Tag Archive for: cardiovascular

How Isometrics Help Lower Your BP

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If you have a home blood pressure monitor, try a little experiment on yourself. Set up your monitor and cuff and sit quietly in a chair. After five minutes or so, take a deep breath, exhale, and hit the Start button on the monitor while breathing normally as your BP is taken. Record the results. Make sure the cuff deflates completely and continue sitting for another five minutes.

Then repeat the deep breath, exhale, and hit the Start button. This time, I want you to contract the muscle in the opposite arm as much as you can and hold the contraction until the BP is done, breathing normally the entire time. Do you notice a difference in the BP without and with contracting your opposite arm? Unless you lift heavy weights on a regular basis, you probably did.

When you contract the opposite arm, you’re restricting blood flow to that arm, thereby increasing the resistance. When you relax, there should be an increase in blood flow to that tissue. When you do isometric exercises regularly, that’s what happens in every muscle group involved.

How Isometrics Can Lower BP

Let’s return to the study. The researchers did a secondary analysis to see if they could find the exercise that lowered BP the most. The wall sit or wall chair worked best to lower systolic blood pressure, while running lowered diastolic blood pressure the most.

What’s the wall sit? It’s depicted in the photo above. The idea is to stand a foot or so from the wall, lean back until your back contacts the wall, and slide down to a sitting position for five to ten seconds, then slide back up. Repeat ten times several times per day; the key is to never hold your breath while you do it. The quadriceps and the gastrocnemius are a substantial amount of muscle. Restricting blood flow with isometrics will increase the resistance on the heart and blood vessels. The benefit is that you will get a training effect on both that lowers BP.

What’s actually going on with the nervous, cardiovascular, and muscular system isn’t quite clear, but knowing why won’t help you do them. If you don’t have orthopedic issues (and you don’t hold your breath while performing the isometrics), no matter what muscle groups you use, you may help lower your BP. I think the wall sit works the best due to total muscle mass involved, but every muscle group will help.

The Bottom Line

Will isometrics make you super fit? No. Super strong? No. There are also limitations as to the angles where strength will increase due to specificity of training. But there seems to be an emphasis on improving health with short episodes of exercise. Isometrics fit that niche quite well and as the study demonstrated, quite effectively as related to BP. We’re not done yet because two other studies have focused on activities that involve movement. We’ll talk about those next week. In the meantime, have a great Labor Day holiday.

What are you prepared to do today?

        Dr. Chet

Reference: British J Sp Med Online July 2023. doi: 10.1136/bjsports-2022-106503

Isometric Exercise Lowers Blood Pressure

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This summer has seen several studies about exercise, so we’ll just continue with the flow from last week. The first study caught me by surprise: isometric exercise lowers blood pressure. When you do isometric exercises, you increase tension in a muscle without moving the joint, such as holding your leg still while you clench your thigh muscles; if you’ve got a wall, a chair, and a floor, you’ve got all you need. We don’t think of isometric, also called static exercise, as being effective in changing the dynamic flow of blood in the cardiovascular system. Let’s take a look at the study.

Researchers conducted a literature search of all published studies that examined the impact of any type of exercise on systolic blood pressure (SBP) and diastolic blood pressure (DBP.) They conducted a pairwise and network meta-analysis to see which exercise helped BP the most. The most important finding was that every form of exercise significantly reduced SBP and DBP when performed for two weeks and longer: aerobic exercise, dynamic resistance (weight) training, combined training, high-intensity interval training (HIIT), and isometric exercise.

When they compared the efficacy of the different forms, isometric exercise lowered SBP the most, followed, in order, by combined training, weight training, aerobic training, and HIIT.

To me, isometrics are somewhat easy to perform because it removes obstacles such as orthopedic issues or equipment. But why would it reduce blood pressure more than other modes of exercise? We’ll check that out on Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: British J Sp Med Online July 2023. doi: 10.1136/bjsports-2022-106503

HIIT Will Get You Fit

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An Insider emailed me a link to a press release about high-intensity interval training, or HIIT for short. I’ve always used interval training, when I was a serious runner, and now as a way to increase my fitness level faster. That’s why I was a little surprised that a study suggested that you have to do intervals that are at least a minute long and shouldn’t rest more than two minutes. I checked out what I could find.

The research was presented at a conference and as much as I tried, I couldn’t get the abstract. Fortunately, the press release contained just enough information to figure out what was what. The researchers recruited 26 previously sedentary subjects and put them on a HIIT program. They either took part in 60-second intervals of high intensity with 60 seconds rest or intervals that lasted 30 seconds with 120 seconds rest. While both groups saw similar changes in body composition and arterial stiffness, the 60/60 groups saw bigger improvements in max VO2, a measure of aerobic fitness. In fact, the release included comments from the lead author that the subjects didn’t improve their fitness level at all.

That didn’t make any sense to me. If the intensity was high enough, 30 seconds of all-out effort would need two minutes to recover. I found the problem. One of the purposes of the study was to use exercises people could do at home, so they used calisthenics: push-ups, squats, sit-ups and exercises such as that. That’s admirable, but it made the headline and her comments misleading—extremely misleading.

Using sedentary subjects means they had to overcome localized muscle fatigue. The localized muscle pain may get the heart rate to increase but it’s limited by muscle stamina, especially in sedentary individuals, until they could actually do enough push-ups, etc., to challenge their cardiovascular system. A six-week study is not long enough for them to really master the movements and do them fast enough in order to get a good aerobic training effect.

The Bottom Line

HIIT can be effective if done properly; running and cycling are still the best options to do that. You can reach aerobic exhaustion in 30 seconds if the intensity is high enough, and if you do, you’ll need every one of those two minutes to recover before the next interval begins. You must make sure your cardiovascular system is ready for it, so get your doctor’s clearance before you attempt it.

What are you prepared to do today?

        Dr. Chet