He exercises every day to strengthen his risorius muscle.

He is doing special exercises to strengthen his rotator muscles.

He goes to the gym every day to train his thigh muscles.

When the arrector pili muscles contract, goosebumps occur.

The cold caused my arrector pili muscles to contract, giving me goosebumps.

Training the respiratory muscles is very important for aiding breathing.

Smooth muscles contract spontaneously and control many internal movements of the body.

It's important to train your antagonist muscles as well when doing muscle training.

If the movement of the eyeball muscles becomes impaired, your vision becomes blurry.

As I was walking down Tenkajiku, there were many shops lined up.