Vigorous exercise helps boost mood but moderate exercise does not, they found.
Researchers drew their conclusions after studying 11 people, who were asked to take part in two 20-minute long work-outs, one moderately intensive and one highly intensive.
The mood of the participants was measured before, during, immediately after and 20 minutes after each work out.
They found volunteers exhibited no mood improvements after moderate exercise. However, 20 minutes after the end of the strenuous work-out – which got them breathing heavily and their muscles burning – the participants reported feeling more positive.