Sports Fitness Training

Muscle mass is dramatically reduced in both men and women with advancing age. Called sarcopenia, this phenomenon has considerable significance because it leads to a decreased quality of life, and often, major health care expenses for the associated medical/nursing care. More­over, these costs represent only a fraction of what is likely to come over the next 20-30 years as the post-war baby boom generation enters the age range in which sarcopenia begins to affect them. Clearly, the effects of aging on the body’s ability to respond undoubtedly playa role in this response-it has been reported that myofibrillar protein synthesis is reduced by 30% in individuals over 60 years of age. However, inactivity must always be a factor. Indeed, strength training has been shown to augment muscle function in both men and women even in the lath decade of life. Further, this type of functional improvement is not the result of neurological changes alone as muscle protein synthesis can be increased with 3 months of strength exercise even in frail 76-92-year­old men and women Some data indicate that as little as 10 days of energy and protein supplementation can enhance protein synthesis and fat-free (lean) mass at least in poorly nourished 60-90-year-old men and women. As nutrient intake is frequently less than ideal in the eld­early and energy and macro nutrient needs are increased with strength exercise. It is logical to assume that nutrient supplementation would enhance the response of muscle to strength exercise. One study observed that a supplements containing 60% carbohydrate, 23% fat, and 17% protein (1500 kJ/day) given to year-old men and women who participated in a 10-week strength training program produced significant increases in muscle strength and size than the same training alone. Although increasing dietary protein intake from 0.6 to 1.2 to 2.4 g/kg did not alter myofibrillar protein synthesis in elderly men and women, these data do not necessarily implicate energy as the causative factor because this latter study only involved 1 day of supplementation and a brief (3-day) strength program. Acute versus chronic exercise could be a significant factor in determining nutrient need. Further, length of time on the dietary treatment is likely critical. Finally, at least in older women, there is some evidence that quantity of the protein per intake may affect subsequent protein synthetic rate. Over a 14-day interval in older women (60-73 years), when the protein intake was divided equally into four aliquots fat-free mass gain was significantly less when compared with a situation in which most of the protein was consumed a large bolus However, the bolus protein-feeding pattern had no such effect in younger women. Although clearly more study is necessary before these data can be explained fully, mass of protein consumed and/or timing of intake throughout the day may be critical to the protein synthetic response. Finally, the latter two studies were conducted on sedentary subjects and it is likely that these factors become even more important when combined with chronic strength exercise. Due to the increased requirements of the growth process, protein intake is also important for young children and adolescents. Although not well studied, it is quite likely that regular strength training could lead to even greater requirements in this population. More­over, from a practical perspective, this is likely to be of increasing importance in the future as strength training is becoming more of an essential component of almost all sporting endeavors. For the same reason, women who are pregnant who continue to exercise would be another group likely to benefit from additional dietary protein.