Dear Mr. President

Dear President Ramaphosa,

They do say that hindsight is 20-20 vision and, as night follows day, you will be criticized for locking down excessively here and not enough there. I am a firm believer that, based on the knowledge we had at the time, your decision to move into early lockdown was the right one. As Health Minister Dr. Zweli Mkhize said, the lockdown achieved its intention: it bought time to get our hospitals ready for Covid-19.

Now, despite winter setting in and infection numbers climbing, I believe you have again made the correct decision in opening up schools and much of the economy. Equally important, in my view, is the decision to allow people to get outside and exercise. Why? That is what this letter is about.

Despite us being a sport-loving nation, we South Africans are not a particularly active one, with almost 40 percent of us categorized as dangerously inactive1. I strongly believe that outdoor exercise is one of the most important things we can do to cut stress and boost our immune system, and in that way try to minimize the impact of this and future pandemics.

The devil, of course, is in the detail. Take alcohol and cigarettes: the National Disaster Management Centre has been criticized for allowing the sale of alcohol yet continuing to ban cigarettes. Are cigarettes dangerous in this time of the coronavirus? That’s unclear. Granted, studies do show that smokers have a compromised immune system and an increased susceptibility to getting viral infections2. And a large, new UK study has shown that Covid-19 patients who smoke are at increased risk of dying of the disease3. On the other hand, a French study suggests that nicotine may prevent the illness by blocking the notorious ACE-2 receptor that the coronavirus uses to attack cells4.

In short, the jury is still out. Yet even if it did prove that cigarettes worsened Covid-19 outcomes, when has a ban ever cured addictive habits? During Prohibition in the US a century ago, the result of the ban on the sale of alcohol was the explosion of the bootlegger liquor trade. A ban on cigarette sales has had much the same result, with the black-market sale of cigarettes skyrocketing (costing Treasury much-needed revenues, for one thing). What is the government’s role here? My view is that it should encourage good habits and prod us in the right direction with sin taxes against the likes of cigarettes, alcohol and sugar (the last is a whole other health story). However, it will always be up to the individual to break bad habits and choose a healthier life.

And that brings us back to exercise – and, more accurately, daily exercise, which is a habit well worth encouraging. Let’s start by seeing what happens when people are cooped up: a survey of over 3,000 Americans found that they exercised far less during lockdown, and watched far more TV. The result was worsening mental health in that population5.

I spent level 5 of lockdown encouraging people to optimize their sleep, to combat stress and to do some exercise in order to minimize the impact of the disease. However, I have elderly patients who have been too scared to go outdoors. I know young adults who isolated so long indoors with excessive computer-gaming and comfort-eating that they are now struggling to break these bad habits. Both groups are less healthy and more depressed than before lockdown.

Or take the experience of UK Prime Minister Boris Johnson, who was criticized for being slow to mobilize the UK into lockdown, which may well have led to thousands of excess deaths – of whom he was very nearly one. His well-publicised illness seems to have been a Damascene moment that changed his approach to his own health. As he admits, at 115kg he was grossly overweight for his height. Since then he has visibly slimmed down and has implored the nation to get outdoors and be active. He knows a nation of couch potatoes is far more vulnerable both in this pandemic – and in others.

Why, then, is outdoor exercise so important for our health? There are three reasons – a hormone called cortisol, vitamin D and the benefits of exercise itself:

Many people know cortisol as our stress hormone and that excessive stress can lead to illness. Yet the opposite is also true: people who run out of cortisol often die from respiratory infections6. Therefore, rather like the Goldilocks principle, we don’t want too little cortisol and we don’t want too much: we want it just right. To achieve this healthy mixture, we need to get a good night’s sleep and do two simple things: get outside and do short bouts of intense exercise. Getting outdoors in the morning boosts our circadian rhythm7, helps to release healthy doses of cortisol8 and boosts our immune system9. Doing short, intense exercise releases healthy amounts of cortisol which boosts our immune system1011. Healthy cortisol levels are hugely important for a healthy immune system. Sleep, stress management and outdoor exercise are the best ways to ensure this.

