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

PMID: 41076795
Journal: Clinics (Sao Paulo, Brazil)
Published: 2025 Jan-Dec
Authors: da Silva VOS, Thirupathi A, Macedo RADS, Santos MF, Borba ACO, Gu Y, Gomes KM, Delevatti RS, Silveira PCL, da Silva LA

## Question

Does aquatic HIIT frequency affect sleep, sleepiness, anxiety, and depression in older adults with multimorbidity?

## Summary

Older adults with multimorbidity completed 12 weeks of aquatic HIIT either once or twice weekly. Twice-weekly training improved sleep quality, daytime sleepiness, anxiety, and depression scores, while once-weekly training did not show significant changes.

## Population

- Fifty-six older adults with multimorbidity were analyzed per protocol.
- Sample size: 56
- Age: Once weekly 70.8 +/- 5.5 years; twice weekly 67.2 +/- 4.6 years
- Sex: 50 women and 6 men
- Health status: At least two of depression, diabetes, and hypertension; obesity on average

## Methodology

- Randomized comparative clinical trial
- 12 weeks
- Aquatic exercise pool
- Randomized and controlled study design.

## Protocol

- Aquatic HIIT.
- Modality: Water-based exercises.
- Work intervals: 30 seconds.
- Recovery: 30 seconds active recovery; 60 seconds between exercises.
- Sets or repetitions: 8 exercises x 4 series.
- Intensity: 80%-90% water-adjusted HRmax; Borg CR10 8-10.
- Session duration: 40 minutes.
- Frequency: Once or twice weekly.
- Program length: 12 weeks.
- Progression: Frequency comparison; overload via drag, speed, and range of motion.
- Lower-frequency aquatic HIIT.
- Modality: Same aquatic HIIT.
- Work intervals: 30 seconds.
- Recovery: 30 seconds active recovery; 60 seconds between exercises.
- Sets or repetitions: 8 exercises x 4 series.
- Intensity: 80%-90% water-adjusted HRmax.
- Session duration: 40 minutes.
- Frequency: Once weekly.
- Program length: 12 weeks.

## Outcomes

### Sleep
Status: improved
Twice-weekly aquatic HIIT improved PSQI by about 49% and ESS by about 50%; once-weekly HIIT did not significantly change sleep outcomes.

G2 PSQI p=.032, ESS p=.041; G1 PSQI p=.079, ESS p=.231.

### Anxiety
Status: improved
Anxiety decreased in the twice-weekly group but not the once-weekly group.

G2 p=.047; G1 p=.436.

### Depression
Status: improved
Depression decreased in the twice-weekly group but not the once-weekly group.

G2 p=.017; G1 p=.652.

## Practical Insights

- For this aquatic protocol, twice-weekly frequency appeared necessary for mental-health improvements.
- Pool-based HIIT can use HR plus Borg targets when movement speed is self-generated against water resistance.

## Limitations

- No nonexercise control group.
- Per-protocol analysis excluded inadequate adherence.
- Participants and instructors were not blinded.
- No stratification by specific multimorbidities.
- No post-intervention weight measure.

## Safety And Adherence

- No adverse effects were reported.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/41076795/) (pubmed)
- [DOI](https://doi.org/10.1016/j.clinsp.2025.100803) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12547450/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.