It depends on the type of stress. Studies have linked aerobic exercise of all intensities with decreased psychological stress. And exercise-related physiological stress releases cortisol, which in the short term can be beneficial鈥攊t can help you set a PR in the local 5K.
However, chronic elevated cortisol has been implicated in everything from diabetes to depression. In a , Nadine Skoluda, a researcher at Germany鈥檚 University of Marburg, found that runners training for distances as short as the half marathon had much higher cortisol levels in their hair鈥攁 marker of cumulative secretion of the hormone鈥攖han non-endurance athletes.
That doesn鈥檛 mean we should shorten up our routines just yet. This field of research is relatively young, and Skoluda says that scientists don鈥檛 yet know whether chronic cortisol secretion due to prolonged exercise is bad for you over time. For now, if exercise is relaxing, keep it up. It certainly won鈥檛 help your stress level to worry about it.