Dr Pravin Gaikwad is a well-known pediatrician in Navi Mumbai. He and his wife Arati, also a doctor, have been running a clinic in the Navi Mumbai suburb of Nerul for the past several years. The two are longstanding distance runners and triathletes. They have been frequent podium finishers in their age category at various events. In addition to being a doctor, Pravin heads coaching and mentoring at Lifepacers, a Navi Mumbai-based fitness group composed mostly of runners. On March 6, 2020, this blog spoke to Pravin on the importance of exercise and balanced lifestyle in maintaining good health, central to which is a strong immune system.

Is it possible to strengthen our immune system naturally? What should we do for that?

Very simply put, immunity is your defence against invading bacteria and toxins. It is the system involved in defending your body. There is still much to be known in this regard. The main organs involved include thymus, spleen, liver, lymph nodes, bone marrow; cells include T-cells, B-cells, some cytokine proteins, phygocytes – they are like scavenger cells, then those that are anti-inflammatory in function – there are so many things involved. Even the bacteria in the gut – microbiota – they help in immunity to a great extent. So, from a bird’s eye view, a lot of things are involved.

In Marathi, there is a saying: sainya pothavar chalta; it means an army runs on food. Similarly, the easiest way to strengthen immunity is nutritious food, naturally cooked and visually having a range of colors. There are of course more detailed technical specifications but the typical balanced diet we were all taught in school – in India we are fortunate that our ancestors have been following it for ages – if you follow that, the immune system will be good. Along with good nutrition, sleep is an important thing. If you compromise on sleep, you risk compromising your immunity due to factors like hormonal imbalance; so sleep and rest are vital. Third, physical activity is important for maintaining a healthy immune system. Stress is capable of compromising immunity and therefore ability to withstand stress – which physical activity can contribute to – helps strengthen immunity. Among things to avoid: smoking definitely impacts immunity. Alcohol beyond a limit also has the same effect. These habits have to be cut. Smoking is a big no; alcohol only in moderation if somebody wishes to have it. To my mind, these would be the natural ways of maintaining a healthy immune system – nutritious food, adequate rest and sleep, developing ways to withstand stress and avoiding bad habits.

Can you explain how regular exercise helps to fortify the immune system?

The immune system is very responsive to exercise.

The initial perception was that exercise causes problems in immunity. That view was based on studies of endurance athletes; it was found that their immunity can be a bit low. Later, it was found that immunity was better in these people while performing acute short term exercises. Research and data showed that generally less than 90 minutes of endurance activity a day, is definitely helpful. More than 90 minutes could also be useful but there are other angles to consider. Next would be the number of days. There is no mention that you should do this all days of a week. If you refer the recommendations of the World Health Organization (WHO) for maintaining a healthy lifestyle, what they say is: 150 minutes in a week plus two strength training sessions. That last recommendation – the strength training sessions – is something most of us neglect. My view of this is: the 150 minutes typically ends up as moderate physical activity because it will include warm-up and cool down. So the real overall time for exercise will exceed 150 minutes per week, I feel. You cannot increase your heart rate to 80 per cent of your maximum heart rate just like that. It has to be gradual. Otherwise there will be repercussions of not warming up properly. So to sum up, regular physical activity genuinely helps in strengthening immunity. It serves as adjuvant (a substance that strengthens the body’s immune response) to strengthening the immune system.

When there is earlier mentioned physical activity of less than 90 minutes the count of anti-inflammatory proteins, cytokines, neutrophils, phygocytes, NK (natural killer) cells, cytotoxic T-cells, immature B-cells – all this goes up. After a certain time, it comes back to normal. But what is important is that a summation effect occurs (summation effect in medicine is described as the process by which a sequence of stimuli that are individually inadequate to produce a response are cumulatively able to induce a nerve impulse). Over a period of time, immunity is found to be better.

The basic concept of any disease is inflammation. Acute inflammation is useful to the body; chronic inflammation is not. Inflammation can be caused by three things. First is trauma, second is infection and third is allergy. Chronic inflammation is caused by stress. Acute inflammation is caused by acute exercise; that is beneficial, over a period of time it develop the ability of the body to withstand the stresses properly. The body becomes stronger. Ultimately, that is immunity. Then, there are different patho-physiologies. One is that thanks to the summation effect, the immune systems itself becomes more active and capable of adapting better. Another thing to mention here is the microbiota. One third of these beneficial bacteria are the same in you and me. Two thirds is different. Initially it was learnt that the more diverse the bacterial flora, the better is our immunity. Then it was found that athletes have more diverse bacterial flora. One reason for this is that once you are into regular physical activity you tend to address your nutrition intake better. Besides diverse bacterial flora, good diet also leads to optimum vitamin levels.

