Relationship Between Mixed Relay Performance And Physiological Measures Of Fatigue And Metabolism In Junior Triathletes.

Abstract

The mixed relay triathlon is a new event in the Summer Olympics consisting of teams of 2 females and 2 males whom each complete a super-sprint triathlon (~20 min per athlete) in sequential order. Given the duration of the event, the intensity will likely be higher than longer distance triathlons. Thus, muscular power and anaerobic metabolism may be more important determinants of performance. To date, no research has investigated the physiological determinants nor the muscular fatigue associated with the event. PURPOSE: The primary purpose was to determine the changes in leg muscle power (to assess muscular fatigue) and anaerobic metabolism during a mixed relay triathlon. A secondary purpose was to determine the relationships between leg muscle power and anaerobic metabolism with overall and leg specific (swim, bike, run) performance. METHODS: Twelve highly-trained junior (5 female, 7 male) triathletes (age:17.6±1.3 years) competed in the Canadian Mixed Relay Championships (300 m swim, 6 km bike, 1.6 km run). Before and immediately after the race vertical jump height (VJH) and blood lactate (BLa) were measured. Paired sample t-tests were used to compare pre- and post-race differences. Pearson correlations were used to determine the relationships between finishing time, and swim, bike, and run times with BLa and VJH. RESULTS: Mean race time was 22.4 ± 1.4 min, including transitions (swim 4.5 ± 0.4 min, bike 10.3 ± 0.6 min, run 6.05 ± 0.5 min). VJH increased pre- to post-race (pre: 43.8 ± 8.4 cm; post: 46.1 ± 8.0 cm, p=0.05) in 7 out of 12 participants. A significant correlation between VJH pre-race and bike time was determined (r=-0.60, p=0.03). BLa significantly increased from pre-to post-race (pre:1.3 ± 0.4 mmol·L-1; post: 10.7 ± 2.4 mmol·L-1, p<0.001) and significantly correlated to bike and overall finishing time (bike: r=-0.71, p=0.02; finishing time: r=-0.76,p<0.001). CONCLUSIONS: Based on the high BLa after the race, the mixed relay event requires a large contribution from anaerobic metabolism and faster athletes had greater post-race BLa. Despite the high physiological demands, muscular fatigue was not found in most participants. Furthermore, the relationship between VJH and bike performance demonstrates the importance of muscular power in the mixed relay event.