List the main contributions of the muscular system to the health of your body .

An epidemic is a large and localized outbreak of a sickness or disease.  a pandemic is a large global outbreak of a sickness or disease. 

People who utilizes the progression principle will ensure their exercise program increases in frequency, intensity, time, and type. the changes need to happen gradually in order to ensure they make gains in their fitness program. a person who doesn't utilize the progression principle can still gain health benefits from exercising, but will not continue to improve in cardiovascular fitness.