Science has spoken: jet lag disadvantages SA Super Rugby teams

10 June 2016 | Story Yusuf Omar. Image Michael Hammond.
Rugger bugger and doctoral graduand Lovemore Kunorozva has found evidence that the performance of South African Super Rugby players is affected by time zone travel.
Rugger bugger and doctoral graduand Lovemore Kunorozva has found evidence that the performance of South African Super Rugby players is affected by time zone travel.

When the Sharks lost 37–6 to the Chiefs in 2012's Super Rugby final, Lovemore Kunorozva texted one of his supervisors: “Do you think it could be jet lag?”

Associate Professor Laura Roden replied: “It certainly looks like it”.

An atypical exchange between two emotionally charged rugby fans during the biggest game of the season, perhaps, but jet lag is Lovemore's game. He will graduate with a PhD in molecular and cell biology from UCT this June, having found that jet lag can have a negative impact on travelling athletes – both in terms of their performance and their health.

With the help of team doctors, Lovemore recruited about 30 players from each of South Africa's five Super Rugby teams in 2011 and 2012. The players' performance, injuries and illnesses were meticulously tracked throughout the two seasons. A player's data that was gathered when there was no time-zone travel was compared to data gathered for that same player when he travelled to Australasia and when he returned to South Africa.

The results support what many sports doctors, commentators and fans have long contended: players who travel eastward are more sensitive to the effects of jet lag, and it shows in their play.

“We tracked their involvement in the game – which didn't differ significantly when they were jet-lagged,” says Lovemore. “But the quality of their involvement diminished considerably.”

Mistakes crept into a jet-lagged player's game and they were more prone to injury and illness.

Whether one operates best in the morning, in the evening or equally well at both times may depend on one's PERIOD3 (PER3) genotype. Individuals with a PER3 variant associated with 'morning people' may cope a lot better with eastward time travel. This could be because 'morning people' tend to fall asleep earlier anyway, which may make it easier for them to fall asleep during the Australian or New Zealand night time, says Lovemore.

“We're still trying to elucidate the mechanisms,” says Lovemore. “We can't say that genes should be a factor in selecting teams. It could really discriminate [negatively]. But for the team doctors, this knowledge could really help them to know which players to look out for, in terms of who might be prone to injuries or illnesses if you're going to play overseas. They'll know what to do in order to try to prevent that from happening.”

Unfortunately, the players weren't available for a key part of the study: the simulated jet-lag experiment. So Lovemore had a group of healthy, male individuals with habitually low levels of physical activity do the simulation instead.

They were housed in a sleep lab for four days and denied access to external time cues while the key hormones melatonin and cortisol were measured (at particular times) to ascertain internal time in the absence of external time cues.

“It was tough. They were away from their families for four days. It was hard enough for me, and I was only observing,” he says.

Plans for the future

Post-capping, the former rugby player (he played on the flank and wing in high school) has big goals. Besides mulling over careers in academia and industry, Lovemore eventually hopes to collaborate with his current research group team to establish South Africa's first national sleep lab, where studies like his jet-lag simulation could take place regularly.

“It was a bit difficult finding a space to do the simulation. It was expensive, and eventually we were able to do it at the Sports Science Institute of South Africa.”

If his wishes of a national sleep laboratory come true, sleep studies won't be a problem for the many institutions who dream of carrying out similar research. He is keen for more people to take on this kind of research in other team sports in the hope that his results will be replicated.

“If we can see the same relationship in other sports – not just rugby – we can start to say something. In as much as there is evidence, this is only one study.”

A Harvard professor who is a consultant for the Boston Red Sox baseball and Boston Celtics basketball teams has been collecting similar data for the past ten years, seeing as those players routinely travel from the East Coast to the West Coast in the United States. Lovemore would love to get his hands on that data, which will be available to him provided he can get the funding to go across the pond for a few years.

Lovemore heaps praise on his supervisors, Associate Professor Roden from the Department of Molecular and Cell Biology and Dr Dale Rae from the Division of Exercise Science and Sports Medicine.

“They've been influential in coming up with the project and have mentored me very well. It's been a good journey with them. We've been an amazing team.”

Lovemore has been at UCT since his undergraduate days and vows to return at some point, should he not get a post here first.

“Even if I get a post overseas, I will always return, because this is my home.”

About that Sharks–Chiefs game, Lovemore laughs: “The Sharks had gone to three different continents in three weeks. It could have been the Sonny Bill Williams factor, but jet lag could have had an impact, too.”

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