Category Archives: High-Intensity Training

Physical Activity/Exercise and Diabetes (ADA 2016 Position Statement)

ADA Position Statement CoverI would like to let everyone know about a new position statement that covers all types of diabetes (type 1, type 2, and gestational) and prediabetes and addresses physical activity and exercise. It is based on an extensive review of more than 180 papers covering the latest diabetes research and includes the expertise of leaders in the field of diabetes and exercise from top research institutions in the US, Canada, and Australia.

The most notable recommendation calls for three or more minutes of light activity, such as walking, leg extensions or overhead arm stretches, every 30 minutes during prolonged sedentary activities for improved blood sugar management, particularly for people with type 2 diabetes. Sedentary behavior—awake time that involves prolonged sitting, such as sitting at a desk on the computer, sitting in a meeting or watching TV—has a negative effect on preventing or managing health problems, including diabetes. Studies have shown improved blood sugar management when prolonged sitting is interrupted every 30 minutes—with three minutes or more of standing or light-intensity activities, such as leg lifts or extensions, overhead arm stretches, desk chair swivels, torso twists, side lunges, and walking in place. Physical movement improves blood sugar management in people who have sedentary jobs and in people who are overweight, obese and who have difficulty maintaining blood sugars in a healthy range.

These updated guidelines are intended to ensure everyone continues to physically move around throughout the day – at least every 30 minutes – to improve blood glucose management. This movement should be in addition to regular exercise, as it is highly recommended for people with diabetes to be active.

Since incorporating more daily physical activity can mean different things to different people with diabetes, these guidelines offer excellent suggestions on what to do, why to do it and how to do it safely. It includes various categories of physical activity—aerobic exercise, resistance training, flexibility and balance training, and general lifestyle activity—and the benefits of each for people with diabetes.

Aerobic activity benefits patients with type 2 diabetes by improving blood sugar management, as well as encouraging weight loss and reducing cardiovascular risks. Movement that encourages flexibility and balance are helpful for people with type 2 diabetes, especially older adults. Regular aerobic and resistance training also offer health benefits for people with type 1 diabetes, including improvements in insulin sensitivity, cardiovascular fitness and muscle strength. Women who are at-risk or diagnosed with gestational diabetes are encouraged to incorporate aerobic and resistance exercise into their lives most days of the week. People with prediabetes are urged to combine physical activity and healthy lifestyle changes to delay or prevent a type 2 diabetes diagnosis.

Recommendations and precautions for physical activity and exercise will vary based on a patient’s type of diabetes, age, overall health and the presence of diabetes-related complications. Additionally, specific guidelines are outlined on monitoring blood sugar levels during activity. The statement also suggests positive behavior-change strategies that clinicians can utilize to promote physical activity programs.

Reference:

(1) Colberg SR, Sigal RJ, Yardley JE, Riddell MC, Dunstan DW, Dempsey PC, Horton ES, Castorino K, Tate DF. Physical Activity/Exercise and Diabetes: A Position Statement of the American Diabetes Association, Diabetes Care, 39(11): 2065-2079, 2016. http://dx.doi.org/10.2337/dc16-1728

Use Exercise to Prevent Activity-Induced Lows

Willa D soccerYou may potentially be able to prevent, treat, or reverse impending hypoglycemia (low blood glucose) during exercise by some novel means (1). One mechanism is short sprints, while another is to alter the order in which you do different types of exercise.

Sprints: Doing a 10-second sprint either before or immediately after moderate exercise keeps blood glucose levels stable for at least two hours afterwards (2). Actually, this technique works anytime during exercise, but it doesn’t reduce the amount of carbohydrate needed to prevent hypoglycemia during the eight hours following such a sprint (3).

Sprinting will have a limited effect if you have high levels of insulin in your system or a blunted hormonal response. However, having been low beforehand doesn’t appear to diminish your body’s ability to respond to a short sprint by releasing enough glucose-raising hormones like adrenaline to raise blood glucose (4).

It’s also possible to keep your blood glucose higher during exercise by interspersing four-second sprints into an easier workout every two minutes or so (sort of like doing interval training) (5). These effects are due to a greater glucose release by your liver during exercise and less glucose uptake by muscles during exercise and recovery (6).

So, whenever you start to feel low during exercise, trying sprinting as hard as you can for 10 to 30 seconds to induce a greater release of glucose-raising hormones. This works best when you have only a limited amount of insulin circulating in your bloodstream and may not prevent hypoglycemia if you have a lot of injected or pumped insulin on board. When the hormonal effects wear off, though, be careful as you can develop hypoglycemia since sprinting uses up more of your muscle glycogen (stored carbs) that have to be replaced with blood glucose (3).

