August Krogh

It is no doubt technically possible to study metabolism and respiration of fishes during swimming at a constant rate, and of certain insects and birds during flight, and to obtain information similar to that obtained on man during work on a bicycle ergometer or a treadmill.

Flexibility is crucial to my fitness. Incorporating a good warm-up and cool-down into every session decreases my chances of injury. I use both dynamic and static stretching in my training. I've starting doing a few yoga sessions which incorporates muscle strength and flexibility.