Strenuous, prolonged exercise is the next level of our treatment plan after diet, and should ideally accompany any weight-loss program or treatment for insulin resistance (as in type 2 diabetes). Before we go into our specific recommendations for exercise, all of which should be approved by your physician prior to putting them into practice, it’s important that you understand the benefits exercise can bring.
While many people may begin exercising out of a sense of responsibility—the way children eat vegetables they don’t like—the main reason they keep exercising is that it feels good. Whether it’s the intense competition of a fast and furious basketball game, or cycling alone in the countryside, exercise brings many rewards—physical, psychological, and social.
The genes of all our cells contain at their tail ends a sequence of identical groups of nucleic acids called telomeres. Every time a cell replicates, it loses a telomere. After the last telomere is gone, that cell line dies off. Thus the lifetime of every cell and, in turn, of the whole person, depends upon the lengths of telomere chains. Intense exercise generates new telomeres and thereby prolongs life. This discovery is very new and obviously very important.
People who aren’t diabetic and exercise strenuously and regularly tend to live longer, are healthier, look healthier and younger, and have lower rates of debilitating and incapacitating illnesses such as osteoporosis, heart disease, high blood pressure, memory loss as a result of aging—and the list goes on. Overall, people who exercise regularly are better equipped to carry on day-to-day activities as they age.
Many type 1 diabetics have been ill for so long with the debilitating effects of roller-coaster blood sugars that they are often depressed about their physical health. Numerous studies have established a link between good health and a positive mental attitude. If you’re a type 1 diabetic, as I am, strenuous exercise will not improve your blood sugar control as it will for type 2s (which we’ll discuss shortly), but it can have a profound effect on your self-image. It’s possible, if you keep your blood sugars normal and exercise regularly and strenuously, to be in better health than your nondiabetic friends. Also, it’s been my experience that type 1 diabetics who engage in a regular exercise program tend to take better care of their blood sugars and diet.
Think of exercise as money in the bank—every 30 minutes you put into keeping in shape today will not only leave you better off right now, it will pay continuing dividends in the future. If going up the stairs yesterday left you huffing and puffing, in a while you’ll bound up the steps. Your strength will likely make you feel younger and possibly more confident. There is evidence that exercise actually does make you look younger; even the skin of those who exercise regularly tends not to age as rapidly.
After working out for a few months, you’ll look better, and people will mention it. With this kind of encouragement, you may be more likely to stick to other aspects of our regimen.
Although most of us who engage in bodybuilding exercise can experience increases in muscle mass and strength, the degree to which we respond is in part genetically determined. With very similar exercise regimens, some people will show dramatic increases in both muscle mass and strength; others will show neither. Most of us lie between these two extremes. There are even people who gain strength but not large muscles, and others who build large muscles without getting much stronger. Unlike men, women who engage in strength training are much more likely to develop muscular definition than bulk. They don’t become “muscle-bound.” If you don’t develop big muscles or great strength, you will still enjoy the other benefits from the weight training described here.
It has long been known that strenuous exercise raises the levels of serum HDL (good cholesterol) and lowers triglycerides in the bloodstream. Recent studies suggest that bodybuilding exercise (anaerobic rather than aerobic exercise) also lowers serum levels of LDL (bad cholesterol). There is even evidence that atherosclerosis (hardening of the arteries) may be reversible in some individuals. I’m nearly eighty years old, I exercise strenuously on a daily basis, I don’t eat fruit, I’ve had type 1 diabetes for sixty-five years, and I have eggs for breakfast every day. Where’s my cholesterol? It’s in a very healthy range that nondiabetics one-third my age rarely attain (see here). Part of that is due to my low-carbohydrate diet, but part of it is due to my daily exercise program.
Frequent strenuous exercise has been shown to reduce significantly the likelihood of heart attack, stroke, and blockage of blood vessels by lowering serum fibrinogen levels. Long-term strenuous exercise lowers resting heart rate and blood pressure, further reducing the risk of heart attack and stroke.
Weight-bearing, resistance, and impact exercise slow the loss of bone mineral associated with aging. Ever hear the slogan “Use it or lose it”? In a very real sense, if we don’t use our bones, we lose them.
Although exercise does make weight control easier, it does not directly—at least not as much as we may wish—“burn fat.” Unless you work out at very strenuous levels for several hours each day, exercise isn’t going to have a significant direct effect upon your body fat. The effects of exercise are broader and more indirect. One of the great benefits is that many people find that when they exercise, they have less desire to overeat and are more likely to crave proteins than carbohydrates. The reasons for this are probably related to the release in the brain of neurotransmitters such as endorphins. (As noted in the previous chapter, endorphins are “endogenous opiates” manufactured in the brain. They can elevate mood, reduce pain, and reduce carbohydrate craving. Brain levels of endorphins are reduced in poorly controlled diabetes.)* It might be said that in the same way that obesity leads to further obesity, fitness leads to further fitness.
Even though your fat won’t “melt away,” exercise, particularly if you’re a type 2 diabetic, is still of value in a weight-reduction program because muscle building reduces insulin resistance. Insulin resistance, remember, is linked to your ratio of abdominal fat to lean body mass. The higher your ratio of abdominal fat to muscle mass, the more insulin-resistant you’re likely to be. As you increase your muscle mass, your insulin needs will be reduced—and having less insulin present in your bloodstream will reduce the amount of fat you pack away. If you remember my old friend Howie from Chapter 12, his insulin resistance dropped dramatically when he lost 100 pounds and radically changed his ratio of abdominal fat to lean body mass.
