The effect of intensive endurance exercise training on body fat distribution in young and older men

Little is known about the effects of exercise interventions on the distribution of central and/or intra-abdominal (IA) fat, and until now there were no studies in the elderly. Therefore, in this study we investigated the effects of an intensive g-month endurance training program on overall body composition (hydrostatic weighing), fat distribution (body circumferences), and specific fat depots (computed tomography [Cl), in healthy young (n = 13; age, 26.2 2 2.4 years) and older (n = 15; age, 67.5 2 5.6 years) men. At baseline, overall body composition was similar in the two groups, except for a 9% smaller fat free mass in the older men (P < .05). The thigh and arm circumferences were smaller (P = .OOl and P < .05, respectively), while the waist to hip ratio (WHR) was slightly greater in the older men (0.92 + 0.04 v 0.97 + 0.04, P < .Ol). Compared with the relatively small baseline differences in body composition and circumferences, CT showed the older men to have a twofold greater IA fat depot (P < .OOl), 46% less thigh subcutaneous (SC) fat (P < .Ol), and 21% less thigh muscle mass (P < .OOl). Following endurance (jog/bike) trainiqg, both the young (+16%, P < .OOl) and the older men (+22%, P < .OOl) significantly increased their maximal aerobic power (Vo,max). This was associated with small but significant decrements in weight, percent body fat, and fat mass (all P < .OOl) only in the older men. Similarly, small decrements were noted in the waist (P < .OOl) and chest (P < .Ol) circumferences, as well as the WHR (P < .05) in the older men alone. On CT, the older men had greater than 20% decrements in the three central (IA, abdominal SC and chest SC) fat depots (all P < .OOl), and a 9% increment in thigh muscle mass (P < .Ol). The young men demonstrated significant decreases in IA (- 17%, P < .05), abdominal SC (- 10%. P < .05), and thigh SC (-20%. P < .Ol) fat depots. Except in the chest SC depot, the absolute change in a depot following endurance training was related to the initial size of the depot. We conclude that older men, who have a more central distribution of adiposity at baseline, had a preferential loss of fat from the central fat depots. It is possible, therefore, that endurance training will also allow preferential loss of central fat in other populations of subjects at risk for obesity-related metabolic complications and might produce impressive improvement in metabolic abnormalities, despite only a small loss of weight and fat. Copyright 0 1991 by WA Saunders Company TH AGING there is a substantial decline in fat free mass; thus, an older individual who weighs the same as he/she did at a younger age, is likely to be “fatter.“’ Not only are the elderly fatter at any given weight or relative weight, they also have a more central distribution of adiposity.’ With rare exceptions,’ studies support the concept that the central distribution of fat in young and middle-aged individuals is a strong independent predictor of many obesity-related metabolic abnormalities, including (1) abnormal glucose tolerance, hyperinsulinemia, and diabetes mellitus4,5; (2) hyperlipidemia and reduced highdensity lipoprotein cholesterol concentration?; (3) hypertension’; (4) stroke’; (5) coronary artery disease7,Y; and (6) death.’ More recently, studies have focused on the intraabdominal (IA) fat depot as being uniquely important as a determinant of obesity-related complications.6.‘0 The importance of central obesity on the development of these same common age-related metabolic problems is less well studied. We have recently published data demonstrating that the absolute size of the IA fat depot, measured by computed tomography (CT), increases with age, and that a greater percentage of total adiposity resides in the IA depot even in healthy older men compared with young controls.” Despite the apparent importance of IA adiposity in obesity-related metabolic abnormalities and its possible importance in common age-related metabolic abnormalities, there is relatively little direct data on the effects of weight-reduction interventions (diet or exercise) on the IA fat depot.“,‘” In this study, we compared the effects of an intensive endurance exercise program on overall body composition, fat distribution, and specific fat depots in a group of 13 young male controls with a group of 15 healthy