Aerobic exercise, also known as cardio, is physical exercise[1] of low to high intensity that depends primarily on the aerobic energy-generating process.[2] "Aerobic" is defined as "relating to, involving, or requiring oxygen",[3] and refers to the use of oxygen to meet energy demands during exercise via aerobic metabolism adequately.[4] Aerobic exercise is performed by repeating sequences of light-to-moderate intensity activities for extended periods of time.[2] According to the World Health Organization, over 31% of adults and 80% of adolescents fail to maintain the recommended levels of physical activity.[5] Examples of cardiovascular or aerobic exercise are medium- to long-distance running or jogging, swimming, cycling, stair climbing and walking.[6]
For reducing the risk of health issues, 2.5 hours of moderate-intensity aerobic exercise per week is recommended.[7][8][9] At the same time, even doing an hour and a quarter (11 minutes/day) of exercise can reduce the risk of early death, cardiovascular disease, stroke, and cancer.[10][11]
Aerobic exercise may be better referred to as "solely aerobic", as it is designed to be low-intensity enough that all carbohydrates are aerobically turned into energy via mitochondrial ATP production. Mitochondria are organelles that rely on oxygen for the metabolism of carbs, proteins, and fats. Aerobic exercise causes a remodeling of mitochondrial cells within the tissues of the liver and heart.[12]