EXERCISING SAFELY WITH DIABETES

by Meg Thompson, MS, RD, LD, CDE

Ms. Thompson, a Registered Dietitian and Exercise Specialist, gave the following as a keynote address at the 1998 annual conference of the Diabetes Action Network of the National Federation of the Blind. The conference took place on July 5, 1998, at the annual convention of the National Federation of the Blind, in Dallas, Texas.

When I first became interested in diabetes, I was working on my Masters Degree in Exercise Physiology and Sports Nutrition. I was also working in a patient population with diabetes, and I really started to notice that exercise, on a regular basis, as all the diabetes associations recommended, just wasn't getting done.

I did my thesis on "reasons why people do not exercise," and, as I guess we would all expect, the number one reason was "time." People just do not have time to exercise, we are all so busy all the time. There were also some other concerns: Having low blood sugars while they exercise or after they exercise, not knowing what to do to exercise, or how to get started...

First of all, I wanted to go over some of the benefits of exercise for people with diabetes. You know them: Lower blood sugar, better mental alertness, good for the heart, circulatory system, and muscles...

Some find it effective for weight control, but others, starting a new exercise program, actually gain weight. This is not a failure; you are losing fat weight—reducing fat cell size—and increasing amount and density of your muscle tissue. Muscle tissue weighs more than fat. A blob of Crisco, in a pan of water, floats right to the top. Put a piece of chicken breast, which is a muscle, into the water, and it sinks to the bottom, even when the two weigh exactly the same.

I try to get people to focus on how their clothes feel, and how they fit, as opposed to what the actual number on the scale says. Think of the benefits you get on your cardiovascular system, and on your blood pressure, mental alertness, physical fitness... These are benefits anyone who exercises is getting, even if they're not seeing a big decrease at the scale.

Unfortunately, in America weight has become the overriding issue. There are a lot of other reasons to exercise, besides just weight! The primary reason for someone with diabetes is improvement in blood glucose control. For the person with type 1, this means you hopefully see a reduced need for insulin. For the type 2, exercise may bring a similar reduction of medication, and in some cases some people can to manage with appropriate meal planning, "diet and exercise," without any medication.

Exercise, like the oral medications glucophage and rezulin, makes your body more sensitive to the insulin you either produce or inject. It reduces insulin resistance. Because of this effect, exercise can be a non-pill way of improving your blood glucose control.

Other benefits are the cardiovascular benefits. Even if you do not lose weight, exercise can result in drastic improvements in blood pressure.

There are also benefits in terms of blood lipid levels, or your cholesterol and triglyceride levels. Exercise is really the only way to increase your HDL cholesterol. Not only is it desirable to get these numbers up, the heart healthy standpoint, are very important, but also low HDL levels have been related to an increased risk of retinopathy.

Exercise can help to lower triglycerides and also lower LDL cholesterol (the bad one you want to keep down), and those are two things that will help to reduce the risk of heart disease.

If you lose weight, and you do it without exercise, that means you are probably losing a lot of muscle tissue. We do not want you to lose muscle tissue, nobody wants to lose muscle tissue! But particularly with diabetes you do not want to lose muscle tissue, because muscle is what burns up blood sugar. Anytime you move a muscle, it takes blood glucose, or the storage form of glucose, which is glycogen, to do it, to give that muscle energy. So you want to maintain your muscle mass, or increase it if you can, and one way to do that is with exercise.

Another benefit of exercise for everyone, but especially for women, is reducing the risk of osteoporosis. Men can develop osteoporosis too! Women should continue to exercise, especially weight-bearing exercise, such as walking... The hips and spine are the areas of your body most prone to osteoporosis. There are a lot of things that can be done in the area of physical exercise to reduce the risk of this condition.

Exercising in extreme heat or cold can bring problems in controlling your blood sugar. This is because your body is expending more energy than it would in more moderate conditions in order to maintain your body's normal temperature. Therefore, you burn up more energy. If it is extremely hot or cold, take your exercise indoors.

Dehydration is a big risk with exercise. You can get dehydrated even in the swimming pool, so make sure you keep those fluids going! I try to get people to drink one to two cups of water before they begin exercising, and then another half cup or so every 20 minutes.

