High- versus low-frequency exercise for depression in university students: a single-blind randomized controlled trial

The core affect (CA) hypothesis posits that exercise serves either to increase positive affect or reduce negative affect. One rarely examined implication of the CA hypothesis is that multiple short exercise bouts distributed throughout the week, rather than one long training bout, would lead to better outcomes.

Fifty-four university students with depression were randomly allocated to one of three groups: (1) a control group participating in weekly health education sessions, (2) a low-frequency exercise training (LFET) group running once weekly for 60 min, and (3) a high-frequency exercise training (HFET) group running four times weekly for 15 min. All interventions lasted 3 weeks without interruption. Depressive symptoms were assessed pre- and postintervention using the PHQ-9 questionnaire.

Compared with the control group, depressive symptoms were significantly reduced in the HFET group (Hedges's g = -0.89, 95% CI [-1.57, -0.20]), but not in the LFET group (Hedges's g = -0.34, 95% CI [-0.99, 0.32]). Moreover, the proportion of participants achieving clinically significant improvement (CSI) was more than threefold higher in the HFET group (38.9%) than in the control group (11.1%), z = 1.93, p = .027, and almost double that of the LFET group (22.2%). Finally, participants in the HFET group, but not in the LFET group, reported significantly higher remission rates than controls (55.6% vs. 27.8%, z = 1.69, p = .046).

Although these findings support the CA hypothesis, they should be interpreted cautiously because of the small sample size and short intervention period.