CliffordK

That is absolutely false.

When pulling up while standing, the force pulling up is added to the force pushing down... So you essentially get DOUBLE the force/power from pulling up.

While sitting, it is unclear. Some of the quoted papers seem to fix the energy output, and even the RPM, so one would expect a tradeoff, add power in one place and loose it elsewhere.

Your body will have two different types of effort, both are necessary in cycling. There is an endurance level, maintaining effort for hours of cycling. This may be somewhat cardiovascular limited, so it would not be unexpected to see tradeoffs. Add power in one place and loose it in another.

The other type of effort is sheer anaerobic power. Here you wouldn't necessarily expect to find any trade-offs, and should expect to see gains by using more muscle groups.

Perhaps a third type of effort is that related to a cumulative muscular fatigue. As I find myself plodding along, I find that I just don't have much extra to push into the downward muscles. However, if I haven't been pulling up for some time, those muscles may be fresh, and good for an extra short boost of energy.

The final element is that horsepower is a rating of power + time. With cars, one often finds a little tiny engine spinning at extreme speeds can match the horsepower of a big engine spinning at slow speeds. In cycling, once one starts maxing out the downward forces, then one must either spin faster, or pull up.