Saez De Villarreal et alia, "Low and moderate plyometric training frequency produce greater jumping and sprinting gains compared with high frequency," Journal of Strength and Conditioning Research 22: 715–725, 2008.