The Anatomy of a Punch
Throwing a punch is usually thought of as an upper body movement but it is actually full body movement that starts from the ground up. The force used to deliver a powerful punch begins from the feet – when we push into the ground, the ground pushes back into us, followed by a sequence of muscular contractions that transfers force up our kinetic chain until our fist hits our target. The transfer of force happens quickly through a series of rotations and torques from the foot, up the legs and thighs, through the trunk and core, and finally out through the shoulders and arms. Every type of punch, whether it is a jab, cross, hook, or uppercut, is delivered the same way, only with slightly different emphasis on different muscle groups. Read further for the complete breakdown.
The muscles of the shoulder are key players that deliver the punch, but also for taking the brunt of the impact. The anterior deltoid along with the pectoralis major, the muscles of your chest and shoulder, project your arm out towards your target. The smaller muscles behind your shoulder, the rotator cuff and scapular stabilizers such as the serratus anterior, help dampen the impact forces that act on your shoulder. Adequate shoulder strength and health is key for delivering repeated strikes without injury and wear and tear. Lastly, the middle trapezius, rhomboids, and latissimus dorsi are used to pull your arm back to get ready for another strike.
The triceps brachii is the main muscle involved in extending the elbow straight out. The biceps brachii performs the opposite motion, bending the elbow or cocking back to get in position to throw another punch.
The muscles of the forearm are primarily used to make a fist and also as stabilizers during a punch to keep the wrist straight. The wrist flexors are on the palm side of the forearm close the fist and stabilize the wrist. The extensors are on the back side of the forearm and also stabilize the wrist. Keeping a straight wrist is important for efficient delivery of force but even more important for staying healthy and able. Impact without a straight wrist can quickly injure the small ligaments of the wrist.
The core or trunk muscles are a key segment between the upper and lower body. The rectus abdominis, the muscles that appear as the “six pack” muscles, keep the ribs and pelvis stacked (with the gluteus maximus) like a barrel instead of an open scissor. The internal and external obliques are responsible for transferring rotational force without any energy leaks by having the rib cage and pelvis turn as a unit.
The muscles of the hips, particularly the gluteus maximus, are the engine of the lower half of the body that turns the hip. This allows rotational force to start to direct forward, which is why it is so important to turn from the hips. It also helps keep the pelvis tilted posteriorly to aid transfer of force from hips to abs.
The quads and hamstrings help transfer force from the knee to the hips. The hamstrings will also help in controlling rotation through stability of the lower leg.
The muscles of the lower leg, particularly the calf, begin the chain of muscular contractions that end up in a good punch. The large gastrocnemius and soleus generate power up the chain while the deeper, smaller leg muscles stabilize the foot to make energy transfer efficient and prevent leaks – a theme we see throughout the body.