When we are sick and try to train, especially training at a high intensity and or for a long duration will make it harder for our immune system to function. No! Don’t exercise when you are sick.
What is the immune system’s role? It protects our body from harmful substances, germs and cell changes that could make us sick.
How does an exercise session affect our immune system?
Short duration combined with high intensity exercise does not bring immune suppression.
Moderate duration and intensity exercise can boost our immune system. (When we are healthy performing consistent, moderate exercise and resistance training can strengthen our immune system.)
Long duration combined with high intensity can depress our adaptive/acquired immune system. When this happens our immune system does not work as it should and we are vulnerable to infections.
Our immune system can be broadly sorted into categories:
Innate Immunity
Innate immunity is the immune system which we are born with, mainly consists of barriers on and in the body that keep foreign threats out, and includes the skin, stomach acid, enzymes found in tears and skin oils, mucus and the cough reflex. Basically it is the first line of defense in the immune response. Innate immunity is non-specific, meaning it doesn't protect against any specific threats.
Adaptive/Acquired Immunity
Adaptive, or acquired, immunity targets specific threats to the body. Our immune system builds a defense against those specific threats. In adaptive immunity, the threat must be processed and recognized by the body before the immune system can create antibodies specifically designed to the threat. After the threat is neutralized, the adaptive/acquired immune system "remembers" it, which makes future responses to the same germ more efficient.
Innate and Acquired Immunity according to the National Library of Medicine
Should I train if I am sick?
No, because..
You wont be able to train hard enough for it to be beneficial.
You will spread whatever it is you have if you train with others.
Your body needs as much energy as possible to heal itself and recover quickly.
You won’t loose much progress if you rest and miss a few days
It is better to recover faster and get back into training sooner than it is to continue and have to be forced to take a much longer period of recovery.
But, you can train if
The intensity is low and duration is short.
You don’t have a fever.
The symptoms are localized only in your head and not in your throat, chest and body.
You are able to train alone.
Hydration and levels of sleep is optimal.
However it is still recommended that you take a break.
Still not sure about what to do? When in doubt leave it out! Don’t exercise when you are sick, continuing to exercise may increase the duration and or severity of the illness.
Recommendations
Screen for and manage infections through regular medical assessments and self-education. It is also important to lower the risk of infection by doing the following:
Develop an awareness of the increased risk of infection after training and competition.
Be aware of where you place your hands especially when you are out in public places.
Avoid touching your face, eyes, nose, mouth and ears.
Avoid people who ill, especially if their illness is contagious.
Maintain good personal hygiene.
Consider an influenza vaccination.
Ensure that your sleep is sufficient and optimal.
Use a training program that has been tailored to you. It should be structured within your current training capacity to attain maximal training impulse with minimum risk of illness.
Consider training with a coach, constant monitoring and frequent recovery is the best the prevention.
Resume training 2 weeks after symptoms have subsided, start slow and easy, and do not return to training at the same level after the illness.
Below is a sample week of what you can do once you have recovered from your illness.
Monday: Rest
Tuesday: 40 minutes of easy cycling with light pressure on the pedals, minimal sensation of leg effort or fatigue.
Wednesday: Rest
Thursday: 60 minutes of easy cycling where your breathing is more regular than Tuesday's easy ride and you but still able to hold a continuous conversation.
Friday: Rest
Saturday: 90 minutes of easy cycling where your breathing is more regular and similar to Thursday's ride.
Sunday: 90 minutes of easy cycling with light pressure on the pedals, minimal sensation of leg effort or fatigue.
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That is it. Thank you for reading. I hope you found it to be a useful resource.