Running When Sick: When to Rest and When to Keep Training

Running While Sick: When to Train and When to Rest

We runners can be disciplined to a fault. We run through rain, snow, heat, and humidity because if you waited for perfect weather, you would rarely ever get a run in. However, that “get-it-done-no-matter-what” logic can be stretched to other circumstances and drive runners to push through illness and run when sick. Should you run when you’re sick?

Running builds a strong immune system, but that doesn’t make you completely immune to catching the cold, flu, or stomach bug. Especially if you are training hard or recently raced, you may have slight immunosuppression. Illness does not take your training plan into consideration. 

Runners are not by nature lazy people and the idea of skipping a run to spend extra time resting in bed is seriously unappealing. It’s hard enough to miss a run during the off-season, but it can be even harder to make the appropriate decision of whether or not to skip a run when you get sick during an important training cycle and are approaching a goal race. 

It can require more discipline to listen to your body and give it rest when needed than to go out for a run. In the era of Strava and Instagram, we are quick to praise those who run through illness or quickly after surgery. However, running when sick can be downright unhealthy. 

Rest is Best When Sick

A good rule of thumb is that if you feel sick and are asking the question of you should run, then you are best just resting. You will not lose fitness in the time it takes to recover from a cold or flu. However, you will quicken your recovery by resting. 

Running with a cold (in the acute days of illness) can be done, but it is generally still recommended to rest. (More on running with a cold in this article.) Once the worst days are over, it is generally okay to run through lingering nasal congestion. 

For any illness that involves the pulmonary system (flu, Covid-19, bronchitis, etc), you will want to rest until your symptoms resolve.

If you have a gastrointestinal illness with vomiting and/or diarrhea, you should rest. You will want to ensure you are rehydrated and able to keep down food before you resume running. 


Whether or not you abide by the “below the neck rule,” you should not run if you have a fever of 99 degrees Fahrenheit or above. Your core temperature increases during a run. If you run with a fever, you will cause your body temperature to increase even more. This can suppress your immune function and delay healing. Your heart pumps harder when your body temperature is increased, in an attempt to cool down. Because of this, you put your heart under greater strain when running with a fever. 

Training Modifications

If you have a head cold and choose to run when sick, do not make this the week that you increase your mileage or do a hard interval workout – even if your training plan calls for it. Running for longer than 90 minutes or doing a hard speed workout stresses your immune system. If your body is already fighting illness, then you are only going to risk prolonging or exacerbating your illness. 

Opt for easy effort runs of 30-45 minutes in duration. Do not expect yourself to hit the same paces as you normally do when healthy. If it helps, run by time and leave the GPS watch at home, so you are not tempted to push too hard. 

If you miss a few training days, do not try to make them up by cramming more mileage or skipping a rest day. Simply resume your training plan as is, with the modification of having your first day back being an easy day. 

Be Mindful of Conditions

Running in the dry and cold conditions of winter can worsen irritation of the nasal passages and mouth. Running in extreme heat can raise your core temperature and expend extra energy. If you choose run while sick, take the impacts of these conditions into consideration. If you suffer from seasonal allergies, be cautious about running outside to avoid allergens worsening your head cold symptoms. 

Most of all, you are better off taking a couple of days off to let your body properly recover. This is far better than prolonging your recovery period or affecting your health and training down the road. Err on the side of caution and treat your body well. You will not lose fitness in just a few days off of running.

Do you run when you are sick? How do you decide when to rest?

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31 Responses

  1. It’s usually pretty obvious when I need to skip my runs when I’m sick. If I feel like garbage, I know that running will do nothing for me except make me feel worse. But if it’s a cold, I usually feel better once I run. It opens up the nasal passages so I can breathe!

  2. hope you are feeling better. I do not run when I’m sick. usually I find myself with a stomach virus rather than colds/sore throats/other things which means I am totally down for the count and running wouldn’t even cross my mind. I haven’t had a cold or anything like that in years though but assume if I didn’t feel well from one, I wouldn’t run.

    1. Allergies are mild enough to run through – plus they are not so much illness as, well, allergic reactions. That’s awesome that you’ve never been derailed by illness during training!

  3. I’ve gotten better at tuning into my body and knowing if I really need to lay low or if I have the energy for a run. The above the throat rule usually works for me!

  4. These are such good reminders, Laura! I remember while training for my first marathon, I wasn’t feeling well and cut a long run short. The next day, I was flat on my back and running a fever. I should’ve listened to my body and not gone in the first place, but thank goodness I stopped my run early or I would have been really sick.

  5. Well, if I feel like something’s coming on, I know I’d rather rest than get sicker longer (not that it’s easy). And I’ve been tracking my resting heart rate a while now — when that suddenly rises I know that I need more rest (like this week). It’s really frustrating, though.

  6. Running with any kind of sickness is a definite no for me. When you add regular illness on top of autoimmune illness, that’s more than enough stress for my body to handle at one time.

  7. You know me—I’ll run through anything. How are you feeling? You’ve got a cough now? That must suck so bad coughing away in this heat. DAMMIT.

  8. I am so paranoid about injury that I usually will not run with a compromised state of health. Of course, if it’s just a mild cold, I’ll head out. if I’m feeling achy all over and just not myself, I take a pass.

    1. It takes time to learn the body’s signals and to override motivation with discipline – but it’s well worth the process of learning and great that you figured it out!

  9. I always abide by the above the throat rule unless I’m feeling extra crappy or have a fever. If I’m sick but not like in bed all day sick then I feel like I recover faster by exercising and running. I also always take it a little easier on pace or impact when I’m sick.

  10. There seems to be no virus or bug I can resist trying out and this has so derailled my attempts to consistently work out in the past that I have become frustrated enough to stop altogether. But you never can lay off good things so I always keep coming back, having to start all over again. Frustrating too. I have opted now to rather walk my training distance (sometimes with hot tea in a bottle) if I feel something creeping up on me rather than break the habit. Or do some yoga instead of strength training or speed work. And paying meticulous attention to what I eat. It has done wonders to my recovery times and although I had to shift down a gear I don’t have the feeling of having lost the momentum. Sometimes I think that makes me so happy that it helps me get well a lot, too.

  11. I found this post while I’m sitting at home in bed! I’m 6 weeks into a training program and I’m sick – it is so hard to force rest but I appreciate the info on this post! And you’re right — in the time it takes to recover, I haven’t lost all that much time. Cheers to getting back out there in a few days 😉

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