KEY GUIDELINES FOR HEALTH


• Physical activity reduces the risk of many adverse health outcomes. • Some physical activity is better than none. • Additional benefits occur with increases in intensity, frequency, and duration. • Both cardiorespiratory and resistance exercise are beneficial. • Health benefits occur at all ages. • Benefits far outweigh the possibility of adverse outcomes. • Substantial health benefits are seen with 150 min/wk of moderate-intensity physical activity or 75 min/wk of vigorous physical activity or a combination.


• Additional health benefits are seen with 300 min/wk of moderate-intensity physical activity or 150 min/wk of vigorous physical activity or a combination.


• Resistance training—moderate or high in intensity—involving all major muscle groups is recommended 2 d/wk or more.


• For health, 2 minutes of moderate physical activity equals 1 minute of vigorous physical activity. SUMMARY


Exercise physiology is the study of the alterations and responses to acute and chronic exercise. Exercise dis- rupts homeostasis resulting in increased energy needs to meet metabolic demands of active muscles. Te respiratory and cardiovascular systems work in a coordinated fashion to supply oxygen and nutrients to working muscles in an attempt to meet demand. At low- or moderate-intensity exercise, the body can use carbohydrate and fat via aerobic metabolism, meeting the energy demands with ease. As exercise intensity increases, the body’s reliance on carbohydrate for a fuel source with some ATP being generated through anaerobic glycolysis increases. Short-term or metabolic fatigue is a result of reliance on anaerobic metab- olism, while long-term or substrate fatigue is a result of glycogen depletion. Exercise training results in positive physiological adaptations that improve performance. Several principles of exercise training are key for determining the performance outcome. RDNs should be comfortable discussing exercise with their patients or clients while staying within their


scope of practice. Te extent of this discussion will depend on comfort level and any additional education and certification. All RDNs should be able to discuss the health benefits of exercise and the general princi- ples in the federal Physical Activity Guidelines for Americans. Beyond this, if the RDN cannot complete a fitness assessment and exercise prescription, then the RDN should refer to a qualified exercise professional.


CHAPTER 1: PHYSIOLOGY OF EXERCISE


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