Eight-week high-intensity interval training is associated with improved sleep quality and cardiorespiratory fitness in patients with depressive disorders

Abstract

This study aimed to examine the effect of high-intensity interval training (HIIT) on both sleep and cardiorespiratory fitness in patients with depression. Using a single pre- and post-test study design with no control group, 82 patients diagnosed with depressive disorders underwent HIIT comprising a total of 24 15-min sessions, three times per week for 8 weeks. Depressive symptoms, sleep quality, and cardiorespiratory fitness were evaluated using the Beck depression inventory-II, the Pittsburgh sleep quality index (PSQI), and cardiopulmonary exercise testing (CPET) in the form of maximum oxygen uptake (VO2 max), respectively. All 82 patients completed the intervention. HIIT training was associated with significant improvements in BDI-II score (diff\u2009=\u2009\u2009−\u20091.57 [95% CI\u2009−\u20092.40 to\u2009−\u20090.73], P\u2009=\u20090.001), PSQI score (diff\u2009=\u2009\u2009−\u20091.20 [95% CI\u2009−\u20092.10 to\u2009−\u20090.32], P\u2009=\u20090.008), and CPET VO2 max (diff\u2009=\u20090.95 [95% CI 0.62–1.28], P\u2009=\u20090.001). Effect size calculations revealed that the greatest improvement occurred in CPET VO2 max (Cohen’s d\u2009=\u20090.64) and that improvements in the BDI-II and PSQI scores were somewhat smaller in magnitude (Cohen’s d\u2009=\u2009\u2009−\u20090.41 and\u2009−\u20090.30, respectively). Sleep quality improvements were observed in sleep latency, habitual sleep efficiency, and the use of sleep-promoting medications (Cohen’s d\u2009=\u20090.18, 0.19, and 0.25, respectively). Change in cardiorespiratory fitness successfully predicted change in sleep quality but not in depressive symptoms. Adverse effects were limited to minor injuries which did not interfere with completion of training. HIIT training delivered over 8 weeks was associated with improvements in depression symptoms, sleep quality, and cardiorespiratory fitness in patients with depressive disorders.