Physical Activity

The Magic of Movement

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“The only exercise some people get is jumping to conclusions.”
–Fred Allen

If jumping to conclusions is your only form of physical activity, you are overlooking one of the top tools available to improve your diabetes control! Healthful eating, medicine if you need it, and blood glucose self-monitoring are important basics of diabetes management, but only physical activity provides a host of benefits for your quality of life, blood glucose control, and overall health. In addition to lower blood glucose readings and decreased body fat, regular exercisers report increased self-esteem, reduced stress, and enhanced clarity of thought. Routine physical activity also improves your self-efficacy, which is confidence in your ability to change and control your behavior.

Despite these and other potential benefits, more than 60% of American adults are not regularly active, and 25% of the adult population are not active at all. Take a moment to learn more about the magic of movement, then get ready, get set, and go! Make a commitment to improving your health by including more physical activity in your life.

The science behind the magic

Simply put, exercise lowers blood glucose. To perform physical activity, the muscles burn glucose for energy and absorb glucose from the blood during and after exercise to replenish their stores. However, most people with Type 2 diabetes have insulin resistance, in which muscle, fat, and liver cells do not respond normally to insulin. As a result, it takes more insulin than normal to admit glucose into the cells. Exercise, in addition to simply burning glucose, improves the body’s ability to use insulin. This improvement in insulin sensitivity may allow some people with Type 2 diabetes to reduce or even discontinue blood-glucose-lowering medicines with increased physical activity. In addition, for those with either Type 1 or Type 2 diabetes, resistance exercise builds muscle mass, which may continue to burn glucose even when a person is not actively exercising.

Regular physical activity increases a person’s aerobic fitness level, reducing his resting heart rate as the heart pumps more efficiently. Lower blood pressure, total cholesterol, LDL (“bad”) cholesterol, and triglyceride levels, as well as increased HDL (“good”) cholesterol levels, are additional benefits that are of special concern to those with diabetes because of their increased risk of heart disease. And if you are trying to lose a few pounds, consider this: Physical activity not only helps people lose weight, but it has been proven to help them keep weight off for months and even years.

It’s really not magic at all. Science supports the recommendation that regular physical activity is one of the most important things you can do to improve your diabetes control and sense of well-being.

Get ready…

If you’re making a commitment to physical activity, start your efforts off on the right foot by meeting with your doctor to discuss any limitations or restrictions you may have. Formal exercise testing prior to beginning a training program can be helpful in many ways, including identifying undiagnosed heart disease and determining your pulse and blood pressure responses to various levels of exercise intensity. In addition, screening for diabetes complications that may be worsened by certain exercises is essential. This evaluation is also valuable in designing an individualized exercise prescription and opening up a discussion about important factors to consider before beginning your program. If you are planning to begin a moderate- to high-intensity physical activity program, you may be a candidate for a graded exercise test (“stress test”) if you meet any of the criteria established by the American Diabetes Association (ADA). (For the ADA’s criteria, see “Risky Business?”)

Diabetes complications can affect your choice of physical activities, making some safer for you than others. For example, if you have retinopathy (diabetic eye disease) you may want to avoid activities that dramatically elevate blood pressure (such as power weight lifting), involve pounding or jarring (such as jogging or boxing), bring the head level with or lower than the heart, or are very strenuous, because of their potential to cause retinal detachment or a vitreous hemorrhage (in which blood leaks from vessels in the retina, blocking vision). Those with neuropathy (diabetic nerve disease) may have lost the protective sensation in their feet. They should limit weight-bearing exercise such as step aerobics or prolonged walking or jogging because repetitive exercise on insensitive feet can lead to ulcers and fractures. However, most exercises can be enjoyed by most individuals with diabetes. Low-impact activities such as swimming, chair exercises, or stationary cycling are good alternatives for those with complications.

When you consider an exercise program, don’t feel as though you’ll be required to run a marathon to improve your health and diabetes control. The Surgeon General’s Report on Physical Activity and Health (1996) states that significant health benefits can be obtained by including a moderate amount of physical activity (such as 30 minutes of brisk walking or raking leaves, 15 minutes of running, or 45 minutes of playing volleyball) on most if not all days of the week. A moderate amount of physical activity is equivalent to physical activity that uses approximately 150 calories of energy per day, or 1,000 calories per week. Greater health benefits can be achieved by increasing the amount (duration, frequency, or intensity) of physical activity.

If you’re not able to set aside at least 30 minutes at a time for physical activity, you’ll be happy to know that research has shown that cardiorespiratory fitness gains are similar when physical activity occurs in several short sessions (10 minutes at a time, for example) as when the same total amount and intensity of activity occurs in one longer session (30 minutes all at once). Think in terms of accumulating physical activity over the course of the day. Walking, gardening, and washing windows are as important to your fitness efforts as a formal exercise class. (For more about walking, see “Step It Up!”)

If you do choose to start a structured exercise program, plan to include proper warm-up and cool-down periods. A warm-up should consist of 5—10 minutes of aerobic activity, such as walking or cycling, at a low intensity, which gets your body ready for the more intense activity to follow. Gently stretch your muscles for another 5—10 minutes, then begin your chosen activity. Afterward, do a cool-down session that lasts 5–10 minutes and is similar in structure to your warm-up. Your goal is to return your heart rate to preexercise levels.

