Push ups mainly work your chest muscles (pectoralis major and minor) and your triceps. These are the key muscles used every time you do a push up.
Push ups also make your shoulders, core, and back muscles work to keep your body straight and strong during the movement.
The chest muscles, known as the pectoralis major and minor, do most of the work when you push your body up from the ground. This makes push ups a great exercise for a stronger, bigger chest.
The triceps at the back of your upper arms are responsible for straightening your elbows as you push up. They get stronger with every set of push ups.
The front part of your shoulders, called the anterior deltoids, help guide your arms during the movement and provide stability.
Your abdominal muscles and obliques work hard to keep your body straight, stop your hips from sagging, and protect your lower back.
The serratus anterior, located under your armpits, and upper back muscles help keep your shoulder blades stable and your posture correct while doing push ups.
Your glutes (butt muscles), leg muscles, and small muscles along your spine tighten so your body moves as a single unit. This means push ups are almost a full-body exercise.