What a person expects from exercise determines, to some extent, the type and amount of exercise he takes, and how serious a business he makes out of something essentially be relaxation. The aims of exercise may be broadly categorized into three: staying healthy, improving physical fitness, and developing specific skills.

Health

Staying healthy or recovering health should be everybody’s goal, although exercise serves other aims as well. Fortunately, this is also the simplest goal to realize. It has been found that a regular thirty minute brisk walk everyday leads to remarkable health benefits. People who practice this or its equivalent have significantly lower all-cause mortality than sedentary persons. Further, making the exercise more strenuous by increasing its duration or severity confers very little additional longevity. It does not mean walking longer is bad. What it means is that you may walk longer if you enjoy it. You do not have to do it to live longer. Therefore, if the aim of exercise is just health, which is true for most of us, we do not need much exercise. A thirty-minute walk does not need any special skills or equipment. It needs an investment of time which we should be able to make even if we think we cannot.

Physical fitness

Physical fitness goes a little beyond health, and refers to the degree of cardio respiratory reserve. Although increasing the severity of exercise beyond that of a thirty-minute brisk walk does not confer additional health benefits, it does offer additional physical fitness. By challenging the body progressively with exercise which is a little harder than what we are accustomed to, we can stretch the limits of our physical fitness further. Physical fitness is reflected in the resting heart rate. The resting heart of a athletes is usually on the lower side. Another indicator of physical fitness is the time it takes for the heart rate to return to normal after a given amount of exercise: the more fit a person, the less time it takes for the recovery.

It is natural to think that there is no harm in aiming at better physical fitness alongwith good health. Up to a point, that is quite true. In fact, even a thirty-minute brisk walk everyday will also improve physical fitness in addition to providing health benefits. But beyond a point, there can arise a conflict between fitness and health. We have all heard of several top athletes getting a heart attack at a relatively young age while running. These athletes are physically very fit, but obviously they are not very healthy. The reasons why this happens are complex, but one simple explanation which applies to many such cases runs somewhat like this. The improvement in fitness is achieved through increase in the thickness of the musculature of the heart (hypertrophy). The hypertrophied heart can pump more blood with each beat. This efficient heart which beats slowly but pumps more blood with each beat, however, comes at a cost. The cost is the greater blood flow which its thick wall need. The result is that a person with such a heart has partly blocked coronary arteries, the imbalance between the blood supply and demand can be precipitated rather easily during exercise when the demand is high. That is why a person might get a heart attack during the athletic event.

Skills

A person who is preparing for competitive sports expects from an exercise programme specific skills such as the ability to run a spirit or a marathon, lift heavy weights, or play a particular game better. Developing these skills needs a specially designed training programme. Any improvement in health or physical fitness resulting from the training is incidental, not the primary goal of the programme. In general, improving the cardiorespiratory reserve, which is important for running a marathon, needs training in aerobic exercises^4. Improving muscle strength needs use of specific groups of muscles against resistance. Improving the flexibility of the body needs stretching type of exercises. Thus the exercise programme is tailored to the needs of the type of sports in which a person wishes to specialize. Specialised training should begin with a good assessment of the baseline characteristics of the person because, partly due to generic factors, everybody is not equally capable of excelling in every type of sport. Best results can be achieved if the sport selected is in keeping with the inherent talents of the person. Most of us, of course, would not reach the top in any sport, and that is quite okay. For the ordinary person, Improvement in health and a moderate gain in physical fitness are quite adequate as the goals of exercise.

THE NITTY-GRITTIES: EXERCISE PRESCRIPTION

The exercise prescription spells out practical details such as which exercise to take, for how long and how often.

Which exercise?

The most important thing to remember is that any exercise is better than no exercise at all. However, since we have a choice, it is better to make an informed choice. For health and fitness, aerobic exercises are better than anaerobic ones. Aerobic exercises are those for which the additional oxygen required can be procured by the body during the exercise itself. Walking, long-distance running, badminton, tennis and yogic postures are examples of aerobic exercises. On the other hand, anaerobic exercises are high-intensity brief exercises, eg, a hundred –metre sprint. These exercises need a lot of additional oxygen, and moreover their duration is too short for the body to adapt to the additional demand. The result is that during the exercise the body incurs an oxygen debt which is paid off after the exercise. Among aerobic exercises, a combination of walking or running and yogic postures is probably the simplest and best choice which improves health, physical fitness, endurance as well as flexibility of the body. However, persons above the age forty should run only after getting clearance from a doctor. Further, if time is enough only for either walking or yogic postures, the latter is a better choice provided a good yoga teacher is available for the first few days. Yogic postures are better than walking because: ^4 The intensity and duration of aerobic exercises are such that all the oxygen required for performing them can be breathed in essentially during the exercise itself. That is not possible with more intense exercise performed for a short time. In the case of these exercises, called anaerobic, the body incurs an ‘oxygen debt’, which is ‘paid back’ by breathing in extra oxygen after the exercise.

