Tag Archive for: high-intensity interval training

HIIT: Specific Fat Loss

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What were the results of HIIT training? The researchers found that there were reductions in overall weight as well as subcutaneous and visceral fat. What’s the difference? The fat just under the skin is subcutaneous fat; visceral fat is behind the abdominal muscles and around the internal organs and is more related to the development of cardiovascular disease and type 2 diabetes. There were no differences in the outcome variables with two exceptions:

  • Those who were in the running group lost a greater percentage of subcutaneous fat than the cycling group at 16.1% vs. 8.3%. The other difference was that positive changes in the microbiome were correlated with the loss of subcutaneous fat. Before you get too excited, the actual loss of subcutaneous fat was close to two pounds in the running group and about one pound in the cycling group. Still, ask your butcher for one pound of fat and see what it looks like. It’s a lot and probably worth the effort doing the HIIT program.
  • The other benefit was an improvement in some positive bacteria in the microbiome. It wasn’t associated with running or cycling; it was correlated with the loss of subcutaneous fat. It seems that visceral fat would show more benefit, but that wasn’t the case. Maybe someday we’ll find out why.

The obvious problem with doing a running HIIT program is that you have to be able to run—at least for 45 seconds. While my running is progressing slowly, I do intervals only while walking or riding the exercise bike. But running for 45 seconds? I can handle that.

Finally, while I was puzzled about the microbiome benefits, I also questioned why there was a difference between cycling and running when it came to the loss of subcutaneous fat. The researchers didn’t have a reason to explain it. I’ll give you my informed opinion: running integrates more of the core during the actual interval than cycling does. My hunch could be tested with sensors that detect the electrical activity of muscles, but that’s fine tuning that might not be necessary. As a scientist, I always want to know why, but that’s not important; it’s just important that it is.

We’ve seen that 30 minutes of moderate walking can prevent the loss of muscle and a HIIT running program can help lose subcutaneous fat in those who are overweight. How about getting fitter faster? Is that possible? Find out next week when we look at SIT training—and sitting does have something to do with it!

What are you prepared to do today?

        Dr. Chet

Reference: Med Sci Sports Exerc 2024 May 1;56(5):839-850.



HIIT and Fat Loss

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One of the “facts” exercise professionals will tell you is that there is no such thing as spot reduction; by that I mean you cannot target a specific area of your body, let’s say your abdominal area, and lose fat by doing a targeted exercise such as sit-ups or leg lifts. You can make the muscles underneath the skin stronger for sure, but there doesn’t seem to be any evidence that you can reduce the amount of fat in that area.

With 35 years of experience in the field, I would say that requires a qualified answer—it needs to be qualified with the word yet. There hasn’t been a study that proves that you can reduce fat in a specific area yet. Is it theoretically possible? Yes, I think it is. The problem is this: who would do the high quantity of exercise focused on one area long enough per workout session to do themselves any good? It may be that we’ve approached it all wrong by focusing on resistance exercise. Let’s take a look at another study that compared high-intensity interval training (HIIT) on a cycle ergometer versus a treadmill.

Researchers began with two questions. Is there any difference in the fat mass in specific areas of the body after training using a cycle ergometer (an exercise bike that measures the energy output of the cyclist) or a treadmill? In addition to that, is there any change in beneficial microbes in the microbiome after training?

Let’s take a look at what they did. Researchers recruited 16 men with a mean age of 54 and initial BMI of 29.9. After assessing initial fitness level, body fat, and body-fat distribution using the DEXA scan, and taking an initial stool sample for analysis of the microbiome, the subjects were randomly assigned to the bike or the treadmill. To make sure that there were no significant changes in diet, the subjects were required to maintain their typical diet and do seven-day diet records periodically during the study.

Think of this as intervals for the everyday exerciser. The HIIT bike program required them to do ten intervals for 45 seconds each at 80–85% of the maximal heart rate (MHR), and then a 90-second active recovery, or a HIIT running program which were nine intervals for 45 seconds at 80–85% of MHR and again with 90 seconds of recovery between intervals. They were to do this exercise under supervision three times per week for 12 weeks. The goal was to have all exercisers use the same number of calories during the workouts, whether cycling or running. The subjects were then retested to examine the differences if there were any. What did they find? I’ll tell you on Saturday.

What are you prepared to do today?

        Dr. Chet

Med Sci Sports Exerc 2024 May 1;56(5):839-850.

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

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

Research Update: Exercise in Short Bursts

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High-intensity interval training (HIIT) has become very popular due to the possibility of gaining fitness in a short amount of time, but when done correctly workouts still take 20 to 40 minutes. A group of researchers examined the United Kingdom Biobank data to see if a sub-group of subjects who wore accelerometers might benefit from short bouts (one or two minutes) of intense physical activity independent of a regular exercise program. Researchers termed the exercise bouts “vigorous intermittent lifestyle physical activity” (VILPA) and they were not part of an intentional exercise program. They just happened with people who were going about their daily routines.

