To determine the relation between habitual endurance exercise status and the age-associated decline in maximal aerobic capacity [i.e., maximal O(2) consumption (Vo(2 max))] in men, we performed a well-controlled cross-sectional laboratory study on 153 healthy men aged 20-75 yr: 64 sedentary and 89 endurance trained. Vo(2 max) (ml. kg(-1). min(-1)), measured by maximal treadmill exercise, was inversely related to age in the endurance-trained (r = -0.80) and sedentary (r = -0.74) men but was higher in the endurance-trained men at any age. The rate of decline in Vo(2 max) with age (ml. kg(-1). min(-1)) was greater (P < 0.001) in the endurance-trained than in the sedentary men. Whereas the relative rate of decline in Vo(2 max) (percent decrease per decade from baseline levels in young adulthood) was similar in the two groups, the absolute rate of decline in Vo(2 max) was -5.4 and -3.9 ml. kg(-1). min(-). decade(-1) in the endurance-trained and sedentary men, respectively. Vo(2 max) declined linearly across the age range in the sedentary men but was maintained in the endurance-trained men until approximately 50 yr of age. The accelerated decline in Vo(2 max) after 50 yr of age in the endurance-trained men was related to a decline in training volume (r = 0.46, P < 0.0001) and was associated with an increase in 10-km running time (r = -0.84, P < 0.0001). We conclude that the rate of decline in maximal aerobic capacity during middle and older age is greater in endurance-trained men than in their sedentary peers and is associated with a marked decline in O(2) pulse.

. Increased abdominal-to-peripheral fat distribution contributes to altered autonomic-circulatory control with human aging. Am J Physiol Heart Circ Physiol 287: H1530 -H1537, 2004. First published June 3, 2004 10.1152/ajpheart. 00322.2004.-Autonomic nervous system (ANS) control of the circulation is altered with aging in adult humans. Similar changes are observed in obesity, particularly abdominal obesity. To determine whether age-associated differences in ANS-circulatory function can be partially explained by increased body fatness, we examined ANS function and three expressions of adiposity (total body fat, abdominal body fat, and abdominal-to-peripheral body fat distribution; dualenergy X-ray absorptiometry) in 43 healthy men: 27 young (25 Ϯ 1 yr) and 16 older (65 Ϯ 1). ANS functions assessed included 1) autonomic support of arterial blood pressure (BP; radial artery catheter), i.e., the reduction in BP during versus before acute ganglionic blockade (GB; intravenous trimethaphan); 2) baroreflex buffering, i.e., the increase in systolic BP with continuous incremental and bolus infusions of phenylephrine during versus before GB; 3) cardiovagal baroreflex sensitivity (Oxford technique); and 4) heart rate variability (time-and frequency-domain analyses). Covarying for abdominal-toperipheral fat distribution reduced or abolished age-related differences in ANS support of BP, cardiovagal baroreflex sensitivity, and heart rate variability but did not affect age-related differences in baroreflex buffering. Covarying for abdominal and total fat had small selective or no effects on age-associated differences in autonomic-circulatory control. Abdominal-to-peripheral fat distribution explains a significant portion of the variance in a number of autonomic-circulatory functions attributable to aging. Therefore, the development of this fat pattern may contribute to several changes in ANS-cardiovascular function observed with aging. These results may help explain how changes in body fat distribution with advancing age are linked to impairments in circulatory control. blood pressure; baroreflexes; cardiac vagal modulation CHANGES IN AUTONOMIC nervous system (ANS) control of the circulation with aging selectively affect physiological function and are a key feature of age-associated cardiovascular disease (13, 40). As such, it is important to understand the factors that contribute to ANS-circulatory dysfunction with aging in adult humans. In this context, we (22, 23) and others (36) previously established that increases in total and abdominal adiposity can explain up to 50 -60% of the increases in muscle sympathetic nerve activity and total norepinephrine spillover with age in healthy men. As recently summarized (39), these findings suggest that increases in total and regional body fat play an important role in sympathetic nervous system activation with human aging.Recently our laboratory demonstrated that other ANS-cardiovascular functions are altered with aging even in healthy men, including greater tonic ANS support of arter...

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