Four weeks of isometric handgrip training results in lower awake ambulatory blood pressure compared with control: a...

We compared the effects of upper-limb (handgrip) and lower-limb (knee extension) isometric training on ambulatory blood pressure in individuals with controlled hypertension. In this randomized controlled trial, 67 adults receiving antihypertensive medication were allocated to a control group (CG, n = 22), small muscle mass isometric training (SMM, handgrip; n = 22), or large muscle mass isometric training (LMM, knee extension; n = 23). Participants completed 12 supervised sessions over 4 weeks, with the exercise protocols performed at 30% of upper-limb MVC or lower-limb maximal isometric load, respectively. Ambulatory blood pressure outcomes were compared using analysis of covariance (ANCOVA), adjusting for the corresponding baseline office blood pressure. Hourly 24-h profiles were analyzed using generalized estimating equations with Bonferroni-adjusted post hoc tests. Significant between-group differences were observed only for awake ambulatory blood pressure. Compared with CG, SMM showed lower awake systolic blood pressure (121.8 ± 3.1 vs. 124.2 ± 2.6 mmHg; p = 0.017) and awake diastolic blood pressure (76.3 ± 3.6 vs. 80.8 ± 4.2 mmHg; p = 0.009). No significant differences were observed between LMM and CG, between the two exercise groups, or for 24-h and sleep blood pressure. These findings indicate that, after 4 weeks of supervised isometric training, modest between-group differences in awake ambulatory blood pressure were observed only for handgrip training compared with the control group. Greater muscle mass recruitment did not result in superior antihypertensive effects, suggesting that the chronic blood pressure response to isometric exercise is not determined solely by the amount of muscle mass involved. Trial registration: "ClinicalTrials.gov," "NCT07147595."