Isometric exercise is best for lowering blood pressure; What does this mean?
Researchers have compared the efficacy of different exercises on reducing blood pressure and found that isometric exercises were more effective compared with the government recommended exercise guidelines.
But what does this mean in practice?
I sat Andrew Telfer, our Head Coach, down and asked him for his thoughts after reading the study. You can find a link to the full study at the foot of this article. Here’s a transcript from our conversation.
GE: Why is this study interesting or important?
AT: The reason this study is interesting is because the research group looked at the existing recommendations for lowering blood pressure through physical activity and exercise. They realised that a lot of the data and recommendations were out dated and they wanted to see if they could do new research or new meta analysis to get better recommendations.
GE: What sort of size study is it?
They pulled roughly 270 randomised control trials from the 1990s up to the present day and they did a huge meta analysis. So they, they combined all the different trials.
And what's interesting is that it conformed to all the best practices. So it followed Prisma (a set of standards to ensure research consistency and quality) and Prospero (a registry for public health research to help prevent bias) and all these other guidelines that ensured that the analysis was done.
So in the end, it has the effect of being one giant study with something like 16,000 participants, looking at the efficacy of all these different exercise modalities to see what is the most effective intervention for lowering blood pressure.
GE: What do the results show?
AT: The results of the study show that within the data, they have the isometric exercises - specifically movements like a wall set, but then a lot of the media coverage is also talking about planks, which wasn't well covered in the actual paper - have had the greatest effect. So essentially, in in order of efficacy.
According to this study, the most effective exercise type for lower blood pressure is isometric work.
GE: What do you mean by isometric movements?
AT: Isometric work is any any kind of muscular contraction, where your body isn't actually moving, or your joints are actually moving, but your muscles are actively contracting.
So classic example would be in PE class, if you did the wall sit, the wall squat where you go against the wall, and you try to hold your knees at 90 degrees with your femurs parallel to the ground. And you just sort of hold that. And while you're not moving, because the leverage of your femurs in your body, your muscles are actively contracting.
So an isometric exercise is when the contraction force of your muscles matches the resistance of whatever external force is acting on your body.
As opposed to other kinds of movements, mostly we think of concentric muscle contractions. So whenever you push something, so like a press up, or jumping up or doing a full pull up, when we think of the concentric action of you overcoming the resistance. Or eccentric action, which we normally think of the negative, so the lowering of the pull up the slow, controlled, lower going to press up, etc.
Isometric exercises been popular for a long time. So if you look a lot of the old muscle building guys - such as Charles Atlas or Bruce Lee - the famously did a lot of isometric exercises, and allowed them to be very simple. For example, you can just put your hands together and press them together, or hold your hands tightly and pull them apart.
There's all kinds of interesting ways to use isometric exercises, you don't have access to external weights.
GE: So the isometric exercises are found to be the most effective at lowering blood pressure. But what comes after that in terms of efficacy?
AT: Then after that, the second most effective would be combined-training. So combined training would be a mix of weightlifting and cardio.
And then after that would probably be running.
And then you see the efficacy kind of down after that.
Now, one of the problems with the study is they define and categorised certain types of exercise which can be a little misleading. Because there were so many categories, they had to shoe-horn in different definitions.
So if you look at the study, it says that high intensity interval training was one of the least effective but the way they define high intensity interval training, they combined two different things which was strength interval training, and aerobic interval training. And their definition of it is probably not the same that a lot of people do.
Because if you saw that you would think a modality, like CrossFit wouldn't do very well. But actually CrossFit programming does tend to have incorporate isometric concentric, heavy weightlifting, running and all kinds of things. So I imagine that people doing CrossFit probably would see would see reduction in blood pressure as with any other kind of mixed exercise programme.
But what it looks like is that low weight HIIT or circuits would be less effective. You really need the strength element in there - so heavy weights than you’d see in more HIIT and circuut classes. That said, they didn’t have a huge amount of data for HIIT in this study.
High Intensity Interval Training probably wouldn't wouldn't do much it looks like the the benefit of the strength training, you sort of need enough resistance to increase your body's internal pressure. That's probably where a lot of the benefits come from.
One other element to consider in this study if you’re already fit, that population will experience a small benefits as they are already fit. If it’s a population that is unfit to begin with, they will see huge benefits.
They also don’t talk about yoga in the meta analysis, I suspect yoga is probably very good lowering blood pressure as it’s mostly isometric movements.
And then the numbers are kind of skewed and other ways. For example, the the isometric exercise is probably skewed in a positive efficacy because they had so little data on isometric exercising exercise, and then the few few studies they had were quite strong.
GE: Are there other issues with the data that need to be considered?
So the way the meta analysis worked, it would have weighted the efficacy of isometric training much higher. So that might not actually be accurate, there might not be anything magical about isometric training, it just so happens in the data they had weighted heavily, whereas some of the aerobic or cardiovascular interventions might appear less effective in the study, because the way that they lumped some of the exercise together, walking would have been lumped together with running. And because walking is such a such a low intensity, exercise, and appears not to be very effective for lowering blood pressure, though I'm sure a base level of walking is important, it does look like in order to really lower blood pressure need a certain level of intensity, you need to strain a little bit like it's actually like the experience of straining either under heavy weight or holding a plank or running long distance, you need to put your body under enough stress that it's going to adapt by lowering your resting blood pressure.
GE: OK, so what’s the take away before we all start wall sitting everywhere?
AT: My takeaway would be that you should do some kind of mixed exercise. And what it found is that exercise is as effective as blood pressure medication as the medication has all kinds of unwanted side effects, whereas exercise has all kinds of amazing benefits.
And really, almost any exercise is going to work.
What's interesting is that one of the reasons the authors of the study said that the data might be skewed is because a lot of the studies that they synthesised, they had a base minimum participation rate, which means that if people didn't adhere to whatever the intervention was, then they wouldn't use their data in the original studies.
So in terms of exercise, doing almost anything is going to be good.
Walking is good, but it's not as good as including some kind of strength training or a little bit of running or other high intensity, weight bearing locomotion.
Do something you enjoy. You want to have variety, you want to make sure it's one that you can stick with. And you want to make sure that you have different levels of intensity, and that it can go heavy enough to get some of these beneficial adaptations.
If you want to throw in additional isometric training, then that's fine.
The reason that they talked about the wall sets is just because it's a very easy isometric exercise to include. Pretty much anybody can do it. There's nothing magical about wall sit specifically. And you probably get a lot of those benefits from picking up heavy objects. And so doing things like deadlifts, or any other kind of pickup increases your intra abdominal pressure, will probably have a lot of the same benefits.
So make sure you lift some heavy stuff.
Make sure you run around a bit,
Make sure you do some bodyweight stuff.
Make sure you do some isometric stuff, whether it's planks or hollow bodies, or all other kinds of things.
Crawling would probably have a lot of the same benefits as well. Pretty much anything where you're using your your core strength for stability, is going to probably have those same benefits.
GE: Got it, keep it mixed, keep it fun and keep it consistent.
