Various studies have examined total daily energy expenditure (TDEE) or exercise energy expenditure (EEE) or changes in non-exercise activity thermogenesis (NEAT) and resting metabolic rate (RMR) in response to changes in exercise regimen. However, no study has examined the interaction of all these components contributing to TDEE during different training periods. There is also a lack of research addressing changes in dietary intake in response to changes in training regimen. The purpose of this study, therefore, was to examine changes in TDEE and its components, specifically EEE, NEAT, and RMR, along with alterations in dietary intake in male endurance trained athletes during high-volume (HV) and low-volume (LV) training periods. Secondarily, it was evaluated whether these athletes met current nutrition recommendations for sport and health.Energy expenditure was measured in 15 male endurance athletes (age 23.6 ± 2.4) during two non-consecutive weeks - one week with about 13 hours of exercise training (HV) and another week with about 6 hours of exercise training (LV). Height (cm), weight (kg), and body composition were assessed according to standard procedures at the beginning and end of each week of data collection. RMR was measured in the middle of each week using indirect calorimetry. The SenseWear Pro3 Armband was used to measure NEAT while EEE was assessed via heart rate using individual regression equations. TDEE was then calculated by summing RMR, NEAT, and EEE. Dietary information was obtained via an online food frequency questionnaire taken at the end of each week of data collection.There was no difference in body composition between the two weeks of training. TDEE and EEE were significantly higher during the HV week, even though training intensity did not differ between the HV and LV training week. In addition, a trend towards higher RMR with higher training volume was observed, while NEAT remained relatively constant. There was a significant reduction in time spent in sedentary activity during the HV week while no differences in time spent in light, or moderate-to-vigorous activity occurred. TDEE and NEAT, however, were significantly correlated with time spent in different intensities and there was a positive relationship between RMR and time spent in vigorous activity. Dietary intake did not differ between the HV and LV week, and carbohydrates (CHO), fat, and protein contributed 51%, 33%, and 16%, respectively. Mean micronutrient intake of these athletes met or exceeded DRI micronutrient recommendations while reported intake for endurance athletes was well below recommendations for CHO, and fat intake exceeded current recommendations.Neither NEAT nor energy intake (EI) differed during different training weeks. The reported caloric intake was significantly lower than TDEE during either training week and the high fat intake, low fiber consumption, and high sodium intake suggests that these athletes were generally consuming a typical Western diet and that they may need guidance to meet dietary guidelines for health and performance. The discrepancy between EI and EE was attributed to underreporting rather than an energy deficit. In addition increased training time did not reduce light and moderate activity, but rather reduced sedentary time in trained endurance athletes.
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