To get in top physical shape, you’ll need to work on three different areas of cardiorespiratory fitness. Capacity is the amount of work you can do, such as how fast you can perform a sprint or dash. Stamina refers to how long you can exercise. For example, a sprinter is faster than a marathon runner, but probably can’t run as long or as far as the marathoner. Anaerobic conditioning helps you work at very high intensities and helps you recover more quickly afterward. For example, many basketball players have no problem making fast breaks down the court, but afterward, you see them grabbing their knees, gasping for breath as they try to recover. Interval training consists of many high-intensity bursts of activity, each followed by a recovery period. These recovery periods, which occur many times during an interval workout, help you improve your ability to catch your breath after a point or play and recover for the start of the next one.
Endurance is your ability to perform physical activity over time. You might be able to serve aces and hit winning forehands and backhands, but if your muscles cramp or you run out of energy after a few games, you won’t win any matches. You build endurance by exercising for longer periods without stopping, working at a slower speed than when you interval train. This type of exercise is usually aerobic, calling on your slow-twitch muscle fibers and burning more fat than glycogen, depending on the speed you work. The slower you work, the higher percentage of your calories burned comes from fat.
The Physical Activity Guidelines for Americans were created by the Office of Disease Prevention and Health Promotion. This publication recommends that all adults should avoid inactivity to promote good health mentally and physically. For substantial health benefits, adults should participate in at least 150 minutes a week of moderate-intensity, or 75 minutes a week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity aerobic activity. Aerobic activity should be performed in episodes of at least 10 minutes, and preferably, it should be spread throughout the week.
Developing research has demonstrated that many of the benefits of exercise are mediated through the role of skeletal muscle as an endocrine organ. That is, contracting muscles release multiple substances known as myokines, which promote the growth of new tissue, tissue repair, and various anti-inflammatory functions, which in turn reduce the risk of developing various inflammatory diseases.[13]
Eccentric training is another type of physical fitness training centered on improving eccentric muscle contraction. As a backgrounder, this type of muscle contraction occurs when the muscle elongates or lengthens from the influence of an opposing force. The contraction happens explicitly when a muscle gives in or goes with the flow or direction of an opposing force.

Endurance is your ability to perform physical activity over time. You might be able to serve aces and hit winning forehands and backhands, but if your muscles cramp or you run out of energy after a few games, you won’t win any matches. You build endurance by exercising for longer periods without stopping, working at a slower speed than when you interval train. This type of exercise is usually aerobic, calling on your slow-twitch muscle fibers and burning more fat than glycogen, depending on the speed you work. The slower you work, the higher percentage of your calories burned comes from fat.


Exercise and physical activity fall into four basic categories—endurance, strength, balance, and flexibility. Most people tend to focus on one activity or type of exercise and think they’re doing enough. Each type is different, though. Doing them all will give you more benefits. Mixing it up also helps to reduce boredom and cut your risk of injury.
To get in top physical shape, you’ll need to work on three different areas of cardiorespiratory fitness. Capacity is the amount of work you can do, such as how fast you can perform a sprint or dash. Stamina refers to how long you can exercise. For example, a sprinter is faster than a marathon runner, but probably can’t run as long or as far as the marathoner. Anaerobic conditioning helps you work at very high intensities and helps you recover more quickly afterward. For example, many basketball players have no problem making fast breaks down the court, but afterward, you see them grabbing their knees, gasping for breath as they try to recover. Interval training consists of many high-intensity bursts of activity, each followed by a recovery period. These recovery periods, which occur many times during an interval workout, help you improve your ability to catch your breath after a point or play and recover for the start of the next one.

Physical activity boosts the immune system. This is dependent on the concentration of endogenous factors (such as sex hormones, metabolic hormones and growth hormones), body temperature, blood flow, hydration status and body position.[37] Physical activity has shown to increase the levels of natural killer (NK) cells, NK T cells, macrophages, neutrophils and eosinophils, complements, cytokines, antibodies and T cytotoxic cells.[38][39] However, the mechanism linking physical activity to immune system is not fully understood.

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