Exercise ! Why, What, How, Where and When

Dr. S.M.Sadikot.
Hon. Endocrinologist,
Jaslok Hospital and Research Centre,
Mumbai 400026

More than 2000 years back, Charak, in his Charak Samhita advocated the use of exercise in treating diabetes. In fact, the use of exercise in the treatment of diabetes was prescribed as early as 600 BC by the Indian physician Sushruta, and was widely recommended by physicians of the 18th century. Elliott Joslin, often called the Father of modern diabetes, identified exercise along with dietary management and insulin administration as one of the three components of good therapy in the 1920's.

It could be argued that in the absence of any other forms of treatment, the older day physicians had no choice but to fall back on diet and exercise! Later, with the wide availability of oral hypoglycemic agents and insulin, the relative importance of exercise as a treatment for diabetes seemed to go into a decline from which it is just emerging.

With the long term safety and efficacy of some of the oral agents being called into question and with reports that ill advised insulin therapy leading to high blood insulin levels can be a factor in leading to many disorders such as high blood pressure, lipid disorders and even atherosclerosis, attention is being again given to diet and exercise as the dominant treatment modalities, as far as possible.

If a diabetic can be managed with the use of diet and exercise alone, or if the addition of exercise can lead to a substantial decrease in the dose of the oral agent or the insulin, can there be any justification for not prescribing exercise to the diabetic!

Diet and exercise are the mainstay of good diabetes management. In fact, many patients can be controlled quite adequately with the use of diet and exercise alone. In pointing out the importance of exercise, one is not saying anything new. More than 2,000 yrs. ago, Sushruta advocated the use of exercise in the management of diabetes! Unfortunately, with the advent of insulin and oral agents, the role played by exercise went into an eclipse from which it is only now emerging. After all, if the patient can be controlled with the use of insulin or an oral agent, why make the patient exercise? Today, the picture seems to have changed radically and exercise has again come center stage.

A regular program of exercise not only helps in correcting many of metabolic abnormalities associated with diabetes, but also makes the person a much more fitter and healthier person. Exercise decreases the blood glucose levels (and it does this even without any change in the weight of the patient), it leads to an increase in insulin sensitivity, decreases the levels of triglycerides and the LDL-cholesterol, whilst increasing the HDL-cholesterol values. The energy spent during the exercise also contributes to the weight reduction of an overweight patient. I do not intend to discuss the beneficial effects of exercise in any further detail, but would rather focus on an aspect which I feel is quite neglected. This is the actual method of exercising. In other words, not so much the why as the what, how, when and where! Unfortunately, many who do understand the importance of exercise in diabetes management, do not really know the actual method by which an exercise program should be prescribed. Often, we just tell patients that they should exercise and patients accept this advice!

Today, if a patient came to a doctor with some infection, no doctor would say "Take antibiotics! ". Neither would any patient be satisfied with such advice. The doctor would need to prescribe the precise antibiotic that the patient would need to take. The patient would also be told the strength of the tablets, the number of times in the day that the tablets have to be taken, the time of taking these tablets, the relationship to meals, and the number of days that the course of antibiotics would have to be taken, and even the side effects which may be seen!

Yet many of us tell our patients that they must exercise and the patients accept this! Such simple instructions may mean different things to different patients and from a therapeutic viewpoint are absolutely useless. Just as a prescription is written for any drug that the patient needs to take, it is essential that a detailed prescription of the exercise schedule be made for every patient. They should be evaluated for fitness to exercise and then given a detailed prescription of the type of exercise, the intensity of the exercise, the timing and the duration of the exercise schedule. The patient must also be advised about any special aspects, precautions and side effects associated with the exercise regime. These are the areas that I would like to discuss in some detail.

