Question

What happens to the legs when ascending and descending stairs?

A) Legs undergo elongation during ascent and contraction during descent.
B) Legs experience contraction during ascent and elongation during descent.
C) Legs remain unchanged regardless of stair movement.
D) Legs alternate between elongation and contraction during both ascent and descent.

Answer 1

The legs experience contraction during ascent and elongation during descent of stairs. Muscles contract concentrically to lift the body on the ascent, and eccentrically to control the descent.

Step-by-step explanation:

When ascending and descending stairs, the legs undergo different movements. The correct answer to what happens to the legs when ascending and descending stairs is B) Legs experience contraction during ascent and elongation during descent. Ascending stairs requires the leg muscles to contract to lift the body against gravity. The muscles involved primarily include the quadriceps, hamstrings, and the calf muscles. These muscles work in a concentric contraction during ascent, which means they contract and shorten as they exert force to lift the body upwards.

Conversely, when descending stairs, the muscles in the legs perform an eccentric contraction, where the muscles are lengthening while still under tension. This type of contraction helps in controlling the descent, managing the force of gravity and preventing a fall. The muscles act as brakes to control the speed and ensure stability. Descending does not require as much energy as ascending because the body is moving with gravity rather than against it, explaining why one can descend for longer periods at a faster rate.