And where did the speed of the swing leg come from? The air?
You really think that Bolt is faster, or one reason he is faster than other, and previous world class sprinters, is because he has better spinal posture while running??
And power is an expression of strength.
You just described 99% of world class sprinters. Once again, you seriously think that Bolt’s technique is THAT much better than EVERY OTHER PERSON WHO HAS EVER SPRINTED??
Whether Bolt has a serious attitude or not in the weight room is irrelevant. What is relevant is that he is a large, muscular sprinter.
Usain Bolt, 20 second plus 200 meter:
Usain Bolt world record holder in multiple events:
Naive is believing the only difference between those two sprinters is their technique.