BACKGROUND: Maximal oxygen uptake (VO2max), VO2 at lactate threshold (LT), and gross efficiency are the three main factors determining endurance performance (1). The skiing component of biathlon is of an enduring nature, involving 3 or 5 bouts each lasting 5-8 min (2). However, the contribution of these endurance factors to skiing performance in biathlon has not previously been investigated. Thus, the purpose of this study was to evaluate the association between performance determining factors and skiing performance in biathlon. METHODS: Twenty-eight Swedish biathletes competing both at national and international levels (14 females, 23+/-3 yr, VO2max 56+/-4 mL/kg/min; 14 males 24+/-4 yrs, VO2max 66+/-3 mL/kg/min) performed a submaximal incremental test followed by a maximal time-trial (TT) prior to the start of the 2016-17 season. Treadmill roller-skiing was used for testing and VO2max, VO2 at LT (4mmol/L), gross efficiency (GE), as well as aerobic (AeMR) and anaerobic (AnMR) metabolic rates were calculated (3). All participants competed in a biathlon competition (BC) within two months of testing, which formed the basis of the 2016-17 international teams. Skiing time during both TT and BC (without time spent shooting) were subsequently correlated to the physiological laboratory measures. RESULTS: TT and BC performance were significantly correlated in both sexes (females r=0.67, p<0.01; males r=0.71, p<0.01). VO2max was related to TT (r=-0.72, p<0.01) and BC (r=-0.54, p<0.05) performances for the females but not the males (TT r=-0.45, p=0.10; BC r=-0.46, p=0.10). LT was not associated to TT or BC performance. GE was correlated with BC performance in both sexes (females r=-0.54, p<0.05; males r=-0.56, p<0.05) but with TT performance only among the males (females r=-0.38, p=0.18; males r=-0.62, p<0.05). AeMR was correlated with TT in the females (r=-0.75, p<0.01; males r=-0.44, p=0.11), while AnMR was not related to TT or BC for either sex. A block-wise multiple regression analysis employing TT performance as the dependent variable and GE, AeMR and AnMR as the independent variables resulted in significant r2 values for both females (r2=0.92, p<0.001) and males (r2=0.94, p<0.001). When BC performance was used as the dependent variable, and VO2 at LT and accumulated O2 deficit as independent variables, the r2 value was not significant for either sex (r2=0.29, p=0.16; males r2=0.36, p=0.09). CONCLUSION: The present results indicate that performance in a TT test associates to skiing performance in biathlon. In addition, GE seems to be a more important factor for skiing performance than LT whereas VO2max seems to be a more important factor only for women, indicating decisive differences between genders in our study population.
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