Pro athletes reveal science of beating jet lag

The pro athletes of Canada’s short-track speed-skating team recover from jet lag in five days when traveling to competitions in Asia, 13 time zones away. This is twice as fast as the typical adaptation time, which is based on the standard theory that air travellers require 12 to 24 hours to recover for each hour of time difference.

This finding is revealed by postdoctoral researcher Giorgio Varesco of Université de Montréal’s Centre for Advanced Research in Sleep Medicine (CARMS) in the journal Experimental Physiology. The study is co-authored by project directors Guido Simonelli of CARMS and François Bieuzen of Québec’s Institut national du sport.

The research outcomes focused on optimising the adaptation process for athletes during intercontinental travel. Researchers analysed data from 19 members of Canada’s short-track speed skating team during competitions in Asia in 2017 and 2019. The group featured eight Olympic medallists and five World Championships medallists, including Charles Hamelin, Marianne St-Gelais, Kim Boutin, and Samuel Girard.

Smartwatch data capture

Each athlete wore a smartwatch that continuously tracked their movements and sleep cycles for five days prior to departure to establish baseline values. The devices were worn during travel days and throughout their 10- to 13-day stay, which included four competition days.

The smartwatches measured sleep duration, sleep efficiency, and physical activity levels during both training sessions and skating competitions.

Physical performance during training was assessed using countermovement jump (CMJ) tests, an indicator of muscular strength. Additionally, athletes rated their perceived effort during training on a scale of one to ten.

“Intercontinental trips pose two challenges for athletes: primarily travel fatigue, followed by jet lag, which throws off the internal body clock since it remains set on its original time zone,” says Varesco.

The Canadian skaters followed an unrestricted sleep schedule upon arrival. Data showed they typically went to bed around 8:00 PM and woke up at 6:00 AM.

More sleep, less training

With each passing day, the athletes modified their bedtimes and wake-up times, although they were given no specific instructions in this regard.

“Each day, their sleep duration increased by approximately nine minutes,” says Varesco.

“After five days, they had recovered nearly one hour. Even more surprisingly, their sleep quality improved during their time in Asia, with higher sleep efficiency than that measured in Montreal.”

The data showed that the athletes maintained their peak activity in the early afternoon, gradually shifting from 7:00 PM to 1:00 PM (local time) over the first few days.

During the athletes’ stay, spontaneous activities and training loads were reduced by 15% compared to their usual routines. This voluntary reduction did not hamper their performance.

The CMJ tests showed a gradual improvement: overall performances were normal upon arrival but after only a few days, results were higher than baseline values.

“Physical activity, light exposure, social interactions and diet all play key roles in the adaptation process.”

Five medals in Seoul

The study results were shared with the speed-skaters, who then put the recommendations into practice at the start of the 2024-2025 season.

“For recent competitions in South Korea and China, we recommended scheduling training sessions in the late morning or early afternoon,” says Varesco. “We also advised athletes to go to bed a little later, around 9:00 PM or 10:00 PM.”

The researchers provided specific recommendations on light exposure and social interactions. For example, to facilitate the adaptation process, it was advised to avoid naps one hour before the scheduled bedtime.

This strategy appears to have paid off: last December, the Canadian team won five medals (three gold and two silver) at the Short Track World Tour, in Seoul.

“All the athletes wore a smartwatch that will provide us with new data to analyse. But the competition results are very encouraging.”

To assess whether these results apply more broadly, the research team plans to expand its study to other sports. The focus will be on disciplines that require sustained physical effort.

“This future research will enable us to further refine our understanding of adaptation to jet lag in athletes, and to optimise preparation strategies for international competitions.”