Long-term, regular, strenuous exercise also reduces insulin resistance independently of its effect upon muscle mass. This makes you more sensitive to your own and injected insulin. As a result, your insulin gradually becomes more effective at lowering blood sugar. If you inject insulin, your dosage requirements will drop, and the fat-building effects of large amounts of insulin will likewise drop. In my experience, daily strenuous exercise will, over time, bring about a steady, increased level of insulin sensitivity. This effect continues for about two weeks after stopping an exercise program. Awareness of this is especially important for those of us who inject insulin and must increase our doses after two weeks without our usual exercise. If you go out of town for only a week and cannot exercise, your increased insulin sensitivity will probably not suffer.
Although increased muscle mass also increases insulin sensitivity independently of the above effect, this is very gradual and may require many months of bodybuilding before its separate blood sugar effects become noticeable.
Exercise does affect blood sugar, and for that reason it can make your efforts at blood sugar control slightly more difficult if you’re taking insulin or sulfonylurea blood sugar–lowering medications.* The benefits, however, are so great that if you’re a type 2 diabetic, you’d be foolish not to get involved in an exercise program.
For years, guidelines for the treatment of diabetes have repeated the half-truth that exercise always lowers blood sugar levels. In reality, physical exertion can indeed lower blood sugar via increased number and mobilization of glucose transporters in muscle cells. Certain conditions, however, must be present: exertion must be adequately prolonged, serum insulin levels must be adequate, blood sugar must not be too high, and for most of us, exercise should not be performed within 3 hours of arising in the morning (see here).
Moderate to strenuous exercise, such as swimming, running, weight lifting, or tennis—as opposed to more casual exercise, such as walking—causes an immediate release of “stress,” or counterregulatory, hormones (epinephrine, cortisol, et cetera). These signal the liver and muscles to return glucose to the bloodstream by converting stored glycogen into glucose. The nondiabetic response to the additional glucose is to release small amounts of stored insulin to keep blood sugars from rising. Blood sugar therefore will not increase. If a type 2 diabetic without phase I insulin response were to exercise for a few minutes, his blood sugar might increase for a while, but eventually it would return to normal, thanks to phase II insulin response. Thus, brief strenuous exercise can raise blood sugar, while prolonged exercise can lower it. For this reason, Dr. Elliott P. Joslin told a group of us (in 1947): “Don’t run a block for a bus, run a mile.”
When insulin is nearly absent in the blood, the glucose released in response to stress hormones cannot readily enter muscle and liver cells. As a result, blood sugar continues to rise, and the muscles must rely upon stored fat for energy. On the other hand, suppose that you have injected just enough long-acting insulin within the previous 12 hours to keep your blood sugar on target without exercise, and then you run a few miles. You will have a higher serum insulin level than needed, because exercise facilitates the action of the insulin already present. Blood sugar may therefore drop too low. The same effect may occur if you are using sulfonylureas, a class of oral hypoglycemic agents. Furthermore, if you have injected insulin into tissue that overlies the muscle being exercised, or perhaps into the muscle itself, the rate of release of insulin into the bloodstream may be so great as to cause serious hypoglycemia. Nondiabetics and type 2s not on insulin or sulfonylureas can automatically turn down their insulin in response to exercise.
It may be unwise for you to exercise if your blood sugar exceeds about 170 mg/dl. This number varies with the individual and the medications taken. This is because elevated blood sugars will tend to rise even further with exercise. This effect will be less dramatic if you’re making a lot of insulin, and is most dramatic for a type 1 diabetic who doesn’t take extra insulin to prevent the blood sugar elevation. I have one type 1 patient who keeps her blood sugars essentially normal. She still makes a little insulin and dislikes insulin injections so much that she works out every day after lunch to save herself a shot to cover the lunch. In her case, the exercise plus the small amount of insulin she still makes together work very well.
One great benefit of regular, strenuous exercise in type 2 diabetes, as mentioned earlier, is that it can bring about a long-term reduction of insulin resistance, by increasing muscle mass. Long-term muscle development, therefore, can facilitate blood sugar control and weight loss. It also reduces the rate of beta cell burnout, because the increased ratio of muscle mass to abdominal fat reduces insulin resistance and thus reduces the demand for insulin production.
Several of my type 1 patients must take additional rapid-acting insulin when they exercise in the morning, but not when they exercise in the afternoon. This is a dramatic example of how the dawn phenomenon reduces even injected serum insulin levels. In the afternoon these patients’ blood sugar drops with exercise, but in the morning it actually goes up if they do not first inject some rapid-acting insulin.
Despite the benefits that exercise can have, an exercise program that isn’t sensibly put together can have disastrous results. Even if you think you’re perfectly fit, your physician should be consulted before you proceed. Keep in mind that there are certain physical conditions that may restrict the type and intensity of exercise you should attempt. Your current age, your cardiac and muscle fitness, the number of years you’ve had diabetes, the average level of your blood sugars, whether or not—and how much—you’re overweight, and what sort of diabetic complications you have developed: all these must be considered to determine what kind of exercise you should undertake, and at what intensity.
Following are several different aspects of your health you should consider and discuss with your physician before embarking upon an exercise program.