Exercise Order: Another strategy you can use for preventing exercise-induced lows is related to the order of the types of exercise you do (cardio and resistance training) (1). Blood glucose levels tend to fall more during moderate cardio training and less afterwards compared to resistance training, which causes less of a decline during and more overnight (7).

Doing both activities in one day can be done strategically. If you’re starting out with your blood glucose on the low side, do resistance training first, followed by cardio to keep your glucose higher throughout the first half of your workouts. If you’re starting out higher, begin with cardio training first (assuming it’s moderate and not intense) to lower your blood glucose levels and follow it up with resistance work, which keeps blood glucose stable (8).

Try these techniques today to stay on top of your lows and remain more active. Your body will thank you for it!

References:

  1. Yardley JE, Sigal RJ. Exercise strategies for hypoglycemia prevention in individuals with type 1 diabetes. Diabetes spectrum : a publication of the American Diabetes Association 2015;28:32-8.
  2. Bussau VA, Ferreira LD, Jones TW, Fournier PA. A 10-s sprint performed prior to moderate-intensity exercise prevents early post-exercise fall in glycaemia in individuals with type 1 diabetes. Diabetologia 2007;50:1815-8.
  3. Davey RJ, Bussau VA, Paramalingam N, et al. A 10-s sprint performed after moderate-intensity exercise neither increases nor decreases the glucose requirement to prevent late-onset hypoglycemia in individuals with type 1 diabetes. Diabetes care 2013;36:4163-5.
  4. Davey RJ, Paramalingam N, Retterath AJ, et al. Antecedent hypoglycaemia does not diminish the glycaemia-increasing effect and glucoregulatory responses of a 10 s sprint in people with type 1 diabetes. Diabetologia 2014;57:1111-8.
  5. Dube MC, Lavoie C, Weisnagel SJ. Glucose or Intermittent High-Intensity Exercise in Glargine/Glulisine Users with T1DM. Med Sci Sports Exerc 2013;45:3-7.
  6. Fahey AJ, Paramalingam N, Davey RJ, Davis EA, Jones TW, Fournier PA. The effect of a short sprint on postexercise whole-body glucose production and utilization rates in individuals with type 1 diabetes mellitus. The Journal of clinical endocrinology and metabolism 2012;97:4193-200.
  7. Yardley JE, Kenny GP, Perkins BA, et al. Resistance versus aerobic exercise: acute effects on glycemia in type 1 diabetes. Diabetes care 2013;36:537-42.
  8. Yardley JE, Kenny GP, Perkins BA, et al. Effects of performing resistance exercise before versus after aerobic exercise on glycemia in type 1 diabetes. Diabetes care 2012;35:669-75.

Should You Do CrossFit Training with Diabetes?

Allison Hirsh Caggia (T1D) brighterWith all the exercise training fads out there, it can be hard to navigate the landscape with diabetes. I am frequently asked about the latest training techniques or gym trends, so I want to specifically address a recent craze, CrossFit training, with regard to whether it’s appropriate and/or advisable for people with diabetes.

In brief, CrossFit training is a strength and conditioning program consisting mainly of a mix of aerobic exercise, gymnastics (body weight exercises), and Olympic weight lifting. Its programming is decentralized, but its general methodology is used by thousands of private affiliated gyms around the world. CrossFit, Inc., licenses the CrossFit name to gyms for an annual fee and certifies trainers, but the actual programs vary tremendously from site to site.

A concerned young man with type 1 diabetes contacted me to ask whether it’s safe for him to do CrossFit. Although he was already doing and benefiting from CrossFit training, he became concerned about it after reading a blog online by a Paleo diet advocate named Robb Wolf who, in an article about CrossFit training and type 1 diabetes, blogged that since intense training causes the liver to release excess glucose during training, people with type 1 diabetes “may be better served by mild to low intensity activities. Power Lifting, due to the low volume, might be a good option.” (This blogger also claimed that “We have seen instance of people REVERSING type 1 diabetes with a Paleo diet because they put their autoimmunity in remission.” That statement alone should make you question his credibility. If you really want to read it, please just don’t believe everything you read online, especially his blog: http://robbwolf.com/2009/08/05/type-1-diabetes-and-crossfit/#sthash.CIZdVMvp.dpu.)

My perspective is that, if you’re young and healthy and just happen to have diabetes, you should be able to engage in CrossFit training without worrying excessively about your blood glucose levels going up temporarily from doing it. To control your blood glucose, you simply have to approach it like any other intense workout, which can cause your blood glucose to go up even in people without diabetes. If you use insulin, you’ll just need to check your glucose frequently and adjust your insulin doses to make sure you have enough to stay in control both during and following your CrossFit (or other) workouts. As a side note, doing some easy cardio exercise after an intense workout can help lower your blood glucose naturally. Also, keep in mind that you’re more likely to have a bigger rise in the early AM compared to doing the same exact training later in the day (due to having more glucose-raising hormones and less insulin on board in the morning, pre-breakfast).

