Osteoporosis and arthritis are common problems of which body system? (fill in the blank with one of the following: nervous system, endocrine system, skeletal system)

the more fit you are, the faster the recovery. your heart rate drops most sharply in the first minute after you stop exercising; it should then fall about 20 beats a minute—a drop of less than 12 beats a minute is considered abnormal. this “recovery heart rate” is measured as part of an exercise stress test.