Heart. Everyone over the age of forty, and diabetics over the age of thirty, should be tested for significant coronary artery disease before beginning a new exercise program. At the very least, an exercising electrocardiogram, stress echocardiogram, or stress thallium scan is usually advised. A recent report published in the Journal of the American Medical Association demonstrated that the best test for predicting a heart attack within the next ten years is the coronary artery calcium score as displayed by high-speed electron beam tomography. I require that this test be performed on adults with type 1 diabetes and all diabetics over the age of forty before I prescribe cardiovascular exercise (see here). This test actually counts the number and volume of calcified plaques in the coronary arteries. If the results are abnormal, I ask the patient to see a cardiologist, who will recommend a maximum heart rate during exercise. If he permits, we will slowly increase the target exercise heart rate over a period of months or years. An abnormal test may not necessarily rule out exercise, but it may suggest restraint or close supervision while exercising. Again, seek your doctor’s advice before starting any new exercise program.
High blood pressure. Although long-term exercise helps to lower resting blood pressure, your blood pressure can rise while you are exercising. If you’re subject to wide pressure swings, there may be a risk of stroke and retinal hemorrhages during strenuous exercise. Again, first contact your physician.
Eyes. Before beginning any exercise program, you should have your eyes checked by a physician, ophthalmologist, or, ideally, a retinologist experienced in evaluating diabetic retinal disease (retinopathy). Certain types of retinopathy are characterized by the presence of neovascularization, or very fragile new blood vessels growing from the retina into the vitreous gel that overlies it. If you strain too much, assume a head-down position, or land hard on your feet, these vessels can rupture and hemorrhage, causing blindness. If your physician or ophthalmologist identifies such vessels, you’ll probably be warned to avoid exercises requiring exertion of strong forces (e.g., weight lifting, chinning, push-ups, or sit-ups) and sudden changes of motion (e.g., running, jumping, falling, or diving). Bicycling and surface swimming are usually acceptable alternatives, but first check with your physician.
Fainting. A form of nerve damage called vascular autonomic neuropathy (caused by chronically high blood sugars) can lead to light-headedness and even fainting during certain types of exertion (see here), such as weight lifting and sit-ups. Such activities should therefore be embarked upon gradually and only after instruction by your physician.
If you take blood sugar–lowering medications. If you take insulin or oral hypoglycemic agents, it is wise to make sure your blood sugars are stabilized before you begin a strenuous exercise program. As previously noted, exercise can have significant effects upon blood sugars and introduce another variable that can confuse anyone reviewing your blood sugar data. It’s much easier to readjust your diet and/or medications to accommodate physical activity after blood sugars are under control.
Sympathetic autonomic neuropathy. If you’re unable to sweat below your waist, there is a possibility that prolonged exercise may cause undue elevation of your body temperature.
Proteinuria. Elevated levels of urinary protein are usually exacerbated by strenuous exercise. This in turn can accelerate the kidney damage that you may already have. Blood and urine tests for kidney function can render false abnormal results for 2–3 days after strenuous exercise.
Following is a list of aspects of health you should consider on an ongoing basis as you pursue your exercise program. Also postpone such exercise if you are scheduled for kidney, blood, or urine tests.
Recent surgery. A history of recent surgery usually warrants restraint or abstinence until you receive clearance from your surgeon.
Blood sugar changes. Even after blood sugars are reasonably well controlled, illness, dehydration, and even transient blood sugar values over 170 mg/dl are reasons for you to refrain from exercise. For many people, blood sugars above 170 mg/dl will increase further with exercise, due to the production of the stress hormones that we discussed previously.
Blood sugars below target values. If you take blood sugar–lowering medications, do not exercise if blood sugar is below your target value. Bring it up to target first with glucose (see the next section and Chapter 20, “How to Prevent and Correct Low Blood Sugars”).
Possible foot injury. If you’ve had diabetes for a number of years, there is a good chance that your feet are especially susceptible to injury while exercising. There are several reasons for this:
The circulation to your feet may be impaired. With a poor blood supply, the skin is readily damaged and heals poorly. It also is more likely to be injured by freezing temperatures.
Injury to nerves in the feet caused by chronically high blood sugars leads to sensory neuropathy, or diminished ability to perceive pain, pressure, heat, cold, and so on. This enables blisters, burns, abrasions, and the like to occur and continue without pain.
The skin of the feet can become dry and cracked from another form of neuropathy that prevents sweating. Cracks in heels are potential sites of ulcers.
A third form of neuropathy, called motor neuropathy, leads to wasting of certain muscles in the feet. The imbalance between stronger and weaker muscles leads to a foot deformity very common among diabetics which includes flexed or claw-shaped toes, high arches, and bumps on the sole of the foot due to prominence of the heads of the long metatarsal bones that lead to the toes. These prominent metatarsal heads are subject to high pressure during certain types of weight-bearing exercise. This can lead to calluses and even skin breakdown or ulcers. The knuckles of the claw-shaped toes are subject to pressure from the tops of your shoes or sneakers. The overlying skin can therefore blister and ulcerate.
Another form of neuropathy makes it difficult to perceive joint position in the feet. This, in turn, can lead to orthopedic injuries (e.g., bone fractures) while running, jogging, or jumping.
All of this implies that the feet must be carefully protected during exercise. Your physician or podiatrist should be consulted before you start any new exercise, as some restrictions may be necessary. Even prolonged swimming can cause maceration of the skin. You should also be thoroughly trained in foot care (see Appendix D, “Foot Care for Diabetics”).
You or a family member should examine your feet daily for any changes, abrasions, pressure points, pink spots, blisters, and so on. Be sure to check the soles of your feet, using a hand mirror if necessary. If you find any changes, see your physician immediately. Bring with you all the shoes and sneakers that you currently wear, so that he can track down the cause of the problem. At the very least he may recommend the use of flexible orthotic inserts and sneakers with a wide, deep toe box while exercising. No attempt should ever be made by anyone (including a podiatrist) to remove calluses, as this is probably the most common cause of foot ulceration and amputation.