One of the effects of regular exercise is that it helps reduce instances of obesity. In obesity, the fat cells can contribute to chronic inflammation and chronic inflammation can compromise immunity. Another angle is that of ageing; with age, immunity reduces. The process is called immunosenescence. When you age, the immune system gets progressively dysregulated. It raises susceptibility to various diseases. When there is regular exercise, there is delayed immunosenescence through improved regulation of the immune system. There is something called telomeres in our chromosomes. With ageing its length reduces. However in the case of those with regular physical activity, their telomere length has a better chance of staying normal. That is part of the anti-ageing effects of regular physical activity.

If you exercise or you run – especially run – everything else falls into place. You automatically give up smoking; limit your alcohol intake, take care of your nutrition, sleep and body composition. Just being into fitness, puts the other components into place. Having a goal catalyzes it.

You mentioned about the WHO prescribed norms for exercise. You have rich personal experience as swimmer, runner and triathlete. What would you say is the apt quantity and quality of exercise for an average individual?

I would definitely insist on strength training sessions; at least twice a week. As we age our growth hormone levels decline. Testosterone level declines. Your muscle mass is going to decline. The fat mass will increase. Ultimately, the muscle is a furnace. This means that with the same diet, the same exercise – aerobic without strengthening – you still gain weight. When you strengthen your muscles, not only do you get the popularly known advantages like reduced chances of injury, improved balance and improved bone density; you also slow down the growth hormone decline. Talking of growth hormone, sleep and growth hormone is related. When you have good sleep, there is good growth hormone secretion. All this gives you that anti-ageing effect, more energy and combined with better muscle mass, the potential for a higher level of activity. So do strength training at least two days a week. It should be for the whole body. It can’t be that you are a runner and therefore you strengthen only your legs. Aerobic physical activity can be anything – running, swimming, cycling. I think, 30-40 minutes of such activity – as WHO says, moderate physical activity – with warm-up and cool down and with heart rate rising to 80-85 per cent of maximum heart rate, is good enough.

Now, there are those who wish to challenge themselves. Let’s take the marathon as example. One study showed there was 2-18 per cent increase in sickness level – particularly respiratory tract infections – was found in marathon runners two months before a race and 15 days after a race. We are subjecting ourselves to multiple stresses during those months leading to a race. After running a marathon, there are a lot of chronic inflammatory changes which occur in the body. In my own case, after a marathon I usually do HSCRP (Highly Sensitive C-Reactive Protein) test. The figures are usually high. Then it settles down. I generally run only one full marathon a year. I rarely run half marathons but I do quite a few 10-kilometer runs. It is those speed runs that are more important from a health point of view. Fast for one minute, then slow for one minute – like that some 6-8 times in one particular run, that will be enough exercise. Running for two hours, three hours – that is not really required; it can cause chronic inflammation. Studies show that when you start exercising, in the initial stage, you are contributing to improving your immunity. As you elevate exercise, the risk increases. In heavy exercise, the risk can go up by two to six-folds.

How do you decide severity of exercise? If you take any of the amateur athletes who are pushing themselves, how can they know if they are exercising beyond acceptable limit or not?

Let us talk of the elite athletes. They do severe exercise. But their bodies have adapted gradually to that level of exercise. This is what amateur runners often miss. Good coaches don’t increase mileage by more than 10-20 per cent a week. Every fourth week, you try to incorporate a cutback-week. Follow these routine things. Let me give you the example of Comrades Marathon. I did Comrades in 2018; myself and my wife, Arati. We did not do Comrades back-to-back. I might do it once more when I turn 60. Given Comrades entails lengthy training of 4-5 months, if you are doing it regularly, you may be erring on the side of greater inflammation. Overtraining may also not give you enough sleep. So to return to your question of what qualifies to be severe: if you are not getting up fresh, if you are not sleeping well, if you don’t have enough energy for the day, if your appetite is less, if you are falling ill, if your immunity is declining – those are all signals from the body telling you to cut down. A new runner, for three years at least, he should not run a full marathon. Also remember – running is a muscle-shortening exercise. With age and with constant running – it’s going to affect your speed. Some of the elite runners in the later part of their life, become triathletes. Swimming has the ability to restore muscles to their original length. Plus it involves a different muscle fiber; it also improves breathing.

I think, accepting your declining pace helps you sustain the act of running and enjoy it for more years. Throw off your watches and measuring devices and run. Go with the flow. Except when training for a race, I don’t resort to these gadgets. The longevity of physical activity and fitness is more important than results delivered by great pace. Unfortunately we are fascinated by that pace.

