Teenagers have long been told that being active and taking part in sports is good for their health. But new research suggests that too much sport for teenagers could negatively impact their well-being just as much as too little sport.

The US Department of Health and Human Services recommends that young people aged between 6 and 17 years carry out at least 60 minutes of physical activity a day, equating to 7 hours a week.

But researchers from Switzerland and Canada say their study, published in the BMJ journal Archives of Disease in Childhood, suggests that 14 hours of physical activity a week is best for promoting good health in teenagers. However, they found that more than 14 hours appears to be detrimental to their health.

To reach their findings, the investigators surveyed more than 1,245 teenagers aged between 16 and 20 from Switzerland.

All participants were required to answer questions regarding demographics, height and weight, socioeconomic status, sports practice, sports injuries and well-being.

Their well-being was assessed using the World Health Organization (WHO) Well-Being Index, which provides scores between 0 and 25. A score below 13 is an indicator of poor well-being.

Of the participants, 50.4% were male with a mean age of 17.95 years. Almost 9% of these males were overweight or obese. The overall average well-being score for all participants was 17.

The researchers categorized sports participation as low (0-3.5 hours a week), average (3.6-10.5 hours), high (10.6-17.5 hours), and very high (more than 17.5 hours).

Low sports activity was found in 35% of subjects, 41.5% had average activity, 18.5% had high, while 5% had very high.

The investigators found that participants in the low and very high activity groups were more than twice as likely to have well-being scores below 13, compared with subjects in the average group.

The researchers say this corresponds to an “inverted U shaped” link between weekly duration of sports practice and well-being.

They also found that the highest well-being scores were obtained by participants who carried out around 14 hours of physical activity a week, but beyond 14 hours resulted in lower well-being scores.

Commenting on their findings, the researchers say:

Physical activity has been associated with positive emotional well-being, reduced depressive, anxiety and stress disorders, and improved self-esteem and cognitive functioning in children and adolescents.

We found that sports practice apparently ceased to be a protective factor and became an independent risk factor for poor well-being when practicing more than twice the 7 recommended hours per week.”

The investigators note that their study highlights the importance for physicians caring for adolescents to monitor their level of sports practice and ask them about their well-being.

“Regardless of their decision to pursue their level of practice, these adolescents probably need a supportive and closer follow-up of their health and well-being. Our findings can inform guideline panels who produce recommendations on sports practice for adolescents,” they add.

Medical News Today recently reported on a study suggesting that exercise can boost teenagers’ academic performance.