A Guide to Leg Muscles with HSS

A broad range of movements, including running, depend on the leg muscles. How do they all work together to keep you moving?

Hospital for Special Surgery physical therapist HSS Hudson Yards Rehabilitation, takes us on a deep dive into the muscles of the legs.

Skeletal muscles—those attached to your bones by tendons—make up about a third of the human body. They are voluntary muscles, which means you consciously control how they work. (This makes them distinct from smooth muscles, which are involuntary, and cardiac muscles, which are specific to the heart.)

The Muscles of the Upper Leg

The upper leg contains large skeletal muscles that generate force and are important for posture and maintaining the stability of the pelvis, Frankinburger says.

Gluteus maximus. TYou're probably familiar with this one. It's the largest muscle in the upper leg, located at the back of the hip, in the glutes (your butt). One of the strongest muscles in the body, the gluteus maximus can generate a large amount of force. It controls motion at the pelvis and plays a role in maintaining posture.

Gluteus medius. Also located above the gluteus maximus, the gluteus medius helps with stability of the pelvis and with hip abduction, which is the side movement of the leg away from the body. The gluteus medius prevents the opposite side of the pelvis from drooping during walking and running.

Iliopsoas. This is a combined term for two of the largest hip flexor muscles, the psoas and the iliacus. Both are connected to the thigh bone, with the psoas originating at the low back and the iliacus on the inside of the pelvis. These muscles help with posture and engage every time we step forward.

Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. These four muscles make up the quadriceps (quad means four) and are located on the front of the leg. They attach to the patella (kneecap) and the tibia (shin) bones and work together to straighten the knee in activities such as kicking, jumping, squatting, and cycling.

Semitendinosus, semimembranosus, and biceps femoris. The three muscles of the hamstrings, in the back of the leg, bend your knees, move your hips backward, and are important for decelerating (slowing down) when running.

The Muscles of the Lower Leg

The lower leg is responsible for stability of the ankle and foot, Frankinburger says.

Tibialis anterior. Located on the outside of the shin bone, the tibialis anterior is the main muscle used to raise the front of your foot upward toward your shin. It also controls the lowering of your foot to the floor during walking.

Gastrocnemius and soleus. These calf muscles, on the back of the leg, both link into the Achilles tendon, the body’s strongest tendon, which can withstand a force up to 10 times your body weight. The gastrocnemius is a powerful calf muscle that works with the hamstrings to bend the knee and propel us forward when walking, running, and jumping. Located behind it is the soleus, which controls plantar flexing your foot, such as when pressing on the gas pedal while driving.

Posterior tibialis. Situated deep in the lower leg, the posterior tibialis is key to stabilizing the arch of the foot.

Avoiding Injuries to the Leg Muscles

Many of the skeletal muscles of the leg work in synergy, Frankinburger says, meaning they coordinate with each other to create movement. The rectus femoris is a quadricep muscle, for instance, but also helps the hip to move. Likewise, the gastrocnemius is a calf muscle that also helps the hamstrings bend the knee. “If there’s a deficit or weakness in one of these muscles, the synergy can become off balance, which can cause injuries to other areas,” she says.

Muscles are made up of fibers that can get stretched or torn. When a muscle is overused—whether by too much repetitive movement or too much force or resistance—it’s prone to straining. A muscle strain, commonly called a “pulled muscle,” is categorized by how much the muscle stretches or tears.

Grade 1 (mild)—A small number of muscle fibers have torn, causing pain and tenderness the day after exercise.

Grade 2 (moderate)—About half of the muscle fibers are torn, causing significant pain and swelling with weakness after activity.

Grade 3 (severe)—The complete rupture of the muscle, causing severe pain and swelling with complete loss of strength.

When to See a Doctor for a Muscle Strain

You can treat a mild muscle strain at home. If you felt a severe popping sensation or heard a popping noise when the muscle strain occurred, that’s a sign you should see a doctor. Also contact your doctor if you have significant pain or do not see improvement in your symptoms after 2 to 3 weeks.

Why It’s Important to Stretch and Strengthen Leg Muscles

Regular stretching and strengthening of your leg muscles can help prevent overuse injuries. “You don’t have to belong to a fancy gym or have expensive equipment at home to exercise your legs,” Frankinburger says.

Exercises to stretch and strengthen the muscles of the upper and lower leg are meant to keep these muscles flexible and strong, which is needed for good movement, balance, and bone health. Improving balance will make any athlete perform better and becomes even more important to prevent falls at an older age.

Four Simple At-Home Leg Stretches

Hip Flexor Stretch

Hamstring Stretch

Quadricep Stretch

Calf Stretch

Four Simple At-Home Leg Exercises

These moves target the whole leg to increase your strength and improve your balance.

Bridge

Squat

To make this exercise more intense, try jumping into a squat position or counting to five as you descend into a squat. Another variation is a side step into a squat.

Lunge

Calf Raise

Molly Frankinburger specializes in sports and orthopedic manual therapy. She ran competitively in high school and college, and is interested in women's distance running.