Kebba,
I think Ralph was missing the point on arm action in how it relates to leg speed. Arms and legs in my opinion are:
(a) Have the same wave length.
(b) Have feedback loops that monitor timing of the other to ensure that the wave lengths are the same. Example of this can be seen when Carl ran a 19.75 with his hands in the air. He did slow down but his legs fired at an near maximal rate showing that they have individual wires but top performance must have both limb sets firing at max speed.
(c) Th Arms receive the information faster then the legs do because the feeback centers for the legs must register feed back of ground contact to ensure balance. The arms have the role of cordinating balace as well based on feedback from the cerebellum, not the ground. This might explain the lag time at the end of the stroke that Mike speaks of.
(D) Evolution turned the the fore limb into an arms. This change was given as a priority for homo erectus and sapien. This might explain the fiber type differences between various muscle combos having more type II fiber in the upper body.
(E) I agree with Charlie that the arms fire first, but they must wait the legs to catch up or you will fall on your face. This is something must be involved with coaching. The arms shift you at speeds but the motor (brain) limits the RPMs per gear. This is monitored by the tendons in the calf and fibers of the glutes and hamstrings.
(F) Research is clear that arms do increase wattage in jumping, but very little research is present on max speed work. I would like someone to go 12mps with no arms. It can’t be done no matter how much leg power they have.