This article was first published in The Sunday Times on 28 October 2018
DR WANG MINGCHANG – You’ve meticulously drawn up a weekly training plan in the lead-up to your race, diligently following it and clocking the mileage. The weekend’s long run is coming as you near the end of the work week. But alas, your plans are blighted when you wake up with your throat feeling like sandpaper and your nose leaky as a tap. Undeterred, you carry on with your scheduled run, dismissing your symptoms as minor.
Should one continue exercising when one is ill?
The neck check
A neck check is a quick way to determine if you should continue to train/run when unwell. If your symptoms are above the neck, e.g. teary eyes, nasal congestion, runny nose, sore throat or a mild cough, then it is probably okay to continue. However, if your symptoms occur below the neck, e.g. fever, chills, body aches, malaise, chest congestion, nausea/vomiting or diarrhea, then I would strongly encourage you to give your body a much-needed rest.
Running with a cold
Exercise may be beneficial when one is suffering from an upper respiratory tract infection, commonly known as the common cold. Symptoms include a runny or congested nose. Adrenaline, a hormone released during exercise, is a natural decongestant and helps in relieving nasal congestion as well as the widening of our airways. Research suggests that heart and lung functions (and hence exercise tolerance) do not appear to be altered by an upper respiratory tract infection. This means that the common cold will not affect your ability to run at your usual intensity. If you’re running in a group, do be mindful that sneezing or coughing in close proximity to others can lead to their not remaining your friends for long.
Running a fever? Do not run
Exercising with a fever is dangerous. Exercise further raises one’s body temperature and heart rate, which are likely already elevated, to begin with when one is having a fever. Our heart rate increases by about 10 beats per minute for every 1 degree Celsius rise in temperature. Running whilst febrile can result in excessively fast heart rates. Viruses are a common cause of fever and side effects may include inflammation of heart muscle. This inflammation, coupled with a fast heart rate, presents much more stress and strain to the heart than the intensity of exercise would suggest. Ultimately, this can precipitate abnormal heart rhythms and, in severe cases, even result in sudden cardiac arrest and/or death.
Protecting your immune system
It has been well-established that regular exercise can boost one’s immunity. On the other hand, too much exercise can have the opposite effect. Prolonged high-intensity endurance exercise (e.g. running a half or full marathon) can cause one’s immunity to be weakened for up to 72 hours. The cause is not clear but one plausible reason could be the excessive free radicals and stress hormones produced during intense exercise which can suppress one’s immune system.
If you find yourself frequently falling ill on the days after an intense training, it may be helpful to take in more foods that are rich in antioxidants, such as green tea, dark chocolate, blueberries, strawberries and beetroot as part of your recovery diet, to give your immune system a boost.
Sufficient rest and sleep are also needed for a healthy immune system. Depending on how fatigued you feel, it is prudent to always listen to your body and schedule a rest day or two after a session of hard running.
