1.   As you get older, your muscles become stiffer.

2.   Her shoulder muscles had become so weak that she could not lift her arms.

3.   As the meat cooks, moisture is reduced and the muscle becomes firmer.

4.   I had not realized how tight my muscles had become working in an office, slouching over a computer keyboard.

5.   In computer users who are not physically fit, certain muscles become overworked, while their supporting muscles are inactive, adding to the problem.

6.   In the first phase, people lose consciousness and their muscles become rigid.

7.   The condition usually arises when muscles in the upper airway become excessively relaxed during sleep, allowing excess tissue at the back of the throat to obstruct breathing.

8.   The devices were developed for people who are dying of heart failure, a condition in which the heart muscle becomes too weak to pump effectively.

9.   The term heart failure refers to a specific condition in which the heart muscle becomes weak and cannot pump effectively.

10.   The underused muscles become relatively weaker with time, placing the tissues in adjacent joints at risk of injury.