Effects of Acute Caffeine Supplementation on Integrated Biathlon Performance in Elite Male Athletes.

Caffeine enhances endurance performance but may impair shooting accuracy, creating a potential trade-off for overall biathlon performance. In a randomized, placebo-controlled, crossover study, seven elite male biathletes consumed caffeine (3 mg/kg) or taste-matched placebo 60 min before a simulated biathlon competition consisting of five "laps" of 6-min treadmill skiing interspersed by four five-shot bouts. Participants further performed precision shooting (20 prone and 20 standing) pre- and postcompetition. Caffeine increased distance covered in Laps 1 (1,824 ± 73 vs. 1,772 ± 66 m; p = .03, dz = 1.12) and 2 (1,801 ± 92 vs. 1,776 ± 84 m; p = .02, dz = 1.19) but did not improve total distance (p = .06). Blood lactate (p = .01, ηp2=.85) and ventilation (p < .001, ηp2=.90) increased with caffeine. Heart rate (p = .07) and perceived exertion (p = .69) did not differ between conditions. Caffeine impaired shooting accuracy in standing (72.9 ± 16.0% vs. 82.9 ± 7.6%; p = .03, dz = 0.87), but not prone. Integrated race times did not differ between conditions for individual (71.72 ± 5.27 vs. 71.58 ± 4.57 min), mass start (52.45 ± 3.67 vs. 52.57 ± 3.27 min), or pursuit (44.18 ± 3.18 vs. 44.23 ± 2.83 min; all p > .77) formats. Caffeine impaired postexercise precision shooting in prone position (88.9 ± 6.0% vs. 93.3 ± 7.5%; p = .04, dz = 0.65). Our findings highlight task-specific effects of caffeine, emphasizing the importance of tailoring supplementation to integrated performance demands.