When we hear the term “fitness” most of us automatically think of exercise. We relate the term to a healthy body composition and also to healthy cardiovascular function. Certainly, these elements contribute to fitness, but the term expands far beyond mere physical appearance and athletic capacity.

Regardless of what term you use or how you think of fitness; by today's standards we obscure the true biological definition with a more focused form – physical fitness – which concentrates on cardiovascular health, muscular strength, flexibility and a healthy body composition. And sure, these elements increase our ability to survive and reproduce, but they are certainly not requirements for it.

The subcategory of physical fitness has been linked to other health outcomes that increase our overall state of fitness. Significant attention has been given to physical fitness in youth, as we witness a rise in sedentary lifestyles and decreased physical fitness leading to poor overall fitness and health, especially in older age. A committee convened by the Institute of Medicine (IOM) to examine Fitness Measures and Health Outcomes in Youth evaluated relationships between various health markers and outcomes and 4 components of individual fitness: (1) body composition, (2) flexibility, (3) cardiorespiratory endurance, and (4) musculoskeletal fitness.

An analysis of the IOM report found that the medical literature supports a link between poor body composition and markers for or occurrence of cardiovascular disease, metabolic syndrome, diabetes, asthma, hypertension, deficits in cognitive function, and poorer psychological health. Cardiorespiratory endurance was associated with reduced risk for cardiovascular disease, hypertension, type 2 diabetes, certain cancers, and premature mortality from all causes. Musculoskeletal fitness and resistance training programs in youth have been correlated with improved bone health, body composition, blood glucose and insulin regulation, blood pressure, blood lipid profiles, and joint health. Finally, flexibility was related to less back pain, reduced risk of injury, and improved postural stability, balance, and functional capacity.

Physical fitness not only directly impacts health and overall wellness, but according to an annual review of exercise genomics literature, physical fitness may override genetic susceptibilities to numerous health conditions. In this way, physical fitness can favorably influence genetic expression and may benefit the general health and fitness of future generations. For example, many studies suggest genetic susceptibility to obesity, but physical activity has been shown to attenuate this genetic expression by 40 to 50 percent and likely also has a substantial role in reducing risk for developing type 2 diabetes. Similarly, the polygenic risk for hypertriglyceridemia was reduced by 30 to 40 percent in individuals with high cardiorespiratory fitness.

Exercise and physical activity are the foremost ways by which physical fitness is enhanced, which is why the term “fitness” has more recently become synonymous with dedicated physical activity. Aerobics, step aerobics, cycling, jogging, calisthenics and bodybuilding have traditionally been the most popular forms of exercise, but today, the options have expanded to suit many more styles and intensity preferences, such as Zumba, CrossFit, spin classes, suspension training, fitness boot camps, kettlebell training, Pilates, yoga, and stretching. Regularly engaging in these activities supports physical fitness and likely has a positive impact on wellness; however, physical fitness alone does not ensure health or overall fitness. A healthy diet, adequate hydration, stress management, supportive relationships, sufficient sleep, efficient detoxification pathways, and a sense of life purpose are also vital for true fitness of the body, mind, and spirit.