Should You Just Do Intense Exercise for Less Time?

Just when everyone was already confused about what types and amounts of training people with diabetes should be doing, along comes yet another study to muddy the waters some more. This latest exercise research was undertaken by faculty at McMaster University in Hamilton, Ontario, and appeared in the December 2011 issue of Journal of Applied Physiology (1).

The study involved eight individuals with type 2 diabetes (mean age of 63 years) who agreed to endure six sessions of high-intensity interval training done on a cycle ergometer over a two-week period. The training sessions consisted of 60 seconds of cycling done 10 times at ~90% of maximal heart rate, interspersed with 60 seconds of rest—for a total of only 10 minutes of actual exercise and 10 minutes of recovery. In other words, it involved almost an all-out sprint for a minute at a time, repeated 10 times with very little rest in between. Some call this low-volume, high-intensity interval training (HIT); others call it pure torture.

Before training and from ∼48 to 72 h after the last training bout, blood glucose responses were monitored using 24-hour continuous glucose monitoring. The exercise definitely had a positive effect on blood glucose levels: both the average levels over 24 hours and the 3-hour postprandial values after all three daily meals were improved significantly even 2-3 days after each training session, suggesting that low-volume HIT can rapidly improve glucose control and induce adaptations in skeletal muscle that improve metabolic health in people with type 2 diabetes.

While interval training is routinely used by sports teams and athletes, I have to question whether doing only this type of training would be beneficial for most individuals with diabetes. It certainly saves time—who can’t fit in 10 minutes of exercise three days per week?—but would it benefit weight control in the average person with type 2 diabetes? Probably not, as it simply doesn’t burn that many calories. Actually, it doesn’t save that much time either: when you add in the interspersed rest intervals and a warm-up and cool-down period, it still takes at least 25 minutes per session and 75 minutes per week. Current recs from the American Diabetes Association suggest that people with diabetes should try to get at least 150 minutes of moderate to vigorous exercise each week—an average of 30 minutes a day if done five days a week—so you’d only really be saving time on the two extra days you’re not doing the HIT routine.

There is no doubt that doing HIT training does have some benefits. This research suggests that doing thrice-weekly short intensive workouts may help lower blood sugar levels similarly to more frequently performed moderate activities. The sessions themselves dropped blood sugar levels from 137 mg/dL to 119 mg/dL, on average, which isn’t bad for only 10 minutes of exercise. In addition, overall and post-meal blood sugar levels were reduced long after training sessions were completed, which may or may not happen with more moderate workouts.

On the flip side, others who wrote articles about this training regimen also commented that “it requires so much suffering that you’re almost destined to quit.” Unless it’s regularly done with others, a coach, or a personal trainer to ensure motivation and positive feedback, most individuals will not have the drive to continue doing this type of training on their own long-term. What’s more, doing really intense exercise can actually cause a short-term elevation in blood glucose instead of a decrease, especially if the intense activity is not repeated enough times (such as the 10 sessions in this study) due to the effects of glucose-raising hormones released by sprinting. (So, you probably couldn’t stop early and gain the same benefits.)

If you can only do five to 10 minutes of exercise, that’s certainly better than nothing, but you really start to see the effects of exercise if you can regularly exercise harder and longer—for 20 to 30 minutes at least a few times a week. Another drawback of doing low-volume HIT is simply that not everyone is going to be able to do it, and it’s certainly not the best routine to start with when you’ve been sedentary for a while. It’s also more likely to result in overuse injuries and other joint problems that will stop you from doing anything after a while.

However, I’m totally in favor of routinely interspersing harder intervals into any regular training session—regardless of how easy or hard it is—both to increase cardiovascular fitness and to use up more blood glucose and stored carbohydrate (glycogen) in muscles, just like was done in one pilot study a few years back (2). Starting with easier workouts and interspersing slightly harder intervals into them is a lot more realistic for the majority of folks out there just getting started.

The bottom line: Just get up and off the couch to do any type of physical activity regularly, and your blood glucose levels will thank you.

References Cited:

(1) Little JP, Gillen JB, Percival ME, Safdar A, Tarnopolsky MA, Punthakee Z, Jung ME, Gibala MJ. Low-volume high-intensity interval training reduces hyperglycemia and increases muscle mitochondrial capacity in patients with type 2 diabetes. J Appl Physiol. 2006;111(6):1554-60.

(2) Johnson ST, McCargar LJ, Bell GJ, Tudor-Locke C, Harber VJ, Bell RC. Walking faster:  distilling a complex prescription for type 2 diabetes management through pedometry. Diabetes Care 2006;29:1654-5.

5 thoughts on “Should You Just Do Intense Exercise for Less Time?

  1. Awesome Athlete

    I was just writing about interval training last night (link in name) on my fitness blog. No one ever tells you about the added risk of injury doing HIIT due to higher impact when running. Be careful.

    Reply
    1. shericolberg Post author

      Absolutely. Injury risk increases more than normal in people with diabetes, too. I don’t see HIT as a long-term exercise for most people, regardless of whether they have diabetes or not. Doing some intervals within normal, moderate training is very beneficial, though, to both blood glucose control and fitness improvements.

      Reply
  2. Daniel

    Dr Colberg, Have you read “Body By Science” by Dr. Doug McGuff and Tony Little. They claim that you only need 12 minutes of HIIT to get the amazing results everyone is looking for.

