Meredith C N, Zackin M J, Frontera W R, Evans W J
USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111.
Med Sci Sports Exerc. 1987 Dec;19(6):557-63.
Aging is associated with increased body fat, decreased muscle mass, lower maximal O2 uptake, and lower energy intake. It has been asserted that these changes are caused in part by decreased activity. In order to determine the effects of aging in men who are habitually active, 6 young men (26.8 +/- 1.2 yr) and 6 middle-aged men (52.0 +/- 1.9 yr) who had been running, cycling, and/or rowing for at least 2 yr were studied in a metabolic ward. The men consumed a diet to maintain constant body weight while keeping to their usual exercise schedule and intensity. Both groups had a similar body mass index and muscle mass, but the middle-aged men had a 77% greater fat mass (P = 0.028). Daily energy requirement was 17% lower in the middle-aged men (P = 0.029) although basal metabolic rate was similar in both groups. Aerobic capacity was 15% lower in the middle-aged men per unit body weight (P = 0.048) but not per unit of lean body mass. The young men exercised for an average 12.3 hr.wk-1 and the middle-aged men for 7.5 hr.wk-1 (P = 0.018). For both young and middle-aged men, weekly hours of exercise were negatively correlated with fat mass, and positively correlated with daily energy requirements and maximal O2 uptake. These findings show that in both young and middle-aged men who habitually exercise aerobically at 65 to 80% maximal O2 uptake, the time spent training was associated with body composition, energy requirements, and aerobic capacity.
衰老与体脂增加、肌肉量减少、最大摄氧量降低以及能量摄入减少有关。有人认为，这些变化部分是由活动减少引起的。为了确定衰老对习惯性运动男性的影响，在代谢病房对6名年轻男性（26.8±1.2岁）和6名中年男性（52.0±1.9岁）进行了研究，这些男性至少有两年的跑步、骑自行车和/或划船运动经历。这些男性食用一种饮食以维持体重恒定，同时保持其通常的运动计划和强度。两组的体重指数和肌肉量相似，但中年男性的脂肪量高77%（P = 0.028）。尽管两组的基础代谢率相似，但中年男性的每日能量需求低17%（P = 0.029）。中年男性每单位体重的有氧能力低15%（P = 0.048），但每单位瘦体重的有氧能力无差异。年轻男性平均每周锻炼12.3小时，中年男性每周锻炼7.5小时（P = 0.018）。对于年轻和中年男性，每周锻炼时间与脂肪量呈负相关，与每日能量需求和最大摄氧量呈正相关。这些发现表明，对于习惯性以最大摄氧量的65%至80%进行有氧运动的年轻和中年男性，训练时间与身体成分、能量需求和有氧能力有关。
