Tag Archive for: exercise intensity

Yes, Intensity Matters

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Can you get away with less time exercising and still protect your cardiovascular system? We know from Tuesday’s Memo that more time spent on physical activity will provide more protection. Can we save some time? Or perhaps better stated, can we do something in short bursts of time that can increase the moderate to intense exercise we get?

Before I answer that, remember that physical activity means everything you do that requires movement: walking to the kitchen, gardening, cooking, and the activity involved in your job. Exercise is also a part of your overall physical activity. In the study, all activity was registered by the accelerometer the subjects wore.

Intensity Matters to Reduce CVD Risk

With that in mind, the answer is yes: exercise intensity matters when it comes to protecting yourself from cardiovascular disease (CVD). I must admit that the charts and graphs published in the study were challenging to understand. They used a percentage of calories used per day as the way to measure outcomes. For the exercise intensity analysis, they considered the percentage of calories at moderate to high intensity. They found that as the percentage of activity at moderate to high intensity increased, the rate of CVD events decreased.

Here’s an example. Let’s take a 180-pound guy who uses a low amount of energy in physical activity such as five calories per kg body weight. The total calories he uses daily would be about 400 calories, including any exercise he did. But let’s say the percentage of moderate to severe intensity exercise rises from 10% of total exercise to 20% of that total. His risk of a CVD event would be reduced from 2% lower to 20% lower. He hasn’t invested any more time, yet he gets a jump in benefit just from increased intensity.

What Does That Mean for You?

Does this mean that everyone should be doing high-intensity interval training? Not in the classic sense; what’s high intensity for you may be impossible for your elderly neighbor and a breeze for your kid’s soccer coach. You don’t have to do special workouts such as high-intensity interval training where you’re going to bust a gut for 60 seconds and then take it easy for five minutes. That is intense, but it takes less time overall and you could do that if you want; there’s more info at drchet.com if you decide to try it.

In physical activity, everything counts from housework to walking the dog to breaking into a run to catch a bus. Those would show up as mild or moderate intensity, or high-intensity exercise for the running. It doesn’t mean that all the exercise you do has to be high intensity, but investing time in higher intensity exercise may provide you with additional benefits. Working a little harder is going to reduce your risk of cardiovascular disease and, while not assessed in this study, your risk of type 2 diabetes, hypertension, and cancer would be reduced as well.

Of course, the question is what’s high intensity for you. The chart above is geared toward weightlifting, but it will give you some ways to think about how hard you’re exercising, no matter what you’re doing. If you’re running for the bus, could you run one more block? If you’re cleaning house, do you have enough juice left to go for a bike ride?

The Bottom Line

You must be fit enough and ambulatory enough to actually do moderate to high-intensity exercise. But you know something? I know of one physical therapist who encourages patients to do jumping jacks while sitting in a wheelchair. Of course they can’t do the actual jumping part of it but for 60 seconds, their arms are going up and down, up and down, up and down at a very high rate, and maybe their legs are moving, too—and that’s high intensity for them. For others of you, it may be doing a two-minute walk up a very steep hill. The intensity of the exercise stresses the heart in ways that a nice easy walk does not. And for that, you get additional benefits, no matter where you’re starting.

So check with your doctor to find out your limitations as it relates to exercise intensity, and then get after it. Not to lose a whole bunch of weight, not to win the next 5K, not every day—but often enough to make your heart stronger and fitter.

What are you prepared to do today?

        Dr. Chet

P.S. Happy Canada Day to our neighbors to the north! We’re taking next week off to enjoy the July 4th holiday and hope you do as well (even if you’re not in the U.S.) We’ll be back with new Memos the week of the 10th. Meanwhile, it’s a great time to try increasing your exercise intensity.

Reference: Eur Heart J (2022) https://doi.org/10.1093/eurheartj/ehac613

How Hard Should You Exercise?