They tracked the subjects for almost seven years to see if there was any reduction in their death rate. The data showed that as few as two or three short bouts or approximately three to four minutes of VILPA per day were associated with substantially lower all-cause, cardiovascular, and cancer mortality risk. More VILPA sessions per day resulted in a greater reduction, but the greatest reduction occurred in three to four minutes per day. The reduction was a 38% to 40% reduction in all-cause and cancer mortality risk and a 48% to 49% reduction in CVD mortality risk. One more thing: the average age of the over 25,000 subjects was 61.8 years.

The facts that struck me was whether a person exercised or not, or ate a high amount of vegetables and fruit or not, they had a reduction in mortality. To be safe, you and your doctor should discuss whether you can try a minute or two of intense physical activity a few times per day. Maybe it will happen organically as part of your day, like sprinting up a flight of stairs to get to a meeting, or running to catch a bus, or chasing a toddler. Or maybe that exercise bike you’ve been using as a clothing rack can be put to use as it was intended. Find your spots and do what you can. You may have years to gain.

What are you prepared to do today?

        Dr. Chet

Reference: Nature Medicine. 2022; 28 (12):2521–2529

Getting to the Exercise Sweet Spot

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Do you realize that five minutes is only 0.3% of a day? Can you really say you can’t at least begin to exercise? “Five minutes isn’t the issue—it’s the 45 minutes a day!” Yes, although 45 minutes is only a whopping 3% of your day, I know it can be hard to work it into your schedule. How about if you could cut the time spent in aerobic exercise in half, from 45 minutes to just over 20 minutes? Interested? Just remember there will be a price to pay.

High-Intensity Interval Training (HIIT)

HIIT as is currently practiced began about 2008 and has been the focus of a lot of research since 2017. The current version alternates very intense intervals from 30 seconds to four minutes with rest periods of at least four minutes; most common is one minute of high intensity and four minutes of rest. Understand that the intensity is an all-out effort, something most sedentary people cannot and should not do—yet.

Remember the price? It’s getting in good enough aerobic condition to be able to handle the increased intensity. When you’re fit enough, four 20-minute HIIT sessions per week can provide you with the exercise sweet spot. Just remember this is only aerobic fitness. Lifting weights, yoga, stretching—that’s all separate.

Intensity

Here’s the real reason I’m getting a knee replacement done: I can’t work hard enough on the exercise bike to reach my target heart rate. Thigh pain above my bad knee hinders me from getting there. I’ve been on the cycle for at least six months, and I’m tired of not getting the workouts I’m used to getting through running.

Although running is not in my future after the knee is replaced, walking will be as well as using the elliptical again. I can replace running with walking uphill in order to achieve the fitness effect I want. It’s not as good but it will give me some variety. I can handle the pain of high-intensity training once I no longer have this level of knee pain. And that’s why I’m doing the knee replacement now.

The Bottom Line

The exercise sweet spot isn’t as precise as I would like, but it does follow a logical progression. Some exercise is better than none; if you’re not exercising at all, start with five minutes. Aspire to at least 30 minutes per day at least four days a week, then work up to 45 minutes.

When you can handle that and your physician says it’s okay, then you can start HIIT training to increase your fitness in less time and still have time to get stronger and more flexible. Even at 45 minutes a day, that’s just 3% of your day committed to exercise. That commitment of time will reduce your risk of just about every degenerative disease, which will help you really live more days of your life and not just struggle through them. Isn’t that worth the investment?

What are you prepared to do today?

        Dr. Chet

Want Fewer Medications? Change Your Lifestyle

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The study that we examined on Tuesday showed that a regular exercise program can help reduce the number of medications related to cardiovascular disease and type 2 diabetes. We’re not talking about youngsters; 51 subjects completed the study with an initial mean age of 54. There were some outcomes that were likely unexpected; for example, waist circumference did not change between the experimental group and control group over the five years. There was a significant decrease in body fat in the exercise group that explained the difference in body weight. Still, the control group lost about two pounds in five years while the exercise group lost about six pounds. That actually turns out to be a good thing, as I’ll explain a little later.

The Exercise Program

The high-intensity interval training was just as advertised: intense. It included a 10-minute warm up, followed by four 4-minute intervals at 90% of maximum heart rate (HRMax) interspersed with 3 minutes of active recovery. They finished with a 5-minute cooldown. They used percentage of HRMax as assessed in the exercise test, because that’s an intense level. The focus is on the 4 minutes but those 4 are brutal. You do get to rest, but then you have to do it over again, and that’s a significant challenge to the cardiovascular system. As people got fitter, the intensity would be changed to sustain the 90% level.

What surprised me was that there was no organized exercise activity in the other eight months of the year; they just kept track of activity levels using the activity monitors. There were no differences between the control group and the exercise group in the eight months with no organized activity. That’s interesting.