People who do not take medications that lower blood sugar are usually able to “turn off” their insulin secretion in response to a drop in blood sugar brought about by exercising. You cannot, however, turn off sulfonylurea hypoglycemic agents or injected insulin once you’ve taken them. (This is one of the reasons I never prescribe sulfonylureas and similar products.) To prevent the occurrence of dangerously low blood sugars, it is wise to cover the exercise with glucose tablets (e.g., Dex4 tablets; see here) in advance of a drop in blood sugar.
Some type 1 diabetics try to use “treats,” such as fruit or candy, to cover an anticipated blood sugar drop. I don’t ordinarily recommend this approach, because it’s not as precise as using glucose tablets, and the timing of their effects may be too slow. My experience with patients who’ve taken raisins or grapes or candies to cover their exercise has been that they suffer subsequent elevated blood sugars. Say you eat an apple. It will contain some fast-acting sugars that enter the bloodstream almost immediately. It will also contain other, slower-acting sugars that may take several hours to have their full effect upon blood sugar. On the other hand, as we will discuss below, certain sustained activities—such as cross-country skiing or physical labor for many hours—can keep your blood sugar dropping all day. For those, you’ll need something longer-acting to help keep you from becoming hypoglycemic.
To discover how much carbohydrate you should take for a given exercise session requires some experimentation and the help of your blood sugar meter. One valuable guideline is that 1 gram of carbohydrate will raise blood sugar about 5 mg/dl for people with body weights in the vicinity of 140 pounds. A child weighing 70 pounds would experience double the increase, or 10 mg/dl per gram, and an adult weighing 280 pounds would probably experience only half this increase (2.5 mg/dl).
My own preference is Dex4 tablets, each of which contains 4 grams of glucose.* If you weigh 150 pounds, ½ Dex4 will raise your blood sugar about 10 mg/dl. Since these glucose tablets start raising blood sugar in about 3 minutes and finish in about 40 minutes, they’re ideal for relatively brief exercise periods.
Let’s run through a hypothetical example to demonstrate how you’d go about determining how many tablets you ought to take. Let’s assume you weigh 170 pounds and ½ Dex4 will likely raise your blood sugar about 8 mg/dl. You’ve decided to swim (or play tennis) for an hour.
First, check your blood sugar before starting (you should always check blood sugar before starting to exercise). If it’s below your target value, take enough tablets to bring it up to target. Wait 40 minutes for them to finish working. If you don’t come up to your target, you may be too weak to exercise effectively. Record your blood sugar level upon starting. (I urge the use of GLUCOGRAF data sheets for recording all exercise-related blood sugars.)
When you begin such an activity—the first time you exercise after beginning our regimen—take ½ Dex4, and then ½ again every 15 minutes thereafter.
Halfway into your activity, check your blood sugar again, just to make sure it’s not too low. If it is, take enough tablets to bring it back up, and continue the exercise. If it’s too high, you may need to skip the next few tablets, depending upon how high the value.
Continue the exercise and the tablets (depending upon blood sugar levels).
At the end of the exercise period, measure blood sugar again. Correct it with glucose tablets if necessary. Remember to write down all blood sugar values and the time when each tablet was taken.
About an hour after finishing your workout, check blood sugar again. This is necessary because it may continue to drop for at least 1 hour after finishing. Bring it back up with glucose tablets if necessary. (Very intense or prolonged exercise may keep blood sugars dropping for as long as 6 hours.)
If you required, say, a total of 8 tablets altogether, this suggests that in the future you should take 8 tablets spread out over the course of your workout. If you only required 4 tablets, then you’d take 4 tablets the next time. And so on. For some exercise programs you may need no tablets.
Repeat this experiment on occasion, because your activity level is rarely exactly the same for every exercise period. If you required 3 tablets the first time and 5 tablets the second time, take the average, or 4 tablets, the next time. If your activity level increases—say you’ve been playing with a slow tennis partner and you find another who makes you sweat your butt off—you may find it necessary to increase the number of glucose tablets.
There are some activities where coverage with a slower-acting form of carbohydrate may be appropriate, and it’s here, perhaps, that you could use the “treats” I would normally discourage. For example, I have two patients, both on insulin, who are housepainters. Neither works every day, and the hours of work vary from day to day. They rarely work for less than 4 hours at a time. The painter in Massachusetts finds that half a blueberry muffin every hour keeps his blood sugars level, while the painter in New York eats a chocolate chip cookie every hour.
Some patients find that their blood sugars drop when they spend a few hours in a shopping mall. I tell them to eat a slice of bread (12 grams carbohydrate) when they leave their car. The bread will start to raise blood sugar in about 10 minutes, and will continue to do so for about 3 hours. The cookies and blueberry muffins contain mixtures of simple and complex sugars, so they start working rapidly but also continue to raise blood sugar for about 3 hours. I discourage the use of fruits, which can raise blood sugar less predictably. If your exercise is not going to continue for many hours, cover it with glucose—not a fun food—if you want predictable results.
Beware, however, if you have a history of craving carbohydrate. Fun foods are likely to exacerbate the problem, making the addiction impossible to control.
Whatever your plan for covering exercise with carbohydrate, always carry glucose tablets with you! If you have gastroparesis, you may do better with a liquid glucose solution (see here).
