Should you exercise with a cold or flu

Most people catch one or two colds a year, but it doesn't have to wreak total havoc on your fitness routine. Some physical activity when you're sick can be alright, but there are times when exercise can make things worse.

The best way to determine whether you should go to the gym, or go to bed is the extent and location of your symptoms. You will need to give yourself a "neck check".

You can exercise safely when… 

If your symptoms are from the neck up, such as a sore throat, then it's okay to exercise. Physical activity won't slow down your recovery, as long as you don't elevate your heart rate and body temperature too much.

US researchers1 studied people who exhibited an upper respiratory tract infection or "head cold" over 10 days. They compared people who exercised for 40 minutes every second day with people who didn't exercise at all. They found no difference in symptoms at the end of the study, and that exercising with a minor cold did not alter the severity or duration of the illness.

Green light symptoms (yes, you can exercise)

• runny nose 
• sneezing 
• watery eyes 
• sore throat 

It's best to rest when…. 

If your symptoms are below the neck, such as a tight chest, then your body needs rest. Exercising with major cold symptoms, particularly a fever, will prolong your illness and can be dangerous. Physical activity will compromise your immune system as the body focuses on energy production and muscle function instead of fighting the illness.

If your oral temperature is at or over 37.5 °C (99.5 °F), your body is fighting an infection, and needs rest to recover. Listen to your body, and take comfort that you won't lose any conditioning by taking a few days break.

Red light symptoms (best to avoid exercise)

• coughing 
• fatigue and tiredness 
• congested or tight chest  chills 
• nausea or upset stomach 
• muscle aches 
• diarrhea 
• high temperature / fever 

Can you sweat out a cold or flu?

When you have cold and flu symptoms, attempting to exercise or "sweat it out" may actually allow your symptoms to become worse. Too much sweat can dehydrate you at a time when you actually need extra fluids to loosen congestion. Dehydration can also dry the mucous membranes in your respiratory tract, worsening a stuffy nose or scratchy throat.

Ease back into your activity

As your symptoms diminish, ease back into your exercise with caution. Start out gently to see how you feel, and if the body responds well, gradually increase the intensity and duration over a few days. Avoid jumping straight back into your old level of effort. Modify your intensity until all the symptoms have completely disappeared.