Q.38 - Biology

Question

Skeletal muscles can only produce a mechanical force as they are contracted, but a leg flexes and extends while walking. How can muscles perform this task? 

Step-by-Step Solution

Answer

When walking, the hamstring muscle contracts first, causing the leg to flex around the knee joint. The quadriceps muscle then contracts (while the hamstring relaxes and extends) to straighten the leg as the foot returns to the ground.

Step 1. Introduction

Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton.

Step 2. Explanation

• On the contraction mechanical force is produced by the skeletal muscles. Muscles helps us in the flexion and extension movement of the leg while walking. This is because muscles are present in pairs so they help in locomotion.
• Muscles are able to drive locomotion (and other tasks involving opposing motions) because they are paired. 
• When walking, the hamstring muscle contracts first, causing the leg to flex around the knee joint. The quadriceps muscle then contracts (while the hamstring relaxes and extends) to straighten the leg as the foot returns to the ground.