The importance of hypertension in health outcomes cannot be understated. Hypertension is a significant, yet modifiable, risk factor to cardiovascular diseases like coronary artery disease, stroke or even heart failure. Because of its prevalence in society, there are many treatments that exist that include exercise, medication, and more. Yet there is another, less talked about treatment that has shown much promise – Isometric Exercise Training.
What Is Hypertension?
“Hypertension or the chronic elevation of resting arterial blood pressure (BP) is estimated to affect 1 billion people worldwide”
Millar et al., (2014)
To put this into perspective, having pre-hypertension already increases the risks of cardiovascular complications. Despite many factors affecting blood pressure and the fact that a simple blood pressure number cannot directly point to specific health outcomes, the correlation between elevated blood pressure and cardiovascular disease seems apparent.
Current Treatments (1,2)
The existing first-line therapies to reduce hypertension do not involve medication. Instead, the proposed treatments to address hypertension begin with lifestyle changes. Some of the common lifestyle changes that are recommended are:
- stop smoking
- exercise
- eat more nutritious foods (see Intuitive eating series)
- reduce sodium intake
Specifically for exercise, the preliminary goal is to attempt to reduce sedentary behaviour. As such, some recommend moderate intensity exercise for a minimum of 30 minutes on most days of the week. This can help reduce the risk of hypertension or manage high levels of blood pressure.
The most studied method and its resulting benefits is aerobic exercise; such as, walking, hiking, running, cycling, swimming, rowing, and more. The benefits of resistance training for hypertensition reduction have also been researched but there is less evidence to support it. Therefore, aerobic training is most often prescribed before other types of training. What about isometric training, you might ask!
In the past couple of decades there has been some studies that have looked into the role of isometric exercise in blood pressure management. Compared to resistance and aerobic training, some evidence has demonstrated a greater mean reduction in resting blood pressure. Although isometric exercise as a treatment method for blood pressure is relatively novel, the American Heart Association has supported its need for further investigation.
What Exactly is Isometric Exercise Training? (1)
“Isometric or static contraction is defined as a sustained muscle contraction (i.e. increase in tension) with no change in length of the involved muscle group.”
Millar et al., (2014)
Basically, the above quote describes that isometric exercise is a muscle contraction without moving the muscle. For example, think of pushing a wall, your muscle contract but there is no “movement”. This is the basis of isometric exercises.
What Has Been Studied? (1)
In terms of how isometric exercise can help blood pressure, the most studied protocols entail:
- four times 2 minutes at 30 to 50 % of maximal voluntary contraction (MVC) of handgrip or leg contractions
- separated by 1 to 4 minutes
- three to five times per week
- over the course of 4 to 10 weeks
Isometric Exercise Effects on Blood Pressure (1,2)
The evidence points to resting blood pressure reductions with isometric exercise training. On average a group can have an important decrease of up to roughly 15 mmHg. This is quite a significant number. However, there is an important amount of individual variability within the different studies. Despite the results being positive overall, they cannot be generalized to everyone.
Currently, it seems most likely that multiple adaptations are responsible for the positive outcomes of isometric training on resting blood pressure. It is likely that the main mechanisms are reductions in total peripheral resistance like the mechanism found in aerobic training, in addition to the role of the sympathetic nervous system. More research is needed to understand the mechanisms at work in the benefits that have been shown.
Is this a revolutionary approach to hypertension? (1,2)
Despite the positive, yet mixed findings, isometric exercise training effects on resting blood pressure can be somewhat revolutionary. Evidently, it is somewhat of an exaggeration, but the time spent conducting the protocols explained above make them very efficient. The outcomes possible for the little time spent doing the training is quite remarkable. To top it off, isometric leg contractions and handgrip training are accessible, easy to perform, and inexpensive. It has strong potential as a therapeutic intervention.
Please be mindful that the first-line of treatment that includes exercise, smoking cessation, and more nutritious foods, have been studied extensively and should not be brushed aside as ineffective. The large amount of studies supporting the first line therapies make them more legitimate than isometric training at the moment. More research is needed to change that. The current research has shown much variability, and therefore, not everyone would find the same benefits with isometric exercise training.
References
1 Millar, P. J., Millar, P. J., McGowan, C. L., McGowan, C. L., Cornelissen, V. A., Cornelissen, V. A., Araujo, C. G., Araujo, C. G., Swaine, I. L., & Swaine, I. L. (2014). Evidence for the role of isometric exercise training in reducing blood pressure: Potential mechanisms and future directions. Sports Medicine (Auckland), 44(3), 345-356. https://doi.org/10.1007/s40279-013-0118-x
