Exercise reduces depression and inflammation but intensity matters.

BACKGROUND: Exercise may help to mitigate symptoms of depression by reducing inflammation; however, little is known about the influence of exercise intensity on depressed mood. METHODS: In the present study, sixty-one university students were assigned to six weeks of high-intensity interval training (HIT), moderate continuous training (MCT), or no exercise (CON) during their academic term. We measured changes in depression, anxiety and perceived stress along with pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1ß), and C-reactive protein (CRP). RESULTS: Depression increased for CON, demonstrating how quickly mental health can decline for students during their academic term. In contrast, MCT decreased depression and pro-inflammatory cytokine TNF-α levels. Although HIT decreased depressive symptoms, it also increased perceived stress, TNF-α and IL-6 relative to MCT. This may be due to the higher level of physical stress evoked by the more strenuous exercise protocol. CONCLUSIONS: Taken together, the results suggest that moderate-intensity exercise may be an optimal intensity of exercise for the promotion of mental health by decreasing TNF-α. This is critical for informing the use of exercise as medicine for mental health.

The Effects of Physical Exercise and Cognitive Training on Memory and Neurotrophic Factors.

This study examined the combined effect of physical exercise and cognitive training on memory and neurotrophic factors in healthy, young adults. Ninety-five participants completed 6 weeks of exercise training, combined exercise and cognitive training, or no training (control). Both the exercise and combined training groups improved performance on a high-interference memory task, whereas the control group did not. In contrast, neither training group improved on general recognition performance, suggesting that exercise training selectively increases high-interference memory that may be linked to hippocampal function. Individuals who experienced greater fitness improvements from the exercise training (i.e., high responders to exercise) also had greater increases in the serum neurotrophic factors brain-derived neurotrophic factor and insulin-like growth factor-1. These high responders to exercise also had better high-interference memory performance as a result of the combined exercise and cognitive training compared with exercise alone, suggesting that potential synergistic effects might depend on the availability of neurotrophic factors. These findings are especially important, as memory benefits accrued from a relatively short intervention in high-functioning young adults.

Enjoyment for High-Intensity Interval Exercise Increases during the First Six Weeks of Training: Implications for Promoting Exercise Adherence in Sedentary Adults.

This is the first study to show that enjoyment for high-intensity interval exercise increases with chronic training. Prior acute studies typically report high-intensity interval training (HIT) as being more enjoyable than moderate continuous training (MCT) unless the high-intensity intervals are too strenuous or difficult to complete. It follows that exercise competency may be a critical factor contributing to the enjoyment of HIT, and therefore building competency through chronic training may be one way to increase its enjoyment. To test this, we randomly assigned sedentary young adults to six weeks of HIT or MCT, and tracked changes in their enjoyment for the exercise. Enjoyment for HIT increased with training whereas enjoyment for MCT remained constant and lower. Changes in exercise enjoyment were predicted by increases in workload, suggesting that strength adaptions may be important for promoting exercise enjoyment. The results point to HIT as a promising protocol for promoting exercise enjoyment and adherence in sedentary young adults.