TRAINING STATUS, RESTING METABOLIC-RATE, AND CARDIOVASCULAR-DISEASE RISK IN MIDDLE-AGED MEN

We investigated differences in resting metabolic rate (RMR) and cardio vascular disease risk factors among 86 middle-aged men (36 to 59 years ) classified as resistance trained ([RT] n = 19), aerobic-trained ([AT ] n = 37), or untrained ([UT], n = 30) according to habitual exercise patterns. RMR, body composition, body fat distribution, supine blood p ressure, maximal aerobic capacity (VO(2)max), plasma lipid levels, and fasting levels of insulin, glucose, and thyroid hormones were measure d. We found that RMR, adjusted for differences in fat-free mass, showe d a tendency to be greater in AT men as compared with RT men (P=.09) a nd was greater in AT men as compared with UT men (P<.05). No differenc es in RMR were noted between RT and UT men. UT men had higher values f or total cholesterol, triglycerides, low density lipoprotein cholester ol (LDL-C), and the insulin to glucose ratio and lower values for high -density lipoprotein cholesterol (HDL-C) (all P<.01) as compared with RT and AT men, whereas no differences in these variables were noted be tween RT and AT men. Supine diastolic blood pressure was lower in RT m en as compared with both AT and UT men. Stepwise regression analysis s howed that variations in body fatness accounted for the greatest varia tion in fasting lipid profile, blood pressure, and the insulin to gluc ose ratio among groups. Furthermore, statistical control for body fatn ess either diminished or abolished differences in cardiovascular disea se risk factors among training groups. We conclude that resting energy requirements are greater in middle-aged AT men as compared with RT an d UT men. Furthermore, Ri and AT men displayed a comparable cardiovasc ular risk profile despite large differences in VO(2)max. These finding s suggest that attainment of low levels of body fat (via high levels o f energy expenditure and/or prudent dietary practices) is an important factor associated with a favorable cardiovascular risk profile in mid dle-aged men. Copyright (C) 1995 by W.B. Saunders Company