4 Ways to Control Blood Sugar With Exercise: Part 1
Learn four ways to control your blood sugar, get rid of stubborn carbohydrate related body fat and reduce your risk of diabetes with exercise.
In last week’s episode, I mentioned that one strategy I use to avoid “getting fat” or experiencing big spikes in blood sugar from a meal is to do some basic strength training with a dumbbell prior to eating, which can activate specific sugar transporters responsible for taking up carbohydrate into muscle tissue.
This is actually a very important topic since not only are type 2 diabetes rates rising, both in the United States and globally, but so are a host of other chronic disease and weight issues directly related to high blood sugar. Characterized by insulin resistance and chronic high blood sugar levels (hyperglycemia), type 2 diabetes can lead to both neural and metabolic dysfunction, and is also a significant risk factor for cardiovascular disease.
When blood sugar is chronically elevated, the insulin released by the pancreas becomes progressively less effective in bringing those blood sugar levels down, and ultimately, pancreatic tissues begin to suffer damage (although some evidence shows this pancreatic damage can be reversed with specific lifestyle and food strategies). Although blood sugar can slightly rise in response to factors such as stress, hard exercise, or long periods of sedentary time, blood sugar typically rises most significantly after a meal, and studies show that these post-meal or “post-prandial” hyperglycemic spikes are the most likely to lead to vascular complications, even when compared to elevated fasting glucose levels.
When it comes to controlling high blood sugar, your body has two choices: get rid of the blood sugar as potential energy via uptake into muscles, or store the blood sugar in fat tissue. So in this two-part article, you’re going to get four ways to control your blood sugar without it simply getting partitioned into fat tissue, you’re going to learn how to get rid of stubborn carbohydrate related body fat, and even reduce your risk of diabetes based on the latest medical research on exercise and blood sugar. I should begin by clarifying the fact that I am not a physician and this is not to be interpreted as medical advice. Please talk to a licensed medical professional about any chronic disease or health conditions related to high blood sugar!
How Sugar Gets Into Muscles
Before discovering why certain movements and exercise strategies can lower or stabilize your blood sugar, it’s important to understand how sugar gets transported into muscle in the first place (you can dig into the science in this research article).
The entry of glucose into muscle cells is achieved primarily via what is called a “carrier-mediated system,” which consists of small protein transport molecules. One of these transport molecules is “GLUT-1” and is normally found in the sarcolemmal membrane (a sheath that surrounds your muscle fibers). It is also thought to be involved in glucose transport under basic resting, non-active conditions.
When the hormone insulin gets released by your pancreas, which is something that can happen after a large meal of protein or carbohydrates, glucose transport can be accelerated even more because insulin upregulates the activity and the number of yet another sugar transporter called “GLUT-4”, which, just like GLUT-1, is found in skeletal muscle. It’s also found in cardiac muscle and in adipose tissue, and helps GLUT-1 transporters get even more sugar and storage carbohydrate into these areas. So think of it this way: insulin causes fat cells and muscle cells to soak up energy, and if your muscle cells are already “full,” which is often the case without the strategies you’re about to learn in this article, then most of the energy winds up getting converted and driven into fat cells.
But here’s the amazing thing: exercise can upregulate GLUT-4 transporters just like insulin can, without the actual release of insulin from the pancreas. This means fewer chronic disease risks related to constant surges of insulin, and a higher likelihood that carbohydrate and protein energy from food gets partitioned into skeletal muscle and cardiac muscle rather than into adipose tissue. Exercise can even increase not just the activity, but also the number of GLUT-4 transporters you have available! Of course, as you probably already know, physical activity can do much more than just play around with your sugar transporters, and can also mobilize fatty acids from your adipose tissue to be used as energy, increase your sensitivity to insulin when it does get released, and cause a host of other extremely helpful metabolic adaptations that make it one of the most powerful “drugs” on the face of the planet.
So, let’s look at for highly effective ways to maximize these blood-sugar controlling benefits of exercise:
Blood Sugar Control Strategy #1: Strength Train
Before diving into strength training, it’s important to understand the concept of “glucose threshold”. What the glucose threshold is is the point at which sugar output and uptake are in balance: if you are above the threshold, then glucose levels rise and you have high blood sugar, and if you are below the threshold, your blood sugar levels fall or stay the same. You can read more about glucose threshold and blood sugar levels in this study.
Research has found that when you strength train, the ability to drive glucose into muscle tissue from strength training occurs, and thus your ability to cause a decrease in your glucose threshold, can occur when you lift weights that are at least 30% of your single repetition maximum weight (1RM). This is surprisingly not that heavy or difficult and means you can control blood sugar and upregulate sugar transporters with even lighter body weight exercises.
Let’s take a closer look at this study. In it, test subjects (both diabetic and non-diabetic overweight middle-aged men with previous resistance exercise experience) were assigned to either a low or a moderate intensity protocol. Both protocols consisted of a weight training circuit of 3 sets of 30 repetitions of six basic weight training exercises that you can find at most gyms: leg extension, bench press, leg press, lat pull down, leg curl, and seated row. Subjects recovered for 15-20 seconds between exercises, and for a full two minutes between circuits. Weights were set at 23% of one repetition maximum (1RM) for the low intensity group, and 43% of 1 RM for the moderate intensity group. Blood sugar and rating of perceived exertion (RPE) were measured both between sets and at 15-minute intervals during a two-hour post-exercise resting period. Subjects also ate a 285-calorie breakfast two hours before the test.
