Physiological Determinants of Ultramarathon Trail Running Performance
The physiological determinants of ultramarathon success have rarely been assessed, and likely differ in their contributions to performance as race distance increases. The aim of this study was to examine predictors of performance in athletes who completed either a 50km (n:23, F:11), 80km (n:14, F:4), or 160km (n:14, F:2) trail race over a 20km-loop course on the same day. Measures of training history, aerobic fitness, running economy, in-race dehydration, and cardiovascular health were examined in relation to race-day performance. Performance was defined as the percent difference from the winning time at a given race distance, with 0% representing the fastest possible time. In the 50km race, higher training volumes, cardiovascular health, aerobic fitness, and a greater loss of body mass during the race were all related to better performance (all P<0.05). Using multiple linear regression, peak velocity achieved in the VO2max test (β=-11.7, P=0.002) and baseline blood pressure (β=3.1, P=0.007) were the best performance predictors for the men’s 50km race (r=0.98, r2=0.96, P<0.001), while peak velocity achieved in the VO2max test (β=-13.6, P=0.001) and loss of body mass (β=12.8, P=0.03) were the best predictors for women (r=0.94, r2=0.87, P=0.001). In the 80km race, only peak velocity achieved in the VO2max test predicted performance (β =-20.3, r=0.88, r2=0.78, P<0.001). In the 160km race, there were no significant performance determinants. While classic determinants of running performance including cardiovascular health, and running fitness predict 50km trail running success, performance in longer distance races appears to be less influenced by such physiological parameters.