Effects of HIIT at different frequencies in an aquatic environment on mental health in multimorbid older people: A randomized clinical trial.

BACKGROUND: This study aimed to compare the chronic effects of High-Intensity Interval Training (HIIT) aqua aerobics performed once a week (G1) versus twice a week (G2) on sleep quality, daytime sleepiness, anxiety, and depression in older adults with multimorbidities. METHODS: Both groups performed the same exercises (9 in total) with identical volume (4 sets of 30 seconds of activity followed by 30 seconds of rest) and intensity (80 %-90 % of Heart Rate max, corresponding to 8-9 on the Borg Scale), in 40-minute sessions. Mental health parameters were assessed 48 hours after the last training session. To analyze the effects of HIIT, a two-way analysis of variance (anova), with Bonferroni post hoc tests, was used with a significance level set at p < 0.05. RESULTS: Initially, one hundred and twenty-nine older adults were assessed for eligibility. Fifty-six older adults with multimorbidities, including diabetes, hypertension, and depression, completed the study. Significant improvements were observed only in G2 (sessions performed twice a week), with increases in sleep quality (+49 %, p = 0.032) and reductions in daytime sleepiness (-50 %, p = 0.041), anxiety (-45 %, p = 0.047), and depression (-62 %, p = 0.017). CONCLUSIONS: The results suggest that HIIT aqua aerobics improves mental health outcomes in older adults with multimorbidities only when performed at least twice a week. TRIAL REGISTRATION: Brazilian Registry of Clinical Trials (ReBEC) RBR-9kqwd5f. Registered on January 14, 2024.