People should really read the research [1] and not this article as the article doesn't actually capture the scope and real impact of the research.
The executive summary highlights:
* Personal wellbeing drops, on average, as children move from primary into secondary school, and continues to drop as children move through secondary school.
* We find a graded relationship between family income and all three outcomes through adolescence: young people’s mental and emotional health scores are worse the lower down their family is on the income scale
*Engaging in physical activity was found to be more important for boys’ mental and emotional health in early adolescence than girls’, with a graded relationship between frequency of exercise and scores on all three outcomes for 14-year-old boys; at age 17, we find a graded relationship with frequency of exercise in both girls and boys. Heavy social media use is associated with worse scores on all outcomes in girls age 14 and 17, but only worse well being for boys at age 14.
> Engaging in physical activity was found to be more important for boys’ mental and emotional health
is because (personal anecdata warning!) guys tend to prefer friends who are physically fit. This is just something I've noticed by observing my school; the stronger guys tend to have a larger social circle.
However, this causation could be flawed, maybe physically active people have better emotional health and that's why people are attracted (friendship-wise) to them.
Your guess makes some sense, but I'd say it could also be that people who work out more often are typically involved in organized sports and have to work out x number of times per week. Organized sports often have a built in social circle.
The executive summary highlights:
* Personal wellbeing drops, on average, as children move from primary into secondary school, and continues to drop as children move through secondary school.
* We find a graded relationship between family income and all three outcomes through adolescence: young people’s mental and emotional health scores are worse the lower down their family is on the income scale
*Engaging in physical activity was found to be more important for boys’ mental and emotional health in early adolescence than girls’, with a graded relationship between frequency of exercise and scores on all three outcomes for 14-year-old boys; at age 17, we find a graded relationship with frequency of exercise in both girls and boys. Heavy social media use is associated with worse scores on all outcomes in girls age 14 and 17, but only worse well being for boys at age 14.
Etc...
[1]https://epi.org.uk/wp-content/uploads/2021/01/EPI-PT_Young-p...