What the science says about staying in shape during the Coronavirus crisis
How should you train in the coronavirus days?
Without a doubt, the Research shows a link between moderate, regular exercise and a strong immune system. 
Make it short.
Exercises are crucial for a healthy body and immune system.
However, there is evidence that too much intense exercise can reverse all the benefits. [2, 3, 4, 5]
You should remember that not only too intense or too long exercises lower the immune system, leaving you vulnerable to the coronavirus.
But also without adequate recovery, you can be exposed to catch colds or flu.
Factors that may lower your recovery:
- Stress 
- Poor nutrition [5,6]
- Fatigue and lack of sleep 
- and more (smoking, age, genetics, gender, hormonal balance)
How long should we exercise?
In the first hours after the exercises, the immune cells move to the parts in the body that are more likely to become infected, such as the lungs. 
Which may even seem quite useful, especially to fight coronavirus as it respiratory tract infection affecting the lungs.
At least if the exercise session was between 20–30 min at moderate intensity (mouse study). 
30-45 minutes of moderate-intensity exercises I believe will be a fair range for humans for maximum health benefits.
I will explain why in the following studies.
Nonetheless important to mention the immune change will be temporary and in most cases will return to the base level after a few hours to days.
The first research shows that high-intensity exercises can make you susceptible to illness for up to 72 hours after the exercise session if the session lasts more than 90 minutes. [8, 9]
Intense exercise may cause a temporary decrease in the immune system.
During intense physical activity, the body produces hormones that temporarily lower immunity. 
The next study  with 416,175 individuals (199,265 men and 216,910 women) who participated for an average of 8 years.
The goal was to find how Physical Exercise duration and intensity affect mortality.
As you can see, the first 15 minutes of exercise reduces mortality by 14% and each additional 15 minutes gives 4% additional mortality benefit.
Until we reach about 45-60 minutes daily, where we need to spend much more time to get an even slight mortality decrease.
You may see the vigorous red line is getting the maximum benefit first, and starting wasting time after 50 minutes, start wasting time and taking other risks.
- Vigorous (eg, jogging and running)
- Moderate (eg, walking and brisk walking)
If you weightlift in the gym, by comparing the Metabolic Equivalent of Task (MET) of vigorous (6-20 MET), moderate (2-4.8 MET).
The weightlift can be put in the middle between, with 3.5-6 MET.
Two later follow-up studies [11,12] find that most of the health benefits occur after only 20-40 minutes.
With each additional duration, the benefits begin to decline and the risk like cardiovascular disease increases.
Although it can be concluded that exercising is super healthy, surprising right?
Even training more than an hour will be much healthier than the lack of training.
At the same time, it will be a waste of our time and without proper recovery can even put us at risk, or even temporarily weakening the immunity, which is a big NO in the corona days.
As you saw above to get the health benefits, high intensity is not required.
It may even harm, as after some point it decreases the immunity even faster.
Every high-intensity workout is taking from the pool of building blocks to repair the muscles and the bones, take it into account.
If you weightlift in the gym, it may decrease the available recovery and hit your gains.
Avoid cardio or exercise that will require heavy breathing or mouth breathing.
As you can breathe and exhale the coronavirus from a greater distance.
If needed, fast walking will be best to boost the heart rate at the beginning of the workout.
But should you go to the gym?
Maybe you like me and going gym turned into a strong habit, maybe you sold your home equipment as the gym gives you much more the motivation to exercise than at home.
Yet the justification of going to the gym now is a source of concern.
So you are young and healthy? Most likely will recover pretty well from the coronavirus.
When it is still worth skipping the gym?
Do you have relatives at a rick group? Or maybe some co-workers you contact every day or often enough with some breathing problems?
Here are the risk groups:
- Heart disease
- Lung disease
- Older adults
If you can stay home, you will make things safer for everyone around you, by just not been there and not helping it spread.
Don’t want to disrupt your everyday life by missing the gym?
Take these tips:
The "make it short" and "Decrease intensity" rules benefits don't stop there.
By reducing the time you spent in the gym, you also reduce the chances to get infected.
Not only for you but for other people, as fewer people are at the same at the gym.
Avoid group training or a large crowd of other gym members.
This is not hard these days since actually few people go to the gym and some even close.
Try to go not at peak hours (from 4 pm to 9 pm is a big NO)
Preparing for the gym
Plan your drink and eat time as during these activities you will probably touch your face and mouth with the hands it will be great to eliminate this at the gym.
Even if your gym equipped with lockers, water coolers, and showers it will be better to put on gym clothes in advance and do not use gym aids.
While most of the Gyms are enhancing their cleaning protocols, by Increasing the frequency and sanitization, especially at high touch areas such as door handles, lockers, equipment, etc.
I would take it with a grain of salt, as we need to be aware that due to the lack of workers, it is very tempting, insist on the presence of an employee at work even with minor symptoms, not hard to suggest that these very workers will be engaged in cleaning.
Ask for precautionary measures your gym is taking, and make sure it meets your safety needs.
As for me, I’m staying at home, with my weight vest that I likely not sold recently.
- 1 The compelling link between physical activity and the body's defense system. 2018
- 2 Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. 2012
- 3 Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise. 2012
- 4 Neuro-computational impact of physical training overload on economic decision-making. 2019
- 5 The risk of marathon runners–live it up, run fast, die young? 2008
- 6 Debunking the Myth of Exercise-Induced Immune Suppression: Redefining the Impact of Exercise on Immunological Health Across the Lifespan. 2018
- 7 Chronic exercise reduces illness severity, decreases viral load, and results in greater anti-inflammatory effects than acute exercise during influenza infection. 2009
- 8 Running: From Middle Distance to Marathon. 2009
- 9 Military Strategies for Sustainment of Nutrition and Immune Function in the Field. 1999
- 10 Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. 2011
- 11 Physical Exercise and Health. 2014
- 12 Exercise at the Extremes: The Amount of Exercise to Reduce Cardiovascular Events 2016