Introduction: Despite increased awareness, treatment and control of hypertension, it is still a major health concern with over 1 billion adults worldwide diagnosed with hypertension. The 2014 NHANES data indicates that only 50% of adults with hypertension meet the recommended aerobic exercise guidelines. Recent studies indicate that isometric exercise training (IET) has shown similar reductions in blood pressure to aerobic exercise studies. To date only 2 published IET studies, both of 8-week duration, have utilized ambulatory blood pressure (ABP) monitoring.
Hypothesis: We assessed the hypothesis that conducting isometric handgrip exercise for 12 weeks would reduce 24hr ABP.
Methods: Twenty pre-mild hypertensive participants, men (n=12) and women (n=8) attended our laboratory 3 times a week for 12 weeks to conduct IET at either 5% or 30% of their maximum voluntary contraction (MVC). Prior to commencing the training, and upon completion of the 12 wk protocol, participants wore an ABP monitor for 24hrs. Blood pressure was recorded every 15mins during the day, and every 30mins whilst sleeping, the overall average was used for analysis.
Results: Isometric handgrip exercise at 30% MVC saw a significant reduction in SBP of -7mmHg from 154±4.5 to 147±3.3 (95% CI -14.3, 0.0; p=0.05) from baseline to post. No reductions in SBP were seen in the 5% MVC group with 148±3.9 to 146±1.9 (95% CI -9.1, 5.5; p=0.59) from baseline to post. Similar results were seen in DBP; with the 30% MVC group having a significant reduction of -5mmHg from 89±2.8 to 84±2.3 (95% CI -8.9, -1.1; p=0.02) from baseline to post. There was no reduction of DBP at 5% MVC which was 86±1.8 to 84±1.6 (95% CI -5.7, 2.5; p=0.40) from baseline to post.
Conclusions: In conclusion 12 weeks of IET saw significant reductions in 24hr ABP measurements of SBP and DBP in the 30% MVC group. There were no significant reductions of SBP and DBP in the 5% MVC group, confirming the suitability of its use as a working control.