Teen balancing act: finding the optimal level of physical activity

Young people who exercise too much are just as much at risk of poor mental and physical health as those who work out too little.

According to the study published today in the Archives of Disease in Childhood adolescents benefit the most from physical activity when exercising between 10 and 17 hours per week.

Researchers followed the physical activity of more than 1,200 adolescents aged between 16 and 20 from Switzerland for over a year. Their physical and mental wellbeing was assessed using scoring criteria from the World Health Organization (WHO).

According to the well-being scale, ranging from 0 to 25, a participant scoring under 13 has poor mental and/or physical health. Weekly sports participation was categorised as low (0-3.5 hours), average (3.6-10.5 hours), high (10.6-17.5) and very high (17.5+ hours).

Adolescents with low or very high exercise levels were more than twice as likely to score below 13 than those with an average level of sports participation.

Researchers believe this shows the optimal amount of exercise for adolescent wellbeing is around 14 hours a week, double the current recommendation for this age group.

Dr Erika Borkoles, an exercise and sport science lecturer at Victoria University, said the study’s findings were concerning.

She said increasing the average number of hours an adolescent spends exercising is important, but it is a fine balancing act as there are a host of mental risks associated with high-pressure sporting activity.

“Children are more stressed at higher levels of activity, especially when there is a problem with getting ambiguous messages about their potential”, she said.

The University of Melbourne Chair of Adolescent Health Susan Sawyer said the study raised questions over the influence of physical activity on adolescent well-being.

“Those who exercise excessively might be driven to exercise because of an underlying mental disorder, such as anorexia nervosa. An alternative explanation is that such high frequency sport might of itself lead to poorer well-being as a result of, for example, disappointment about unrealistic performance expectations.”

But Sawyer also questioned the way the study authors gathered data.

“There is a real question about whether the association they describe is real,” she said.

Although it was “innovative” to access participants through online and social networking services, participants were then asked by researchers to recruit their peers for the study. This practice may have compromised the quality of the data, as the participants may not have been from a diverse social spread.

Sawyer noted the data was not adjusted to appropriately reflect this.

Of the study overall, she said, “Tantalising? Yes. Definitive? No.”