Leg weights

Exactly. My point entirely.

But thats speculation, Yeah? Bolt doing squats & heavy weighted ab work. Or is that fact?.

The core/hip flexors are the powerhouse to limb speeds (IMO). Not glute, quad & ham strength (Squats etc).

If your running sub 10’s, your qualified to say that.

For the general, yeah squatting 400-500 will probably make them run faster. But from what I’ve witnessed this isn’t the case.

No doubt!.

Just too conclude. I was doing weighted ab work for almost 2 years straight & I was in denial all along believing I was strong there.