Abstract

Objective: To describe the fat-oxidation rate in triathlon and different modalities of endurance cycling.

Methods: 34 endurance athletes (15 male triathletes, 4 female triathletes, 11 road cyclists and 4 male mountain bikers) underwent a progressive cycloergometer test until exhaustion. Relative work intensity (VO_2max), minimal lactate concentration (La⁻_min), lactic threshold, individual lactic threshold (ILT), maximal fat-oxidation rate (Fat_max, Fat_max zone) and minimal fat-oxidation rate (Fat_min) were determined in each of the groups and were compared by means of one-way analysis of variance.

Results: No significant differences were found for Fat_max, Fat_min or for the Fat_max zone expressed as fat oxidation rate (g/min). Intensities −20%, −10% and −5% Fat_max were significantly lower for mountain bikers with respect to road cyclists and female triathletes, expressed as % VO_2max. Intensities 20%, 10% and 5% Fat_max were significantly lower for mountain bikers with respect to male triathletes and female triathletes, and for male triathletes in comparison with female triathletes, expressed as % VO_2max. Lactic threshold and La⁻_min did not show significant differences with respect to Fat_max. Lactic threshold was found at the same VO_2max with respect to the higher part of the Fat_max zone, and La⁻_min at the same VO_2max with respect to the lower part of the Fat_max zone.

Conclusions: The VO_2max of Fat_max and the Fat_max zone may explain the different endurance adaptations of the athletes according to their sporting discipline. Lactic threshold and La⁻_min were found at different relative work intensities with respect to those of Fat_max even though they belonged to the Fat_max zone.