As you are by now aware, insulin resistance, which is the hallmark of type 2 diabetes, is enhanced in proportion to the ratio of abdominal fat to lean body mass. One of the best ways to improve this ratio in order to lower your insulin resistance is to increase your lean body mass. Therefore, for most type 2 diabetics, the most valuable type of exercise is muscle-building exercise. (It’s good for type 1s too, because it makes you feel better, look better, and can improve your self-image.) There also is cardiovascular exercise, which benefits the heart and circulatory system, and will be discussed later in the chapter.
First, what is muscle-building exercise? Resistance training, weight training (weight lifting), or gymnastics would all qualify. If done properly, weight lifting has many attributes that make it superior to the so-called aerobic exercises. Aerobic exercise is exercise mild enough that your muscles are not deprived of oxygen. When muscles exercise aerobically, they don’t increase much in mass and they don’t require as much glucose for energy. Anaerobic exercise deprives the muscles of oxygen; it tires them quickly and requires nineteen times as much glucose to do the same amount of work as aerobic exercise. When you perform anaerobic exercise, your muscles break down for the first 24 hours, but then they build up over the next 24 hours. I have little old ladies performing weight-lifting exercise. They’re never going to look like Arnold Schwarzenegger—it’s physically impossible because women don’t have the hormones for it—but they feel much better and are certainly stronger and younger-looking because of it. They also build enough muscle to reduce their insulin resistance.
But what about aerobic exercise, such as jogging or outdoor biking? I don’t think it’s as uniquely valuable for diabetics—or for anyone really, for reasons we shall discuss. Still, I usually suggest that my patients engage in activities that they will enjoy and will continue to pursue in a progressive fashion. Progressive exercise is exercise that intensifies over a period of weeks, months, or years. Below are listed various characteristics of an appropriate exercise program:
It should comply with any restrictions imposed by your physician.
The cost should not exceed your financial limitations.
It should maintain your interest, so that you’ll continue to pursue it indefinitely.
The location should be convenient, and you should have the time to work out at least every other day. Daily activity is very desirable.
It should be of a progressive nature.
It should ideally build muscle mass, strength, and endurance.
The same muscle groups should not be exercised anaerobically 2 days in a row.
You’ve often heard of aerobics, and now you’ve seen me mention “anaerobic” several times. What makes one of these types of exercise better for diabetics than the other?
Our muscles consist of long fibers that shorten, or contract, when they perform work like lifting a load or moving the body. All muscle fibers require high-energy compounds derived from glucose or fatty acids in order to contract. Some muscle fibers utilize a process called aerobic metabolism to derive high-energy compounds from small amounts of glucose and large amounts of oxygen. These fibers can move light loads for prolonged periods of time, and are most effective for “aerobic” pursuits, such as jogging, racewalking, aerobic dancing, tennis, nonsprint swimming, moderate-speed bicycling, and similar activities. Other muscle fibers can move heavy loads but only for brief periods. They demand energy at a very rapid rate, and so must be able to produce high-energy compounds faster than the heart can pump blood to deliver oxygen. They achieve this by a process called anaerobic metabolism, which requires large amounts of glucose and virtually no oxygen (anaerobic = without oxygen).
This is of interest to diabetics for two reasons. First, the blood sugar drop during and after nearly continuous anaerobic exercise will be much greater than after a similar period of aerobic exercise because of this requirement for large amounts of glucose. Second, as your body becomes accustomed to this requirement, it will adjust to the stresses you put on it and more efficiently transport glucose into your muscle cells. As muscle strength and bulk develop, glucose transporters in these cells will increase greatly in number. Glucose transporters also multiply in tissues other than muscle, including the liver. As a result, the efficiency of your own (or injected) insulin in transporting glucose and in suppressing glucose output by the liver becomes considerably greater when anaerobic exercise is incorporated into your program.
In relatively short order, you will develop greater insulin sensitivity for lowering blood sugar. Similarly, your requirements for insulin (that which you create or inject) will diminish. The overall drop in insulin in your bloodstream will reduce your body’s ability to hold on to stored fat, thus further lowering insulin resistance.
Think here of the Pimas. Not only did they gain access to an almost unlimited carbohydrate food supply, they also went from a strenuous existence, one that naturally incorporated both aerobic and anaerobic activity, to one that was almost entirely sedentary. Thus their circumstances were changed utterly from what you might call the biological expectations of their bodies. Of course, it’s not just the Pimas who are sedentary. When you understand how to meet your body’s evolutionary expectations, you can begin to bring it back into balance.
Anaerobic metabolism produces metabolic by-products that accumulate in the active muscles, causing pain and transient paralysis—for a few seconds, you just can’t contract that muscle again. Since these by-products are cleared almost immediately when the muscles relax, the pain likewise vanishes upon relaxation, as does the paralysis. You can identify anaerobic exercise by the local pain and the accompanying weakness. This pain is limited to the muscles being exercised, goes away quickly when the activity stops, and does not refer to agonizing muscle cramps or to cardiac pain in the chest. Anaerobic activities can include weight lifting, sit-ups, chinning, push-ups, running up a steep incline, uphill cycling, gymnastics, using a stair-climber, and so forth, provided that these activities are performed with adequate loads and at enough velocity to cause noncardiac pain or transient discomfort (not heart attack, but the pain of “no pain, no gain”).
Continuous anaerobic activity, as you can well imagine, is really impossible. The pain in the involved muscles becomes intolerable, and the weakness that develops with extreme exertion leaves you unable to continue.
