A jogger who bounces up and down while running is said to waste more energy than a jogger with a smooth stride whose center of gravity remains at about a constant elevation Why?

Answer 1

For each little 'bounce', the runner has to expend the energy to raise his weight by those few inches ... which gravity immediately reverses as it pulls him down to his original elevation. None of this adds anything to his forward progress. So in the course of the same forward distance, the bouncer expends more total energy than the guy who keeps his center of mass at a constant elevation.

Answer 2

When a jogger bounces up and down, they are expending extra energy to move vertically as well as horizontally. This extra vertical movement increases the work required and can lead to a less efficient stride. A jogger with a smooth stride maintains a more consistent center of gravity, requiring less energy to move forward and leading to better energy efficiency.