Originally Posted by
milkbaby
I think this same result has been found in other studies as well. On normal bike cranks, nobody is really pulling up enough to generate an upwards force on the "backstroke" of the pedaling motion; you are just lessening the amount you are pushing down, and that's why people call it "unweighting" the upwards traveling leg/foot. The force diagram shows that the foot is still pushing downwards on the backstroke... This is not to say that single leg pedaling drills are not worthwhile either...
Yes, no one is pulling up (hard/with a lot of power) normally. I think it might not work that well at a high cadence anyway. Biomechanically, legs are much more powerful pushing than pulling, which implies that not a lot of pulling is going to happen.
Humans unweight (lift) their legs all the time (when walking and running), which means the muscles for doing that task are well-developed.
If you can unweight the non-power leg, the power applied on the downstroke is going into moving the bike rather than some of it being used to lift the other leg.
Considering that (generally) the maximum power that you can apply is about your body weight, the extra propulsion power you can apply by lifting the non-power leg is about leg-weight/body-weight more (which isn't trivial).
Many riders don't lift the non-power leg.
It seems it would be hard to apply a lot of power on the upstroke routinely (and it might not be so good for your joints).