What Joint Is Working When You Do a Squat?

Although the squat is a compound, multijoint exercise that strengthens the entire body, it principally works the hip, knee and ankle joints. Squats target the muscles that extend those joints, including the glutes, hamstrings, quadriceps and calves. You can perform this versatile exercise using just your body weight or with added resistance such as a barbell or dumbbells.

Squatting

To perform a squat, stand with your feet a little wider than hip-width apart, with the toes pointed out slightly. Keep your spine extended and your chest lifted as you push your pelvis back, bending your hips and knees simultaneously. Track your knees in the direction of your toes. Keeping your heels grounded, lower your hips until your thighs are parallel with the floor. Press through your heels into the floor to stand up, returning to the starting position.

Hip Joint

The hip joint and hip muscles are a primary focus of the squat. As you descend, your hip joints flex, stretching the hip extensor muscles, particularly the gluteus maximus muscle of the buttocks as well as the hamstring muscles on the back of the thigh. The hip joints also abduct slightly as the thighs widen apart, lengthening the adductor muscles of the inner thighs. When you stand up, the gluteus maximus and the hamstrings extend the hip joint powerfully. The adductors aid the hip extensors by drawing the thighs toward each other.

Knee Joint

The knee joints and their associated musculature also work during a squat. As you lower your torso, your knees flex, lengthening the quadriceps muscles on the front of your thigh. When you stand up, the quadriceps contract, extending the knee joint. The alignment of your knees is crucial in squatting. Allowing your knees to collapse inwardly or pushing them too far forward past your toes can stress the knee joints and lead to injury. Keep your knees aligned in the direction of your second toe, and do not allow them to travel forward past your toes.

Ankle Joint

The ankle joints also play a role in squatting. As you lower into a squat, your shins tilt slightly, an action of the ankle joint called dorsiflexion. When you stand up, your shins move back as your ankles plantar flex. Two of your calf muscles -- the soleus and the gastrocnemius -- are responsible for the action of plantar flexion. Tightness in your ankle joint or calf muscles can limit your ability to dorsiflex your ankles as you descend into a squat, making it difficult to keep your heels grounded. To stretch your calves, stand with the balls of your feet on a step, holding the railing or other support for balance. Lower one heel toward the floor until you feel a stretch in your calf. Hold the stretch, and then switch to the other leg.