Resting metabolic rate, body composition and aerobic fitness comparisons between active and sedentary 54-71 year old males

Objective: To test the hypothesis that 55-70 y old male longterm exercisers (LE) have higher resting metabolic rates (RMR) than longterm nonexercisers (LNE). Design: A power analysis demonstrated that this cross-sectional study requi red 12 subjects per group to detect a 10% RMR difference (kJ . kg FFM-1 . d (-1)) between the LE and LNE (power = 0.8; alpha = 0.05). Subjects: Twelve LE (X +/- s.d.; 63.5 +/- 3.4 y; 1.75 +/- 0.06 m; 69.01 +/- 8.24 kg; 20.4 +/- 4.9%BF) and 12 LNE (63.6 +/- 5.6 y; 1.72 +/- 0.07 m; 79. 44 +/- 12.4 kg; 29.6 +/- 4.4%BF) were recruited from advertisements placed in a newspaper and on university and community noticeboards. Interventions: Measurements were conducted for: RMR using the Douglas bag t echnique; body composition via a four compartment model which is based on d etermination of body density, total body water and bone mineral mass; and a erobic fitness using a submaximal work test on a cycle ergometer. Results: The LE (93.00 +/- 7.16 kJ . kg(-1) . d(-1)) registered a significa ntly greater (P = 0.04) RMR than the LNE (84.70 +/- 11.23 kJ . kg(-1) . d(- 1)) when energy expenditure was expressed relative to body mass, but this d ifference disappeared (P = 0.55) when the data were corrected for the non-z ero intercept of the graph of RMR (MJ/d) against body mass. ANCOVA with FFM as the covariate also indicated that the RMR (MJ/d) difference between the groups was not statistically significant (P = 0.28). The adjusted means fo r the LE and LNE were 6.39 and 6.62 MJ/d, respectively. Conclusions: There are no RMR (MJ/d) differences between LE and LNE 54-71 y old males when statistical control is exerted for the effect of FFM and th e higher value of the former group for RMR normalised to body mass disappea rs when this ratio is corrected for statistical bias.