There is never a good time as today to start building up on good habits.
Exercising has been known to make us strong physically as well as mentally. Researchers have accumulated data that support that moderate exercises have a beneficial effect on our immunological system also.
A number of studies over the years have yielded results that exercises boost the cell mediated immune system that is responsible for fighting viruses.
In a study of healthy adults, It was shown that pursuing aerobic exercise for 5 days in a week decreased the risk of URI by 43 % in general and the figure increased to 46% while comparing the subjects who were most physically active as compared to those who were least physically active.1
Another study by Mathews et al, in a cohort of 641 healthy adults pursuing variable levels of physical activity , found the reduction of a 29% reduction in Upper respiratory tract infection( like sore throat) risk was observed in comparing the upper to the lower quartile of activity, after controlling for age and gender.2
Even though moderate exercise has been associated with beneficial effects , it has also been shown that high intensity vigorous exercises are supposed to decrease the immunity and predisposes athletes to frequent flu episodes by compromising their immunity. But this viewpoint is controversial as refuted by a recent review that was published in the month of January 2020 as many of these so called infective episodes were either because of allergic phenomenon or because of contributory factors like psychological stress, poor sleep, attendance to mass sporting events like marathons etc.3
So for a normal person to protect themselves from viral infections including COVID 19, it is simply enough to be physically fit and be consistently active to garner the health benefits of the exercises while taking precautions to stay away from the mass events or big gatherings.
Q. Mechanism by which Immunity is boosted by exercise ?
Our immune system is made of Cell mediated and humoural immune systems. And these work in conjunctions to create a step by step immune defence mechanisms whenever an infective organism invades our body.
Each time we exercise , our immune system promptly releases billions of effector T Cells ( which directly attack on the viruses by directly recognising and killing the viruses. These cells come out of the hibernation from the lymphoid tissues where they sleep; they are called for help in a case of acute infection. Through the bloodstream they reach the various organs like lungs or gut which might be the primary seat of infection. Frequent release of these cells help us maintain good immunity against these viral intruders.
Exercise also helps in release of certain chemicals in our body which help in fighting the infections - namely IL6 , IL7 and IL 15 ( IL - interleukins) . Together they help mobilise the T cells which attack on viruses and prepare the immune system for further attacks in case the organisms are successful in invading the body.4,5
Why do you need to measure exercises ?
Exercises with different intensity impact your body system, especially immunity, in a different way. Evidence from studies suggest maximum immune boosting effect is derived from moderate intensity exercises. So, it is important to understand what kind of intense exercise we are doing and what kind of effect it will have on your body.
How do we measure exercise ?
Exercise experts measure activity in metabolic equivalents, or METs.
WHO defines METs as MET is the ratio of a person's working metabolic rate relative to their resting metabolic rate. Or One MET is defined as the energy it takes to sit quietly. For the average adult, this is about one calorie per every 2.2 pounds of body weight per hour; someone who weighs 160 pounds would burn approximately 70 calories an hour while sitting or sleeping.6
Another easier way to classify exercises into moderate and vigorous is on the basis of an increase in heart rate achieved in percentage of your maximal heart rate after exercise.
Moderate Exercise would be any exercise that will increase your heart rate to 50-60% of your maximal heart rate.
Vigorous Exercise would increase your HR to 70% to about 85% of your maximum heart rate.
How to measure pulse rate : Pulse rate(PR) is a surrogate indicator of the Heart rate (HR) and can be used at home to replace HR for calculation purposes.
Just keeping 3 fingers on the outward edge of the wrist would help you perceive the pulsations. Taking the pulse for 6 seconds and multiplying by 10 would give you an approximate Pulse rate in a minute.
For example if you want to create a target of PR for Vigorous exercises
Subtract your age from 220 to get your maximum heart rate.
Calculate your resting heart rate by counting how many times your heart beats per minute when you are at rest, such as first thing in the morning. It's usually somewhere between 60 and 100 beats per minute for the average adult.
Calculate your heart rate reserve (HRR) by subtracting your resting heart rate from your maximum heart rate.
Multiply your HRR by 0.7 (70%). Add your resting heart rate to this number. You can call it Target PR 70
Multiply your HRR by 0.85 (85%). Add your resting heart rate to this number. You can call it Target PR 85
These two numbers are your average target heart rate zone for vigorous exercise intensity when using the HRR to calculate your heart rate. Your heart rate during vigorous exercise should generally be between these two numbers.
Understanding this value would help you categorise the exercise as moderate or vigorous.7
How do I decide what is good for you ?
The intensity of different forms of physical activity varies between people. The intensity of physical activity depends on an individual's previous exercise experience and their relative level of fitness. Consequently, the examples given below are provided as a guide only and will vary between individuals.
What is good for you depends on what your targets are. Goals to pursue exercise may be varied for different people.
For sense of well being
Diabetes management or management of metabolic syndrome
Lifting up of mood
Any athletic activity might be one of the goals
So exercises that would be best suitable for a person depends on what is the goal of the person to pursue that physical regime. Keeping in mind the final target, a person needs to build a plan to reach that goal gradually. Remember there are no shortcuts and it is the discipline, persistence and determination in the long run that will matter and decide if you will achieve your goals.
