Dark-coloured sports jerseys could lead to poor performance, increased rates of injury, and even jeopardise the careers of young rugby league players, researchers say after a surprising discovery among junior teams in far north Queensland.
The study of 64 young rugby league players in Cairns looked at factors influencing rates of injury.
While the ground moisture and hardness appeared to have no impact on how often players were hurt over the season, the colour of their jerseys did.
The study found the rate of injuries was higher among under-14s players who wore black jerseys with 69.9 injuries per 1,000 hours of games played, compared to those who wore orange jerseys with 55.9 injuries per 1,000 hours of games played.
James Cook University sport and exercise lecturer Kenji Doma said the link was likely due to heat stress.
“Particularly in rugby league there is a lot of collision, so you need to be able to know how to tackle and avoid opponents to actually minimise the risk of injuries,” Dr Doma said.
“When you’re exposed to a lot of heat, it can impact your performance, your balance, your technique, and your decision-making skills can also be impaired.
“Jersey colours that are darker will have greater absorption capacity for heat.”
Dr Doma said the findings were “surprising” and could have far-reaching applications.
“In most sports you find teams will have light-coloured jerseys and dark-coloured jerseys,” he said.
“It’s how they differentiate themselves.
“So this can be transferred to other sports as well.”
Minimising risk a focus for clubs
North Queensland Cowboys game development officer and long-time coach Liam Bartlett said the findings were a huge surprise.
“It’s very interesting from a coaching point of view,” he said.
“Over a year your team can use different coloured jerseys a number of times. There is obviously quite a lot of merit in what they have found.
We’re always trying to make the game as safe as possible for everyone we can. It’s nice to know there is another angle being investigated.”
He said the findings could be used to improve performance as well as player safety, especially in tropical climates.
But junior coach Alby Anderson cautioned clubs against changing their colours before more research was conducted.
“There is a massive legacy and history behind the colours and the jerseys,” he said.
“Changing uniforms can be a massive cost to the club.”
Dr Doma also called for further investigation, saying the study was unable to determine exactly what type of injuries were likely as a result of jersey colour.
It’s also uncertain whether the findings would apply to older age groups and professional-level rugby league players.
But he said the risk of sports injuries needed to be treated seriously, especially among children.
It could impact on an athlete’s career, particularly if there is an athlete who has been identified as highly talented with really good prospects in the future,” he said.
The study suggested a range of strategies for minimising risk.
They included taking appropriate breaks, changing game times to reduce heat exposure, staying hydrated, and making sure players got enough rest.
Mr Anderson said clubs already took these strategies into consideration.
“We have one of the best safety programs for junior players out of any sport,” he said.