I spent the first two weeks of January in bed, self-isolating in my room because I had tested positive for Covid. On day 11, I pulled on my trainers and decided to celebrate my new-found freedom with a jog around my local park.
Before Christmas, I had been building up my stamina through the NHS’s trusty Couch to 5k app. But on my first post-Covid jog, I felt out of breath within 10 minutes and more than a little tempted to sack it off and go home. All of my progress, it seemed, had vanished.
“You decondition a lot more quickly than you think,” explains Dr David Salman, academic clinical fellow in primary care at Imperial College. Also, doing too much exercise after bed rest can affect your breathing and your musculoskeletal system – making it more likely you will sprain something, for instance.
That’s part of the reason why experts recommend a “phased” return to exercise following Covid-19, suggesting you, quite literally, walk before you can run. However, this isn’t just to protect you from a sprained ankle. “This approach is to make sure that the body’s immune system is not challenged too much too early,” says Dr Manoj Sivan, associate clinical professor in rehabilitation medicine at the University of Leeds.
If you had symptoms while you had Covid, “that means your immune system has struggled a little bit to manage this infection”, Dr Sivan says. You need to bear that in mind during recovery – even if you now feel fine. “Even though the person does not show symptoms any longer, we don’t know whether that immune system resets completely or not,” Dr Sivan explains. He recommends gradually increasing your level of activity.
If you over-do it too soon, you could delay your recovery. “When a person exerts themselves straight away to that [pre-Covid] level of activity, they run the risk of actually getting new symptoms and worsening their existing symptoms,” says Dr Sivan. “We believe that is because your immune system is not ready for that kind of challenge yet.”
Jumping back into your usual exercise regime before a full recovery also increases your risk of developing more serious illnesses like “post-exertional malaise” (PEM), according to advice published by the World Health Organisation. PEM can affect your energy levels, concentration, sleep and memory and can cause muscle and joint pains. If you experience it, you need to avoid strenuous activity and aim to conserve your energy.
Continuing to over exert yourself has other risks too. “After illness there’s a period where you’ve got to be very careful that you don’t challenge your immune system too much because if you keep doing it and you keep crashing, it might become permanently dysfunctional – and that is what is can lead to long-term problems like chronic fatigue syndrome,” says Dr Sivan.