by Dr. Sheri Colberg, Ph.D., FACSM
Given that fear of hypoglycemia during exercise is a known barrier to exercise participation, particularly for insulin users with diabetes, it is worthwhile to discuss some novel approaches to using exercise itself to manage blood glucose levels during activities. Based on some newer research, it may be possible for some diabetic exercisers 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 of different types of exercise.
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 8 hours following such a sprint (3). Sprinting will have a limited effect if exercisers have high levels of insulin in their system or a blunted hormonal response (such as from hypoglycemia-associated autonomic failure related to prior exercise or lows). However, having experienced hypoglycemia beforehand doesn’t appear to diminish the 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 blood glucose higher during exercise by interspersing 4-second sprints into an easier workout every two minutes or so (interval training of sorts) (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).
Thus, whenever people start developing hypoglycemia during exercise, one thing that they can try is sprinting as hard as they can for 10 to 30 seconds to induce a greater release of glucose-raising hormones. This works best when only a limited amount of insulin is circulating in the bloodstream and may not prevent hypoglycemia if someone has a lot of injected or pumped insulin on board.
When the hormonal effects wear off, though, everyone also needs to be aware that it’s possible to develop hypoglycemia for up to 24 or more hours afterwards since sprinting uses up more of muscle glycogen (stored carbs) that have to be replaced with blood glucose following activities (3). Those later-onset lows frequently occur overnight when hypoglycemia may be harder for many individuals to detect and treat quickly.
Another strategy people can use for preventing exercise-induced lows is related to the order of the types of exercise (i.e., cardio and resistance training) that they choose to do (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).
Including both activities in one day or during one workout can be done strategically. If starting out with blood glucose on the low side, individuals can do resistance training first, followed by cardio to keep blood glucose higher throughout the first half of the workout. If starting out higher, they can begin with cardio training first (assuming it’s moderate and not intense) to lower blood glucose levels and follow it up with resistance work, which keeps blood glucose stable (8).
In conclusion, while neither of these approaches is foolproof for managing activity-related lows, it is good to know that exercise doesn’t just cause hypoglycemia, but that it can also be used to prevent it in some cases—when used strategically. The body’s release of glucose-raising hormones is elicited exponentially, meaning that more intense, short burst of activity will have the greatest impact on raising blood glucose.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
As a leading expert on diabetes and exercise, I recently put my extensive knowledge to use in founding a new information web site called Diabetes Motion (www.diabetesmotion.com), the mission of which is to provide practical guidance about blood glucose management to anyone who wants or needs to be active with diabetes as an added variable. Please visit that site and my own (www.shericolberg.com) for more useful information about being active with diabetes.
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