Isometric hand grip training on populations with different baseline resting blood pressure: a systematic review and...

Hypertension is a major global public health challenge. Previous studies have confirmed that isometric hand grip training (IHG) reduces resting blood pressure (BP). However, most existing trials have focused on mixed populations, and the differential effects of IHG on participants with varying baseline BP classifications remain unclear. While guidelines vary globally, it is essential to determine whether IHG exerts similar efficacy across Normal, High-Normal, and Hypertensive categories to optimize exercise prescriptions.

Based on the blood pressure classification criteria aligned with international standards (e.g., ISH 2020 and Chinese 2024 guidelines), this study aims to systematically evaluate the effect of IHG on populations with different baseline blood pressure levels. It seeks to clarify IHG's impacts on baseline SBP and DBP using data from randomized and non-randomized controlled trials, compare commonalities and differences across subgroups, and explore sources of heterogeneity (e.g., age, gender, training protocols).

Following the PRISMA guidelines, 12 databases were searched from inception to November 2025 (complete search strings are provided in the Supplementary Materials). Meta-analysis was performed using RevMan 5.41 and RStudio software. The Mean Difference (MD) was calculated to evaluate the effect of IHG compared to control groups, defined such that a positive MD value indicates a reduction in blood pressure. A random-effects model was used for pooling main effects, and heterogeneity sources were explored through meta-regression and subgroup analysis using the DerSimonian-Laird estimator.

A total of 20 trials (626 participants) were included. Meta-analysis results showed that compared with control groups, IHG significantly reduced SBP by 4.05 mmHg (MD = 4.05 mmHg, 95%CI: [2.52, 5.58], p<0.0001) and DBP by 2.26 mmHg (MD = 2.26 mmHg, 95%CI: [0.78, 3.74], p<0.05) overall. Subgroup analysis revealed significant reductions in SBP for participants with normal baseline SBP (MD = 2.68 mmHg, 95%CI: [0.22, 5.13]) and high-normal baseline SBP (MD = 3.83 mmHg, 95%CI: [1.79, 5.87]); DBP decreased significantly in those with high-normal baseline DBP (MD = 3.18 mmHg, 95%CI: [1.42, 4.93]). Meta-regression indicated that in the high-normal DBP subgroup, age was negatively associated with the magnitude of BP reduction (R²=100.00%, p < 0.0001; note: this high fit may reflect the limited number of studies).

IHG demonstrates the optimal blood pressure-lowering effect in populations with high-normal blood pressure. In specific subgroups, age may influence efficacy. Based on current evidence, IHG can be positioned as an effective exercise modality for hypertension prevention in individuals with elevated or high-normal blood pressure.