Purpose: Warming up in very cold climates and maintaining an elevated body temperature prior to a race is challenging for snow-sport athletes. This study aimed to investigate the effects of active (ACT), passive (PAS) and a combination of ACT and PAS (COM) warm-ups on maximal physical performance in a sub-zero environment. Methods: Ten junior alpine skiers completed three experimental trials in -7.2 ± 0.2°C. ACT involved 5-min of moderate cycling, 3 x 15-s accelerations, a 6-s sprint, five counter-movement jumps (CMJs) and a 10-min passive transition phase, while in PAS participants wore a lower-body heated garment for 24 min. In COM participants completed the active warm-up, then wore the heated garment during the transition phase. Two maximal CMJs and a 90-s maximal isokinetic cycling test followed the warm-up. Results: CMJ performance was likely (P=0.150) and very likely (P=0.013) greater in ACT and COM, respectively, versus PAS. Average power output during the cycling test was likely (P=0.074) greater in ACT and COM versus PAS. Participants felt likely to almost certainly warmer (P<0.01) and more comfortable (P=0.161) during ACT and COM versus PAS. In addition, participants felt likely warmer (P=0.136) and very likely more comfortable (P=0.161) in COM versus ACT. Conclusions: COM resulted in significantly improved CMJ performance versus PAS, while both ACT and COM led to likely improved 90-s cycling performance. Participants felt significantly warmer during ACT and COM versus PAS, and likely warmer in COM versus ACT. Therefore, a combined warm-up is recommended for alpine skiers performing in sub-zero temperatures.