Before the actual prescription of the exercise schedule, every patient should be evaluated regarding fitness to undertake the exercise programme. Theoretically, this would mean that all the patients would need to undergo a cardiac stress test, but this is obviously not feasible on such a large scale and frankly, not really necessary. In my opinion, a good history and clinical examination along with a few routine investigations would show us the patients who may be at an extra risk whilst undergoing an exercise program. If a patient has a significant degree of ischemic heart disease, they would do better to follow a special cardiac program. Patients with proliferative retinopathy should avoid vigorous exercise at least until they have been adequately managed by laser therapy. Similarly those with a significant degree of kidney involvement would also do well to avoid any sudden and vigorous activity. The feet of the patients, especially those with a severe degree of anesthesia and peripheral vascular disease would require special attention. But the vast majority of diabetics can well follow an exercise schedule and should be made to do so!

The following questionnaire has been shown to be very useful to assess the fitness of the patient before carrying out any exercise program.

Modified Physical Activity Readiness Questionnaire (PAR-Q) Regular exercise associated with many health benefits, yet any change of activity may increase the risk of injury. Completion of this questionnaire is a first step when planning to increase the amount of physical activity in your life. Please read each question carefully and answer every question honestly:

Yes No 1) Has a physician ever said you have a heart condition and you should only do physical activity recommended by a physician?
Yes No 2) When you do physical activity, do you feel pain in your chest?
Yes No 3) When you were not doing physical activity, have you had chest pain in the past month ?
Yes No 4) Do you ever lose consciousness or do you lose your balance because of dizziness?
Yes No 5) Do you have a joint or bone problem that may be made worse by a change in your physical activity?
Yes No 6) Is a physician currently prescribing medications for your blood pressure or heart condition?
Yes No 7) Are you pregnant?
Yes No 8) Do you have insulin dependent diabetes?
Yes No 9) Are you 55 years of age or older?
Yes No 10) Do you know of any other reason you should not exercise or increase your physical activity?

If a patient responds positively to any of these questions, it may be worthwhile to assess that patient more thoroughly. Moreover, the patient can be given this Questionnaire to keep and if the response for any of the questions changes from a negative to a positive, the patient should be asked to contact the doctor as soon as possible.

It is needless to say that all diabetics who are put on an exercise program should be closely monitored at least in the initial stages. I would also like to point out that this initial evaluation does not entail any extra cost to the patient as this is a routine part of any good initial evaluation for every patient with diabetes!

Once the patient is found fit to undertake the exercises, the first and possibly the most important, step in the prescription of exercise is to choose the type of exercise. The exercise schedule would need to be followed for many a year and therefore, the exercise chosen should be individualised for every patient. Consideration must be given to the needs, work schedule, hobbies, interests, skills, ability and also, quite importantly, to the financial capacity! In other words, the type of exercise that the patient chooses should be one that one would be able to carry out easily, regularly and for a long period.

Most patients need and should be prescribed, isotonic exercise. These involve movements and use of the large muscles of the body. Isometric or muscle tensing exercises like weight lifting, Bullworker and pushups are not suitable for most of the patients and should be reserved for the very young patients and athletes with a special interest in developing certain muscles. These isometric exercises are specially meant to develop muscles and stamina, but they also cause a significant rise in the blood pressure and this can be very dangerous for many patients especially if they already have retinal and renal complications or have hypertension. These exercises are not easy to carry out on a regular basis. Isotonic exercises are definitely more safer, easier and more than sufficient to meet the needs of most patients.

It is important to take into consideration the work schedule of the patient when planning the type of exercise. A patient holding a nine to five job obviously cannot plan to play games or go swimming every afternoon. The patient must also have easy access to, or an opportunity to undertake the exercise that is chosen. Tennis, swimming, badminton, etc, are all excellent forms of isotonic exercises but one must consider whether the patient would be able to regularly carry out these forms of exercise! Does one have a regular and easy access to a swimming pool or a tennis court? This often means that one should belong to some club or hotel. These are not only quite difficult to come by, but are also quite expensive. Add to this, the cost of playing some games like tennis! Thus, one would not only have to consider if the patient would have an opportunity to carry out the exercise schedule regularly, but also if one would able to bear the financial burden of this exercise schedule! The skills and ability of the patient should also be considered. To give an extreme example, the patient cannot be allowed to choose hill climbing as the form of exercise, when one finds it difficult to climb up one or two floors. It is also important to realise that the type of exercise chosen should be of interest to the patient. The patients will need to do this exercise for a long time and one cannot get "bored" with the exercise. One way out of this dilemma would be to choose different forms of exercise so that the type of exercise could be varied. But when patients are given too many choices, I find that they end up doing none!

