Originally Posted by
koala logs
If these cyclists are recruiting their muscles in similar manner to your charts, then they're wasting a significant amount of effort from around 180 to 360 degrees of the crank angle. You'll see the pull up force they make on the upstroke is very little to matter at all and they can only pull the pedals up at low cadence (60 rpm) which is not really an efficient cadence especially for long distance riding.
Experienced cyclists recruit muscles in roughly the same way, at roughly the same point in the pedal cycle. And no, they are not "wasting effort". Almost all of the muscle effort in the 270º-360º pedal range is the quads flexing the hip, thus lifting the leg and unweighting the pedal.
A single leg is heavy (~20% of total body weight), and by lifting it the cyclist unweights the upwards moving pedal. Consider the extra effort that would be required to move the cranks if that leg was not being lifted on the upstroke.