Most people with Type 1 diabetes who exercise have experienced low blood sugars after exercise. These low blood sugars can become dangerously low within a couple of hours after exercise up to 24 – 36 hours later. An experienced athlete or exercise enthusiast taking insulin knows he or she has to make adjustments with food, insulin, or both. An interesting study was conducted at the University of Western Australia recently showing another way to potentially reduce the occurrence of low blood sugar within two hours of moderate-intensity exercise.
Before going into the study a few points of discussion are worth talking about to fully understand the study. When the body recognizes a stress it releases hormones such as adrenaline (also called epinephrine), growth hormone, glucagon, and cortisol. It does not matter whether it is a physical or mental stress but in this case we are talking about a physical stress which is exercise. These hormones signal the liver to produce and release glucose into the bloodstream causing an increase in blood sugar level. As with most things in diabetes management balance is the key. Too much hormonal activity may cause blood sugars to go too high and too little may not be enough to help offset a low blood sugar. A second point of discussion is one of the contributing factors to why we go low after exercise. We eat food to give us energy to exercise. Once the body burns the food eaten prior to exercise it uses a stored form of glucose (called glycogen) in the liver and muscles. After glycogen is depleted; if food is not eaten the body will get glucose from the blood which is a contributing factor that causes us to go low. This does not happen quickly but over a number of hours. For some people it may only be a couple of hours while others it may be 24 or even 36 hours later. There are also other contributing factors such as intensity, duration, and type of exercise. There is a twofold reason for eating carbs after exercise. One is to help prevent a low, but probably just as important is to restore the glycogen lost during exercise. This will not only help with decreasing the chance of a low blood sugar but will help with performance for the next exercise bout.
The more intense exercise is, the greater the secretion of glucose from the liver which is the basis of the study done in Australia. The level of stress hormones in the blood may be elevated for several hours after intense exercise causing the liver to continue the production of sugar. Below is a summary of the study published in Diabetes Care, 2006.
Short, Maximal Sprint Prevents Post exercise Hypoglycemia in Type 1's
A 10-second maximal sprint after moderate-intensity exercise reduces the risk of post-exercise hypoglycemia in young, otherwise healthy patients with type 1 diabetes.
Dr. Paul A. Fournier from University of Western Australia, Crawley, stated that, "It is our view that the effect of sprinting on reducing the risk of post-exercise hypoglycemia is probably not as marked in children and sedentary middle-age individuals with type 1 diabetes, in part, due to their reduced capacity to engage in a maximal sprint effort."
Dr. Fournier and colleagues investigated whether a short (10-second) maximal sprint could counter the continual decline in glycemia during recovery from moderate-intensity exercise in seven men, who were an average of 21 years old, with type 1 diabetes.
After 20 minutes of moderate-intensity exercise, the subjects experienced a rapid and significant decrease in blood glucose levels, the authors report.
However, a 10-second maximal sprint immediately following the moderate-intensity exercise stopped a further decline in blood glucose levels for the next 2 hours, the results indicate. In contrast, moderate-intensity exercise followed by a rest period led to a further decrease in blood glucose levels.
Increased epinephrine and norepinephrine levels returned to pre-exercise levels within 5 minutes after the 10-second sprint, the researchers note, whereas catecholamine levels remained elevated when exercise was followed by rest.
Growth hormone and cortisol levels increased when exercise was followed by a maximal sprint, report indicates, whereas increases were not seen when exercise was followed by rest.
Insulin levels showed similar patterns after sprint and after rest. "This study provided the first evidence that a short maximal sprint effort performed immediately after moderate-intensity exercise is preferable to only resting as a means to counter a further fall in glycemia after exercise, thus decreasing the risk of early post-exercise hypoglycemia in individuals with type 1 diabetes," the authors conclude.
"On this basis," the investigators write, "one might tentatively recommend that after exercise of moderate intensity, young individuals with complication-free type 1 diabetes consider performing a short 10-second sprint to counter a further fall in their blood glucose level...particularly if a source of dietary carbohydrate is not readily available."
"Although the use of a 10-second sprint constitutes a novel and simple approach to decrease the risk of post-exercise hypoglycemia that will revolutionize blood glucose management in type 1 diabetes," Dr. Fournier said, "it would be premature and irresponsible at this stage to advocate its widespread adoption, because much more research is required to identify the target population of type 1 diabetic patients likely to be responsive."
The study investigator Dr. Paul Fournier realizes this approach has its limitations. It was only tested in healthy young adults (average age of 21) so replicating this study and using other age groups such as children would help reinforce his conclusions. Ideally, food should be eaten within 15 minutes after completing activity to maximize the replenishment of glycogen stores. Perhaps the approach in this study can be used as a back up when food is not available after exercise.
Rick Philbin, MBA, M.Ed., ATC
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Last Updated: Friday September 07, 2012 11:14:48
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