Should you exercise with a cold? What the neck check gets right

A runny nose does not always mean a rest day. Here is what studies on exercising with a cold show, and the simple neck check for when to train and when to stop.

In 1998, a group of researchers in the United States deliberately gave 50 young volunteers a common cold virus. Then they did something even stranger: every 12 hours, they collected the volunteers' used tissues and weighed them. ¹

All that soggy paper was there to answer a question every regular exerciser asks at this time of year. When your nose starts running and your throat feels scratchy, should you still train, or will a workout make the cold worse?

November in north India is peak season for this dilemma. The weather turns, the smog settles in, wedding functions run past midnight and half the office is sniffling. Here is what the research says, and the simple rule doctors use to decide.

What happened when people with a cold kept exercising?

In that trial, 34 of the infected volunteers were assigned to exercise. They did 40 minutes of supervised exercise every other day at 70% of their heart rate reserve, a solid moderate effort, while the other 16 did none. Everyone filled in a 13 item symptom checklist twice a day for 10 days. ¹

The result was no difference. Symptom scores and the weight of mucus in the tissues were about the same in both groups, and symptoms did not jump after individual exercise sessions either. ¹ The researchers concluded that moderate exercise did not change how bad the cold was or how long it lasted.

This was one small study in young, reasonably fit adults, aged roughly 18 to 29, infected with a single cold virus. It does not prove that a hard interval session is harmless when you are ill. But it does push back on the old belief that any exercise during a cold will drag the illness out.

The neck check: a simple rule for working out when sick

Doctors and sports physicians usually boil the decision down to one quick test, often called the neck check. Mayo Clinic's guidance puts it plainly. ⁵

• Symptoms above the neck, such as a runny or blocked nose, sneezing or a minor sore throat: mild to moderate exercise is usually fine, but make it shorter and easier than normal. A walk instead of a run, for example.
• Symptoms below the neck, such as chest congestion, a hacking cough or an upset stomach: skip the workout.
• Fever, unusual fatigue or aches all over the body: no exercise at all.

Mayo Clinic also points out that a few days off when you are sick should not affect your performance, and that you should not exercise around other people if you have something contagious. ⁵ That last point matters in a crowded gym or a group class. Your sniffle is your business. Sharing it with the person on the next treadmill is not.

A cold in your nose can come along for a walk. A cold in your chest needs your bed.

Why exercising with a fever is a different story

Fever is more than a higher number on the thermometer. A clinical review in the journal Sports Health found that fever increases fluid losses, raises the body's metabolic demands and disrupts its control of its own temperature, while also reducing muscle strength and endurance. ⁶ You are already working hard simply by being ill.

The same review reported that strenuous exercise during a feverish illness can make the illness worse, and that in animal studies it increased the risk of death. ⁶ There are no consensus guidelines supporting a return to training before the fever has gone, and the advice is to build back gradually once the fever and any dehydration have settled. ⁶

So the line is clear. A stuffy nose with a normal temperature leaves room for gentle movement. A fever means rest, fluids and patience, however guilty you feel about the sessions you are missing.

Does regular exercise mean fewer colds?

Here the story gets more encouraging, with an important caveat attached.

One study followed 1,002 adults aged 18 to 85 through 12 weeks of autumn and winter. People who did aerobic exercise on five or more days a week had 43% fewer days with cold symptoms than those who were largely sedentary, exercising one day a week or less. Those who rated themselves the fittest had 46% fewer sick days than the least fit, and their symptoms were 32% to 41% milder. ²

That was an observational study, so it shows an association rather than proof that exercise caused the difference. Active people may sleep better, smoke less or differ in other ways that matter.

A 2021 meta-analysis pooled data from more than half a million people. Higher levels of regular physical activity were linked to a 31% lower risk of community-acquired infectious disease and a 37% lower risk of dying from infectious disease. ⁴ In studies where people added an exercise programme alongside vaccination, antibody levels afterwards were slightly higher. ⁴

The randomised trials are more modest. A 2020 Cochrane review of 14 trials involving 1,377 adults found that exercise did not clearly reduce how many respiratory infections people caught. It did reduce how severe the symptoms were, and it cut the total number of symptom days during follow-up by a little over two days on average. ³ The reviewers rated the overall evidence as low certainty and called for better trials. ³

Put together, the honest reading is this. Regular moderate exercise probably will not make you immune to the office cold, but it may make the colds you do catch milder and shorter.

How to handle a cold and your workouts this week

If you wake up with a cold in the next few days, run through this before you lace up.

1. Check for fever. If you have one, or you feel achy and wiped out, rest today and return only once the fever has gone. ⁵⁶
2. Do the neck check. Nose and minor throat symptoms only? A brisk walk, an easy cycle, gentle yoga or a light mobility session is reasonable. Keep it noticeably shorter and easier than usual. ⁵
3. Listen during the first few minutes. If you feel worse once you get going, stop and head home. If you feel the same or a little clearer, carry on at that easy pace.
4. Leave heavy lifting and hard intervals for later. Personal bests can wait until you can breathe through your nose again.
5. Keep your germs to yourself. If you are contagious, train at home or outdoors on your own rather than in a busy gym or class. ⁵
6. Ease back in. After a few days off, make your first sessions deliberately easy and build up over the following week.

If you live in Delhi NCR, check the AQI before an outdoor walk. On very poor air days an indoor session is kinder to an already irritated nose and throat, and there is more on that in our piece on exercising when the air is bad. Late wedding nights do not help either, so protect your sleep while you recover.

If you have asthma, a heart or lung condition, are pregnant or take regular medication, speak to your doctor before exercising through any illness. And whoever you are, stop and get checked if you notice chest pain, unusual breathlessness or symptoms that keep getting worse instead of better.

General information for healthy adults, not medical advice. Speak to a doctor before changing your training or diet if you have a health condition, are pregnant or take regular medication.