Isometric handgrip training, but not a single session, reduces blood pressure in individuals with hypertension: a systematic review and meta-analysis

Aerobic exercise is a leading strategy for the prevention/management of systemic arterial hypertension, but other modalities of exercise have also been explored. Thus, we examined the acute effect of isometric handgrip exercise (IHGE) and the chronic effect of isometric handgrip training (IHGT) on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in individuals with hypertension without comorbid conditions. We conducted a systematic review with meta-analysis of randomized controlled trials (RCTs) involving adults with hypertension. We searched the electronic databases MEDLINE (PubMed), Cochrane, Web of Science, LILACS, EMBASE and PEDro. We used random-effects model for the analyses, RoB2 tool to assess the risk of bias, and GRADE to assess the strength of evidence. A total of 9 RCTs (2 for IHGE and 7 for IHGT) were selected. Compared to a control condition, IHGE did not have any effect on SBP/DBP. Unlike, the pooled mean effect of IHGT showed SBP was reduced by 6.7 mmHg (95% CI -10.3 to -3.4 mmHg) and DBP by 4.5 mmHg (95% CI -7.3 to -1.7 mmHg) in individuals with hypertension. Also, the 95% prediction interval (95% PI) of IGHT was -10.9 to -2.5 mmHg for SBP and -10.2 to +1.2 mmHg for DBP. In conclusion, while IHGE did not produce post-exercise hypotension in the population studied, IHGT reduced SBP/DBP in individuals with hypertension with clinically important reductions in SBP (-6.7 mmHg) and DBP (-4.5 mmHg). This review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) (CRD 42021217958).