To Train or Not to Train While Sick

By Mackenzie Madison, M.S. & Dr. Greg Madison, ER Physician, ACSM | Feb. 12, 2018, 6:41 p.m. (ET)


If you’re an athlete, becoming sick while training can be frustrating. Deciding whether to keep training or even to stop training is equally frustrating. Your decision should be based upon the benefits and risks of training during the illness and the severity of the illness. We are balancing compromises between detraining but hastening recovery, maintaining fitness but potentially prolonging the illness or disease.

In your favor, athletes are generally less susceptible to common viral illness, have better immune competency and recover quicker.(1, 2) Studies have shown that exercise at low to moderate intensities boosts the immune system activity, temporarily. Not in your favor, the immune system weakens following highly stressful training or racing. The perfect storm for crippling the immune system includes cumulative high-intensity and long-duration training to exhaustion, sleep deprivation, severe caloric restriction, strong psychological stress and having more than a single illness. Gremlins aside, just doing a longer race typically suppresses the immune system for up to 72 hours.

Dr. Greg Madison exposes the dangers of pushing too hard when under the weather. “A couple of rare but dangerous complications of viral illness are viral cardiomyopathy and viral polymyositis. In these conditions, the virus invades the muscle of the heart and skeletal systems to a much greater degree than the typical body aches of cold or flu.” These effects can be permanent so don’t overdo it.

So how should you determine whether or not to get in a training session? If symptoms are "above the neck" such as sneezing, coughing or a runny nose, then you can still exercise with some limitations. However, you should simply rest If your symptoms are "below the neck" such as chest congestion, stomach and intestinal symptoms, achiness, a measured fever or if you have the flu.(3)

How much exercise is OK during the average common cold? Listen to your body and be conservative. After an adequate warm-up, quit if you feel poorly, or continue if you feel OK but make sure to finish your session with energy to spare. Each athlete has different "easy" and "stressful" thresholds. When you are sick, the stress of an intense or long workout is likely to hamper the immune system thus regressing any progress your body has made in overcoming illness. If you have the flu or a fever, wait a full 24 hours after your symptoms have ceased before easing back into training.

You will not lose much fitness while resting through the average duration of a common cold. But don't expect to emerge tapered and sharp. Lingering fatigue happens for a week or two, even after the immune system rids the virus after one to two weeks. Even after symptoms cease, make sure to gradually increase your training sessions. Start at what would be 50 percent of your normal training load for a couple days, then 75 percent for several days. Hold off on exceeding your baseline training sessions until you’ve had a week of consistent training back at 100 percent.

Avoid the spread of viruses. Remember that you are contagious for the first several days so it is best to train alone or outside and not inoculate your training partners or others at the gym. If you have to go to a gym, make sure to wipe down the equipment you use and avoid coughing on others. Prevent acquiring a cold by avoiding touching your face, washing hands and using antiseptic wipes on surfaces as viruses remain infectious for at least a day on surfaces.

 See your doctor if your symptoms persist more than two weeks, if fevers exceed 100.5 degrees, if strong pain of chest or body occurs, if cough production increases, or new symptoms develop. This article offers general science-backed guidelines that are meant for athlete interpretation and should not be considered professional medical advice or treatment.

Truth or Myth?

The real truths and myths about the common cold with physician and exercise physiologist Dr. Greg Madison.

  1.  "You’ll get over a cold faster with an antibiotic." Myth. Antibiotics can kill bacterial infections but they can’t kill viral infections a.k.a. your run-of-the-mill cold. If a bacterial infection component is present, then an antibiotic may be beneficial. If there is no significant bacterial component present, then an antibiotic is "just along for the ride" and is ineffective.
  2.  "There is no cure for the common cold." Truth. If antibiotics don't kill the viruses, then what does? Your immune system does! There are specific antiviral medications (not antibiotics) for influenza A&B, but there is no antiviral available for the common cold. Vaccines are available for the flu (influenza A and influenza B) and for other viral infections, but no vaccine is available for the common cold. Medications treat the symptoms of the infection, but do not provide a cure.
  3.  "Sweating it out helps." Myth. Although a mild fever is a natural and beneficial immune response, sitting in a sauna has not been proven to alter the course of a common cold infection. Inhalations of heated moist air, with or without medicated vapor, has not been shown to shorten the overall course of the common cold. Medical professionals often "allow" a mild fever, reserving Tylenol or ibuprofen for higher fevers.
  4.  “Vitamin C, zinc, echinacea supplements can stop a cold." Myth. Again, no matter what passes over your lips, your immune system ultimately handles the viral infection. There is no direct viral antidote or chemical "viral killer" available. The immune system works on its own schedule. The immune system can be "boosted" with relative rest, stress-relief, hydration, proper nutrition and other modalities.
  5.  "Hand washing and antiseptic wipes help." Truth. Above all, preventing the virus from entering the nose and eyes and mouth is the most important method to avoid the common cold. The vast majority of cold infections are transmitted from the hands to the face. Antiseptic hand washes and wipes can kill viruses on surfaces and on the skin. Lysol, chlorine and alcohol-based antiseptics are effective against the common cold viruses. Of course, once you have a cold infection, using antiseptic products helps prevent getting a second cold infection of a different serotype, and helps to prevent infecting someone else.


(1) Nieman DC, et al. (2011) Upper respiratory tract infection is reduced in physically fit and active adults. British Journal of Sports Medicine. 45:987-992.
(2) Nieman, D.C. Moderate exercise improves immunity and decreases illness. American Journal of Lifestyle Medicine. 2010. 5: 4:338-345.
(3) April 07, 2015 Advisory sponsored by the American College of Sports Medicine.
Freidenreich DJ & Volek JS. Immune responses to resistance exercise. (2012) Exercise Imunology. 18:8-41.
Gleeson M, Bishop N, & Walsh N. (2013) Exercise Immunology. Routledge.
Walsh NP, et al. (2011) Position Statement. Part One: Immune function and exercise. Exercise Immunolology. 17:6-63.

Mackenzie MadisonMackenzie Madison is a professional triathlete and USA Triathlon Certified Coach. She has been competing in triathlon for 18 years and coaching for 15. Mackenzie acquired her B.S. in kinesiology & coaching and master’s in exercise physiology. She is also a former D1 runner and elite cyclist. Mackenzie also is an instructor at the University of Oregon. Contact her at

Dr. Greg Madison is a board-certified ER physician who has participated in triathlon and running events for over 30 years based out of Des Moines, Iowa. Dr. Madison is also an ACSM Certified Clinical Exercise Physiologist, NCSA Strength and Conditioning Specialist and USA Triathlon Certified Coach. Dr. Madison also owns and runs Precision Multisport Testing and works with Zoom Performance Coaching Company. Contact him at

The views expressed in this article are the opinion of the author and not necessarily the practices of USA Triathlon. Before starting any new diet or exercise program, you should check with your physician and/or coach.