Bodybuilding, or resistance exercise—which includes weight lifting, sit-ups, chinning, and push-ups—may focus on one muscle group at a time and then shift the focus to another muscle group. After you finish exercising certain of your abdominal muscles by doing sit-ups, for instance, you switch to push-ups, which focus on various arm and shoulder muscles. From there, you go to chinning. Similarly, different weight-lifting exercises also focus on different muscle groups. Anaerobic exercise also can increase the benefits of exercise by stimulating heart rate and thereby exercising the heart. To maintain an elevated heart rate, you switch immediately from one anaerobic exercise to another, without resting in between.*
I personally prefer anaerobic activity for type 2 or obese diabetics because—as I have said before and will say again—the buildup of muscle mass lowers insulin resistance and thereby facilitates both blood sugar control and weight loss. A number of my patients engage in bodybuilding exercises, including men and women over seventy years of age. They are all very pleased with the results.†
Since the publication of the first edition of this book, there has been a change in our society in the recognition of the importance of this kind of exercise. A significant benefit is its ability to help increase bone density. Bones, like muscles, tend to be only as strong as they need to be. When you strengthen your muscles, you’re also exercising your bones—your muscles, after all, are attached to your bones; when they contract, your bones move on their joints. If your bones weren’t as strong as the muscles attached to them, they’d snap.
Please refer back to “Restrictions on Exercise,” here. These restrictions and cautions apply especially to bodybuilding.
Even if you have room in your home, and the finances, to equip your own private gym, I usually recommend that people go to an outside gym or health club to learn the different exercises before beginning an anaerobic exercise program. Then, if you want to buy dumbbells or a weight-lifting machine for use at home, that’s fine. But it’s important to learn good technique and good form first. You can also consult books on the subject, but attending at least a few sessions supervised by an experienced instructor is best.
Equipment. For your upper body, you’re going to have to use weights. I don’t recommend that you lift barbells—they can be dangerous, and you therefore must have assistance if you’re using them—but I do recommend dumbbells and weight-lifting machines, which for the most part are quite safe to use.* Whether you’re using dumbbells at home or in the gym, they should be solid cast iron, usually painted black enamel or gray. They’re inexpensive—usually 50–75 cents a pound, so a 10-pound dumbbell costs about $5–$7.50. Don’t use dumbbells consisting of a bar with plates on either end that can be added or removed. These can be dangerous—the plates frequently slide off.
Exercises. If you’re going to a health club or gym to learn the ropes, I suggest that you learn fifteen upper body exercises, and as many lower body exercises as are available. Upper body would be for the arms, hands, shoulders, flanks, chest, abdomen, and back. If you’re going to the gym every day, which I recommend, you’d do your upper body exercises on one day and your lower body exercises on the next. Why alternate days? Because of the muscle breakdown over the first 24 hours after exercise and the need for time to rebuild. So on the second day, while you’re doing your lower body exercises, your upper body muscles are rebuilding.
As you can guess, there are more muscle groups that work in more ways in the upper body than in the lower body, so there are fewer sensible lower body exercises. If you’re using a treadmill, a stair-climber, a bike, and a cross-country ski machine all in the same day, you’re exercising more or less the same lower body muscles with each apparatus, which isn’t sensible. The other types of lower body exercises that involve weight lifting are few in number: leg presses, knee curls, toe presses, and knee extensions. In all, there are at most six leg exercises commonly available.*
As a consequence, I always add some other exercises on the days I do lower body exercises: grip strengthening, side bends (which exercise the side muscles), and sit-ups or crunches, as well as what’s called cardiovascular exercise (see here). The instructor at your health club will be able to help you with all of these.
Form. To get the most out of your weight-lifting exercises, it’s important to have as close to perfect form as possible. This means that you isolate and use only the muscles targeted by a particular exercise. You shouldn’t, for example, use your back muscles to help perform an arm exercise. You should also lift slowly, say gradually over about 10–15 seconds, and let the weight down very slowly over about 15– 20 seconds, so that the entire individual repetition takes about 25– 35 seconds—or as long as you can tolerate. This tends to be much easier on joints and has been shown to be a higher quality of exercise. It also makes the weights easier to control. Do not fully flex or extend your muscles while weight lifting. Instead, stop just before you would reach the end point of any motion. This is where having good instruction can pay off. Your instructor can critique your form and help you select the right equipment for each exercise. I usually use a weight that is just heavy enough to give me about 2 minutes (on a RadioShack or West Bend timer) until my muscles are exhausted. Frequently, my entire body vibrates as I near the point of exhaustion. I keep a record of the weight and time for each exercise and try to increase them slowly from session to session.
Many weight lifters follow a regimen that requires 10 repetitions (“reps”) of a lift, followed by a rest, another 10 reps, another rest, and another 10 reps. The rest between each set of reps allows the heart to slow, replenishes oxygen to the muscles, and thereby defeats our central goals. Anaerobically, you must continually keep your muscles deprived of oxygen and force them to develop new metabolic pathways that demand less oxygen. The idea is quality, not quantity, and it’s my belief that you can accomplish a more thorough and sensible workout in 30 minutes than you can in an hour and a half of conventional, less strenuous aerobic activity.
Once you’ve done your reps for a particular muscle group, you don’t need to do that exercise again until the day after tomorrow. You immediately go on to the next exercise. In this way, you can accomplish considerably more in a shorter time frame.
