Ambulatory blood pressure reduction following high-intensity interval exercise performed in water or dryland condition

• High-intensity interval exercise was safe in hypertensives.
• High-intensity interval gave greater results than mild-intensity continuous mode.
• High-intensity interval exercise decreased 24-hour systolic blood pressure.
• High-intensity interval exercise in water also decreased 24-hour pulse-wave velocity.

We aimed to compare blood pressure (BP) responses following moderate-intensity continuous exercise (MICE), high-intensity interval exercise (HIIE) in dry land or HIIE in immersed condition, using 24-hour ambulatory BP monitoring. Forty-two individuals (65 ± 7 years, 52% men) with a baseline BP ≥ 130/85 mm Hg (systolic/diastolic blood pressures [SBP/DBP]) were randomly assigned to perform one of the three following exercises on a stationary cycle: MICE (24 minutes at 50% peak power output) or HIIE in dry land (two sets of 10 minutes with phases of 15 seconds 100% peak power output interspersed by 15 seconds of passive recovery) or HIIE in up-to-the-chest immersed condition. While MICE modified none of the 24-hour average hemodynamic variables, dryland HIIE induced a 24-hour BP decrease (SBP: −3.6 ± 5.7/DBP: −2.8 ± 3.0 mm Hg, P < .05) and, to a much greater extent, immersed HIIE (SBP: −6.8 ± 9.5/DBP: −3.0 ± 4.5 mm Hg, P < .05). The one condition that modified 24-hour pulse-wave velocity was immersed HIIE (−0.21 ± 0.30 m/s, P < .05).