Spring theory & Bolt

[pakewi]

@pierrejean

Yes, the air time is the same when comparing a fast group and a slower group of sprinters (although they are huge individual variations). But it doesn’t mean that their legs are moving at the same speed through the air! In fact, faster sprinters tend to accelerate their legs at a higher rate and hit the ground at a faster speed than slower sprinters.
Comparing Bolt’s mechanics at 65% and 100% of max speed, I have found that the leg was x2 faster just before hitting the ground, and even more significant was that he was accelerating his leg towards the ground x3 more at 100% max speed. Basic maths will tell us that: if force = mass * acceleration, the mass of the leg remaining the same, the force will be x3 bigger.

If we only moved during training and our daily routines accelerating and not resisting gravity as we are designed for…