# Postexercise hypotension and heart rate variability response after water- and land-based high-intensity interval exercise in prehypertensive obese men

PMID: 35356142
Journal: Journal of Exercise Rehabilitation
Published: 2022 Feb 28
Authors: Sriton B, Ruangthai R, Phoemsapthawee J

## Question

How do acute water-based and land-based high-intensity interval exercise affect postexercise hypotension, heart-rate variability, affect, enjoyment, and soreness in prehypertensive obese men?

## Summary

In nine prehypertensive obese young men, single water- and land-based HIIT sessions both lowered blood pressure after exercise. Water-based HIIT produced longer systolic blood-pressure reductions, better late-session affect and enjoyment, less thigh soreness, and no adverse events in this small crossover study.

## Population

- Nine young prehypertensive obese men completed water HIIE, land HIIE, and control sessions.
- Sample size: 9
- Age: 23.6 +/- 2.4 years
- Sex: Male
- Fitness level: Recreationally active
- Health status: Prehypertensive and obese; major disease exclusions

## Methodology

- Randomized crossover acute repeated-measures study
- Single sessions separated by at least 72 h
- Laboratory and chest-deep water exercise environment
- Randomized and controlled study design.

## Protocol

- Water-based HIIE.
- Modality: Chest-deep water maximum-speed intervals.
- Work intervals: 30 s.
- Recovery: 4 min active recovery at 50-60% HRmax.
- Sets or repetitions: 5 sprints.
- Intensity: Maximum speed; achieved 93.7% +/- 5.5% HRmax.
- Session duration: About 40-42.5 min including warm-up and cool-down.
- Frequency: Single acute condition.
- Program length: Single session.
- Progression: None.
- Land-based HIIE and no-exercise control.
- Modality: Land maximum-speed intervals.
- Work intervals: 30 s.
- Recovery: 4 min active recovery at 50-60% HRmax.
- Sets or repetitions: 5 sprints.
- Intensity: Maximum speed; achieved 96.4% +/- 5.0% HRmax.
- Session duration: About 40-42.5 min including warm-up and cool-down.
- Frequency: Single acute condition.
- Program length: Single session.
- Progression: None.

## Outcomes

### 24 h BP
Status: improved
Both HIIE modalities reduced 24 h MAP; water HIIE reduced 24 h SBP.

Water SBP -9 mmHg, p<0.01; MAP -6.7 mmHg for both water and land, p<0.01.

### Night BP
Status: improved
Both HIIE modalities lowered nighttime BP, with stronger systolic effects after water HIIE.

Water nighttime SBP -20.1 mmHg, DBP -14.2 mmHg, MAP -16.1 mmHg; all p<0.01.

### HRV
Status: mixed
No between-modality HRV differences; land HIIE showed more signs of slower autonomic recovery.

No significant HRV differences between water and land; land increased daytime LF/HF vs control.

### Affect
Status: improved
Water HIIE produced better late-session affect and enjoyment and less soreness.

Final affect/enjoyment comparisons favored water; thigh soreness 1.1 +/- 1.5 vs 3.3 +/- 2.6, p<0.05.

## Practical Insights

- Water-based HIIT may be a lower-soreness option for higher-BMI users.
- Long active recoveries can still produce postexercise blood-pressure reductions.
- Affect and enjoyment may diverge from physiological intensity and should be tracked.

## Limitations

- Very small sample.
- Young men only.
- Acute-only study.
- VO2 not directly measured during HIIE to confirm equal energy expenditure.
- Water temperature can affect BP response.

## Safety And Adherence

- No adverse events occurred in any trials.
- Water HIIE produced less anterior thigh soreness than land HIIE.
- One enrolled participant did not complete the study because of lack of time.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/35356142/) (pubmed)
- [DOI](https://doi.org/10.12965/jer.2142716.358) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8934611/) (full text)

## Agent Guidance

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