2.Vitamin D3:
One of the most interesting facts to emerge from coronavirus studies is that people with low vitamin D levels are susceptible to bad bouts of Covid-19 while those with higher vitamin D levels fare much better1213. Studies also show that people who spend all day indoors have low vitamin D levels with a higher infection rate, while those who spend time outdoors have higher vitamin D levels and fewer and less serious infections.
To explain how the sun affects our vitamin D levels, it is useful to look at the studies of skin cancer. UVA radiation breaks down vitamin D, while UVB builds up levels of vitamin D14. Sunlight is comprised of both UVA and UVB, and therefore tends to have a beneficial effect on vitamin D levels. People who work indoors receive only UVA radiation through windows and from fluorescent tube lights, and so suffer from reduced vitamin D levels. As a result, people in a cancer study who were isolated indoors suffered more skin cancer than those who worked outdoors. What that means is simple: to boost our vitamin D levels, to boost our immune system we must get outdoors on a daily basis.

If we want to live a long, healthy life then one of our key priorities should be daily exercise. Although there is still much debate as to whether long-distance marathons are good or bad for us, short sharp bursts of breathless exercise have been shown to be exceedingly beneficial. What does this sort of functional fitness do? It reduces insulin resistance (which cuts our risk for obesity, heart attacks and strokes15.) and increases the activity of the genes that help us to live longer16. Most importantly, it boosts our immune system17. If people can’t manage this, then a daily brisk walk or even working in the garden is a very good start.

As a nation we surely cannot afford another lockdown when the next pandemic arrives – and arrive it will – so we must use the time we have to boost the nation’s health. For the most part, of course, health is a personal choice: a government cannot compel it, a doctor cannot prescribe it – the individual needs to choose it. In this era of diabetes, obesity, inactivity and heart disease, encouraging people to make the right, healthy choice is one of the biggest challenges for governments. Among many other aspects, an unhealthy nation is a financial burden. The solution is cheap – indeed, it is free: encourage people of all ages to get outdoors for some daily exercise, which will boost their healthy cortisol levels, their vitamin D levels and their immune systems.

1Almost 40% of South Africans dangerously inactive – WHO study. Medical Brief. 2018:
2Van Zyl-Smit. Tobacco smoking and Covid-19 infection. The Lancet. 2020:
3Williamson E et al. OpenSAFELY: factors associated with COVID-19-related hospital death in the linked electronic health records of 17 million adult NHS patients. MedrxIV. May 2020.
4Does nicotine protect us against coronavirus. The Conversation. 2020.
5Meyer J et al. Changes in physical activity and sedentary behaviour due to the COVID-19 outbreak and associations with mental health in 3025 US adults. Cambridge Engage. May 2020:
6Addison’s patients lack killer immune cells. ScienceDaily. 2017.
7Blume C et al. Effects of light on human circadian rhythms, sleep and mood. Somnologie. 2019: 23: 147-56.
8Hadlow N et al. The effects of seasons, daylight saving and time of sunrise on serum cortisol in a large population. Chronobiol Int. 2014: 31: 243-51.
9Quing Li. Effect of forest bathing trips on human immune function. Environ Health Prev Med. 2010: 15: 9-17.
10Hill EE et al. Exercise and circulating cortisol levels: the intensity threshold effect. J Endocrin Invest. 2008: 31: 587-91.
11Goldman B. Study explains how stress can boost immune system. Stanford Medicine. 2012:
12Mitchell F. Vitamin-D and COVID-19: do deficient risk a poorer outcome? The Lancet. 20 May 2020.
13Ilie P C et al. The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality. Aging Clin and Experimental Research. May 2020.
14Lucas A et al. Increased UVA exposures and decreased cutaneous vitamin D3 levels may be responsible for the increased incidence of melanoma. Med Hypotheses. 2009: 72: 434-43.
15Keshel, T. E. et al. ‘Exercise training and insulin resistance: a current review.’ J Obes Weight Loss Ther (2015): 5: S5–003.
17Regular exercise benefits immunity – even in isolation. ScienceDaily. 2020: