Muscle activity when walking downstairs

Question

Amanda is walking downstairs. Explain what muscle(s) are involved at the knee of the descending lower extremity: what is the prime mover(agonist) and what type of muscle contraction is utilized (concentric, eccentric or isometric)? What muscle is inhibited? What muscle(s) might be a synergist? Is walking downstairs considered a power or control motion?

Answer 1

The prime mover (agonist) muscle involved in the descending motion at the knee is the quadriceps femoris muscle group. This group consists of four muscles: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. These muscles work together to extend the knee joint, allowing the leg to straighten during the downward movement.

During the descending motion, the quadriceps femoris muscles undergo eccentric muscle contraction. Eccentric contraction occurs when the muscle lengthens while generating force, such as when lowering the body down the stairs. This type of contraction helps control the movement of while going downstairs.

The muscle that is inhibited during the descending motion is the hamstrings. The hamstrings are a group of muscles located at the back of the thigh, including the biceps femoris, semitendinosus, and semimembranosus. These muscles are responsible for flexing the knee joint. However, during the descending motion, the hamstrings are inhibited to allow the quadriceps to perform their function optimally.

The potential synergist muscles during the descending motion at the knee include the gastrocnemius and soleus muscles. These muscles, located in the calf, work together to control the movement and provide stability during the descent.

Walking downstairs is considered a control motion because it requires coordination, balance, and control to navigate the steps safely and smoothly. The muscles involved work together to control the movement and provide stability, rather than generating maximum force or power.

In summary, during the descending motion of walking downstairs, the prime mover (agonist) muscles are the quadriceps femoris group, which undergo eccentric muscle contraction. The hamstrings are inhibited, and the gastrocnemius and soleus muscles act as synergists. Walking downstairs is considered a control motion that requires coordination and stability.