This study examined the anaerobic and aerobic contributions to muscle metabolism during high intensity short duration exercise. Six males [mean (SD): age 25.0 (6.0) years, height 179.0 (8.2) cm, mass 70.01 (7.42) kg, VO2max 4.63 (0.53) l.min-1, body fat 12.7 (2.3)%] performed three counterbalanced treatments of 30, 60 and 90 s of maximal cycling on an air-braked ergometer. All treatments were also performed on days when biopsies were not taken from the vastus lateralis muscle and cannulae not inserted into a forearm vein to ascertain whether these procedures adversely affected performance. The mean results can be summarised as follows: (Table: see text). The muscle lactate and O2 deficit data suggested that 60 and 90 s were more appropriate durations than 30 s for assessing the anaerobic capacity on an air-braked cycle ergometer. The mean power outputs also indicated that the invasive procedures did not adversely affect performance [corrected].

Nine 'large-eating ' (approximately 12 MJ/d) and nine 'small-eating ' (approximately 5.3 MJ/d) women were selected from the population on the basis of diet and activity diaries. At rest and in the postabsorptive state the rate of oxygen consumption ( poJ/kg fat-free mass (FFM) and rate of carbon dioxide production (&,)/kg FFM were 9-17% higher (P < 0.05) in the 'large-eaters' than in the 'smalleaters'. As energy expenditure was increased by walking at 2.4,3.9 and 5.4 km/h the differences between the two experimental groups for both & / k g FFM and ec0Jkg FFM were decreased to negligible values, but energy expended on a body-weight basis (MJ/kg per min) remained significantly higher (510 %) in 'large-eaters'. Oral temperature was also consistently higher (up to 0.5") in this group both at rest and during sitting, standing and walking activities. Although the average thermic effect of a standardized liquid meal tended to be higher (27 YO ; not significant) in the 'small-eaters', the other results demonstrate that the 'large-eating' females had a markedly higher rate of energy expenditure at rest and during light physical activities.Energy metabolism : Indirect calorimetry : Women

This study examined differences between long-term exercising (LE) and long-term nonexercising (LNE) women [n = 24; age 56.4 +/- 6.2 (SD) yr] for resting metabolic rate (RMR) and energy expenditure in the free-living state by using doubly labeled water (DLW). There was a statistically significant difference (P = 0.0002) between the 12 LE (94.85 +/- 8.44 kJ . kg-1 . day-1) and 12 LNE (81.16 +/- 6.62 kJ . kg-1 . day-1) for RMR, but this difference was only marginally significant (P = 0.06) when the data (MJ/day) were subjected to an analysis of covariance with fat-free mass as the covariate. The DLW data indicated that the eight most active LE (12.99 +/- 3.58 MJ/day) expended significantly (P = 0.01) more energy than did the eight least active LNE (9.30 +/- 1.15 MJ/day). Energy expenditures ranged from 7.64 to 18.15 MJ/day, but there was no difference (P = 0.96) between the LE and LNE in energy expenditure during activity that was not designed to either improve or maintain fitness. These cross-sectional data on 49- to 70-yr-old women therefore suggest that 1) aerobic-type training results in a greater RMR per unit of body mass and also when statistical control is exerted for the effect of the metabolically active fat-free mass, 2) there is a large range in the energy intake necessary to maintain energy balance, and 3) aerobic training does not result in a compensatory reduction in energy expenditure during the remainder of the day.

The effects of the sequential addition of glucose, noradrenaline, propranolol and oleic acid on the rates of O2 consumption and heat production by isolated interscapular brown adipocytes from control and cafeteria-fed rats were compared. Although the chemical agents produced very similar changes in oxidative metabolism, the actual rates of O2 uptake and heat output in adipocytes from the cafeteria-fed rats, when expressed per g dry wt. of cells, were approx. 65% less than those obtained with cells from the control rats. However, when the same results were expressed per 10(8) multiloccular brown adipocytes, rather than gravimetrically, rates of O2 consumption and heat production were equivalent. Further interpretation of these data is complicated, because the average volume of multiloccular brown adipocytes from cafeteria-fed rats was 2.5 times that for multiloccular cells from control animals.

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