Push-ups, also called press-ups, are calisthenic exercises that use the body weight of the person working out to provide resistance. You lie in a prone position, face down on the floor, with your hands below the shoulders and placed flat against the ground, palm-down. You keep the body in a straight position with the weight on the toes -- or knees, in the case of a "female" or modified push-up. You use your arm and chest strength to press yourself up, then lower the body to the starting position and repeat. Push-ups work the pectoral muscles and the triceps muscles as the primary muscle groups used, with secondary benefit to the coracobrachialis, the deltoids and the serratus anterior.
Weight
Push-ups are the original bench press and use similar muscle groups, although the mechanics are very different. Many people prefer to use the bench press to work these muscles because they can put a number to the weight they are capable of lifting, and push-ups don't provide a specific number. Yet there is a way to estimate the amount of weight being lifted in a push-up.
The Math
According to the American College of Sports Medicine, a woman doing traditional push-ups lifts approximately 71 percent of her body weight; a man lifts approximately 77 percent. A woman performing modified push-ups from her knees lifts about 55 percent of her body weight; a man lifts approximately 56 percent. That means a 140-lb. woman doing traditional push-ups lifts about 99 lbs., and in modified push-ups, she lifts 77 lbs. A man who weighs 170 lbs. doing traditional push-ups lifts about 131 lbs.; with modified push-ups, he lifts about 95 lbs.
Reasoning
Males usually lift more of their body weight during a push-up because of where their center of gravity is and how much bulk they carry in their shoulders and chest. More weight carried over the arms means more weight lifted during a push-up. Women lift less compared to men because they carry more weight in the hips and thighs and less in the chest and shoulders. That makes their center of gravity lower, which puts more weight on the knees or feet rather than what's lifted in the push-up. Modified push-ups keep more weight on the knees instead of being lifted by the arms. Large-chested women lift more of their body weight, and men with more weight centered on their hips lift less than the numbers stated.
Testing
Another way to figure out how much weight you lift during a push-up involves the use of a bathroom scale and basic math. Assume a push-up position with your hands resting on the scale. Write that weight down, then the weight from a modified push-up position, then your full weight while standing on the scale as you would normally weigh yourself. Divide the weight recorded while in push-up position by your full body weight. For example, if your push-up weight is 108 lbs. and you weigh 150 lbs., you're lifting approximately 72 percent of your body weight during push-ups.
References
- American College of Sports Medicine, Strength Training Guidelines, 2008
- American College of Sports Medicine, Resources for the Personal Trainer, 2007
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