Although many previous studies have found that physical activity can be beneficial for mental health conditions such as depression and anxiety, working as both prevention and treatment, less is known about how it can affect positive mental health conditions, such as contentment.
To research further, Weiyun Chen and co-author Zhanjia Zhang, both at the University of Michigan, reviewed 23 studies on happiness and physical activity.
The studies included data from thousands of participants in several different countries and included a variety of ages and populations including adults, seniors, adolescents, children, and cancer survivors.
Although the eight interventional studies included in the research showed inconsistent results, the 15 observational studies all showed a positive direct or indirect association between happiness and exercise, with the team finding that one day of exercise per week may be enough to boost happiness in some cases.
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The researchers found that those who were classed as insufficiently active were still 20 percent more likely to be happy than those who did no exercise at all, with this number increasing to 29 percent for the sufficiently active, and 52 percent for those who were very active.
However, for those concerned that they can't reach "very active" levels, the researchers also found that there did appear to be a threshold for the relationship between happiness and physical activity, with several studies showing that happiness levels were the same whether people exercised 150-300 minutes a week or more than 300 minutes a week.
When looking at the effect of exercise in different age groups, the results also showed that physical activity appeared to have a positive effect on happiness levels of both young and old, and when the team assessed the effect of exercise in specific populations, they found that physical activity could also improve the happiness of ovarian cancer survivors, children and adolescents with cerebral palsy, and drug abusers.
Some of the types of exercise observed to have a positive effect on different populations included aerobic exercise, mixed school activity classes for children, and stretching and balance exercises.
However, the team added that future research is needed to help determine how physical activity influences happiness, and which type and what dosage of physical activity is best for boosting happiness.
The results can be found publishing online in the Journal of Happiness Studies.