I always encourage people to check their feet on a regular basis for blisters, cracks, sore spots, red spots, anything that could cause a problem later on. Wearing good shoes is very important. They do not have to be the most expensive shoes in the world, just shoes that fit well and do not cause blisters. If you are going to be doing something in the swimming pool, I encourage you to wear aqua socks. The bottom of the pool can be pretty rough, and this could be a real good place to get a break in your skin and get an infection. So always try to wear aqua socks (or other "swim shoes") in the pool.

If you are exercising away from home, be sure to tell someone where you are going and how long you expect to be gone. Also carry "medical ID," bracelet, dogtags, or wallet card identifying that you have diabetes. If you cannot not speak for yourself, this will be a starting point for those caring for you. Always carry some form of fast acting glucose. I think it is really easy to carry the glucose tablets, and I recommend those over hard candy. This is because for any of this to do any good, it has to get into your system. The glucose tablets are easy to chew up, and are so intensely sweet so you are less likely to use them up as a snack (they're for emergencies!). Yet if your blood sugars are dropping, they are going to taste pretty good.

Another thing I want you to keep in mind is that for most of us, when we exercise, our hearts beat a little faster, and we begin sweating. Yet for some people these are also the first symptoms of hypoglycemia. If this is the case for you, you can not depend on sweating and rapid heart beats to tell you that your blood sugars are dropping because you are likely to have some of that anyway from the exercise.

There are three kinds of exercise. One is aerobic activity. This is the form of exercise with the most benefits the population in general is looking for. Most of us are interested in the cardiovascular benefits, in this group we're interested in blood sugar benefits, and some of us are able to get some changes in body composition with exercise. Blood pressure and cholesterol also respond to aerobic exercise.

Aerobic Activity does not mean going to a gym and bouncing around! It just means that you are doing something at a pace where you are able to take in enough oxygen to keep going.

Anaerobic activity means without oxygen, and that happens when you are working so hard that your body's need for oxygen outstrips oxygen intake. You can't keep this up for very long. This type of activity could occur in a quick-paced swimming competition, weight lifting, racquetball, golf... These are good physical activities, they are not particularly aerobic activity. Aerobic activity includes things like riding a bike, swimming, walking in a swimming pool(which is an excellent activity for those limited in the water), ski machines, or a combination of the ski machine and the step machine.

Another form of exercise is strength activity. Strength activity includes weight lifting, or any exercise type that works against your body's resistance. If you have problems with retinopathy, especially if it is proliferative, be very careful here. When people lift weights, they tend to hold their breath as they exert against the weight. When you do that, it raises your blood pressure. For someone with retinopathy, that can be very dangerous. So if you are interested in doing any kind of strength training, I would strongly encourage you to have eye exams, see a retinologist (an ophthalmologist who specializes in retina care), and be sure that strength training is safe for you to do. You do not want to cause any further damage with the weight lifting, and if you do decide to pursue some kind of strength training, you will also want to use very low weight and lots of repetition. By doing this you reduce the risk of elevating your blood pressure, and causing any of the negative effects that can bring.

Flexibility. Everyone needs to be flexible. It doesn't matter how healthy you are, if you do not have good range of motion in your muscles, you run a risk of getting hurt. You probably heard about someone, and all they did was reach across the counter and pick up a coffee cup, and they "pulled out their back." This occurs because of a lack of flexibility. If you can start doing some gentle stretching exercises (you can do them almost anywhere), they will help you to increase or maintain your flexibility and reduce your risk of injury. Here again a warning about holding your breath. A lot of times when people are stretching, they hold their breath, thinking that they will be able to better complete the stretch. However, if they would exhale while stretching that would give them more range of motion.

How do you get started exercising and not get frustrated? Anybody who has ever exercised has probably run up against this. I have been exercising since I was a little kid, and my dad was always an exerciser. As soon as I was old enough, he started taking me with him to exercise. I can remember trying to keep up with my dad, who had been exercising for years, and how frustrating, how sore, and how unpleasant that was. You are not trying to compete with anyone, or keep up with them. If you have not been exercising, and you are interested in starting to exercise, you want to start with what you can do. If walking to the mailbox is exercise for you, and that is more than you have ever done before, that is great! It is a start.

