Teenagers who play sport and exercise for more than 14 hours a week are worse off physically than those who are less active. Excessive exercise could be causing inflammation which affects physical and mental well-being, say researchers.
The 14-hours level-which is double the recommended amount of exercise teenagers need-seems to be the tipping point, after which more harm than good is done.
Researchers from the University of Lausanne in Switzerland made the discovery after they questioned more than 1,200 teenagers aged between 16 and 20 about their sporting activities.
Around 35 per cent had less than three hours exercise a week, 18.5 per cent had between 10 and 17 hours exercise, and five per cent were doing more than 17 hours of sport and exercise every week.
The researchers found that he highest scores for well-being were recorded by those doing 14 hours' exercise, but it started falling away dramatically beyond that.
Apparently, you can have too much of a good thing, say the researchers.
(Source: Archives of Disease in Childhood, 2013; doi: 10.1136/archdischild-2013-303729)