Question

Name the muscles of the hip, knee, and ankle that act as agonist, antagonist and stabilizing muscles when ascending and descending stairs. Be sure to include the type of contraction during the different phases of the task. *Please answer all parts of the question - thank you!!!

Answer 1

Co-activation of the agonist-antagonist leg muscles:

Muscles that Extend the Hip

Hip extension is a major component in walking up stairs. You can increase the degree of hip extension you experience by taking the stairs two at a time or by running up the stairs. You have two primary hip extension muscles -- your gluteus maximus and your hamstrings, both located on the rear of your hip/thigh. As these muscles contract, they drive your femur or thigh bone backward to provide forward and upward momentum.

Knee Extension:

Climbing stairs requires active knee extension. The degree of knee extension depends on the height of each stair. A higher stair will require you to bend your knees more deeply and the greater the amount of knee flexion, the greater the involvement of your knee extensor muscles -- the quadriceps. Your quadriceps are located on the front of your thigh, originating near your hip and terminating just below your knee. These are the muscles that can feel tired and hot as you climb a long flight of stairs.

Hip Flexion:

As you climb stairs, you must swing your leg from an extended position and into a flexed position in preparation for another stride. This is the job of your iliacus, psoas major and psoas minor. Collectively these muscles are called iliopsoas and are located on the front of your hip. In addition to extending your knee, one of the quadriceps, rectus femoris, also flexes your hips as your swing your leg forward and up onto the next step.

Ankle Platarflexion

Extending your ankle, correctly called plantarflexion, is the job of your calf muscles -- specifically soleus, gastrocnemius and tibialis posterior. These muscles work to keep your ankle braced as your climb the stairs so that the energy produced by your leg muscles is not wasted. They also provide assistance as they extend your ankle which results in a strong push off from the balls of your feet.

The degree of involvement of your calf muscles in stair climbing depends on how much you push off the balls of your feet. If you climb the stairs using a flat footed technique, there will be relatively little in the way of calf muscle work. If, however, you actively push off your toes, for example when running up stairs two at a time, your calf muscles will have to work much harder.

Going down stairs is also good exercise. It uses the thigh muscles—quadriceps and, to some extent, the hamstrings. Be careful not to overextend or lock your knees as you go down. If you go down stairs (or downhill) a lot, you may put excessive strain on the knees and/or develop sore quadriceps (though the soreness will decrease with practice)

MUSCLE CONTRACTION:

a muscle contraction, you usually think of a muscle getting shorter, which is called “concentric” contraction. “Isometric” contractions, in which there’s no change in length, “clenching.” And then there’s the weird one, a mysterious but routine bit of muscle trickery known as “eccentric” contraction, and it is odd indeed: contraction while lengthening, also sometimes called a braking contraction.

The quadriceps muscle group contracts eccentrically as you descend stairs or a hill. The quadriceps are “anti-gravity” muscles when contracting concentrically, extending the knee powerfully to lift you up. But when you step down, your knee starts straight and then bends like a spring as your body follows: the quadriceps contract eccentrically to keep the knee from collapsing too fast or too far.