1. A judiciously selected set of 15-20 postures can improve the flexibility of the whole body which walking cannot.
2. A person with a temporary disability of a joint can also do atleast few yogic postures, with the result that regularity is better maintained. On the other hand, injuries which produce these disabilities are also least likely with yogic postures. A person who runs may sometimes sprain an ankle; a person who plays tennis may sprain the shoulder. After such injuries, the exercise has to stop for one or two weeks. If a permanent disability makes even walking difficult, a set of yogic postures which needs only the functional parts of the body can be devised.
3. Although yogic postures are low-intensity exercises, the changes in thoracic and abdominal pressure and fluctuations in oxygen supply (due to breath holding) are comparable to those produced by rather high-intensity non-yogic exercises. Therefore, yogic postures yield health and fitness benefits which are out of proportion to the intensity of effort involved.
4. The sequence of postures is so designed at the end of the session a person is relaxed rather than tired.
5. The gentle and graceful movements, and the breathing and relaxation techniques incorporated in the session have a soothing effect on the mind.
6. Yogic postures can be performed at home in any loose and comfortable dress (including the night pyjamas). They need no company, and only the bare minimum of preliminaries. For these reasons, heat, cold, and rain also need not disturb the regularity of the routine. Thus, any exercise is better than no exercise at all, all exercises are not alike.

How long?

Thirty minutes of walking is quite satisfactory. Running for ten minutes may be quite enough, but to that should be added about ten minutes of warming up and about ten minutes of cooling down. A session of yogic postures generally takes about an hour, but that includes warming up and cooling down. If one is short of time, the time can be cut short, but warming up, cooling down, and in case of yogic postures, relaxing postures, should not be neglected. The minimum duration of an exercise session – yogic or otherwise – should be about twenty-five minutes, comprising of five minutes of warming up, fifteen minutes of harder exercise, and about five minutes of cooling down. Older people generally need a little longer warm-up time.

A beginner starting exercise after years of sedentary life should also start with a shorter duration (about ten minutes), and increase the duration gradually. Persons having health-related problems such as high blood pressure or heart desease should also begin slowly, and follow their doctor’s advice.

How intense should the exercise be?

The intensity of exercise is graded in terms of its energy cost, which in turn is determined from the rate of oxygen consumption, ie the volume of oxygen consumed by the person per minute. A rough but fairly reliable assessment of the intensity of exercise can be obtained from the heart rate during the exercise. The simplest formula to find how hard is hard enough but not too hard is based on the percentage of maximum heart rate (MHR) reached towards the end of the exercise. The MHR for a person is 220 minus age. The target heart rate (THR) during exercise is forty-five to eighty per cent of MHR, depending principally on the health status of the person, and whether the person is at the beginning of an exercise programme or has been in it for some time. For example, the MHR of a fifty year old is 220 — 50 = 170 beats per minute. If he is prescribed exercise at sixty per cent of the MHR, his THR will be 170 x 0.6 = 102 beats per minute. At no point during his walk (or any other exercise he is taking) his heart rate should exceed 102 per minute. The heart rate (HR) is generally taken for 10-15 seconds immediately at the end of the exercise. It is difficult to take the HR while exercising. On the other hand, after stopping the exercise, the HR comes down rapidly. Therefore, it is important to count the pulse immediately upon stopping the exercise, and count it for only 10-15 seconds. The ten-second count may be multiplied by six, or the 15 –second count multiplied by four, to get the HR per minute.

However, sometimes we run into difficulty with this approach. Suppose a sixty—year old person is advised to exercise such that his THR is fifty per cent of the MHR. His MHR = 220 - 60 = 160 per minute. Therefore his THR is 160 x 0.50 = 80 per minute. If his resting HR is also 80 per minute, he cannot exercise at all! Another approach (called the Karvonen equation), although a little complex, does not have this problem, and is even otherwise more reliable. In this approach, a percentage of the heart rate reserve (HRR) is added to the resting HR. Suppose the sixty-year old is advised to exercise such that he encroaches upon fifty percent of the HRR. 

MHR            =     220 — 60     = 160 per minute 
Resting HR   =     80 per minute
HRR            =     160 — 80     = 80 per minute 
THR            =     (160 — 80) x 0.5 + 80 
                   =      40 + 80
                   =      120 per minute

Let us take another example. Suppose a forty—year old has been told to encroach upon sixty per cent of the HRR, and suppose his resting heart rate is 70 per minute. 