Blood sugar levels in the non-diabetic subjects fell initially during exercise, then rose after exercise as the body released some sugar into the bloodstream to support the exercise (a process known as glycogenolysis), then leveled off again. No surprises there. In subjects with type 2 diabetes, both the low and moderate intensity circuits lowered blood glucose, but surprisingly, the low intensity circuit produced lower glucose levels, along with a lower rating of perceived exertion and less metabolic stress. This finding should be particularly relevant to overweight or untrained individuals who are just beginning a blood sugar management program, because it means that even a single session of low intensity resistance exercise at a relatively easy weight offers significant benefits for blood sugar control.
Now, before leaving the topic of strength training for blood sugar control, it is important to understand that the heavier and more intense your strength training, the more rapidly you will deplete muscle and liver glycogen levels, the higher your post-exercise metabolic rate will be, and the greater your amount of blood sugar control will be, so you eventually should progress to workouts such as a heavy 5×5 protocol or any of the other strength training strategies I describe here. But it’s also important to realize that even light weight training will suffice for basic blood sugar control.
Blood Sugar Control Strategy #2: Pre-Breakfast Fasted Cardio
A study published in The Journal of Physiology suggests a second, potent strategy for controlling blood sugar, especially in response to a meal: exercise before breakfast, particularly in a fasted state.
In this study, researchers in Belgium recruited 28 healthy, active young men and began stuffing them what would be considered a pretty poor diet comprised of 50 percent processed, unhealthy fat (we’re not talking extra virgin olive oil, but more like soy and lard) and 30 percent more calories than the men had been consuming prior to the study. A portion of the men (the control group) did not exercise during the experiment, and rest of the subjects were assigned to one of two exercise groups, working out four times a week in the mornings by running and cycling at a hard intensity for 60-90 minutes.
Now, here’s the kicker: two of the groups—the control group and just one of the exercising groups—were fed a huge, carbohydrate-rich breakfast. In the case of the fed exercising group, this meal occurred before exercising and then they continued to ingest carbohydrates, in the form a sports drink, during their workouts. But the second group worked out without eating and drank only water during the training. The researchers did, however, made up for the abstinence of calories in this second group by matching their energy intake of the first group with a big breakfast later that morning after training, exactly comparable in calories to the other group’s big pre-exercise and during-exercise portions.
The experiment lasted for a total of six weeks. At the end, the nonexercising group had, not surprisingly, packed on an average of more than six pounds of fat. Furthermore, they also developed insulin resistance, meaning their muscles were no longer responding to insulin and weren’t pulling sugar out of the bloodstream efficiently, resulting in the storage of extra fat in adipose tissue and within muscle.
And the men who ate breakfast before exercising gained weight, too, although only about half as much as the control group. Surprisingly, just like the sedentary eating group, they also become more insulin-resistant and were storing away a greater amount of fat.
You’re probably anticipating what comes next. Only the group that exercised before breakfast gained nearly no weight and showed zero signs of insulin resistance. In addition, their metabolic rate changed in such a way that they also burned the fat they were taking in far more efficiently (a higher rate of fat oxidation). The study’s authors concluded that “that exercise training in the fasted state is more effective than exercise in the carbohydrate-fed state to stimulate glucose tolerance despite a hypercaloric high-fat diet.”
And what was one significant characteristic of that pre-breakfast exercise group? You guessed it: increased levels of the muscle protein GLUT-4, which, as you may recall, is responsible for insulin-stimulated glucose transport in muscle and plays a pivotal role in regulation of insulin sensitivity.
Summary
One last note here: should a 60-90 minute pre-breakfast exercise session seem daunting to you, you should be aware of another study review entitled “The impact of brief high-intensity exercise on blood glucose levels.” In this study, researchers investigated the effect on insulin sensitivity and blood glucose from a relatively small amount of high intensity exercise – just 7.5 to 20 minutes per week. They found that two weeks of sprint interval training increased insulin sensitivity for up to three days after the exercise session! Furthermore, they found that twelve weeks of near maximal intensity interval running (for a total exercise time of 40 minutes per week) improved blood glucose to a similar extent as running at a lower, aerobic intensity for 150 minutes per week. In type 2 diabetics, they found that a single high intensity exercise session improved postprandial blood glucose for 24 hours, while a 2-week high intensity exercise program reduced average blood glucose by 13% at 48 to 72 hours after exercise and also increased GLUT4 transport protein expression by 369%! The researchers concluded that “very brief high intensity exercise (HIE) improves blood glucose (BG) 1 to 3 days post exercise in both diabetics and non-diabetics. HIE is unlikely to cause hypoglycemia during and immediately after exercise.”
So there you have it. When it comes to blood sugar control, there’s no need to hop on the treadmill for a full, epic hour and half. You can simply do brief, high intensity exercise, and here’s a full article I wrote that reviews some of the best, most up-to-date research on what kind of exercise counts as high intensity.
That’s all for now, but next week, we’re going to dive into two more potent strategies to control blood sugar with exercise. In the meantime, if you have more questions about how to control blood sugar with exercise? Join the conversation at Facebook.com/getfitguy.
You May Also Like…
About the Author
Ben Greenfield received bachelor’s and master’s degrees from University of Idaho in sports science and exercise physiology; personal training and strength and conditioning certifications from the National Strength and Conditioning Association (NSCA); a sports nutrition certification from the International Society of Sports Nutrition (ISSN), an advanced bicycle fitting certification from Serotta. He has over 11 years’ experience in coaching professional, collegiate, and recreational athletes from all sports, and as helped hundreds of clients achieve weight loss and fitness success.
