Getting sick is certainly no fun. A bout with a cold or the flu can sideline you from working out and it can destroy your endurance for days or even weeks.
You feel tempted to go to the gym regardless to sweat whatever you have out of your system, but you do not know if this will help or make it worse.
How is Your Immune System Affected by a Workout?
The immune system does respond to physical activity. Mid to moderate activity can boost immune function. However, instead of pushing yourself through a cardio session or struggling to complete the last set of an exercise, drop your intensity to 40-60% of your maximum heart rate. You can roughly calculate this by subtracting your age from 220 and multiply by .40 or .60. Your white blood cells will function more efficiently and protective immunoglobulin levels in the mouth and nose may increase, lowering your risk of suffering from an upper respiratory tract infection.
On the other hand though, intense exercise (70-80% of your max heart rate) or prolonged exercising (longer than 60 minutes) can be detrimental to your body’s immune function. Studies have shown increased rates of infections in runners after increasing milage during the time of being sick.
How is Your Body Affected During Illness & How Can that Impact a Workout?
Infections can compromise the body’s ability to perform at its best. Illness and fever can impair concentration, coordination, muscle strength and power. Hydration is also significantly altered, draining the heart and other vital tissues. This causes the heart to work harder to compensate for fluid loss which significantly reduces the body’s ability to complete endurance sports.
If you push yourself during your workout, you are depleting your body’s energy resources and possibility slowing your recovery time.
Basically, hitting the gym too hard may be setting back your long-term progress.
When Can You Workout While Sick & What Can You Do?
If you cannot sit on the couch and watch Netflix anymore during your recovery and you HAVE to get in the gym while your under the weather use ‘the neck rule’. Anything above the neck, such as a respiratory infection or a cold are fine to work though. Remembering to only do about 40-60% of your maximum heart rate. Anything below the neck, like gastroenteritis or pneumonia should be viewed as a more serious illness and you should not head into the gym to workout under those conditions. Also, a fever greater than 101 degrees F should be seen a systemic illness and would not pass ‘the neck rule.’ Taking a few days off is recommended to prevent your body from compromising your immune system any further.
If you are a runner, try slowing your pace or shortening your duration. If you like to hit the weights, try lowering the weight or reducing sets/reps.
Even after you kick your cold goodbye you may be weak and low on energy. With that in mind, start at 50% of your usual workout and remember to fuel up on nutrition rich foods and drink plenty of water. Remember to get a good nights sleep and listen to your body.