Energy turnover during 24 hours and 6 days of adventure racing |
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| Authors: | Jonas K Enqvist Patrik H Johansson Thibault Brink-Elfegoun Linda Bakkman Björn T Ekblom |
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| Institution: | 1. Swedish Winter Sport Research Centre , Mid Sweden University , ?stersund;2. ?strand Laboratory of Work Physiology , The Swedish School of Sport and Health Sciences , Stockholm;3. ?strand Laboratory of Work Physiology , The Swedish School of Sport and Health Sciences , Stockholm;4. Department of Physiology and Pharmacology , Karolinska Institutet , Stockholm, Sweden |
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| Abstract: | Abstract Energy turnover was assessed in two conditions of mixed ultra-endurance exercise. In Study 1, energy expenditure and intake were measured in nine males in a laboratory over 24 h. In Study 2, energy expenditure was assessed in six males during an 800-km Adventure race (mean race time 152.5 h). Individual correlations between heart rate and oxygen uptake (Vdot]O2) were established during pre-tests when kayaking, cycling, and running. During exercise, energy expenditure was estimated from continuous heart rate recordings. Heart rate and Vdot]O2 were measured regularly during fixed cycling work rates to correct energy expenditure for drift in oxygen pulse. Mean energy expenditure was 18,050 ± 2,390 kcal (750 ± 100 kcal · h?1) and 80,000 ± 18,000 kcal (500 ± 100 kcal · h?1) in Study 1 and Study 2 respectively, which is higher than previously reported. Energy intake in Study 1 was 8,450 ± 1,160 kcal, resulting in an energy deficit of 9,590 ± 770 kcal. Body mass decreased in Study 1 (?2.3 ± 0.8 kg) but was unchanged in Study 2. Fat mass decreased in Study 2 (?2.3 ± 1.5 kg). In Study 1, muscle glycogen content decreased by only 60%. Adventure racing requires a high energy expenditure, with large inter-individual variation. A large energy deficit is caused by inadequate energy intake, possibly due to suppressed appetite and gastrointestinal problems. The oxygen pulse, comparing start to 12 h of exercise and beyond, increased by 10% and 5% in Study 1 and Study 2 respectively. Hence, estimations of energy expenditure from heart rate recordings should be corrected according to this drift. |
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| Keywords: | Energy intake energy expenditure ultra-endurance exercise muscle glycogen fat mass |
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