Effect of exercise on the thermic effect of food in women

Abstract

The influence of exercise on the thermic effect of food (TEF) was examined in 28 non-obese women using two different protocols. The energy expenditure of exercise (walking on a motor driven treadmill at 4.8 km/h and 0% gradient) at 50–55% VO₂ max before and after ingestion of a high carbohydrate-low fat meal (2520kJ) was determined using the Douglas bag technique. In both protocols subjects performed the exercise before the meal (post-absorptive condition) following which there was a 30 min rest and then reassessment of resting metabolic rate (RMR). The basal metabolic rate of the subjects was 3.94 ± 0.13kJ/min and the post-absorptive RMR was 4.02 ± 0.14kJ/min. There was no significant difference (P = 0.57) between these two values. In protocol 1 (n = 11) after reassessing the RMR the meal was eaten for 10 min and subjects performed the exercise for 40 min following which there was a 2.5 h rest during which measurement of postprandial resting metabolic rate (PPMR) was carried out. The energy expenditure of exercise in the post-absorptive state was 15.37 ± 0.75 kJ/min and in the absorptive state (after meal) was 15.66 ± 0.75 kJ/min being an increase of 2%. No significant differences were observed between these two values (P = 0.78). The PPMR measured 45, 95 and 150 min post exercise was found to be 21%, 20% and 18% above the pre-meal RMR. In protocol 2 (n = 17) after reassessing the RMR the meal was eaten for 10 min and 30 min later the PPMR was measured followed by the same exercise as before eating. The energy expenditure of exercise in the post-absorptive state was 17.24 ± 0.50kJ/min and 17.41 ± 0.47kJ/min in the absorptive state (after meal), being an increase of 1%. There was no significant difference between these two values (P = 0.79). The PPMR was 4.94 ± 0.08kJ/min. This was an increase of about 19% above the pre-meal RMR (4.14 ± 0.14kJ/min).