How to Use Data to Maximize Power Development and Guide Safe Training Progression in Plyometric Jump Training

Plyometric jump training is one of the most effective methods for developing speed and power in many sports. But how do you know if you’re jump training is effective and safe for your athletes?

In Part 1 of this 2 part series we discussed the theory behind safe and effective Plyometric training. Now in Part 2, we will highlight how objective measurements can be used in the daily training environment to ensure the correct use of Plyometric training in your program.

Goals of Plyometric Training

Plyometric training, including jump training, is a great way to maximize the speed and power of your athletes. If you are going to use “plyos” in your program however, you need to make sure you are using them safely and effectively.

Using repeated jump training exercises as an example, the main goals should be

1. To maintain the correct ground contact times to ensure movements are performed within the ‘window’ for maximizing use of the stretch reflex, without generating potentially dangerous amounts of force and
2. To jump as high as possible for a given ground contact time, providing specific overload to increase power production during fast movements.

What is a Good Contact Time?

In 1992 Researcher Dietmar Schmidtbleicher explained that there are effectively two phases to the stretch-shortening cycle (stretch reflex) that is paramount to plyometric training. A fast component, where contact times should be less than 250ms, and a slower component where contact times can be up to around 350ms. If your goal is to specifically target activities such as sprinting, then you really want to focus on the left side of the curve, with contact times around the 80-120 millisecond range.

Coaching Good Contact Times

As you can see, there is a very small difference between what is right and wrong in plyometric training. To maximize benefits and minimize injury risk, you need to ensure your athletes are hitting the appropriate contact times for the exercise they have chosen. If they can’t, then they should probably stop doing the exercise.

Making judgements of 50 milliseconds one way or the other is challenging with the naked eye, even for an experienced coach. Even if you can “spot a good contact”, it is then often very hard to communicate this to the athlete and have them truly understand what a good contact time should feel like.  I’m sure we have all used cues like “imagine you are jumping on hot coals” to try and get athletes to understand the importance of getting off the ground as quickly as possible.

Technology to the Rescue: Making it Objective

When we first developed our SMARTJUMP system the focus was mainly on testing jump height. We soon realized however that contact times between jumps was something that could be used to aid in coaching.

We then found that whilst telling an athlete after their set what their contact times were, it still wasn’t completely effective – the athletes would often struggle to understand how much they needed to adjust. So we then added a real-time feedback function, whereby the coach could put in a goal contact time depending on their target exercise and while the athlete is jumping, they can get immediate feedback from the unit – even while they were in the air between jumps. So within a few milliseconds of leaving the ground, they had real-time feedback on the contact time they had just made.

This was the real breakthrough point. Not only were we now able to measure the contact time very accurately, but by providing real-time audio and visual feedback, the athletes could actually “get a feel” very quickly for the right contact time, and within 1-2 sets of trying, they were “in the zone” for that exercise. By offering the feedback immediately in a really simple form (green is good, red is bad), athletes could use trial and error during a set to figure out what a good contact should feel like.

Here’s the Catch: Focusing on Contact Time Alone is Not Enough

When we started using SMARTJUMP with athletes, we quickly found that athletes could stay under the desired contact time quite easily – if they didn’t try to jump as high as they could. Whilst nice and safe, the training effect was lost because there was no longer overload on the muscles to produce power.

So, we added secondary feedback – not only providing feedback on the contact time, but also on the power that was generated during the contact time. As you will see in the following video, the athlete now receives instant feedback during the jump set on both the contact time quality and the jump power or height.

The goal of training over time should be to either maintain contact time or increase power output (jump height) or to decrease contact time while maintaining power output and jump height.

Summary

After 10 years in the market there are many client examples of the use of SMARTJUMP feedback in training on Youtube and we have assembled some great examples below. We have worked with a variety of clients and athlete groups from young children through to the world’s highest paid athletes and we have seen them use plyometric training safely and effectively throughout all stages of the training year, even leading into grand finals.

The key is simply to ensure that plyometric training is all about quality and not quantity . If you don’t have access to objective technology like SMARTJUMP, then you need to start with fast contact time activities and really focus on being fast off the ground before starting to introduce load or combined focus on power and height. Using technology which is objective provides the added benefit of being able to get your athletes hitting the desired targets immediately and without subjective doubt, allowing for progression to occur more quickly yet still in a safe manner.

References

Schmidtbleicher D (1992) Training for power events. In: Komi PV (eds) Strength and power in sport. Blackwell, London, pp 381–395

Fleck, S.J. and Kraemer, W.J. (1997) Designing Resistance Training Programs. 1^st Edition. Human Kinetics, Champaign, Ill.