One may feel from the above discussion that what I am saying seems to be very obvious to most people, but from my experience I know that unless we help the patient in choosing the type of exercise, most of them have an inherent tendency to choose the most exotic and fancy forms of exercise which they have no hope of carrying out for any period of time, thus defeating the very purpose of an exercise program. Let us take an example from clinical experience. All of a sudden one finds that when we ask many of our patients, especially the younger ones, about the type of exercise that they would like to undertake, quite a few of them choose to play tennis. This usually occurs in the month of July. A closer analysis would show that this is after the massive coverage given to the Wimbledon Championships on TV. I usually discourage all these sudden flights of fancy as these have a tendency to be quite short lived, even if they ever take off in the first place.

It should be clear from this discussion that choosing the type of exercise requires careful consideration, taking into account all the various factors that have been referred to. I do not leave the choice entirely to the patient, but discuss the various options before him and then jointly reach a consensus about the type of exercise to be carried out.

Personally, I am in favour of walking as the type of exercise best suited for most patients. Walking needs no learning or special skills; after all, everyone can walk! Walking can be done easily, regularly, anywhere and anytime, needs no special equipment, clothes or place, is relatively the safest and costs nothing.

Once the type of exercise has been finalised, the next step in the prescription of exercise is to discuss the pace or intensity at which the exercise would be carried out. It should be realised that the aim of the exercise is to "train" and not "strain" the body!

Therefore, the pace, initially, would need to be gentle and this could then be stepped up to optimal levels at a rate depending on the individual patient. It must be remembered that what one has not done for a lifetime, cannot be accomplished overnight! Inability to appreciate this simple but important point gives rise to a large number of patients who give up the exercise program. The usual sequence is that patients in their initial enthusiasm exert at a strenuous pace and for a prolonged time. This causes in many cases, a severe body ache and joint pains. In some cases, sprains and other more serious joint problems may also develop. Patients conclude that the exercise is causing too much hardship, has done more harm than good and whilst it may be excellent in principle, it is definitely not meant for them. That is the end of any exercise program!

One cannot blame the patient for these excesses as these are quite human traits, and it is imperative that the doctor curb this initial exuberance by closely monitoring the intensity of the exercise programme. One only has to think back about one's childhood days when we went away for the holidays. On the first day, we would get our hands on a bicycle and pedal away furiously for hours on end. The next day, the body would be so stiff that it was difficult even to get up. All thought of doing any more cycling would be the furthermost from our minds. Therefore, the best maxim is slow and steady initially and this can then be gradually paced up.

How does one judge the intensity of the exercise? One method that is widely recommended and which I have used in quite a few patients is by asking patients to keep a count of the pulse rate. Taking one's pulse is very easy and I teach this to most of the patients who undertake the exercise program. The next step is to introduce the patient to the concept of Maximum Heart Rate (MHR). This can be calculated for every patient from the standard formula: MHR = 220 - age of the patient.

In other words, if the age of the patient is 40 years, his MHR is 180. Because I believe in the slow and steady maxim, I instruct patients that during the first couple of weeks of exercising, they should not allow their pulse to go beyond 60% of their MHR. Later, this can be increased to 70-75% of the MHR, provided that there are no symptoms of undue breathlessness, excessive fatigue or chest discomfort. In my opinion, most patients should not aim for a higher intensity, although many texts do advise that once patients get attuned to the exercise, they may opt for a more rigorous schedule.

