Gymnastics tumbling is generally about “punching” not jumping. It is primarily utilizing the stretch reflex in our musculature instead of the concentric contractile action. This stretch reflex matched to the timing in the spring floor can send gymnasts skyward. If their positions are also spot on then movements that appear impossible can occur. Steven Legendre is one of the premier examples of this. His power is incredible. I discussed Steven’s power output in “Extreme Power Applied”. The key point here is a tremendous amount of this power comes from the stretch reflex. This type of muscle action is incredibly powerful and incredibly efficient.
The stretch reflex is effectively utilizing a muscle as a spring. There are mechanical losses, but it is an amazingly efficient action. Muscles are far less efficient than a well made spring at returning energy put into stretching them, however they can do something that a spring will never do. They can add energy to the system on the rebound. This allows us to bounce higher than an initial drop. There is an awful lot of mechanics that go into this additional energy. Some is from the stretched muscle itself, some is from mechanics of other muscles and body parts pre-stretching to enable a high energy rebound. Whatever the mechanisms we want to utilize these forces whenever possible.
There has been a tremendous amount of debate on the mechanics of punching in the gymnastics community. For a while there were two camps. The straight limb camp, and the bent limb camp. Many were arguing that optimal tumbling power was going to come from straight arms and straight legs. High frame rate video analysis of the best tumblers in the world would certainly indicate otherwise. There is a slight bend in anticipation of contact with the tumbling surface and a rapid extension to meet the surface to block away from it. Many coaches still direct toward straight limbs even though they know some minor bending will occur. Most athletes will intuitively bend and prepare for the floor if they are trying to keep their limbs straight. Excessive bending results in “mushy” tumbling and a significant loss of power.
Look at the mechanics of various jumps. There are significant differences in what physiology is at play depending on approach, surface and athleticism. It is fascinating to see how many different things the human body can do.