Objective: To examine the efficacy of isometric handgrip exercise for reducing resting SBP and DBP in adult humans.
Methods: Meta-analysis of studies retrieved from five electronic databases as well as cross-referencing from identified articles. The criteria for inclusion were randomized controlled trials published in any language over an approximate 38-year period (1 January 1971 to 1 February 2009), isometric handgrip training of at least 4 weeks performed by adults of at least 18 years of age, and data for changes in resting SBP and DBP available. Dual coding of studies was performed by both investigators. Data were analyzed a priori using random-effects models and nonparametric 95% bootstrap percentile confidence intervals (BCIs, 5000 iterations). Because of the small sample size, analyses were also performed using fixed-effects models post hoc.
Results: Eighty-one men and women (42 exercise and 39 control) from three of 287 reviewed studies were pooled for analysis. Using random-effects models, statistically significant exercise minus control group reductions of approximately 10% were observed for both resting SBP and DBP (SBP: Xd , -13.4 mmHg; 95% BCI, -15.3 to -11.0 mmHg and DBP: X , -7.8 mmHg; 95% BCI, -16.5 to -3.0 mmHg). Results were also statistically significant when fixed-effects models were used (SBP: X , -13.8 mmHg; 95% BCI, -15.3 to -11.0 mmHg and DBP: X , -6.1 mmHg; 95% BCI, -16.5 to -3.2 mmHg).
Conclusion: Isometric handgrip exercise is efficacious for reducing resting SBP and DBP in adult humans. However, the generalizability of these findings is limited given the small number of studies included.