The Intensity of Exercise

Most patients should start in Zone 1 and later can opt for Zone 2. In my opinion, most patients should not aim for a higher intensity, although many texts do advise that once the patient gets attuned to the exercise, he may opt for a more rigorous schedule. I feel that is only the younger group of people undergoing athletic training who should aim for the very high rates.

As a matter of interest, once the person becomes very fit, his heart rate may not rise to a significant extent and may even remain at very low levels. Bjorn Borg, even when he was playing the Wimble don Championships, would have a steady heart rate of about 45. This shows how fit Borg was.

Unfortunately, some of our patients get quite confused with all this talk about MHR and the need to take their own pulse. How then are they to judge the intensity of exercise? One simple, though not ideal, way out is for patients to judge whether they would be able to talk normally (i.e. as if they were carrying on a routine conversation whilst sitting comfortably) during the exercise. If they can easily do so, they are obviously not exceeding the targeted intensity and can be told to gradually increase the pace of exercise up to a limit where they feel that they would be able to just carry on a normal conversation, without huffing, panting and getting unduly out of breath.

Every time the patient exercises, there should be a five minute warming up period and a five minute cooling off period. In other words, the exercise should never be started or stopped abruptly.

Another important precaution that the patient must always observe is that if, for any reason, there is an interruption to the exercise schedule, one cannot restart at the same level that one was at previously. The patient should begin the exercise schedule anew as if starting to exercise for the first time and then gradually come up again to the target intensity. If the patient is not aware of this and restarts the exercise at the same high level of intensity, it would be as if one were undertaking a sudden and very rigorous exercise and this can cause quite a few problems in patients with some degree of retinopathy and also in those with some degree of kidney involvement.

I usually advise the patient to choose walking as the form of exercise. I ask patients to judge a certain known distance from their house (or from wherever they will regularly walk) and time themselves to see how long it takes to walk the distance at their "normal" pace. They then gradually increase the speed of walking such that they can cover the distance in a shorter time and this speed is increased until they are walking at the target intensity. The distance is then increased such that they are able to exercise at the required intensity and for the required period each time. This is an approach that most of the patients can understand quite easily and follow regularly. Even when the form of exercise is walking, there must be a five minute warming up and a five minute cooling off interval.

Ideally, the patient should exercise every day, but if this is not possible, it has been shown that for exercise to have a beneficial effect, it should be done for at least five days in a week. As I usually ask the patient to exercise at a moderate rate of intensity, the time period of each exercise schedule should be 30 minutes and this may include the warming up and cooling off periods.

The patient needs to be advised about the clothes that he wears during the exercise. Unfortunately, there seems to be craze for wearing track suits during the exercise. These are usually made from impermeable materials and are totally unsuited for our climate. They prevent heat loss from the body and also stop the sweat from evaporating. This could lead to a dangerous increase in the body temperature and in some severe cases, may even cause a heat shock. There is absolutely no need to spend any money on special clothes for the exercises. Any old tee shirt and a pair of loose comfortable pants (which allow the free circulation of air) are the best clothes to wear. After the exercise, especially if the weather is cold, it would be preferable to cover oneself more thoroughly in order to avoid catching a chill. I advise the patients to wear a pair of loose cotton socks, without elastic garters and a pair of broad and comfortable shoes. If a patient feels that it is necessary for one to spend some money in order to get any benefit from the exercise, (and you will be surprised as to how many feel like this!), they would be well advised to spend it on a good pair of tennis shoes.

Careful attention should be paid to the feet when planning an exercise regimen. A meticulous search should be made for any evidence of cuts, cracks, bruises or any other injury. If these are present, the exercise regimen should be postponed until the problem is treated completely. It is essential that this meticulous search should be made on a very regular daily basis. Foot care is such an important aspect in the management of diabetes although, often a neglected one, that this has been discussed in more detail in another section.

