Being fit and lean. The two most powerful weapons against virus

After the pandemic, health has certainly risen to the top of the list of consumers personal priorities, especially after so many weeks of lockdown. Among the primary strategies for strengthening health is a wellness lifestyle based on exercise, balanced nutrition and a positive approach to life. In this regard, a number of studies have shown that the fitter and leaner you are the better your immune system, while reducing the risk for several types of respiratory illnesses.

Always focused on promoting physical exercise as a medicine for people's health, Technogym has organized Technogym Talks, a series of exclusive webinars to offer knowledge and experiences of international guests from the world of fitness, sport and health. One of the most attended was  held by Prof. David Niemann of the Department of Biology of the Appalachian State University, a pioneer of research in the field of exercise applied to immunology, entitled Being fit and lean: the two most powerful weapons against Covid-19.

The professor illustrated how the adoption of lifestyles consistent with good immune health are adjuvants in the treatment of the virus. These primary prevention strategies are particularly important in ageing societies with a high prevalence of obesity and related comorbidities and are essential adjuvants to COVID-19 mitigation practices.

A virus that spreads quickly  

Acute and chronic respiratory illness (e.g. influenza) have been the most common infectious diseases with widespread morbidity and mortality even before the COVID-19 pandemic. However, with the speed of which the COVID-19 has spread these types of illnesses have become a worldwide issue.

COVID-19 can cause severe symptoms and even death and has spread to almost every country in the world. COVID-19 is highly transmissible (primarily airborne droplets when coughing, sneezing, talking) which has led to the number of cases rapidly increasing. This is primarily due to the virus having a fairly long incubation period (on average 6 days, but it can be as long as 22 days) where the person can pass on the virus. Each infected person spreads the infection to an average of 2-3 people. Therefore, we need to protect ourselves the best we can for the sake of our health and others.

One way we can do this is by becoming fitter and leaner as a society. 

Epidemiology: Who is the most likely to get infected?

With significant resources being devoted to developing a vaccine hopefully one will be developed soon. However, the vaccine will be targeted initially to healthcare workers and vulnerable people, so it may be some time before it is available to the majority of the population. Also, there is no guarantee that the vaccine will be effective and so we have to try and reduce our risk of infection.

There are two strategies to reduce the risk of COVID-19. The first is mitigation by reducing the spread of gems by following government guidelines such as regularly washing your hands and avoiding touching your face. The second is the adoption of lifestyle practices consistent with good immune health so that if you do become infected your chance of recovery is improved. A number of studies have shown that generally the fitter and leaner you are the better your immune system.

Studies have shown that the people at higher risk for severe illness from COVID-19 include older males, and people of all ages with obesity and underlying medical conditions such as hypertension, cardiovascular disease, chronic lung disease, and chronic metabolic diseases such as type 2 diabetes. In fact, one study done in March this year in 19 states in the US showed that 88% of all people hospitalized with COVID-19 had one or more underlying health condition with hypertension, obesity and chronic metabolic disease such as diabetes being the leading 3. This study also showed that the risk also increases with age.

Aging and obesity impair host viral defense

Across the world there has been and will continue to be a demographic shift towards an older, obese population. It is estimated that by 2030 60% of the worldwide population will be overweight/obese. Obesity has been shown to increase the risk of developing hypertension, type 2 diabetes, and cardiovascular disease, three of the most important underlying conditions for severe cases of COVID-19. Obesity also causes systemic inflammation which could prime the cytokine storm that is linked with the most severe cases of COVID-19. Also, vaccine-elicited responses are diminished in the obese, leaving them more vulnerable to infection after receiving a vaccine. There is also an increased severity and duration of viral infections, and potential for the evolution of pathogenic viral variants in obese people.

Aging also leads to similar negative changes in viral defense. Aging increases the susceptibility to infectious diseases and reduced the effect of vaccinations. It is estimated that by 2050 16.7% of the world population will be over 65, up from 8.5% in 2015. These figures have shown us that if we do not do something to counteract the effects of aging and obesity, this COVID-19 pandemic could just be the start of a number of infectious disease pandemics spawned by novel pathogens that will continue to inflict widespread morbidity and mortality.

Viral illness and the exercise workload continuum

Exercise has been shown to increase the viral defence of the body. Regular aerobic exercise similar to 30-60 minutes of near-daily brisk walking improves the body’s defence against viruses. This reduces illness risk and lowers systemic inflammation. Thus, regular exercise training can be viewed as an immune system adjuvant and is of particular clinical value for obese individuals with comorbidities, and older individuals. Epidemiological and randomized clinical trials support a 40-45% reduction in illness days with acute respiratory infections in adults of all ages who engage in near-daily aerobic activity compared to sedentary behaviour. A study done into the risk of infectious disease mortality showed results that physical activity more than halved your risk of mortality from bacterial and viral infections.

These studies support the viewpoint that regular physical activity and the avoidance of obesity maintain immune health while reducing the risk for several types of respiratory illness. These primary prevention strategies against respiratory illnesses are particularly important in aging societies with a high prevalence of obesity and related comorbidities and are essential adjuvants to mitigation practices.

However, at the other end of the continuum there is overtraining. Extreme training can lead to overtraining which has been linked to greater chance of infection. A study in marathon and ultramarathon runners found that there was a 5.9 times higher risk of getting sick after running the marathon than if they did not especially when combined with mental stress, sleep disruption and travel. These data lead to the suggestion that: overtraining is not recommended in areas of the world where COVID-19 transmission is high; and intense exercise when infected with COVID-19 or other systemic viruses should be avoided.

However, it is important to note that overtraining is very rare and requires an extended period with extreme exhaustive training for the state of overtraining to be reach and so for the vast majority of the population overtraining is not an issue to be concerned about. Overtraining mainly applies to elite level athletes who are training multiple times a day at a very high intensity.

In conclusion, this COVID-19 pandemic is a wake-up call to the world that primary prevention countermeasures focused on better health behaviors and, as a population, becoming more active are necessary to help boost our immune systems and viral defense. The fitter and leaner members of society are shown to have improved immune defense and this needs to be the aim for all. A study into active old people showed they had similar immune function to those half their age. Secondary and tertiary prevention approaches centered on vaccine and therapeutic development will take time and may not be fully effective, giving even more urgency to staying fixated on primary prevention.