PURPOSE
While the physiological determinants of road running have been widely studied, there is a lack of research in trail-running racing performance. The aim of our study was to determine the physiological predictors of trail-running performance in races of different distances in similar terrain and weather conditions.
METHODS
Seventy-five trail runners participating in one of the races of the Ultra-Trail du Mont-Blanc were recruited. Previous to the race, each runner was evaluated with (1) an incremental treadmill test to determine maximal oxygen uptake, ventilatory thresholds, cost of running, and substrate utilization; (2) a power-force-velocity profile on a cycle ergometer; (3) maximal voluntary contractions of the knee extensors and plantar flexors; and (4) anthropometric characteristics. Neuromuscular fatigue was evaluated after the races. Twenty-four runners finished a SHORT (<55 km), 16 finished a MEDIUM (101 km), and 14 finished a LONG (>145 km) race. Correlations and multiple linear regressions were used to find the determinants of performance in each race distance.
RESULTS
Performance in SHORT was explained by maximal oxygen uptake and lipid utilization at 10 km/h (r2 = .825, P < .001). Performance in MEDIUM was determined by maximal oxygen uptake, maximal isometric strength, and body fat percentage (r2 = .917, P < .001). A linear model could not be applied in LONG, but performance was correlated to peak velocity during the incremental test.
CONCLUSIONS
Performance in trail running is mainly predicted by aerobic capacity, while lipid utilization also influences performance in races <60 km and performance in approximately 100 km is influenced by muscle strength and body composition.