The recommendation that most people hear is from the American Heart Association: 20 minutes a day, three times a week. If you have never exercised, that is too much to start with. You might start out with 2-3 minutes. When you are comfortable with 2-3 minutes, go 3-4. Eventually you will get to were you can do 20 minutes. Or, you might start with everyday doing five minutes. Then, as you increase, maybe do every other day for 10 minutes and the days in between do five minutes. You need to progress very gradually.

It is important that you listen to your body—if something hurts, then don't do it. The old saying, "no pain, no gain," is not true. If you are experiencing pain, you are doing too much. Exercise is not suppose to hurt, and stretching is not suppose to hurt—try to keep that in mind, and as you gradually progress you will see more and more benefits.

This is a time when you might see your blood sugars go up with exercise instead of going down. When you first start to exercise, if you are doing just short bouts of exercise, short sessions, you might see your blood sugars go up right after you exercise. That is because the liver kicked in; it's pumping out blood sugar and the insulin has not had time to pull it back down, that's ok. As you go along, as you increase your duration and your frequency then you will start to see the benefits of exercise on a more regular basis. I can not emphasize enough the importance of that very gradual progression.

Also, an exercise program needs to include a warm-up and a cool-down, that is another reason why people get sore. The cool down will help you prevent from getting sore. The warm-up gradually gets the muscles going, gradually gets the blood flowing to those muscles, increase your breathing, increase your heart rate, so that when you are ready to exercise your body is ready. The cool-down will be the exact opposite.

You are only going to get lactic acid buildup with exercise if you are exercising anaerobically, which means you are working too fast and too hard for your breathing and oxygen intake. If you are doing something, an endurance activity (Nordic track), if you are doing it at pace that you can maintain a conversation and you are able to breathe (not gasping), then you should not be having a build-up of lactic acid in your muscles. Lactic acid build-up is a sign that the carbohydrate or the glucose is not being burned for fuel.

If you do get lactic acid buildup, then the best ways to dissipate that will be stretching and fluids.

What time of day is best? As far as I am concerned, the time of day that someone exercises is the time that works for them. Some people prefer to exercise at the time of day they know that their blood sugars will be the highest, and for many, that is first thing in the morning. Another good time, for a lot of people, is about a hour and a half to two hours after a meal.

For someone who is using insulin, it's a little more complicated, as you want to be sure that you don't exercise the muscle underneath your injection site too soon. If you are injecting insulin you may want to wait 45 minutes before exercising that area (if you are injecting NPH, you want to give it 1 � hours before you exercise). With Humalog insulin (much faster-acting than regular), it is in and out pretty quickly and it is not a problem with exercise.

If you are injecting insulin, and you exercise at a consistent time of day, you will find that you will probably have to adjust the amount of insulin that is active at that time of day. Other than that, the time of day for exercise is purely a personal preference.

Most of the pills now do not have a peak time. Generally with the pills we do not see the abrupt onset of low blood sugars that we do with insulin.

What about exercise equipment? A lot of stores offer used exercise equipment. Exercise equipment is not inexpensive, but is expensive when you buy it and do not use it. I am a little leery about buying out of the newspaper, because you really don't know what you are getting, there are no guarantees.

I would recommend that when buying some electronic exercise equipment, anything motorized (like a treadmill), that is has an automatic stop switch. If you start having trouble, you need to be able to stop the machine without bodily harm to yourself.

Note that exercise does increase the risk of hypoglycemia for both type 1 and type 2's on medication. As you exercise, you burn up blood sugars. But the stored form of glucose, glycogen, also is burned up during exercise. When you finish exercising, your body must "reload" its stored glycogen. So for a period of time after you exercise, you can still have your blood sugars drop. Depending on the activity level, this "refueling" process can go on for 24 to 48 hours, and during that time, you are at increased risk. It is not uncommon at all for a type 1 child who goes out and plays soccer in the evening, and does not eat enough of a snack when he comes home, to experience hypoglycemia the next morning, or even into later that day. So that is something that you have to protect yourself against.

