Originally Posted by cubewheels

It helps engage the glutes and also happens naturally when your legs are very tired / fatigued (instinct to relax the tired calves, the toes starts pointing up). It's not necessarily more efficient, just the body switching to different muscle groups to help save tired muscle groups from injury.

I've read that tour riders probably from Steve Hogg or another pro fitting article lower their saddle height as the tour progresses as they start pointing their heels down (toes up) from fatigue.

You'll notice Marco have down pointing toes pedaling style in his popular Giro video with chain dropping incident. His legs are probably fresh in that video compared to his race with Lance



Absolutely. Using your glutes in a greater degree during the power stroke will more strain on the core muscles.

I found that if the core muscles starts to hurt, simply disengage your glutes and hamstring from the pedal stroke and concentrate only using quads and calves (sitted) and your core muscles will recover.

A predominant quad and calf "driver" will seldom hurt their core even if their core is not very strong. Using the glutes+core with the quads and/or calves will allow you to push down on the pedals with a force higher than your own weight. Quite advantageous in some disciplines like track sprinting.
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