PERIOD3 VNTR genotype and individual variation in match performance of professional rugby players following trans-meridian travel

Trans-meridian travel disrupts circadian rhythms and consequently impairs cognitive and physical performance, albeit with notable inter-individual variability. Rapid re-entrainment of the circadian system is critical to athletes crossing multiple time zones ahead of tournaments to minimise the effects of jet-lag on performance. The aim of this study was to determine whether the PERIOD3 variable number tandem repeat (PER3 VNTR) polymorphism might contribute to inter-individual variation in changes in athletic performance in rugby players following trans-meridian travel. We compared individual performance of 60 professional male rugby players (mean age: 25.8 ± 2.9y, PER34/4: n = 20; PER34/5: n =20; PER35/5: n = 20) taking part in a 21-week tournament involving trans-meridian travel between matches. The PERIOD3 polymorphism is associated with differential vulnerability to sleep loss and circadian misalignment, which may affect adaptation to jet lag and, consequently, athletic performance. Performance metrics (quality of play and game activity rate) were assessed through video-based analysis across 166 matches. Quality of play decreased following trans-meridian travel (p<0.001), with greater impairments following eastward compared to westward travel (p=0.022). Players with the PER35/5 genotype showed a smaller reduction in quality of play following trans-meridian travel compared to the PER34/4 group. These findings indicate that PER3 VNTR genotype modulates the extent of jet lag-related performance decline, underscoring the importance of individualised travel and recovery strategies for athletes.