Objective: Isometric handgrip training (IHT) has been shown to reduce blood pressure (BP) in hypertensives. However, factors that predict responsiveness to IHT are largely unknown. The aim of this study was to investigate the patient characteristics associated with the anti-hypertensive response to IHT using a recommended statistical approach for evaluating interindividual responses.
Methods: Data from four randomized controlled trials were joined, totaling 81 patients undergoing IHT (48.8% women; 60±11 yr) and 90 control patients (45.6% women; 62±12 yr). IHT consisted of 4x2-minute isometric contractions at 30% of maximal voluntary contraction, performed three times/week for 8-12 weeks. BP was measured at baseline and following IHT and control interventions. The interindividual variation was assessed by the standard deviation of the individual responses (SDir), and linear regression analyses were conducted to explore response predictors.
Results: IHT significantly decreased both systolic (-5.4; 95%CI: -9.5 to -1.3 mmHg) and diastolic (-2.8; 95%CI: -5.1 to -0.6 mmHg) BPs. The interindividual variation of BP change was moderate for systolic (SDir=5.2 mmHg, 0.30 standardized units) and low for diastolic (SDir=1.7 mmHg, 0.15 standardized units). Sex, age, and body mass index were not associated with the anti-hypertensive effect of IHT. However, a higher baseline systolic BP (b=-0.467, p<0.001) and absence of dihydropyridine calcium channel blockers use (b=0.340, p=0.001) were associated with greater BP reductions.
Conclusion: IHT reduced BP in medicated hypertensive patients regardless of age, sex, and BMI. Patients with a higher baseline systolic BP and those not prescribed dihydropyridine calcium channel blockers were more responsive to IHT
