Explosive strength means that an external load is overcome with a high contraction speed. Therefore, fast strength is the ability to free maximum of strength within the shortest possible time. The difference with regard to the maximum strength is that the motion must be carried out as fast as possible.

On the level of muscles, this sort of strength has to do with the number of myosin heads that can be turned down simultaneously and in case of fast strength, can recover again. A high jumper has one moment of time after the run-up in which he transforms the forward strength of the run-up into height. This moment is when he jumps.

With conventional training methods, a high jumper has to rely on a lower resistance than what he is able to maximally lift, because otherwise a high acceleration is not possible anymore. This can be compared with a car that wants to accelerate. As soon as the car is loaded to the maximum, it is harder to get it accelerated. The resistance in combination with the acceleration eventually define the effort of the high jumper, which is maximum effort.
With conventional training methods he is not able to do many repetitions, since he cannot supply the maximum effort ones he gets tired. That’s why a fast strength athlete trains with a minimum number of repetitions in order to have more time for resting (recovery 3-5 minutes), so that the muscles can recover completely.

With vibration training, the recruiting threshold of the motor units is lower than during voluntary contractions (as in conventional trainings), which probably results in a faster activation and training of the motor units with a higher threshold (type 2 muscle fibres, also called fast twitch muscle fibres).
Athletes training explosive strength therefore have a great advantage with vibration training. It takes less time, the load on the passive organs is low and the efficiency is high. The research sited below shows that the efficiency of vibration training is at least as high as in conventional training methods.

Research

In 2002, prof. S. Torvinen did research into the effects of vibration training on the explosive strength and the maximum isometric strength after two and four months.
52 Volunteers divided into two equal groups took part in the study. The first group of 26 people (17 women, 9 men) underwent vibration training and the second group of 26 people (16 women, 10 men) did the same exercise without additional vibration.
The training was built up in a way that during the first two weeks, only two minutes of training in a slight squat position was done. The first minute was trained at 25 hz, the second minute was trained at 30hz.
During the remaining six weeks, the extent of the training was increased to three minutes with an additional minute of training at 35hz. During The last two months, one minute at 40hz was added. This means that this research made use of a minimum effort.

The explosive strength was measured by determine the time after a moment of short floor contact between two jumps. The time measurement started after the jump and stopped after the landing, which made it possible to calculate the height.
The maximum isometric strength of the leg extensor was measured with a standard dynamometer. The participants sat on a chair with their knees and ankles bended 90 degrees while they where supplying a maximum strength effort. The dynamo registered the number of KG that were pushed away.