There are many variations to the traditional push-up, each designed to work your body differently. In the knuckle push-up, you assume the basic push-up position, bringing your hands on the floor below your shoulders; they should be a bit closer in than with regular push-ups. Instead of using a flat hand on the floor, make a fist and balance on your knuckles. Popular with martial artists and boxers, this type of push-up works your arms, wrists and shoulders in a different way than traditional push-ups.

Wrists Knuckle push-ups require you to hold your wrist straight instead of bent. This puts more pressure on the wrist to help it support the weight of your body, making your wrists stronger. This helps keep you from breaking your wrist if you fall; when you break your fall with your hand, a weak wrist can snap easily. Strong wrists also are essential in fighting sports. Landing hard punches or off-center punches can sprain your wrist if the muscles aren't powerful.

Forearm Traditional push-ups work your upper arm and shoulder muscles, but performing the exercise on your knuckles moves part of the workout to your forearms. Making a fist requires you to contract your forearm muscles, which then remain contracted to help hold your wrist steady and keep your balance on the smaller surface area of your fist. This helps define your forearm muscles and improves your gripping strength.

Chest and Triceps Knuckle push-ups require you to bring your arms in slightly, keeping them immediately below your shoulders. In traditional push-ups, your hands are spread slightly wider than your shoulders. Even though the positioning difference is minor, it works your chest and triceps muscles differently than traditional push-ups. It brings some of the workout from your back to your chest, building those muscles. It also bends your arm at a slightly different angle, working more of the triceps. The triceps get additional work by helping balance the upper body on the small surface area of the fist.

Painful Wrists If the base of your hand and your wrist hurt after traditional push-ups, knuckle push-ups can help relieve the pain. When you perform the wrist extension by flattening your hand, weak tendons and muscles can pull and become sore. Knuckle push-ups keep your wrists straight, reducing pain from weight-bearing wrist extensions.