CrossFit does carry some risks, however. The risk of injury from some of its exercises outweighs their benefits when they are performed with poor form in timed workouts (although there are similar risks from doing other high-intensity programs incorrectly). One concern in particular is that CrossFit’s extensive online community enables anyone to follow the program without proper guidance, increasing the risk of improper form or technique that leads to getting injured. I have heard of at least one young man who caused significant damage to the cartilage in both of his knees doing such training inappropriately. When undertaken correctly, CrossFit is not inherently bad or ineffective, but beginning exercisers starting such a program may be encouraged to do too much and not be able to discern between training to failure and simply getting a good workout.

By way of example, a young woman who was a physical therapist and a regular CrossFit participant woke the morning after a particularly grueling session consisting of hundreds of reps of arm exercises and found she could not bend her elbows. She was diagnosed in the emergency room with rhabdomyolysis (“rhabdo” for short), a condition in which damaged muscles break down rapidly. This is not the first time CrossFit has been associated with rhabdo as the workouts can be particularly grueling and excessive, although any strenuous exercise can cause it. It’s worrisome because rhabdo can lead to kidney failure when excess breakdown products of damaged muscle cells (myoglobin) are released into your blood (see a video by the Mayo Clinic about exercise-associated rhabdo: https://www.youtube.com/watch?v=Hy0uEPo8-7w). Severe symptoms like muscle pain, vomiting, and confusion are symptoms of greater muscle damage and possible kidney failure. If you ever have severe muscle pain and dark colored urine, get medical attention immediately.

Should You Just Do Intense Exercise for Less Time?

Dave and Julie Joffe (crop)Everyone is confused about what types and amounts of training people with diabetes should be doing for optimal blood glucose control and health. When I last wrote about this topic, the latest exercise research older adults with type 2 diabetes enduring six sessions of high-intensity interval training (HIIT) was done on a cycle ergometer over two weeks (1). The training sessions, which were typical of some of the latest HIIT, 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.

So, that protocol 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–even though it did lower overall and after-meal blood glucose levels in those participants.

While interval training is routinely used by sports teams and athletes, is this type of training 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? It simply doesn’t burn that many calories. Actually, it doesn’t save that much time either: when you add in rest intervals and a warm-up and cool-down period, it still takes at least 25 minutes per session and 75 minutes per week.

Including training intervals of some sort does have benefits. The latest research done in adults with type 1 diabetes involved 90 minutes of moderate cycling on two occasions: one when they interspersed 10-second sprints every 10 minutes during otherwise continuous cycling without lowering insulin and one time without the sprints (2). Not surprisingly, their blood glucose levels stayed more stable and dropped less overall when they sprinted occasionally, even though their sprints were significantly shorter than typical HIIT training involves. Likely, their muscles used more stored carbs (glycogen) to fuel the sprints and less blood glucose—but then you have to worry about preventing later onset hypoglycemia for up to 24 or more hours afterwards.

Another point about HIIT is that it’s painful, and many people will not want to continue doing it over the long haul. Doing it with a coach or a personal trainer is one thing, but most people won’t 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.

A big drawback of doing low-volume HIT is simply that not everyone is going to be able to do it, and it may lead to a greater incidence of overuse injuries and other joint problems that will stop you from doing anything after a while. Only the healthiest people who volunteer to participate in those studies are actually able to be included, which gives us no information about how it will work for the rest of us. I use “the grandmother test”: if I can’t imagine my obese grandmother with type 2 diabetes doing it, it’s not likely to work for the majority of people with diabetes who are older and likely overweight.

 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 fitness and to use up more blood glucose and stored carbohydrate (glycogen) in muscles. 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 or wanting to be active over a lifetime. Just do any type of physical activity regularly, and your blood glucose levels and overall health are likely to benefit.

 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. 2011;111(6):1554-60. (http://www.ncbi.nlm.nih.gov/pubmed/21868679)

 (2) Bally L, Zueger T, Buehler T, Dokumaci AS, Speck C, Pasi N, Ciller C, Paganini D, Feller K, Loher H, Rosset R, Wilhelm M, Tappy L, Boesch C, and Stettler C. Metabolic and hormonal response to intermittent high-intensity and continuous moderate intensity exercise in individuals with type 1 diabetes: a randomised crossover study. Diabetologia 2016 (epub before print). (http://www.ncbi.nlm.nih.gov/pubmed/26739816)

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