Most Variables Didn’t Change

This probably surprised the researchers, but it was a desirable outcome. There were no significant differences in body fat, waist circumference, BMI, or overall percentage of body fat. While the subjects probably would have liked to have lost more weight, the fact that they didn’t shows that the changes that occurred in the risk factors for cardiovascular disease, such as high blood pressure and low HDL cholesterol as well as a lower insulin levels, showed that the difference was the actual exercise program itself. The differences in distribution of nutrients in the diet and in the total caloric intake were insignificant. As I mentioned earlier, the number of steps per day and other activities were still even. That means, again, the changes could be attributed to the exercise program alone.

The Bottom Line

What is abundantly clear is that if you really want to reduce medications, you have to pay the price by changing your lifestyle. In this study they focused on one variable: exercise. If you add a change in dietary intake, and or a change in the distribution nutrients, you may get even more benefits. But for me, it answers the question that I started with. You want to reduce medications? Change your lifestyle.

Is it worth it? That’s your call. But that’s what Aging with a Vengeance is all about.

What are you prepared to do today?

        Dr. Chet

Reference: MSSE. 2021. 53(7):1319-1325.

Can You Reduce Your Medications?

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One of the questions that I get asked frequently goes something like this: “Dr. Chet, how can I reduce the medications I’m taking?” Along with that question is, “I don’t want to have to take medications for blood pressure or cholesterol or diabetes. What can I do?” As we proceed with a focus on Aging with a Vengeance, a recently published study illustrated at least a partial answer to these questions.

Researchers in Spain recruited 64 subjects for an exercise program. The exercise program was a high-intensity interval training (HIIT) program, three days a week, that ran for four months under staff supervision. The rest of the year these subjects were given activity monitors that automatically uploaded data on activity, sleep, etc. The researchers also took a variety of blood samples for testing metabolic variables, tested the subjects’ fitness levels, assessed anthropomorphic measures such as body weight and waist circumference, and recorded medications related to blood pressure, cholesterol, triglycerides, and blood sugars. The subjects were retested after two years and again after five years.

Over the period of five years, an amazing 51 subjects completed the exercise sessions and all the testing required. That, in and of itself, is remarkable—I’ve done this type of study, and holding on to the subjects is one of the main challenges.

The primary question was answered: those who exercised as the study required took fewer medications for blood pressure, cholesterol, and blood sugar control. As you might expect, that isn’t the entire story, so we’ll wrap this up on Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: MSSE. 2021. 53(7):1319-1325.

Aging with a Vengeance and Your Proteome

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This year’s Super Bowl Webinar focused on aging with a vengeance—becoming the best version of yourself, no matter your age. The study we just reviewed on the proteome suggests that the people were healthier who were biochemically younger than their actual age. Here are the actions I believe can help at the three critical phases of aging that were identified in proteome study. As I find out more, I’ll be more specific.

31 to 37

If you have weight to lose, now is the time to lose it. Take it from me and my decades of experience with weight loss programs: it becomes more difficult the older you get. Find a way to eat that will maintain a reduced body weight and stick with it.

Reduce your protein intake. That may seem a little odd, but this is a time to focus on vegetables, fruit, whole grains, and quality oils.

Focus on your cardiovascular system by doing aerobic exercise on a regular basis. Use interval training to make the most of your time, and when you’re fit enough, you can add high-intensity interval training (HIIT) to your routine.

57 to 63

The kind of 80- to 85-year-old you’re going to be is dependent on what you do now. If you haven’t achieved a normal body weight, that’s a high priority just as it was in the prior age group. I know how difficult this is because it’s eluded me throughout my life; I lost a lot of weight and kept it off for years, but I’d still like to weigh less.

Increase protein intake to 1–1.5 grams per kilogram body weight per day.

Supplement your diet with essential amino acids. While the amounts are still not absolutely clear from the research, 10–20 grams per day is a good goal.

If you’re not already doing so, add weight training to your exercise routine. Start with using your own body weight, then add exercise tubes or light weights, and then use machines or free weights. Now is the time to retain or even increase your muscle mass.

75 and Older

If you haven’t achieved a normal body weight, there’s still time. My wonderful mother-in-law lost a significant amount of weight at this age, and she was an overweight diabetic in a wheelchair.

Increase protein intake to 1.5–2 grams per kilogram body weight per day. It’s difficult because appetite decreases and protein makes us feel full. It will help reduce the muscle loss that’s happening.

Supplement your diet with essential amino acids; the amounts are still between 10–20 grams per day.

Add weight training to your exercise routine. It will help you to retain or even increase your muscle mass. Stay within any orthopedic or other limitations, and get some help if you need to, but do it. Your primary caregiver will probably be glad to refer you to a physical therapist who can get you started safely.

The Bottom Line

For all that’s been written about healthy aging, we still don’t know very much. Healthy aging begins the day we are born, but we realize that only when it dawns on us that we’re aging. No matter your age, no matter your current state of health, it can be better. You can learn more in the replay of this year’s Super Bowl Webinar, but it will be available for only a little while longer.

The simple things I’ve talked about in this Memo are a beginning. When I know more, so will you. Inevitably, it comes back to a single question:

What are you prepared to do today?

        Dr. Chet

Reference: Nature Medicine. 2019. https://doi.org/10.1038/s41591-019-0673-2

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