Q. What are the recommendations for the general population by various Medical Bodies ?
Many leading organisations throughout the world have suggested routine physical activity to get benefits on cardiovascular, metabolic health and to get benefits on bone mass, for depression, and to decrease the risk for breast and colon cancer.8
AHA - American Heart association suggests following physical activity guidelines for adults aged 19 to 64 :
All adults should do some type of physical activity every day. Any type of activity is good for you. The more you do the better.
aim to be physically active every day. Any activity is better than none, and more is better still
do strengthening activities that work all the major muscles (legs, hips, back, abdomen, chest, shoulders and arms) on at least 2 days a week
do at least 150 minutes of moderate intensity activity a week or 75 minutes of vigorous intensity activity a week
reduce time spent sitting or lying down and break up long periods of not moving with some activity.
WHO agrees with the above recommendations and there are few more additions.9,10
1. Adults aged 18–64 should do at least 150 minutes of moderate-intensity aerobic physical activity throughout the week or do at least 75 minutes of vigorous-intensity aerobic physical activity throughout the week or an equivalent combination of moderate- and vigorous-intensity activity.
2. Aerobic activity should be performed in bouts of at least 10 minutes duration.
3. For additional health benefits, adults should increase their moderate-intensity aerobic physical activity to 300 minutes per week, or engage in 150 minutes of vigorous-intensity aerobic physical activity per week, or an equivalent combination of moderate- and vigorous-intensity activity.
4. Muscle-strengthening activities should be done involving major muscle groups on 2 or more days a week.
Q. How to build up on exercises ?
You can also achieve your weekly activity target with:
several short sessions of very vigorous intensity activity
a mix of moderate, vigorous and very vigorous intensity activity
You can do your weekly target of physical activity on a single day or over 2 or more days. Whatever suits you.
These guidelines are also suitable for:
pregnant women and new mothers
Make sure the type and intensity of your activity is appropriate for your level of fitness. Vigorous activity is not recommended for previously inactive women.
Q. Are there any special precautions to be taken by elderly ?
It has been shown in studies across the world that the frailty increases as we grow old and older people lead the most sedentary lifestyle.11
The importance of physical activity in an increasingly elderly population can not be over emphasized as it has been shown to improve cardiovascular health, decrease falls, decrease dependency of the elderly individuals in varied studies.12
The targets in elderly are the same as the adult population. WHO adds the following targets in addition:
Adults of this age group, with poor mobility, should perform physical activity to enhance balance and prevent falls on 3 or more days per week.
When adults of this age group cannot do the recommended amounts of physical activity due to health conditions, they should be as physically active as their abilities and conditions allow.
The precautions that elderly people who are more than 65 years of age should take is :
Start the exercise regime under supervision
Start slow and build up more gradually and only introduce new exercises once the previous ones are consolidated
Keep undergoing balance training so that while exercise they do not lose balance.
Q. What is Moderate Exercise ? What are the examples and how does it affect my body ?
Moderate exercises mean any exercise which increases your METs to 3-6. That is any exercise that will increase your heart rate by 50-60% of your baseline heart rate. Simply put, moderate activity will raise your heart rate, and make you breathe faster and feel warmer.
Examples are :
like brisk walking, water aerobics, hiking, rollerblading, dancing, double tennis cycling, working out on treadmill or a cross trainer and swimming etc
American Heart Association and Center for Disease Control recommends different durations. But the general consensus is 30 minutes for 5 days in a week or 150 minutes in a week.13,14
Q. What is Vigorous Exercise? What are the examples and how does it affect my body ?
Generally vigorous exercises would increase your energy cost more than 6 times and so METs is more than 6 times
In general, 75 minutes of vigorous intensity activity can give similar health benefits to 150 minutes of moderate intensity activity.
Examples of vigorous activities : Jogging, fast swimming, riding uphill or fast, walking upstairs, sports - football, hockey, netball, hockey, skipping rope, aerobics, gymnastics, martial art.
High intensity short burst exercises are known to increase the stress hormones in the body which might transiently increase your predisposition for infections.
You do not need to compete with others in terms of building your exercise stamina. The only person you need to beat you yourself and that too gradually and step by step. It is more about giving yourself that extra nudge to do just few more sets. Just building on your maintenance Heart Rate one day at a time.
Even if you start with 1 minute per day, just make it your daily target to beat your self the next day by increasing by 1 minute daily.
Nieman DC, Henson DA, Austin MD, Sha W. Upper respiratory tract infection is reduced in physically fit and active adults. Br J Sports Med. 2011;45(12):987‐992.
Matthews CE, Ockene IS, Freedson PS, Rosal MC, Merriam PA, Hebert JR. Moderate to vigorous physical activity and risk of upper-respiratory tract infection. Med Sci Sports Exerc. 2002;34(8):1242‐1248.
Simpson, Richard & Campbell, John & Gleeson, Maree & Krüger, Karsten & Nieman, David & Pyne, David & Turner, James & Walsh, Neil. (2020). Can exercise affect immune function to increase susceptibility to infection?. Exercise immunology review. 26. 8-22.
David C. Nieman, Laurel M. Wentz. .The compelling link between physical activity and the body’s defense system. Journal of Sport and Health Science. Volume 8, Issue 3, May 2019, 201-217
McPhee JS, French DP, Jackson D, Nazroo J, Pendleton N, Degens H. Physical activity in older age: perspectives for healthy ageing and frailty. Biogerontology. 2016;17(3):567‐580.
Langhammer B, Bergland A, Rydwik E. The Importance of Physical Activity Exercise among Older People. Biomed Res Int. 2018;2018:7856823. Published 2018 Dec 5.
Dr Sweta Singla
Neurology & Sleep Medicine
Kalpavriksh Superspeciality Center