Kris Lee asked:


Fitness, itself, is composed of four different elements: cardiorespiratory endurance, muscular fitness, flexibility, and body composition.

Cardiorespiratory endurance, or aerobic fitness, relates to the body’s capacity to absorb, transport, and use oxygen during work or exercise. As the body is trained to endure a greater cardiovascular workload, the heart and lungs become stronger thereby increasing an individual’s endurance. A marathon runner would be a prime example of an athlete with a high level of aerobic conditioning.

Muscular fitness can be best described as a balance of strength and endurance. Muscular strength is the body’s ability to generate force at a given speed of movement. Muscular endurance refers to the ability of the body to repeat movements and resist muscular fatigue. A better way to distinguish between muscular strength and endurance would to imagine lifting a fifty-pound weight just one time-strength-versus lifting a five-pound weight ten times-endurance.

Flexibility is often the most overlooked component of physical fitness. Flexibility is the range of motion around a joint or a group of joints. Range of motion is limited primarily by the amount of soft tissue, including muscle and the joint capsule, surrounding the joint. A gymnast would rely on his or her flexibility as well as strength to complete a strenuous tumbling routine without injury.

Body composition is the fourth and final component of fitness. There are two distinct elements with body composition: fat mass and lean body mass. Fat mass, as it implies, is the percentage of fat, both essential and nonessential, that makes up an individual’s body. Essential fat can be found in bone marrow, nerve tissue and in various internal organs.Woman have a significantly greater percentage of essential body fat, around 12 percent, than men, around 4 percent, due to the demands of child bearing. Nonessential fat can be found subcutaneously, or beneath the skin, and is primarily used for excess body fat storage. “Based on data from physically active young adults, it would be desirable . . . to strive for a body fat content of 15% for men (certainly less than 20%) and about 25% for women (less than 30%)” (McArdle et. al. 1996, 570). Lean mass, on the other hand, is comprised of everything in the human body other than fat, such as muscle mass, bone mass, and the weight of the internal organs. An ideal body composition, therefore, would be an individual possessing a healthy body fat percentage: 15-20 percent for men and 25-30 percent for women.

These four components are essential for maintaining optimal health and fitness while preventing injury and muscular imbalances. Imagine a long-distance runner who spends her training time running without any regard for strengthening or stretching.While her cardiorespiratory endurance and body composition are favorable, she neglects her muscular strength and flexibility and can possibly set herself up for serious injury in the future. Along similar lines, imagine an amateur bodybuilder who spends a large amount of time lifting weights and increasing muscle mass, but who neglects his cardiovascular health and flexibility. He, too, increases his chance of injury by ignoring two very important components of fitness.

While it is ideal to have a balance of cardiorespiratory endurance, muscular strength and endurance, flexibility, and a favorable body composition, it is not something that is easily attainable. Good health takes work, but it does not have to resemble work.

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