Effects of aquatic and land high intensity interval training on hemodynamics and vascular function of middle-aged men
Question
How do 8 weeks of aquatic versus land-based HIIT affect hemodynamics and vascular function in low-activity middle-aged men?
Summary
This randomized 8-week trial compared aquatic HIIT with land-based running HIIT in low-activity middle-aged men. Both groups improved body composition, cardiac function, blood pressure, blood-flow measures, flow-mediated dilation, and pulse wave velocity, with several larger changes in the aquatic group. The study supports supervised interval running as a vascular-health intervention in this narrow population, but it did not include a non-exercise control group.
Methodology
- Thirty low-activity middle-aged men were randomized to aquatic or land HIIT; final analysed sample was 27 after attendance exclusions.
- 30 participants.
- Fast running in 1.2 m deep pool water.
- Work intervals: 12 x 30-second fast-running intervals.
- Recovery: 1 minute complete rest between intervals.
- Intensity: 75-80% HRR in week 1, then 80-85% HRR from week 2 onward.
- 40 minutes.
- 3 sessions per week.
- 8 weeks.
- Randomized two-arm intervention comparing aquatic HIIT with land HIIT across baseline, 4-week, and 8-week assessments.
- Body composition, Cardiac function, Blood pressure, and Carotid hemodynamics were tracked.
Outcomes
Body composition
Both groups reduced weight, BMI, and body-fat percentage after 8 weeks; aquatic HIIT produced a larger body-fat improvement.
Aquatic p < 0.01 and land p < 0.05 for within-group changes; body-fat improvement aquatic greater than land p < 0.05.
Cardiac function
SV, EDV, CO, and FS increased while HR and ESV decreased in both groups, with larger aquatic improvements.
Aquatic p < 0.01 and land p < 0.05; aquatic better than land for SV, HR, EDV, ESV, CO, and FS p < 0.05.
Hemodynamics
SBP and DBP decreased while WSS and PSV increased in both groups; aquatic training showed larger improvements for SBP, WSS, and PSV.
Aquatic p < 0.01 and land p < 0.05; interactions included SBP p = 0.035, DBP p = 0.041, WSS p = 0.033, PSV p = 0.029.
Vascular function
Basal diameter and FMD increased and PWV decreased in both groups; aquatic HIIT showed a larger FMD improvement.
Both groups p < 0.05 after 8 weeks; interactions: basal diameter p = 0.043, FMD p = 0.025, PWV p = 0.045.
Insights
- A land-running version of the protocol is directly programmable as 12 x 30-second fast intervals with 1-minute rests.
- Aquatic HIIT may be useful as a lower-impact or pool-based variation, but it requires supervision and pool access.
- Claims should stay focused on surrogate vascular and hemodynamic measures, not clinical cardiovascular events.
Limitations
- Small sample.
- Men only.
- No non-exercise control group.
- Attendance-based exclusions may overstate real-world adherence.
- Eight weeks may be too short to fully compare some vascular outcomes such as PWV.
Safety
- No explicit adverse events were reported in the article text read.
- Participants with cardiovascular disease or other exercise-limiting diseases were excluded.
- Exercise intensity was monitored with Polar Team 2 heart-rate monitors.