title: Modelling the influence of age, body size and sex on maximum oxygen uptake in older humans.
abstract: The purpose of this study was to describe the influence of body size and sex on the decline in maximum oxygen uptake (O2,max) in older men and women. A stratified random sample of 152 men and 146 women, aged 55-86 years, was drawn from the study population. Influence of age on O2,max, independent of differences in body mass (BM) or fat-free mass (FFM), was investigated using the following allometric model: O2,max = BMb (or FFMb) exp(a + (c ' age) + (d ' sex)) [epsilon]. The model was linearised and parameters identified using standard multiple regression. The BM model explained 68.8 % of the variance in O2,max. The parameters (+/- s.e.e., standard error of the estimate) for lnBM (0.563 +/- 0.070), age (-0.0154 +/- 0.0012), sex (0.242 +/- 0.024) and the intercept (-1.09 +/- 0.32) were all significant (P < 0.001). The FFM model explained 69.3 % of the variance in O2,max, and the parameters (+/- s.e.e) lnFFM (0.772 +/- 0.090), age (-0.0159 +/- 0.0012) and the intercept (-1.57 +/- 0.36) were significant (P < 0.001), while sex (0.077 +/- 0.038) was significant at P = 0.0497. Regardless of the model used, the age-associated decline was similar, with a relative decline of 15 % per decade (0.984 exp(age)) in O2,max in older humans being estimated. The study has demonstrated that, for a randomly drawn sample, the age-related loss in O2,max is determined, in part, by the loss of fat-free body mass. When this factor is accounted for, the loss of O2,max across age is similar in older men and women.
authors.affiliation: Department of Exercise Physiology, De Montfort University Bedford, Bedford MK40 2BZ, UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Johnson
authors.forename: E M
authors.initials: EM
authors.lastname: Winter
authors.forename: D H
authors.initials: DH
authors.lastname: Paterson
authors.forename: J J
authors.initials: JJ
authors.lastname: Koval
authors.forename: A M
authors.initials: AM
authors.lastname: Nevill
authors.forename: D A
authors.initials: DA
authors.lastname: Cunningham
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism* / Q000502:physiology*; D001823:Body Composition; D001824:Body Constitution; D001835:Body Weight; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010101:Oxygen Consumption / Q000502:physiology*; D012727:Sex Characteristics