Energy expenditure and dietary intake of athletes during an ultraendurance event developed by hiking, cycling and mountain climbing.

AIM: To investigate exercise intensity, energy expenditure and energy balance of athletes during an ultraendurance event (UE) consisting in hiking, cycling and mountain climbing. METHODS: Four athletes participated in this study. Maximal oxygen uptake (VO2max) and "VO2-heart rate" relationships during cycling and walking were determined by indirect calorimetry during two graded exercise tests. Body mass and body fat mass were measured before and after the UE. During the UE, heart rate (HR), diet intake, gastrointestinal disturbances and route characteristics were monitored. RESULTS: UE duration was 19 h29 min over a distance of 108 km, with 6768 meters of altitude difference. Body mass and percent of body fat mass tended to decrease after UE (-3.2% and -8.9%, respectively). During the locomotion phases, mean exercise intensity was 50.8±10.4% of VO2max and 65.8±7.6% of HRmax. Energy expenditure amounted to 51.0±3.4 MJ. Energy supplied from diet and body fat mass oxidation was 20.4±10.7 MJ and 17.3±2.4 MJ, respectively. During the UE, athletes did not suffer of any gastrointestinal disorder. CONCLUSION: Mean exercise intensity corresponded to 51% VO2max: it was independent from the locomotion type, and it can be considered an adequate intensity for UEs with similar characteristics. Although athletes successfully completed the UE, the self regulation of energy intake led athletes to a negative energy balance. Estimation of energy expenditure prior the begin of UEs would allow athletes to better plan the diet energy intake.

Bioenergetics of a slalom kayak (k1) competition.

The aim of this study was: i) to compute an energy balance of a slalom kayak competition by measuring the percentage contributions of the aerobic and anaerobic energy sources to total metabolic power (E(tot)); and ii) to compare these data with those obtained, on the same subjects, over a flat-water course covered at maximal speed in a comparable time. Experiments were performed on eight middle- to high-class slalom kayakers (24.8 +/- 8.1 years of age, 1.75 +/- 0.04 m of stature, and 69.8 +/- 4.7 kg of body mass) who completed the slalom race in 85.8 +/- 5.3 s and covered the flat water course in 88.1 +/- 7.7 s. E(tot) was calculated from measures of oxygen consumption and of blood lactate concentration: it was about 30 % larger during the flat water all-out test (1.72 +/- 0.18 kW) than during the slalom race (1.35 +/- 0.12 kW). However, in both cases, about 50 % of E(tot) derives from aerobic and about 50 % from anaerobic energy sources. These data suggest that, besides training for skill acquisition and for improving anaerobic power, some high intensity, cardiovascular conditioning should be inserted in the training programs of the athletes specialised in this sport.