Get set…

The benefits of physical activity are immense, but you also should give consideration to staying safe while exercising with diabetes. Obtaining medical clearance if needed, and developing an appropriate exercise plan are important steps to safe fitness. In addition, consider the following issues:

Foot care. Properly fitted shoes are essential if you are participating in aerobic physical activity. The ADA recommends using shoes with cushioned midsoles (gel or air) as well as polyester or blend (cotton—polyester) socks to prevent blisters and keep the feet dry. Monitor your feet closely for blisters and other potential damage both before and after physical activity, particularly if you have neuropathy in your feet.

Medical ID. A diabetes identification bracelet or shoe tag should be clearly visible when you exercise.

Carbohydrate source. People who use insulin or certain diabetes drugs that cause the pancreas to increase insulin production are at risk for low blood glucose, or hypoglycemia, when they exercise. For this reason it is important to carry a source of carbohydrate to raise low blood glucose levels if necessary during and after physical activity. Most people are advised to treat themselves if their blood glucose falls below 70 mg/dl by consuming at least 15 grams of carbohydrate. These foods provide 15 grams of carbohydrate per serving: 3 glucose tablets, 1/2 cup fruit juice, 2 tablespoons raisins.

Because the major effect of physical activity is lower blood glucose levels, monitoring before, during, and after exercise is important. Be sure you are familiar with the symptoms of low blood glucose and the steps for treating it. It is possible to develop exercise-induced hypoglycemia several hours after the activity has ended because your muscles continue to take up glucose from the bloodstream, so be prepared to check your blood glucose level and have a source of carbohydrate available in the hours after exercise.

The effect of activity on your blood glucose level depends on many factors, including the time of day you exercise, the timing and dosage of your insulin or pills, when you last ate, your level of fitness, and the duration and intensity of your exercise session. You may need to eat additional carbohydrate before or during exercise if you plan to engage in vigorous or prolonged activity (lasting more than 45 minutes). In these situations, an intake of 15 to 30 grams of carbohydrate every 15 to 30 minutes should be enough to keep hypoglycemia from occurring. Each person’s reaction to exercise is different, though, so it is important to check your blood glucose level regularly during prolonged activity.

Hypoglycemia with physical activity is generally not as common in people with Type 2 diabetes as in those with Type 1, particularly if they don’t take blood-glucose-lowering medicines. These individuals probably won’t need extra food when participating in physical activity. Indeed, the extra calories can prevent a person with Type 2 diabetes from losing weight and reaching his blood glucose goals.

If a person’s blood glucose level is high before exercising, it may be dangerous to exercise. The ADA recommends that people with Type 1 diabetes avoid physical activity if fasting blood glucose levels before exercise are greater than 250 mg/dl and ketones are present in the blood or urine. They should also use caution if preexercise blood glucose levels are greater than 300 mg/dl and no ketones are present. Ketones are a sign that the body doesn’t have enough circulating insulin. When this is the case, the muscles don’t have access to enough glucose for the extra energy demands of exercise, causing the liver to produce more glucose and the body to break down fat stores for energy. If ketones – potentially toxic by-products of this process – build up in the bloodstream faster than the body is able to process them, a person is at risk for diabetic ketoacidosis, a serious condition that can lead to coma and even death.

People who have Type 2 diabetes, on the other hand, can often exercise safely with elevated blood glucose levels. In fact, since physical activity tends to lower blood glucose, a little exercise may be “just what the doctor ordered.” However, it is still prudent for people with Type 2 diabetes who begin exercise with high blood glucose to check their level after about 15 minutes of activity to see whether it is going up or down.


If you’ve carefully considered your exercise options and planned ahead for safety issues, it’s time to jump in and begin enjoying the benefits of physical activity. Start your exercise program gradually. Some soreness is common in the early stages, particularly if you have not been physically active in recent years. There are several ways to tell if you are overdoing physical activity while you are exercising. One is to do the “talk test.” You should be able to talk comfortably with someone while you are participating in an activity. If you are so short of breath that you can’t converse with your exercise buddy, you need to slow down to avoid becoming overtired or injured.

Another way to determine if you are exercising at an intensity that is appropriate for you is to think about how much effort you are putting into the activity. This method is called the Borg RPE (Rating of Perceived Exertion). Using this scale, you rate your level of effort from 0 (“feels like nothing at all”) to 10 (“very, very hard/maximal”). A Borg rating of 3 to 5 (“moderate” to “hard”) is probably the right spot for you to improve your health and fitness without endangering yourself. Anytime you experience pain, shortness of breath, dizziness, weakness, or other discomfort, stop exercising and direct your attention to resolving the problem.

And keep on going…

It’s easy enough to make well-intentioned New Year’s resolutions aimed at improving your physical fitness. The trick is to stay motivated to reap the rewards of a healthy lifestyle and better diabetes control. Making physical activity a regular part of your life means planning ahead. Set a specific fitness goal for yourself with very detailed and realistic terms. For example, your goal might be “to walk at lunchtime for 30 minutes three days per week.” Mark your walk days on your calendar so you won’t forget them, and give yourself a pat on the back for each week you reach your goal.

Inviting your friends and significant others to exercise with you can make your physical activity plan more enjoyable and easier to stick to. Even if they don’t have diabetes, this fact may convince them to join in: Published research has shown that lifestyle modification (weight loss and regular moderate physical activity) can reduce a person’s risk of developing Type 2 diabetes, delaying or even preventing the onset of the condition.

The benefits of physical activity are amazing. Take them to heart and get moving!

Originally Published July 18, 2006

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