Notes

Muscles: All exercises involve muscles; they are biochemical motors that use energy to provide the movement and power your body’s activity needs. Cellular respiration and anaerobic respiration are reactions in the muscle cells that convert stored chemical energy from carbohydrates or fat to energy that can be used for muscle movement.

Lungs: During exercise, the rate and depth of your breathing increases as your lungs work to bring in more oxygen and release carbon dioxide, which is formed by cellular respiration. Regular exercise actually strengthens the muscles that expand and contract your lungs. Strengthened muscles make it easier to meet oxygen demands that keep your muscles moving to complete your workouts.

Blood: Oxygen from your lungs is carried throughout the body by the blood. Working muscles can take oxygen out of the blood about three times as fast as resting muscles, and that efficiency is very important! Your body also adapts to demanding physical activity by dilating the blood vessels for increased blood flow, pumping the heart faster, increasing the amount of oxygen carried in the blood, and diverting blood flow away from nonessential organs like the stomach, kidneys, and liver during exercise.

Heart: The blood might carry the oxygen to muscles, but the heart is what gets the blood moving! As you work out, you will feel your heart rate increase as it pumps the blood out throughout the body. Maximum oxygen uptake (VO2 max) is a measure of how much oxygen your body takes in and distributes to muscles during exercise. Your heart rate and the volume of blood pumped with each heartbeat play a big role in your aerobic capacity. The good news is you can work to improve your aerobic capacity. The heart is a muscle, so it can be strengthened by regular exercise in the proper target heart rate zone.

Skin: Muscle movement and cellular and anaerobic respiration all produce heat, increasing your body temperature as you exercise. Your body attempts to release this extra heat by dilating blood vessels (evident by warm, flushed skin) and increasing perspiration, also called sweat.

Perspiration: Sweat keeps body temperature in a safe range. As it evaporates, it removes heat from the skin’s surface and brings down the body’s temperature. However, sweating also removes water and ions, like sodium and potassium, from the body, so it is important to stay hydrated with plenty of water or even a sports drink.

Nervous System/Brain: Have you ever heard of a “runner’s high”? Endorphins are chemicals that produce a feeling of well-being when they are released into your bloodstream. They are produced by the pituitary gland and the hypothalamus during long, continuous exercise or extreme excitement.