He is doing squats to strengthen his rectus femoris muscle.

He is training his rectus abdominis muscle every day.

He is doing special exercises to strengthen his superior rectus muscle.

He is doing special exercises to strengthen the lateral rectus muscle.

He is doing a special exercise to strengthen his inferior rectus muscle.

He is doing special exercises to strengthen his medial rectus muscle.

The rectus capitis anterior muscle is part of the neck muscles, helping to bend the head forward.

His opinions are always direct, and that's part of his charm.

He is a very sincere person.

I should do my duty.