Climate variables as predictors of basal metabolic rate: New equations

The purpose of this study was to compare age and gender effects of strength training (ST) on resting metabolic rate (RMR), energy expenditure of physical activity (EEPA), and body composition. RMR and EEPA were measured before and after 24 wk of ST in 10 young men (20-30 yr), 9 young women (20-30 yr), 11 older men (65-75 yr), and 10 older women (65-75 yr). When all subjects were pooled together, absolute RMR significantly increased by 7% (5928 +/- 1225 vs 6328 +/- 1336 kJ.d-1, P < 0.001). Furthermore, ST increased absolute RMR by 7% in both young (6302 +/- 1458 vs 6719 +/- 1617 kJ x d(-1), P < 0.01) and older (5614 +/- 916 vs 5999 +/- 973 kJ x d(-1), P < 0.05) subjects, with no significant interaction between the two age groups. In contrast, there was a significant gender x time interaction (P < 0.05) for absolute RMR with men increasing RMR by 9% (6645 +/- 1073 vs 7237 +/- 1150 kJ x d(-1), P < 0.001), whereas women showed no significant increase (5170 +/- 884 vs 5366 +/- 692 kJ x d(-1), P = 0.108). When RMR was adjusted for fat-free mass (FFM) using ANCOVA, with all subjects pooled together, there was still a significant increase in RMR with ST. Additionally, there was still a gender effect (P < 0.05) and no significant age effect (P = NS), with only the men still showing a significant elevation in RMR. Moreover, EEPA and TEE estimated with a Tritrac accelerometer and TEE estimated by the Stanford Seven-Day Physical Activity Recall Questionnaire did not change in response to ST for any group. In conclusion, changes in absolute and relative RMR in response to ST are influenced by gender but not age. In contrast to what has been suggested previously, changes in body composition in response to ST are not due to changes in physical activity outside of training.

A considerable number of physiological functions are known to show a gradual decline with increasing age. However, the effects of ageing differ widely between organ systems. It is believed that basal metabolic rate (BMR) falls dramatically with age. These observations, largely based on cross-sectional surveys, are discussed in light of our present understanding of the biology of ageing. This paper reviews both the longitudinal and cross-sectional studies of BMR and presents evidence that the fall in BMR with ageing may be less dramatic than previously perceived. Indeed, some subjects may show an increase in BMR with ageing. The mechanism of changes in BMR during ageing will be discussed. Organ weight changes appear to have a profound impact on BMR. The use of BMR to predict total energy expenditure in the 'old elderly' (>75 y) is unlikely to be of any practical use due to wide intra- and inter-individual variation in BMR. This wide intra- and inter-individual variation in BMR is due to illness, disease and other metabolic disorders seen in the elderly. Finally, the importance of measuring BMR in elderly populations for its use in clinical medicine will be discussed.