Is inactivity contributing to children’s mental health problems?

“A RECENT large-scale survey conducted by the University College London has found that children aged 12-16 who spend a lot of time sitting are more likely to develop depression by the age of 18. The message is that people of all ages should be encouraged to move more, with even light activity providing mental health benefits. The study is cross-sectional so cannot show causation however we have been involved in other studies which support that children's mental and physical health are linked. 

The authors recommend that more needs to be done to increase light physical activity in younger groups, such as standing lessons or increase active travel time between classes (see also our study on classroom-based physical activity as another idea to promote physical activity in the school setting).  

Is “sitting” the new “smoking”?

Increases in mental health problems, including depression, appear to be rising and at the same time people are sitting more, there have been suggestions that “sitting” maybe “the new smoking”. The media highlighted the risks of sitting for too long on an increased risk of mortality and emphasised that the risks were not reduced even if exercise was taken into account.

More recent studies, however, showed that this is not the case. Smoking is by far more risky than sitting (2000 deaths per 100,000 for heavy smoking compared to 190 deaths per 100,000 per high volume of sitting). Likewise, another study has shown that even if you sit for very long periods (> 8 hours per day), the risks or mortality are substantially reduced or eliminated if you are physically active (≥300 min of moderate to vigorous physical activity per week). We also found in one of our studies, that replacing 10 min of sedentary time with an equivalent amount of moderate to vigorous physical activity resulted in a 12% cardiovascular disease relative risk reduction.

How do we reduce “sitting”?

So, sitting is not the new smoking, but it is associated with many health risks in adults and children. For children, in particular, sitting has been associated with obesity, lower fitness, higher cardiovascular risk score, unfavourable behavioural conduct and lower self-esteem. In one of our systematic reviews, we found that although many studies show that sedentary behaviour is associated with obesity in children, interventions which target sedentary behaviour only show small and clinically irrelevant effects. 

However, sedentary behaviour interventions can reduce body weight if targeted with other behaviours (e.g. diet and physical activity) and if they also address mental health. Likewise, we found that in early years sedentary behaviour interventions targeting the after school period, providing incentives and setting progressing goals and are effective in reducing sedentary behaviour.” 

• Read more about this on the BBC News website