    Reply
  3. John Balor

    Hi,

    I really enjoy this site and particularly this article On my blog I have started writing about Unexpected Benefits of Exercising and Becoming Fit. The primary reason being both of us talk about Benefits of Exercising.

    I feel like I have some great content that would work really well on your website. Would you be interested in using my content on your site? Here is an example below of an article that you could post. Please let me know if you have any questions!
    Unexpected Benefits of Exercising and Becoming Fit

    While most of us have heard that exercising more helps you to lose weight and lessen the risk of diabetes and heart disease, you might be surprised at the overlooked benefits of exercise and being fit. Recent studies have indicated that regular exercise improves your mental health, your physical beauty, and your relationships.
    How Exercise Improves Brain Power and Mental Health
    When you exercise, you experience an increased blood flow your brain, which helps you concentrate better. If you feel sluggish, often taking a brisk walk is better than reaching for another cup of coffee or glass of pop. Besides offering an immediate release, exercise offers several other mental and cognitive benefits that we don’t often think of.
    • Simply put, exercise makes you smarter. Even in young children, just running around or jumping rope helps with memory games and passing exams. So find that young child in you and challenge a friend to a race because running sprints is known to help with memory and vocabulary retention in adults too. In particular, cardio work-outs can lead to neurogenesis, the creation of more brain cells. If you do an extremely hard work-out on the treadmill, it will increase your BDNF levels, assisting with better decisions and cognitive reasoning.
    • Exercise makes you happy. It releases endorphins, which make you feel almost euphorically happy. Often, doctors recommend that you work out for 30 minutes at least three times a week to ward off depression and anxiety. Think of your “work-outs,” as your “happy pills.” Try to work-out outside whenever possible so you have access to the mood-boosting Vitamin D and sunshine.
    • Exercising regularly reduces your stress levels. After a long day at work, engage in a cardio work-out for at least a half hour. Raising your heart rate and getting sweaty increases your norepinephrine levels and regulate your brain’s reaction to stress. In fact, if you do a vigorous 45-minute work-out on the elliptical or the treadmill three days in the row, you may slow down the aging process, and who doesn’t want that.
    • Working out helps your creative process and your work productivity. While you may feel exhausted after an hour-long aerobics class or a 7-mile run, make good use of it. Studies have shown that inspiration and creativity is heightened for up to two hours after your work-out. Taking your run through a scenic trail in a park will help the process even more. In addition, if you’re feeling uninspired at the office, try fitting in a work-out on your lunch hour, such as walking nearby or even hitting the gym. You’ll return with more energy ready to tackle the rest of the day.
    Exercise and a Healthy Lifestyle Improves Your Beauty Habits
    Exercising regularly not only sharpens your brain power, but enhances your natural beauty and gives you better skin and better eyes. It also helps you get more restful sleep.
    • Technically, your skin is the largest organ in your body, and many dead skin cells are sloughed off daily. In order to replenish them, you need proper nutrients, lots of water, and a healthy exercise program. Sweating gives your skin a healthy glow, and seeing tight skin over muscle looks really appealing too.
    • You can lower your risk of developing glaucoma by 25 percent by participating in moderate exercise. You’ll find you’ll reap these benefits even 15 to 20 years later so exercise as much as possible while you can.
    • Working out for around 30 minutes a day or 150 minutes a week leads to more restful nights. In fact, scientific research states that a vigorous work done at least five or six hours before bedtime often will help you sleep better than medication.
    Exercise Improves Both Social Relationships and Your Sex Life
    As you find more motivation and self-confidence, you’ll notice you’re happier and that you have healthier relationships at both work and home. In addition, due to your new confidence as well as your toned body and flexibility, you’ll find that you’re enjoying a more active sex life.
    • Exercising helps you make good first impressions, which is key in forming relationships, be it at a job interview, a first date, or meeting your future in-laws. This is partly because exercising releases chemicals to relax you, and partly because you’re more likely to feel confident if you’ve lost weight or toned up from exercising.
    • This new confidence and happiness also helps you in your current relationships as others will notice your new determination as well as your body, and not your negative approach to unrealistic goals.
    • Exercising regularly can improve your sex life. According to numerous studies, exercising vigorously by jogging two miles and burning around 200 calories lowers your risk of having issues with erectile dysfunction. Women also benefited from exercise partly because you often want to more because you feel prettier, but from being toned and more flexible from all those yoga classes, you can try different techniques and spice up your love life.
    Exercise Has Surprising Health Benefits
    Besides helping you reach your weight loss goal and prevent high-risk diseases, exercise helps with daily health occurrences and annoyances and prolongs your life expectancy.
    • Exercise reduces your cravings. So the next time you’re craving that giant homemade chocolate chip cookie, try working out on the treadmill for an hour instead. It causes your blood flow to concentrate on your muscles instead of your hunger pains, in turn lessening the pleasure response of food. In addition, exercise strengthens your abdominal muscles and helps you digest food better in your intestinal tract, without feeling sluggish.
    • Aerobic exercise helps in preventing migraines or lessening the strength of the headache. Combined with relation therapy, you may experience similar benefits to prescription drugs. Just be careful not to do any vigorous exercise during a migraine attack, or you could make it worse.
    • Even exercising for 15 minutes a day could add three more years to your life. Therefore, join a fun dance class or meet a friend for a game of basketball or a brisk walk to make it more fun.
    With all these unexpected benefits to exercising and a healthier lifestyle, is it time to follow through on your New Year’s resolution to actually use the gym membership you bought months ago?
    Thanks!
    John

    Reply

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