Should You Workout When Ill?

When fitness is your everything, sometimes it's hard to stay still. But, when your health is at risk, can getting back in the gym help, or hinder?

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We’ve all been there: just as training is going well, and you're starting to get into a good routine and notice progress, illness strikes. 

We’re not talking about those clear-cut reasons for staying out of the gym – your sprained ankles, your broken backs – but those less tangible indicators of illnesses, the aches, the exhaustion, the general ‘run down’-ness that signals impending sickness. 

When we’re not feeling our best, common sense tells us to load up on tissues and chicken soup, confine ourselves to bed and a Netflix marathon. But, when the physical act of fitness makes you feel so good, instinct can tell us we just need a good session to blow the cobwebs away. So which is right?

For gym bunnies, mind over matter may be the mantra, but can you ever train your way back to good health? Or is swapping the sick bay for the weights bench a sure-fire recipe for disaster? We tasked Abigail Ireland, physiologist and peak performance strategist at Understanding Performance, with writing up your fitness prescription. 

How will an illness affect your workout?

On the fact of it, it seems obvious that exercising when ill isn’t a good idea. No one has ever bench-pressed a PB or achieved a 5k best when they’ve felt like death. Instead, we’re more likely to train when we’re ill because we don’t want to break a habit and because we believe that something is better than nothing, even if we aren’t at our best.

From a psychological aspect, this could be right. There’s plenty of research that shows the endorphins released post-exercise can block pain and increase sensations of pleasure, meaning you will feel better, at least for a while.  

There might be something in it from a physiological perspective, too. “Sometimes exercise is the best cure when you’re feeling under the weather,” explains Ireland. “It can help to get the blood flowing, encouraging nutrients and oxygen to move around to all body cells.” 

The thinking here is that the stress exercise places on our blood vessels encourages the release of immune cells called killer cells and T cells, which then move around between our blood and tissue, helping them get to where they need to be to make us well again.

Research has found exercise helps us boost levels of these beneficial hormones – which is one reason why exercise can help us live longer and healthier lives. But, it’s important to note that while exercise does get these guardian cells moving, the largest benefits are mostly pre-emptive: if you’re fit, you’re less likely to get ill

When we’re legitimately ill, exercise can be the straw that breaks the camel’s back. “There are times when we need to rest and direct energy towards getting better rather than exerting ourselves,” adds Ireland.

“We hear so much about “no pain, no gain” but it can actually be dangerous if we take this mindset too far. We can end up putting a lot of pressure on our organs and body systems, forgetting that recovery is an equally critical part of the health equation.” 

Can exercise help you recover from an illness? And could it harm you?

As mentioned above, there’s plenty of evidence to show exercise can help prevent illness, but when it comes to its efficacy when you’re actually bed-bound, the jury is out. 

“Exercise is a crucial part of recovery, but it really does depend on the illness,” warns Ireland. It also depends on the intensity and duration of exercise. Some evidence suggests long-distance running while ill can suppress your immune function, meaning it won’t work as well as it should. Another study found that in cross-country runners, the physical stress meant their immune system was working overtime, making its task more difficult. 

What’s more, Australian research from the 1990s has suggested that athletes who continued to exercise while suffering from flu developed years-long chronic fatigue syndrome. In a post-Covid world, that’s certainly worth taking into consideration. Ireland also warns of short-term burnout, as well as dehydration which can prolong sickness.

“Exercise requiring concentration (such as weight training or boxing), makes us more prone to injury due to muscle weakness and fatigue, while brain fog and lack of focus can mean we hurt ourselves more easily when using equipment,” she adds.

“It’s important not to push too hard whilst feeling ill,” Ireland continues. “At the end of the day, your immune system is fighting hard to recover and get back to full health, so it needs all the energy it can get. If we ignore the signs and symptoms, we can cause more harm than good.”

How can we tell when we’re well enough to exercise again? 

We’re all different with our own health issues, tolerances and lifestyle factors so it’s impossible to quantify when you should hit the gym again. The answer, of course, is ‘When you feel up to it’, but we need to qualify that by asking have you really rested as long as you should? And do you really feel 100% better? 

“I prefer to rest and recover before I get back to exercising properly,” explains Ireland. “Recovery is such an important piece of the puzzle, and it does in fact lead to even stronger benefits and results from exercising.”

Ireland does say that she still might exercise on a “very light cold”. Wellness is such a subjective thing that the answer really is ‘How long is a piece of string?’. With that in mind, it’s best to test the water instead of going all-out your first session back. 

“Take it easy with something gentle like a light jog or light weight session,” advises Ireland. “Listen to your body and stop if you’re feeling fatigued or weak. Don’t push hard when getting back into things, as this might set you back a lot further than if you waited a little longer to be running at full speed.”

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If you're going to workout when ill, what should you do? 

If you simply can’t resist the gym, there is hope for you, with new research from Ball State University finding that moderate exercise actually has no effect on the duration or severity of the common cold.

Clearly, this contradicts other findings referenced elsewhere in this article, so the decision whether to exercise or not really lies with you. “For many of us, exercise is the daily drug that keeps us grounded, happy and sane, but it’s important to take a step back if feeling ill,” warns Ireland.

If you must get moving, Ireland recommends gentle stretching and yoga as both are low impact and calming on the nervous system. In addition, you’ll benefit from improved flexibility, improved blood flow, and reduced tension, all of which can help us feel better. 

“The sun salutation is a brilliant sequence that supports the body and mind,” advises Ireland. “Poses such as downward-dog, child’s pose, cat-cow stretch and seated twists are all low intensity, low impact, restorative and therapeutic. Being able to concentrate on the breath also supports bringing more oxygen into the body and getting this to all body cells.”

It might be a good, slow stretch is all you need to get yourself back on top. Or it might be that a week in bed is the ultimate cure. Either way, whether you’re laid up or in the gym it’s vital to listen to your body because ultimately, you only have one. Look after it, and it will look after you.

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