Q: Isn’t it true that you activate the most muscle fibers in the flexed position, like at the top of a leg extension or leg curl? I know that [Nautilus creator] Arthur Jones said that. So shouldn’t I really flex at the top of those isolation-type exercises? Come to think of it, why should I do compound exercises [like squats] at all? Isolating the muscle appears to be the logical way to stimulate the muscle growth best.

A: We respect the late Arthur Jones and value much of his research, theories, and opinions (Steve met him many years ago in Florida); however, newer research states the contrary—that the contracted, or flexed, position of an exercise is not where the most force/fiber activation occurs—it’s the bottom, where the target muscle is somewhat stretched. Here’s a quote from respected scientists Steven J. Fleck, Ph.D., and William J. Kraemer, Ph.D., that makes the point (we’ll put their statements in simpler terms in a moment): [Read more…]