Exercise is associated with a reduced mental health burden, but this benefit does not always continue to increase with duration and frequency, researchers have found
The study used data from 1.2 million adults who took part in a US national health survey in 2011, 2013 or 2015.
Overall, those who reported exercising had 1.49 (43.2%) fewer days of poor mental health per month than matched individuals who did not exercise. Engaging in team sports and cycling was associated with the lowest mental health burden.
The optimal duration and frequency of exercise for minimising the number of poor mental health days appeared to be 45 minutes and 3–5 days per week, respectively.
By contrast, extreme ranges of more than 23 times per month and periods of exercise longer than 90 minutes per session were associated with worse mental health than not exercising at all.
“These data suggest that the argument that more is better fails to hold beyond certain volumes, and that exercising beyond six hours per week is associated with worse mental health,” the researchers concluded.
They suggested that future research could lead to recommended types, duration and frequency of exercise that could maximise the effect on mental health burden.
 Chekroud S, Gueorguieva R, Zheutlin A et al. Association between physical exercise and mental health in 1.2 million individuals in the USA between 2011 and 2015: a cross-sectional study. Lancet Psyc 2018;5:739:746. doi: 10.1016/S2215-0366(18)30227-X