Effects of isometric handgrip training on blood pressure (resting and 24 h ambulatory) and heart rate variability in medicated hypertensive patients

Abstract

Isometric handgrip (IHG) training (four, 2-min sustained contractions at 30% of maximal voluntary contraction, three times per week for 8-10 weeks) lowers resting arterial blood pressure (BP) in hypertensive patients, including those receiving pharmacotherapy, although the mechanisms remain elusive. Ambulatory BP measurements are more efficacious in predicting cardiovascular disease-related events, yet the effects of IHG training on ambulatory BP are unknown. The objective of the current investigation was to test the hypotheses that 8 weeks of IHG training lowers resting and 24 h ambulatory BP concomitantly in medicated hypertensive patients, and may be the result of improved vagal modulation. BP was assessed using brachial artery oscillometry, and coarse-graining spectral analysis was used to determine spectral power. Resting and 24 h ambulatory BP and heart rate variability (HRV) were measured pretraining, midtraining, and post-training in 11 medicated hypertensive patients (mean ± SD, resting BP: 113.9 ± 12.7/60.7 ± 11.6 mmHg), and in nine medicated hypertensive controls (resting BP: 117.8 ± 14.3/67.5 ± 4.2 mmHg). Indices of BP and HRV were not significantly altered with IHG training (all P > 0.05). IHG training does not lower resting or ambulatory BP in hypertensive patients successfully treated with pharmacotherapy to within the normal range (≤ 120/80 mmHg), nor does it improve HRV. Future studies should examine alternative IHG training protocols in well-managed hypertensive patients and/or target poorly controlled medicated hypertensive patients.