The push-up exercise may just be the perfect workout. Although it focuses on two muscles, all your muscles must work to move your body up and down as you hold your own weight. It is an amazing upper body exercise and an excellent total body workout, challenging your core at all times. If performed regularly, push-ups will promote muscle endurance and overall fitness.
The push-up exercise requires the recruitment of many muscles, but there are two primary movers. The chest muscles are the first primary movers and include your pectoralis major and minor. Imagine a Japanese hand fan rotated 90 degrees with the top of the fan pointing toward your sternum and the bottom of the fan pointing out to you upper arm bone -- the humerus. This orientation of the fan represents the shape and location of your pectoralis major. The pectoralis minor is a cross section of the fan and is angled 45 degrees, up toward your shoulder.
The triceps, which consist of three heads -- lateral, medial and long -- are the second primary movers during the push-up. The long head commences at your scapula and inserts into your elbow. The lateral head spans the length of your humerus bone and the medial head, which is slightly shorter, sits underneath the lateral and long heads. Together, the three heads extend or straighten the elbow. On the way down, your triceps eccentrically contract and lengthen, and on the way up they concentrically contract and shorten.
Stabilizers: back body
The push-up demands a lot of muscle stabilization as you lower and lift the weight of your body. Your erector spinae group is the main stabilizer of your back. It is made up of three muscles: spinalis, longissimus and iliocostalis. The spinalis runs adjacent to your spine, the longissimus runs adjacent to the spinalis, and the iliocostalis runs adjacent to the longissimus and over your ribs. Two small butt muscles called the gluteus medius and gluteus minimus stabilize you your upper leg bone -- the femur -- inside your hip joint. The medius and minimus sit underneath the largest butt muscle, the gluteus maximus.
Stabilizers: front body
The stabilizers of the front body include your deltoids, abdominals, pelvic, quadriceps and shin muscles. Your deltoids cover the front, side and back of your shoulder, stabilizing the humerus bone inside your shoulder joint. All four abdominal muscles support your torso and prevent hyperextension of the lower back. The iliopsoas tilts your pelvic back, also preventing hyperextension. The quadriceps keep your legs straight, and the tibialis anterior -- which spans the length of your shin -- aides in the flexing of your ankle -- or dorsiflexion.