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Exercise is my most favorite thing to talk about—not surprising for an exercise physiologist. There’s no question that diet is important to our health, but if I had to focus on just one habit that people should adopt, it would definitely be exercise first before anything else. I believe we should all eat more vegetables and fruits, take supplements for gaps in our diet, and try to reach a normal body weight. But aside from quitting smoking, the most important thing you can do for your health is to be physically active.

Let’s look at the study. The subjects in the study were a subgroup of people from the United Kingdom Biobank study. The data were collected from 88,412 middle-aged adults, with 58% women, who were specifically chosen because they had not been diagnosed with cardiovascular disease before the study.

The researchers broke the data into three equal groups by activity level. The average age of the subjects in the study was 62, and the average BMI was 27. They tracked the subjects for 6.8 years, and in that amount of time there were 4,068 cardiovascular disease (CVD) events: ischemic heart disease (reduced blood flow to the heart) or cerebrovascular disease (reduced blood flow to the brain).

Their findings were interesting and confirmational. Using no or differing covariates in the statistical analysis, as the amount of physical activity increased, the incidence of CVD decreased. That would confirm what we would expect: regardless of intensity, the risk of CVD decreased and it continued to decrease for every level tested.

How does exercise intensity impact all this? We’ll take a look at intensity on Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: Eur Heart J (2022) https://doi.org/10.1093/eurheartj/ehac613

Does Exercise Intensity Affect Obesity?

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As I wrote on Thursday, exercise intensity did not seem to impact mortality, or death rate, in a large group of older women. Of course, living longer is important to many people. Could exercise intensity provide benefits as it relates to reducing the staggering 40% rate of obesity in the U.S.? Maybe. Let’s look at a recent study from Taiwan.

The Taiwan Biobank Study is a longitudinal study that recruits Han Chinese subjects 30 to 70 years old. Much like the All of Us study, researchers take anthropometric data such as height and weight as well as blood samples for multiple DNA analyses. They also collected data on physical activity; their objective for this part of the study was to see if exercise and the intensity of exercise impacted genetic manifestations of obesity.

Genes and Obesity 

What manifestations? Body mass index, percent body fat, and waist circumference among others. Researchers asked the subjects what type of exercise they did, how long they exercised, and how many times per month they exercised. Then they calculated a BMI Genetic Risk Score (BMIGRS) based on the genetic markers for five obesity-related gene combinations. This was complicated; you know I like to see raw data, but with over 16,000 subjects and all of the compounding variables, that’s not realistic.

When they divided the subjects into quartiles based on BMIGRS, they found that the exercise with the greatest impact on the obesity-related genes was jogging. That was followed closely by mountain climbing, walking, exercise walking, international standard dancing (the kind of ballroom dance you learn at a studio or see on Dancing With the Stars), and a longer practice of yoga. Those activities had an impact on the expression of the genes related to obesity. It means that it down-regulated those genes, which means that if you jog, your BMI is lower, you have a lower percent body fat, and your waist circumference will be smaller.

Do you have to jog? No. All the listed exercises had an impact on the obesity genes so if you can’t jog, that’s fine. Extended yoga and dance were also on that list, and they don’t have the impact on joints that jogging or even mountain walking would have.

There were also some other interesting findings. Joggers exercised less time, about 30 minutes, and fewer days per month, about every other day. Walkers walked nearly an hour at a time and walked two out of three days.

The Bottom Line      

One thing was clear: every type of exercise was better than no exercise. I’ve said many times before that exercise by itself is not a great way to lose weight because you have to invest so much time in it to have an impact, and no matter what exercise you choose, you still have to eat less. But if you want an advantage that will impact any obesity genes you have, higher intensity exercise is better. You have to adjust for orthopedic and any other issues, but the more intense the exercise, the better the results. If you’re going to walk 10,000 steps per day, walk them like you mean it.

What are you prepared to do today?

        Dr. Chet

 PLOS Genetics | https://doi.org/10.1371/journal.pgen.1008277.