The same system applies to sit-ups, whether you’re doing them with your legs straight or bent, or with one of those sit-up boards. Initially, it may be too difficult for you to sit up slowly, so do it rapidly and record your total time. Eventually, you will be able to do it slower and slower. When you find yourself doing dozens of slow sit-ups, you can get an inclined board or a Roman chair, which is like a sit-up board but is raised about four feet off the ground and permits you to begin with your head below your waist. Again, you follow the same tactic. You can also get an abdominal crunch machine with variable resistance (not those with removable weights that take time to change). They’re the best, but they’re expensive. Use the same technique as you would with any other weight-lifting machine.
There is an amazing yoga exercise called “the plank”—also “the right plank” and “the left plank.” You put your forearms on a mat and lift your straight body off the floor, so that it is supported by your forearms and your feet. The right or left plank uses only the right or left forearm and is more difficult. You can see this exercise illustrated on the Internet if you search for “yoga exercises the plank.”
Cardiovascular exercise is widely associated in the public mind with what the popular press calls aerobic exercise. However, aerobic exercise as many people practice it—a leisurely jog, a relaxing bike ride, mild calisthenics, even a brisk walk—is really of only limited benefit to your cardiovascular system, doesn’t build muscles, and has relatively little impact on your stamina and capacity. The kind of cardiovascular exercise I recommend to my patients (and follow myself) is very strenuous, operates intermittently in the anaerobic range, and accomplishes tremendous things. For example, many years ago, before I became a physician, I used to go to diabetes conventions. There was always a group of doctors who would get up in the morning, don their running togs, and go running. These were people who ran every day. I’m not a runner; I work out in the gym every day. But I do a particular cardiovascular workout on a recumbent exercise bicycle that I will explain. I would go out with these mostly younger doctors on their runs. After a few miles, people would start dropping out. Eventually, I’d be the only one left—and then I’d go another five miles and come back. Clearly, although I was older than most of these people, and not a runner, I had much more stamina. The stamina was created by this anaerobic cardiovascular exercise.
Cardiovascular workouts can be performed on a treadmill, stair-climber, or bicycle. If you’re female, I’d recommend a treadmill, because running impacts your feet and thus helps increase bone density in your legs. However, if done to excess or with inadequate arch supports, the impact can injure your knees. If you’re male, I recommend a recumbent bicycle rather than the standard upright bike; it’s much more comfortable for men because the seat is like an ordinary chair.
Ideally, your machine should have a meter that reads the amount of work that you’re doing in calories (or joules) per minute as well as total calories (or joules), but certainly you can get a good workout with just a mileage meter. It is important to wear a pulse meter. The brand that I like best is the Timex Personal Trainer; it costs about $50, and you wear a sensor around your chest with a wristwatch-type readout. If you belong to a health club that has a treadmill with a pulse meter in the handlebars, you won’t have to put one on your chest, but some sort of pulse meter is essential. The degree of workout you’re getting is measured by how fast your heart beats. If you get evaluated by a cardiologist before you start your exercise program, you should ask him or her what your initial target pulse rate ought to be. Over time, you can increase it.
There’s a formula that we use to specify a theoretical maximum attainable pulse rate: we take 220 and subtract from it your age. So if you’re sixty years old, you’d have a theoretical maximum pulse rate of 160—that is, in theory, you shouldn’t be able to exercise at a faster pulse rate. Your doctor will decide based on your overall health and fitness level what percentage of this would be a good initial target rate for you—say, 75–80 percent of maximum. Rarely would a doctor start you out at 85 percent of maximum or higher if you were not in shape. I insist that most of my patients get a coronary artery calcium test (discussed earlier in this chapter) before starting cardiovascular exercise, so that their physicians will know if they have coronary artery disease and how severe it is. Eventually, you may find that you can get up to and beyond your theoretical maximum—I can exercise at 155 even though my theoretical maximum is 143. I can do this without having a heart attack in part because I’ve been exercising strenuously for forty-four years. Don’t expect—even after years of this kind of exercise—to get your heart rate up to or even near your theoretical maximum, or to your target, right after you begin this kind of workout. It takes time. I get to my target pulse rate at the end of about 10 minutes of trying.
To do a really effective nearly anaerobic/cardiovascular workout, start out by selecting a slow speed and setting the resistance of your machine to the point where your muscles are so tired after about 2 minutes that you can’t go any further. As soon as you reach this point, either slow down slightly or lower the resistance setting slightly and keep going. For treadmills, the resistance will be the angle at which you’re running uphill. So if you’re using a treadmill, you need to be able to set the incline of your treadmill from the handlebars—you don’t want to get off, reset the angle, then get back on. You’ll lose your rhythm, regain some of the oxygen in your muscles and heart, and defeat the point of the workout.
Lower your speed or the resistance a little at a time, and only if absolutely necessary. Each time you lower it, continue until you can’t go anymore. Nearly from the beginning you’re almost wiped out, yet you keep doing it at a lower and lower speed or resistance. This is a real workout.
Your goal will be to get your heart rate up to (but not above) the training level recommended by your physician. If you can’t reach the recommended rate when you have lowered the resistance of your machine to the point where you can barely notice it, increase the resistance and use a lower speed until you get to your target pulse. Try to maintain this rate for up to 5 minutes, or until you decide that you have had enough. Although I’m pretty wiped out when I reach 155, I have one patient who can continue at his target for 45 minutes.
A major goal of cardiovascular exercise is to enhance your heart rate recovery time—that is, to shorten it. (Cardiologists now believe that the faster your heart rate slows from your target to your resting rate, the better your cardiac fitness.) A minimal test of recovery would be to slow your heart rate by 42 beats per minute from your maximum within 2 minutes of stopping.
