Source: Harvard University
The push-up engages your body from top to bottom. It works several muscle groups at once: the arms, chest, abdomen (core), hips, and legs. Push-ups also can be modified as needed. “By adjusting the speed you perform a push-up, the angle of your body, and even hand placement, you can add more or less intensity, or focus on specific muscles,” says Dr. Phillips.
A study published in the February 2016 issue of the Journal of Physical Therapy Science found that the chest muscle activity was greater when push-ups were performed with the hands placed halfway inward from their normal position. Hands placed outward work the triceps more.