I would advise you to check your blood sugars before you start to exercise. Depending then on how long you are going to exercise and how strenuous your regular exercise will be, you will probably need to adjust your food intake. One of the things we try to work with people on, if they are having low blood sugars on a regular basis while they exercise (or as a result of their exercise program), is the possibility of reducing their medication. We would rather see the medication be reduced than the food intake increased, because if you are just eating in order to prevent low blood sugar, those are extra calories most of us do not need. Recognizing that regular exercise can cut the need for medications, adjustment may be made, if your health care team approves, to reduce your medication and prevent low blood sugars.

Checking your blood sugars after you exercise is important. You want to see how much your blood sugar dropped. Let's say your blood sugar was at 150 before you exercised, and when you finished your blood sugar was at 90 -- your blood sugars dropped 60 points. So the next time you go to exercise, and your blood sugars were only 110 at the start (and you now know that on average your sugars drop 60 points during exercise), you know you'll need to eat quite a bit before you exercise, or else you'll finish down in the danger zone! This is important! Exercising with hypoglycemia is not only uncomfortable, it is dangerous.

Another reason to monitor before you start your "workout" (especially if you are type 1), is that sometimes, if you start exercising with blood sugars are in the 240 to 250 range, and you have ketones, then the risk for your blood sugars to go up, not down, while you exercise is great. Every once in a while we will see someone come into our emergency room, in DKA, who was out exercising and maybe did not check their blood sugar levels beforehand, or did not even know they had diabetes.

When you start to exercise, that is a stress on the body (depending on how you look at it, it is either positive or negative). Our body's stress response is to put out blood sugar. This is to prepare us for that fight or flight. The liver kicks in and starts pumping out the blood sugar, and if there is not enough insulin there to begin with (and that is what is indicated by your high blood sugars), when your liver starts pumping out more blood sugar there is not going to be any more insulin coming in to cover it either. The cells are not getting enough nutrition, they are hungry because there is not enough insulin to deliver their sugar, and they send the message to the liver, "we need more sugar!, we need more sugar!" The liver obeys, and more sugar comes out into the blood—where it stays, because there isn't the insulin to process it.

In the meantime, because your body is not getting enough energy, it is trying to burn its stored fat. Fat metabolized in this manner produces residues called ketones. Ketones (a normal product of exercise or fasting) are very acidic, but are normally excreted through the kidneys. However, the combination of ketone production and sustained high blood glucose can lead to a dangerous acidic environment in the bloodstream; DKA, Diabetic Ketoacidosis.

So there is yet another reason to check your blood sugar levels before exercising. We also encourage you to check for ketones if you are in the 240 to 250 range or higher. Another time that we encourage you to delay or postpone exercise is if you check your blood glucose and it is 300 or above, fasting. That lets you know that something is not right. If you have not had anything to eat since the night before and your blood sugars are already 300 early in the morning, it may or may not be insulin. It may be that you are getting ready to be sick. It would be a good idea to promptly find out the reason why your levels are so high -- it is not a good idea to exercise if you are sick or are having insulin difficulties.

But later in the day, if you find your levels way up, it may be because you may have eaten more than you planned that day. If you know it is food-related, and you do not have ketones present, then exercise will probably help bring those levels down. One of the things I encourage people to do, say after a Thanksgiving or Christmas meal, is to go out for a walk or bike ride to burn some of those extra carbohydrates.

One of the things we always stress (before we start working on exercise with anyone in our program, we insist on) is having a medical clearance from their physician. We do a pretty detailed health report in our program, but still the physician is going to have the bigger picture. The physician will know if there are underlying foot problems, or if there are some problems with retinopathy that the person has not told us. These problems need to be addressed before that person begins exercising.

We use the American Diabetes Association's blood glucose ranges in our program. They consider 80 to 120mg/dL to be "normal" (though that does not mean that will be normal for everyone!). But you can certainly see that 260 to 270mg/dL is definitely above normal, putting you at risk for complications.