Training through illness; Maybe not such a great idea?

author : TriDoc5280
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Exercise performance will invariably be negatively affected. Add to this the feelings of malaise and weakness and one might wonder, “Why bother?”

As the days lengthen, the flowers bloom and the weather warms, it becomes self evident to all that spring is finally upon us. At this time we forget about the onslaught of seasonal viruses that appear between November and April each year. While the vast majority of these illnesses are benign and self-limited in nature, they still cause varying degrees of discomfort and misery. Unfortunately, the passing of winter does not mean that these viruses are gone, just that they will be contracted much less frequently. And so the perpetual dilemma for the triathlete who has the misfortune to catch one of these bugs out of season is what to do about training.

Although all illnesses are different, certain physiologic parameters are fairly uniform across individuals when they fall ill. Resting heart rate, basal metabolic rate and respiratory rate are invariably elevated. This translates into elevated fluid losses, which are often under-replaced. More dramatic increases are seen in the presence of a fever that also worsens the level of dehydration. The net result of all of this is that exercise performance will invariably be negatively affected. Add to this the feelings of malaise, weakness and overall lethargy incumbent with illness and one might wonder, “Why bother?” Triathletes often do bother, but is that a good idea?

In deciding whether to continue exercising when ill, you should first reflect upon the following considerations:

-Will you benefit from exercising when ill?
Triathletes are obsessed with training schedules. To them, the mere suggestion of skipping a workout is met with disdain and scorn. Triathletes are so averse to taking time off from training that it is not uncommon to see individuals putting in long workouts the day before a big race or when they are ill.

The universal reason given to explain this behavior is that athletes fear losing the benefits of long periods of training by taking time off, no matter how brief. Detraining, or fitness loss, is a real entity, but how fast it occurs is the subject of much misinformation. The fact of the matter is that a brief respite from exercise because of illness will result in minimal, if any, detraining.

Several studies have looked at the time dependent effects on fitness of a total cessation of training, i.e., the rate of detraining. The results were dependent on how long an athlete had been training prior to stopping. For individuals who had been training regularly for over a year, a complete cessation of exercise resulted in a loss of 50% in all measured parameters of fitness after three months. For those individuals who had been exercising for three months prior to stopping, there was a 100% loss of measurable improvements in fitness at three months. Thus, the longer you have been training regularly, the longer it takes to detrain upon the termination of exercise.

Furthermore, if you reduce training volume rather than stopping altogether, detraining is retarded. Seasoned athletes who decrease training frequency to once a week will prolong the rate of detraining significantly while those individuals who have only recently started training obviate any detraining altogether.

In any case, when you are ill your body is unable to perform at its usual level since so many of its resources are being commandeered to fight off the infection. Thus, the benefit of exercise in this state is questionable. You must then ask yourself if working out at a less than optimal level is any better than not working out at all. Exercise may have certain benefits on your symptoms that may make the decision to continue more justifiable. For instance, cold symptoms such as congestion are often improved by working out in the cold air.

-Will the illness be prolonged?
It has long been understood that exercising vigorously over prolonged periods of time depresses the immune system. Participating in such activity would thus seem counterintuitive, and indeed it likely is, though no studies have ever been done (from a dearth of volunteers, I imagine). However, working out at mild to moderate intensity for short periods of time likely poses little risk to prolonging the duration of illness.

-Will you make the illness worse?
As for the possibility of worsening illness, there is no doubt that in many cases this is indeed a risk. Furthermore, illness itself may predispose to injury by increasing the risk of dehydration, heat illness and even physical injury. In deciding on the safety of exercise in any given illness the following guidelines may be helpful.

Consider the location of the illness. If your symptoms are restricted to the head and neck only, e.g. congestion, sore throat, headache, then you are unlikely to make things worse by exercising. If however your symptoms are below the neck, e.g. cough, fever or diarrhea, then exercise may pose a significant risk.

-Are you a risk to others?
A final consideration is whether or not you are a risk to others. Certainly you wouldn’t appreciate an infectious partner getting you sick at a group workout? If you do decide to continue to exercise, ensure you have your own water bottle (not to be shared by anyone else) and that your workout group knows you are sick so that they can protect themselves. The vast majority of viral illnesses are passed by hand-to-hand contact, i.e. you touch something then they touch it. So do everyone a favor and avoid shaking hands or using someone else’s telephone when at home or at a workout until you are better. The general rule is that the day your symptoms begin to improve is the day you are no longer contagious.

Based on all of these considerations, if you do decide to exercise when ill follow these suggestions:

  • Start slow. If you feel well enough then increase your intensity gradually but never to your highest capacity. If you feel unwell, stop. In other words, listen to your body.
  • Ensure you increase your fluid intake by at least 50% during your workout.
  • Try to minimize your infectious risk to others.
  • See a physician if your symptoms persist more than ten days or seriously worsen.

Whatever you decide, train hard, train healthy.


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date: May 1, 2006


Long time triathlete with multiple IM finishes and over 30 HIM since 2001. 70.3 WC x4, Kona x 1.

Previous medical contributor to Triathlete Magazine and Inside Triathlon now the author and producer of the TriDoc podcast on iTunes, Google Play and Stitcher


Long time triathlete with multiple IM finishes and over 30 HIM since 2001. 70.3 WC x4, Kona x 1.

Previous medical contributor to Triathlete Magazine and Inside Triathlon now the author and producer of the TriDoc podcast on iTunes, Google Play and Stitcher

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