Let us now consider some other exercise related problems that may be unique to diabetic patients. We have already discussed that any patient who has a severe degree of proliferative retinopathy should get the eyes treated with laser therapy before embarking on any exercise. Any person who has retinal problems should avoid any sudden and vigorous spurt of exercise. The reason is that in an unfit and uncontrolled diabetic, this could lead to a sharp rise in blood pressure and cause a bleed in the eye. This is also the reason why I ask patients to avoid isometric forms of exercise as these tend to raise the blood pressure. This does not mean that a diabetic with even a small degree of retinal problem should ever exercise. I feel that gradual increase in the pace of the exercise to reach moderate levels, would be the ideal method of exercising for these, or for that matter, most patients.

Quite a few patients also suffer from involvement of the autonomic nerves. These are nerves that have a myriad of functions, one of which is to regulate the blood flow to the different regions of the body. During exercise, more blood flows to the peripheral areas, like the skin and the exercising muscles. This is the blood that is diverted from the internal organs. The autonomic nerves finely regulate this change in the blood flow such that the periphery gets the additional blood, and at the same time, the internal organs are not starved of their requirements. In patients with a severe degree of diabetic autonomic neuropathy, sudden and vigorous exercises may divert so much blood to the periphery, that the internal organs may not get sufficient blood. Patients with nephropathy may, in exceptional cases, have so much of a decreased blood flow to the kidneys that these may "shut down". In some others, blood flow to the brain may decrease such that the patient may get quite faint. Once again, I would like to make it clear that this usually occurs in patients who undertake very sudden and vigorous exercises without being trained to with- stand such stress. The method that I follow would rarely show such catastrophic results. I also closely monitor patients who may be at some risk and so are able to avoid these complications.

Here again, the key words are slow and steady!

Is there any need for a change in the treatment or diet when a diabetic exercises? Change may be necessary for some of the patients although this may not be something that the patient would have to do every time that he exercises. The reason for this is that, if the patient were to exercise regularly, then his treatment and diet would have been adjusted to take care of the changes required by the exercise schedule. At the same time, all patients must be aware about the modifications that they may have to make during exercise schedule. It is possible that they may have to do a vigorous activity unexpectedly or on occasion, they may feel like exercising for a more prolonged period, or at a time which is not their usual time for exercise and therefore, this may not have been taken into account whilst planning the diet and treatment.

Instead of just laying down the do's and dont's, it would be better to try and understand why certain changes in the treatment schedule may be required during exercise.

When a normal person exercises, the insulin level in his body decreases. At the time, the level of the insulin antagonist hormones, like catecholamines, increase. The levels of glucagon may remain the same, but in view of the fact that there is a decrease in the insulin level, one could consider this as being a relative increase in the glucagon action during exercise. The reason for this is that when a person exercises, the muscles utilise the glucose and there is a need to replenish the blood glucose such that hypoglycemia is averted. This is done through the liver making new glucose and pouring it into the circulation. Insulin inhibits this, whilst glucagon and other antagonist hormones increase the amount of glucose formed by the liver. It is apparent that there is indeed a fine tuning of the balance between the insulin and its antagonist hormones such that the blood glucose levels would be maintained within acceptable limits. Although the changes during exercise are definitely much more complicated than this, I have kept the discussion to these simple terms so that the modifications required in the treatment can be self apparent.

Let us first consider the patient who has just taken his insulin injection. Obviously, his blood insulin levels would be high and since this is insulin which has been injected, there is no way that the body mechanism can decrease the levels of the insulin when exercise commences. These relatively high insulin levels would exert their effect and prevent the liver from forming new glucose. This would be in spite of the increase in the amount of the antagonist hormones. Therefore, as the patient exercises, and the muscles use up the glucose, the body may not be able to increase blood glucose levels and there would be tendency for the patient to go into hypoglycemia. Whilst this decrease in the levels of the blood glucose is one of the benefits of exercise, in a finely controlled patient, undue exercise could make one severely hypoglycemic.

Thus, it becomes quite apparent that the problem for patients taking insulin would be to try and decrease the blood levels of insulin such that this would not inhibit the ability of the liver to form new glucose and thus maintain the blood glucose levels to within acceptable limits. Also, to increase the intake of carbohydrates such that this would make up the decrease in the capacity of the liver to form new glucose;

How can these problems be managed?

