Exercise Intensity and Depression

Depression is the leading cause of disability worldwide, so researchers are working to identify effective interventions.  Prior research indicates that inflammation may contribute to depression, so researchers were interested in the impacts of exercise, which is an anti-inflammatory intervention, on depression symptoms.

Researchers assigned 55 university students (71% female) to 3 groups: high-intensity interval training, moderate continuous training, or no exercise for 6 weeks during the academic term. The interval and continuous training consisted of cycling for 27 minutes, 3 times per week.  This population is at higher risk for perceived stress due to continuous high-stakes assessments across an academic term.  Researchers measured changes in perceived stress, depression, and inflammation.    

The no exercise group reported higher levels of perceived stress than the exercise groups and increased depression symptoms at the end of 6 weeks.  They also had elevated inflammation markers.  These results demonstrate the rapid decline in mental and physical health for university students under chronic stress. 

The moderate intensity continuous cycling group had less inflammation and fewer depression symptoms than the no exercise group. 

The high-intensity interval group had fewer depression symptoms than the no exercise group, but they had higher perceived stress and more inflammation than the moderate continuous exercise group.  Researchers hypothesized that high-intensity training may exacerbate the response to psychological stressors, which increases stress and anxiety because both stress and exercise activate the fight-or-flight stress response, increasing heart and respiration rates, and cognitive vigilance.    

Takeaway: The optimal exercise intensity for people under persistent stress may be moderate continuous intensity.  Moderate intensity exercise promotes mental health by decreasing depression symptoms, and it promotes physical health by reducing inflammation in the body. 

Source

Emily M. Paolucci, et al., Exercise Reduces Depression and Inflammation but Intensity Matters, Biological Psychology, Mar. 2018, Exercise reduces depression and inflammation but intensity matters - ScienceDirect

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