Uh, wrong. On subjects like this, I try not base my opinion on studies done by persons I do not know, on other persons whom I also do not know. I base my opinions on personal experience and first person discussions with other persons.

When out of the saddle, I sometimes pull up so hard on the upstroke, I lift the rear wheel right off the ground. That's what your heel cups are for. If you watch videos of Lance, you can see he uses his heel cups the same way. When loaded, Stoker and I will do the same thing to get over a little steep hump without gearing way down. We can do the same thing seated. It's very effective when one needs some extra power. When a bit out of shape, I cramp as frequently in the hams as in the quads. In fact, if I cramp my quads, I can pedal very effectively by using only my hams, no quads at all. Or switch off between them.

The fact that most people have an inefficient pedal stroke shouldn't stop one from developing a very efficient stroke. An efficient stroke is perhaps the main thing that's kept me riding with people 20 or 30 years younger than I. So I preach the gospel to anyone who'll listen. The way to get faster and ride easier farther is to use more of the muscles in your leg. That way, one can develop more power for short periods and tire more slowly. Spreading out the work among one's leg muscles is more efficient, even when one is aerobically limited, as on a long climb. What one wants to do, regardless of what each leg does, is to apply constant torque on the bottom bracket. That way there is no acceleration applied to the bicycle by any individual pedal stroke or part of a pedal stroke, and thus no wasted energy. So talking about force on the downstroke or upstroke is partly a distraction because it leaves out half the pedal stroke.

This is how one does what I and many other cyclists have found to be the most efficient, with each foot, starting at top dead center: push forward as though trying to kick a dog on your front wheel, then in the first part of the downstroke, let your leg weight come down with little apparent effort, then at about 120° begin pushing down and back, continuing the back pressure through to 210° or so. The bottom part of the stroke is very important because your leg is almost at full extension and your muscles have good leverage on the pedal. Continuing to pull back into the start of the upstroke makes up for not really pushing down at the start of the downstroke. On the upstroke simply unweight the leg, with the feeling of trying to throw your knee over the handlebars. Just before your knee stops its upward motion, begin pushing forward, thus applying torque at the top of the upstroke, and carrying that forward push into the start of the downstroke.

I've attached a graph showing the approximate desired force inputs into each crankarm. Adding the two torques together produces approximately the straight line at the top of the graph. Notice that probably half the total torque shown on this graph cannot be applied with platform pedals, needing either clips or clipless to push forward and pull back.

One-legged pedalling is one of the best ways to improve your efficiency, and is best done on trainer, rollers, or on a climb, being too easy to do on the flat.