Isometric resistance training shown to safely reduce high blood pressure
Isometric resistance training (IRT) is a type of strength training exercise that involves applying tension to muscles without movement of the surrounding joints, examples of which include wall sits or planks. IRT is different from traditional exercises where joints are put under strain and muscles lengthen/shorten – it can increase blood pressure during exercise, and so thought to be poor management for high blood pressure.
Researchers from the University of New South Wales (UNSW) in Australia, however,suggest that IRT may reduce systolic and diastolic blood pressure (SBP and DBP, respectively). Observed changes were similar to those seen with blood pressure-lowering medications.
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UNSW researchers further suggest that IRT may be safer than other forms of exercise for some people.
Dr. Matthew Jones, an accredited exercise physiologist and lecturer in the School of Health Sciences, Faculty of Medicine & Health at UNSW, said exercise is important for the management of high blood pressure.
“IRT is a time-efficient means of reducing blood pressure, needing only 12 minutes a day, two to three days per week to produce the effects we found in our review.”
“While the studies included in our review normally used a specialised handgrip device, it’s possible we would see the same effects simply by asking participants to make a fist and squeeze it at a certain intensity for the prescribed amount of time. This means IRT could easily be performed while participants are sitting down watching TV,” said Dr Jones.
The new meta-analysis at UNSW involved 1,143 participants in 24 randomised control trials. The participants in the study were individuals who had either:
- High-normal blood pressure: A SBP of 130–139 millimeters of mercury (mm Hg);
- Grade 1 hypertension: An SBP of 140–159 mm Hg;
- Grade 2 hypertension: An SPB over 160 mm Hg or a DBP of more than 100 mm Hg.
*The researchers only included IRT trials that had lasted at least 3 weeks, which previous research suggests is the minimum length of time to produce a significant blood pressure change.
It was found that SBP reduced by an average of 6.97 mm Hg among the IRT group compared with controls; DBP also decreased by an average of 3.86 mm Hg.
In addition, pressure in the aorta — which contributes to central blood pressure and is an important indicator of cardiovascular disease — reduced by an average of 7.48 mm Hg for SBP and 3.75 mm Hg for DBP. Average DBP over 24 hours also went down, although to a lesser degree, with a reduction of 2.39 mm Hg.
IRT may still be of value for people unable to engage in aerobic exercise. According to Dr. Jones, “It’s particularly exciting for people who may have difficulty performing more ‘traditional’ exercise, such as walking, cycling, or strength training, knowing they have another exercise type in their toolkit to help manage their high blood pressure.”
IRT’s low rates of adverse events in older adults, or those with mobility restrictions who may not be able to do other exercises like aerobic or dynamic resistance training may be equally appealing, added Dr. Jones.
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