This can be quite easily managed by decreasing the dose of insulin that the patient takes prior to the exercise; and take additional carbohydrates before, during or after the exercise or he may have to do all three if the exercise is sufficiently vigorous and of long enough duration. In other words, one takes a carbohydrate supplement before the activity, and after the completion of the exercise.

I advise the patient to decrease the dose of the insulin injection prior to the exercise. I also advise that the exercise not be undertaken to coincide with the time of peak activity of the injected insulin. The patient carries a carbohydrate supplement and takes it if necessary at any suitable time.

Some authorities advise that the site of insulin injection should not be in the limb which is going to bear the brunt of the exercise. In other words, if the patient is going to play football, one should avoid injecting the insulin into the legs and should either use the arms or the abdominal wall. At the same time, there should be a word of caution. Whilst, not using the exercising limb to inject the insulin, may help in retarding the absorption of insulin from that site, it should also be remembered that insulin is absorbed faster from the arms and the abdominal walls, and therefore, the value of changing the site of the injection may be negated. I do not pay too much attention to this aspect, unless the patient is taking "regular" insulin and is going to exercise the limb within half an hour of the injection. After this time period, most of the regular insulin has already been absorbed and therefore the exercise would not cause a significant increase in the amount of insulin absorbed.

Patients with Type 1 diabetes and even those with Type 2 diabetes should avoid exercise until they are fairly controlled. The reason for this is also evident from the preceding discussion. In such patients, there is either no insulin or the levels of insulin are very low. When the patient exercises, these low insulin levels decrease further. Along with this is the rise of the antagonist hormones. This imbalance would lead to unrestricted new glucose formation in the liver and would shoot up the blood glucose levels still further. In the ketosis prone patient, the levels of serem ketones would go up and the patient may precipitate diabetic ketoacidosis. Therefore, whilst care needs to be taken to adjust the dose of the insulin prior to the exercise, it is also as important to see that there is at least some insulin present in the body before one starts any exercises.

I would once again like to make it clear that if the patient follows a regular schedule of exercise, all these factors would have been taken into account when planning the diet and treatment an therefore, most of the patients would not really have to worry about these aspects. This would be especially so if the pace of the exercise would be moderate, or even high, provided that this were gradually built up. These adjustments are very important when the patient suddenly undertakes unaccustomed activity of relatively high intensity or long duration.

In this context, I would like to make two other points. It is not generally well known that the glucose lowering effect of acute exercise may last for up to 14-15 hrs. Therefore, after a severe and prolonged exercise or sports, it may be necessary to decrease the dose of insulin injection that one takes after the exercise. Failure to understand this, and make the adjustment, may cause the patient to have delayed hypoglycemia. The second point is that even patients on oral hypoglycemic agents and who are tightly controlled may undergo hypoglycemia when they undertake a sudden and vigorous exercise especially for a long duration. In this case, omitting the tablet prior to the exercise may not help as many of the tablets have a prolonged duration of action. The best way out would be to make provisions for extra snacks and possibly adjust the dose of tablets that are taken later. But in these patients, it would be the provision of extra carbohydrates that would be the centrepiece of management, whilst in insulin taking patients, it is decrease in the dose of injected insulin that would pay the more important role.

Finally, I would again like to point out that the energy spent during the exercise would help in the weight reduction regimen of the obese diabetic. It is known that to lose one kilogram of weight there has to be a negative balance of 7700 calories. In other words, the body must lose 7700 calories. This can be done either by a decrease in the intake of calories, through dieting or by an increase in the expenditure of calories through exercise or both. In my opinion, trying to lose weight only by dieting tends to put the patient through a very restricted diet whilst the addition of exercise to the regimen not only allows them some leeway with the diet (and therefore the patient is more happy to follow it), but gives the patient the added benefit of physical fitness.