MHR         =    220 - 40         = 180 per minute 
HRR         =     180 - 70         = 110 per minute
THR         =     (110 x 0.6) + 70
                = 66 + 70
                =136 per minute

Hence this person’s exercise should be of such an intensity that towards the end of exercise, his heart rate is about 136 per minute or less.

‘Towards the end of exercise,’ means the end of the phase of vigorous exercise. During cooling down, the heart rate starts coming down, we are interested in the highest steady heart rate during exercise, which may be measured by counting the pulse as soon as possible at the end of the phase of vigorous exercise. 

How do we count the pulse?

The pulse may be counted at the front of the wrist towards the thumb-side. If you are right—handed, and have a watch on your left wrist, the simplest thing to do is to place two fingers (index and middle linger) of the left hand over the ‘pulse area’ of the right hand. There is an instinctive tendency to press the ‘pulse area’ with the tips of the two fingers. But the pulse is actually felt better if you place the pulp of the two fingers rather gently over the ‘pulse area’. lf you do as described here, you will be able to have a good look at the watch. Start counting the pulse when the fast-moving ‘seconds hand’ of the watch reaches a specific point. Keep that point in mind, and count the pulse for ten to fifteen seconds.

Walk and talk

lf you find calculating the THR and counting the pulse too cumbersome, there is a simpler alternative. As you might have figured out, the idea behind the tedious task is that the severity of exercise should be such that it is challenging enough to coax the body to improve, and yet not so hard as to be unsafe. Both these ends, particularly the latter, can be met by the ‘walk and talk’ method, but for that you need a companion. The principle of the method is that you can carry out a conversation comfortably while walking only if you are within your safe limits. When the safe limit is crossed, you get breathless while talking. ^5

How often should we exercise?

The next point in an exercise prescription is the frequency, or how often one is to exercise. Ideally, it should be understood that one must exercise daily. But most of us are likely to be irregular and unless the point is emphasised, slipping is likely to become more frequent than the exercise. Therefore, the prescription emphasizes that the exercise should be taken at least five days a week. Although some studies have shown that exercise programmes with a frequency of three days a week are also effective, two points are important in this context. For a three—days-a-week programme to be effective, either the intensity or the duration of exercise, or both, have to be increased. Secondly, many of us might find it easier to maintain regularity if something has to be done everyday rather than on alternate days.

How much exercise is necessary?

The total amount of exercise taken by a person is the product of the duration, intensity and frequency of the exercise. This product, which combines all these three factors, is the most exact determinant of the efficacy of an exercise programme. That is why many different combinations of duration, intensity and frequency may be equally effective in improving cardiorespiratory fitness and adding years to one’s life. Thus a thirty—minute daily walk may be taken in three instalments of ten minutes each. Further, a thirty—minute walk everyday or a sixty-minute walk on alternate days may be equally effective.

Having said that, however, a few things should be pointed out. First, there is a limit to this formula. A 200-minute walk every Sunday instead of a thirty-minute walk everyday may give more cramps than health benefits. Secondly, one cannot play around too much with the intensity and duration.

^5 A companion may not be necessary for the walk and talk test if you talk on the cell phone as you walk! But this not advisable because talking on the cell phone while walking is risky.

Mild exercise does not enhance cardiorespiratory fitness even if the duration is prolonged. Heavy exercise, on the other hand, even for a shorter duration, may be unsafe if the existing health status is not good. Therefore, medical advice and at least the ‘walk and talk’ test should guide the intensity. The—main idea behind pointing out that some flexibility is possible in the duration, intensity and frequency of exercise so long as their product is reasonably constant is that one should not make a rigid ritual out of the exercise schedule. The rigidity robs the exercise programme of its joy. And, the secret of any successful exercise programme is that the person should enjoy it.

Climbing step by step

A sedentary person just starting on an exercise programme should start with only 10-20 minutes of moderate exercise (encroaching on about 40% of HRR) a day, 3-5 days a week. The duration of exercise may be increased by about twenty per cent after every fortnight. At this rate, it is possible to achieve a duration of 30-45 minutes in 3-4 months. The frequency should also by then reach close to seven days a week. After that the intensity of the exercise may be increased, increasing the encroachment on HRR by about five per cent every fortnight, finally stopping any further increase in intensity when either it becomes difficult to talk while exercising, or when eighty-five per cent of the HRR has been encroached upon, whichever is earlier.

These are only general guidelines. Older persons might End it necessary to progress at a slower pace, as might those who have been sedentary for a few decades. Those having any serious illness which compromises the ability for exercise should consult their physician before starting an exercise programme, before increasing the duration or intensity, or if they notice any untoward symptoms such as breathlessness, palpitation, dizziness, sweating, or excessive fatigue during the exercise.