Too much exercise ‘can be as bad as too little'
More than 14 hours of sport a week puts teenagers at risk, say researchers
TOO much exercise could be as bad as getting none at all, according to researchers, who found that those who exercised for more than 14 hours a week were in worse health.
Although playing sport generally has a positive impact on mental and physical wellbeing, researchers found that the benefits begin to decline after a certain threshold.
Researchers of the University of Lausanne in Switzerland questioned more than 1 200 people aged between 16 and 20 about their sporting habits between February 2009 and January 2010.
Up to a maximum of 14 hours a week — twice the official recommendation for teenagers — were linked to lower levels of stress and anxiety, and higher self-esteem and brain power.
But the benefits were lower among the 5% of teenagers who participated in longer periods of physical activity, suggesting that excessive exercise could be harmful rather than protect-ive, the scientists concluded.
This could be owing to inflammation caused by excessive exercise, which has been linked to poorer physical and mental health in previous studies, they said.
They analysed the teenagers’ health using a scoring system developed by the World Health Organisation to measure physical and mental wellbeing together. It runs from nought to 25 and a score of below 13 indicates poor wellbeing. The average score among the group was 17.
The teenagers were then grouped according to how much sport they played in an average week. Some 35% were categorised as “low” (less than 3.5 hours a week), 41.5% were “average” (3.6 to 10.5 hours), 18.5% were “high” (10.6 to 17.5 hours) and 5% were “very high” (more than 17.5 hours).
The results, published in the Archives of Disease in Childhood journal, showed that those in the low and very high groups were more than twice as likely to score below 13 on the wellbeing scale.
Participants in the high group had a better outcome, however, with a 50% lower chance of scoring below 13 than the average group.
The best scores were among those who got 14 hours of exercise each week, but the benefits were cancelled out after 17.5 hours, researchers reported.
They said their findings could be of
The results highlight the importance for physicians caring for adolescents to follow up their level of sport practice
“major clinical interest” to doctors who advise teenagers on how exercise can benefit their health.
Although the results do not necessarily prove that excessive exercise causes lower wellbeing, the results of biological studies suggest that very high levels of exercise can cause inflammation, which in turn harms physical and mental health.
“We found that the sport practice apparently ceased to be a protective factor and became an independent risk factor for poor wellbeing when practising more than twice the seven recommended hours a week,” they said.
“These results highlight the importance for physicians caring for adolescents to follow up their level of sport practice and concurrently inquire about their wellbeing.” — © The Daily Telegraph, London