You spoke of the importance of mixing fast and slow running for meaningful work out. There are many people who prefer not to run and are instead into walking. Can they too leverage this blend?

It can be done. In terms of evolution, we are born to run. Once we get used to a certain level of activity, it is normal for the body to learn to use less calories to deliver the same outcome. You do a particular activity, you get some benefits. But later, you don’t. I have been running for years in Navi Mumbai. In that time I have seen many people walking religiously in the morning. But some of them are also gaining weight. That’s because their bodies have got adapted to the routine. They are no longer getting the benefit of walking. You can get the benefit by challenging yourself. There are simple things you can do. For example, you can change the time of your walk; sometimes walk in the morning, sometimes walk in the evening. That way, the body gets a bit shocked. Second, change the terrain. Go to the hills for a change; the body gets challenged in a different way. You can try brisk walking. People try aerobic walking too; you walk like you run. Normal walking burns 4-5 calories per minute. Aerobic walking will burn 8-10 calories per minute. You can introduce the Fartlek concept in walking. Or keep an app that collects data about your walking, if data is a source of motivation for you. Anything that can be measured can be improved upon. I feel somebody who can walk for 30 minutes should be able to run. And if you have been running regularly for three months, you can become a runner. The point is – whatever physical activity you are engaged in, you should challenge yourself a bit. Plus, don’t forget strength training. That helps you walk faster too.

What kind of effect does stress have on the immune system?

Stress impacts the immune system. Stress is of two types. There is the psychological type. Then there is the physico-chemical type which encompasses environmental stress, food, toxins we inhale etc. The body has a tenacious ability to adjust to the challenges in the environment. But if your immune system is compromised or you are under so much duress that the resultant stress is beyond your capacity to cope with, then it can manifest as disease. It can give rise to chronic infections, auto-immune diseases, inflammations and even cancer. I remember a study on anti-depressants used in the treatment of cancer. They don’t address the cancer per se; they address the stress factor. Beta blockers are medicines used to tackle the higher levels of hormones like adrenalin that can be triggered by stress. Prolonged chronic stress can result in more pro-inflammatory cytokines and health conditions thereof.

How important is rest and recovery in the scheme of things?

Seven to nine hours of sleep will maintain your growth hormones properly. Memory consolidation also happens during sleep. This is important for children. There was a time when school used to be from seven in the morning till twelve noon. You come home and sleep. That consolidates memory. Evening you play. Then you study, eat and sleep. You find something similar in elite runners. They train twice a day. For them, their sleep consolidates their training. Amateur runners, who hold down jobs and pursue their passion, are probably at a disadvantage here. If you can catch a nap some time in between, it helps. It should also be mentioned in this context that use of alcohol and excessive use of mobiles disturbs sleep pattern. If you want good performance, eventually it is about TNR – Training, Nutrition and Recovery. Recovery is where our muscles actually get trained. Then they perform better. On partially trained muscles if you exert, they will be prone to injury. Rest and recovery are the same things. It is very important. I can give you an instance from personal experience. My personal best in the marathon is three hours 38 minutes, which I got at the 2017 Mumbai Marathon. Some days before the event I developed pain in my left calf muscle. So I stopped everything. After 15 days of rest, a Thursday night, I ran around six kilometers to see how the leg held. On Sunday, I got my PB. That forced rest of 15 days helped. The body always gives you a signal of how it is feeling. You just have to listen to it. I also strongly believe in the seasonality of endurance activities. We were typically expected to peak in the winter months because that is when most of the events were held. But now there is an event every weekend. People participate. I feel we should not. Constant racing is not going to improve your performance. You have to give your body time to recover.

Herein, on the nutrition front, one study found that 30-60 grams of carbohydrates per hour for a marathon or any activity beyond 90 minutes, helps reduce the post-race inflammation. Polyphenols – found in fruits – also help similarly. Banana and good carbohydrate intake is thus good for your recovery.

There is the observation that you are good in-season depending on how well you trained off-season. What do you recommend for the off-season?

Mileage has to be less. I would put emphasis on agility, strength training, nutrition and making sure your weight does not increase too much. Don’t compromise on sleep. One hour of physical activity in this period is good enough.

In terms of the quality of running you do in the off-season: take it easy – would that be correct?

Take it easy. But then don’t run easy every time. Do simple things like – open up your strides for 20 seconds, recover for a minute and then open up again. Do that six to eight times. Cool down. Or you can do Fartlek with your friends around; that is enjoyable. Keep long runs fewer in number than when you are training for a race. Similarly reserve tempo runs for the time you are training towards a race.

(The author, Shyam G Menon, is a freelance journalist based in Mumbai.)