[nonameiguess]

Doesn't exactly seem like a particularly well-validated model at this point. Given they're saying muscle speed is limited by the speed at which water can move through the muscle, pushing more water through the same sized tube takes longer, so that would seemingly mean anything that caused greater water retention would slow you down.

But obviously that breaks down pretty quickly. You can't make yourself faster by dehydration. Your body maintains the water level it does for a reason. Catalysts and enzymes need to exist in specific concentrations to work best. Presumably, you retain extra water when taking creatine because creatine's role in catalyzing ATP production relies upon being at a specific concentration and more creatine means you need more water. But even if that excess water slowed down the maximum theoretical rate at which a muscle could contract, muscles that contract are also limited by the availability of ATP. If creatine is doing its job, then you'd have more available more quickly. You can contract faster with available energy than you can with no energy. You can't just isolate a single factor in muscle contraction and intervene in that without having other effects on the same complex, multifactorial process.

[xarope]

Right, tell the hordes of olympic weightlifters, boxers etc deliberately losing water to make weight, that they should lift/fight at that depleted state. They'd probably collapse after the first lift/minute or cramp like crazy.