Muscles are attached to bones, and they relax and contract. Muscle and fat are not the same thing. Muscles fatigue and change in size when a person exercises. Poor grasp - this student understands that there are different types of muscles. Muscles move with bones, and relax and contract.
Muscles get tired when a person exercises.
We use muscles when we walk across a room, eat and digest an apple, or simply live. Anatomy and Physiology Laboratory Manual , 11th ed. Phipps, Long and Woods. Medical-Surgical Nursing Concepts and Clinical Practice , 3rd ed.