To examine the effects of 24-h travel west across 11 time zones on subjective jet-lag and wellness responses together with self-reported sleep and upper respiratory symptoms in 18 professional rugby league players.
Measures were obtained 1 or 2 d before (pretravel) and 2, 6, and 8 d after travel (post-2, post-6, and post-8) from Australia to the United Kingdom (UK) for the 2015 World Club Series.
Compared with pretravel, subjective jet-lag remained significantly elevated on post-8 (3.1 ± 2.3, P < .05, d > 0.90), although it was greatest on post-2 (4.1 ± 1.4). Self-reported sleep-onset times were significantly earlier on post-2 than at all other time points (P < .05, d > 0.90), and large effect sizes suggested that wake times were earlier on post-2 than on post-6 and post-8 (d > 0.90). Although significantly more upper respiratory symptoms were reported on post-6 than at pretravel (P < .05, d ˃ 0.90), no incidence of injury and negligible changes in wellness and muscle strength and range of motion (P > .05, d < 0.90) were evident after travel.
Results suggest that westward long-haul travel between Australia and the UK exacerbates subjective jet-lag and sleep responses, along with upper respiratory symptoms, in professional rugby league players. Of note, the increase in self-reported upper respiratory symptoms is a reminder that the demands of long-haul travel may be an additional concern in jet-lag for traveling athletes. However, due to the lack of sport-specific performance measures, it is still unclear whether international travel interferes with training to the extent that subsequent competition performance is impaired.
Fowler is with Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar. Duffield and Lu are with the Sport & Exercise Discipline Group, University of Technology Sydney (UTS), Sydney, NSW, Australia. Scott is with the Dept of Performance Sciences, Brisbane Broncos Rugby League Football Club, Brisbane, QLD, Australia.