The six elements of physical fitness

In 1st grade, my gym teacher made us all memorize the definition of "physical fitness." Decades later, I still recall it as: "Physical Fitness–learning to use your body in many different ways."

While this serves as a fine elementary definition, I now realize the actual definition is much more involved. So, what defines true physical fitness? Considering the total body, there are six elements of fitness: aerobic capacity, body structure, body composition, balance, muscular flexibility and strength. Let's consider each one of these.

Aerobic capacity is your cardiovascular system's ability to transport oxygen to working muscles to serve as fuel for energy. Aerobic capacity improves with cardiovascular exercises, like walking, running, bicycling, jumping rope, swimming, hiking, and dancing. Performing any of these types of activities at an intensity of approximately 60-80% of your total maximum heart rate (220 minus your age) for 30-60 minutes daily will provide you with the first element of fitness.

The second element of fitness is body structure. This is your overall posture, looking for any misalignments of the arms, legs and trunk. Even a small imbalance in the way you regularly stand or sit may lead to pain or injury. Ideal posture aligns your ears over your shoulders, shoulders over your hips, equal leg lengths, pelvic symmetry and neutral joints throughout the body, creating equal pressure on both feet. Any deviations from good posture need to be corrected with the proper stretching, strengthening and muscle releasing exercises.

Body composition is the third element of fitness. This is the ratio of body fat to lean body mass (bones and muscles). Weight alone does not tell us about body composition. Body composition measurements are taken with calipers at specific parts of the body to determine the percent of total body fat. There are also scales and devices that measure body fat. In general, the ideal range of body fat is 10-15 percent of total body mass for males and 15-22 percent for females. Your body functions most efficiently at the ideal fat-to-lean ratio.

Balance makes up the fourth element of total body fitness. There are simple balance tests that can be administered to determine your balance level. For example, standing on one leg with eyes open versus eyes closed. Depending on your age, there are set values of time for this test to determine if your balance is good. 30 seconds is the goal for younger, healthy individuals. Even minor balance problems place you at risk for injuries like ankle sprains, muscle strains, falls and fractures.

The fifth element of fitness is muscular flexibility. Your muscles should be flexible enough to allow for the full range of motion required by life's many activities. Muscles can become shortened if not purposefully stretched and by completing the same sport or lifting routine without enough variation. Inactivity also causes muscles to shorten, become inflexible and more susceptible to stress and injury. Muscle imbalances lead to many of the most common injuries in people who have strong, but tight muscles in some areas and weaker, unstable muscles/joints in others.

The sixth element of fitness is muscular strength. In addition to being flexible, your muscles should be able to exert force and control movement. Strength is improved with weight- resistance exercises. Strengthening programs can be designed using body weight, machines, free weights, kettle bells, TRX, etc. based on individual preferences and goals. In general, strengthening muscles appropriately uses resistance heavy enough to allow 8-15 slow and controlled repetitions with good form completed in 1-3 sets.

A person who is physically fit has a properly aligned and balanced body, flexible yet strong muscles, an efficient heart and healthy lungs, and a good ratio of body fat to lean mass. Being physically fit, according to the true definition, does not come easy. It is something we all should continually work towards in our daily routines.

Read more Sports Doc for Sports Medicine and Fitness.