I recommend that rather than timing your workout, you look at the calorie counter on the machine, if it has one, and decide on a particular number of calories that you want to shoot for. Calories are a measure of work done and therefore a reasonable gauge of your workout. Minutes or even miles don’t take effort into account. When I was seventy years old, I aimed for about 200 calories. Now I shoot for 100 calories. When it gets up to that range, I call it quits. But the point of this kind of exercise isn’t weight loss, so don’t start looking at the calorie counter thinking that if you burn 200 more calories you’ll lose another pound—exercise just doesn’t work that way. Incidentally, I have a retired patient who actually has the time and the stamina to continue intermittent sprinting for an hour.
There is a neat trick that will enable you to more easily reach your target heart rate. My goal is to exceed 150 beats per minute. On the first try, I feel tired at about 130, so I stop for 2 minutes. Then I try again and easily get to 147 before feeling tired. I again stop for 2 minutes. On the third try, I easily exceed 150 and continue until I feel I’ve had enough.
If you’re doing cardiovascular exercise of this type, you have to be very careful, especially if you’re a long-term diabetic, or a recent-onset diabetic over the age of forty, or you have a family history of coronary disease. One rule is that you never finish a cardiovascular workout and stop cold if you are using a standard bicycle or a treadmill. I had an overweight nondiabetic cousin who started jogging when he was about fifty years old. He was in his second month of exercising, not doing anything more than jogging with friends. One day, after they stopped jogging, he dropped dead of a heart attack. He and his jogging buddies were in the habit of stopping cold after their run to chat. Stopping cold is an extremely bad idea—if someone is going to drop dead of a heart attack from running or biking, it’s most likely to happen immediately after the exercise. Why?
While you’re exercising, your heart is beating very rapidly because it and your legs require a lot of blood. By pumping your legs up and down, you’re pumping blood from your legs back to your heart. The muscles that are demanding a lot of blood are both in your legs and in your heart, but the blood’s getting pumped back to your heart by running. If you stop cold, your muscles are still going to demand a lot of blood—they’ve been depleted of oxygen and glucose—and gravity is going to help them get the blood. The problem is, they’re no longer pumping the blood back to the heart. Suddenly your heart is deprived and, if your coronary arteries are narrowed by atherosclerosis, you’re set up for a heart attack.
Whether you’re on a treadmill, standard bike, or stair-climber, cut the resistance setting to zero and proceed at a very slow pace after your workout until your heart rate slowly comes down to no higher than about 30 percent above your initial starting rate. If your resting pulse is 78, you don’t want to stop your biking, walking, or stair-climbing until your heart rate is 101 or below. This protocol can be safely avoided if you use a recumbent bicycle, as I do. Here your legs are level with your heart, and blood will not drain from your heart to your legs.
As your strength and endurance increase for any exercise, it will become progressively easier to perform. If it becomes too easy, you won’t get any stronger. The key to getting progressively more strength and endurance is to make the exercise progressively more difficult. This can be done for almost any activity.
If you are lifting weights, for example, every few weeks (or months) you can add a very small weight (say a separate 2½-pound plate) to the weight stack for any exercise. You can also increase the exercise time for a given set. When doing a cardiovascular exercise, you might try to increase your maximum heart rate by, say, 2 beats per minute every 2 months, preferably by increasing your resistance setting. A swimmer can assign a fixed time period, say 30 minutes, for doing laps. The goal would be to gradually increase the number of laps. Thus, after a month you might increase your speed to get 15½ laps instead of 15 laps in 30 minutes, and so on. Of course, a waterproof wristwatch would be helpful.
Even walking can evolve into both an endurance and a bodybuilding activity. All you need is a wristwatch, a few lightweight dumbbells, and a pedometer. The pedometer is a small gadget from a sporting goods store that you clip onto your belt. It measures distance by counting your steps. Suppose you wish to set aside 30 minutes per session for walking. You begin by walking at a leisurely pace for 15 minutes and then returning at the same pace. Record your distance from the pedometer. Thereafter, try to walk at least that distance in the same time period. After five to ten sessions, you might try to increase distance by 5 percent over the same time. If you increase distance by this amount every five or ten sessions, you’ll eventually find yourself running. You can then gradually increase your running speed in the same fashion.
Suppose your doctor has told you not to run because of a bad knee or fragile retinal blood vessels. Limit your speed to a fast walk, but start swinging your arms a little bit. Over time, try swinging them higher and higher. When you think they are going so high that you look silly, start with the dumbbells. You might begin with a pair of 1-pound dumbbells and short swings of the arms. Wear gloves if the dumbbells feel cold. Again, gradually increase the distance you swing. When you eventually feel you look silly, try 2-pound dumbbells. After a year or two, you may be going at a very fast walk, swinging 5-pound (or even heavier) dumbbells. Imagine what your physique will look like then. You’ll also probably feel younger and healthier.
The exercises I’ve mentioned above are by no means the only ones. There are countless different ways you can exercise—volleyball, snowboarding, surf-kayaking, cross-country skiing, you name it. The most important considerations are keeping within the restrictions your physician might place on your activity, and discovering what you like best to do—and sticking with it. After that, all you have to do is monitor and correct your blood sugars, record the exercise on your GLUCOGRAF form, and keep exercising in a progressive fashion. The payoff—longer life, lower stress, weight loss if you’re overweight, and better overall health—is usually worth the time and effort.
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