Can too much exercise make you sick?

A recent publication of the Gatorade Sport Science Institute titled Can too much exercise make you sick? By David C. Nieman, Dr. P.H. a well respected expert on exercise an immune function provides useful perspective for rowers and coaches. Rowing is a high-volume sport for both physiological and technical reasons. Even those who ever increasing volumes of exercise. How does this affect immune function?

Nieman’s report points out that a recent study at the Los Angeles Marathon reported:

  • One out of seven runners who participated in the event got sick after it was over.
  • Runners training more than 60 miles a week during the two months before the race, doubled their odds for sickness compared to those training less than 20 miles a week.
There is evidence that regular moderate exercise enhances immune function, but there is also evidence that too much exercise suppresses immune function.

What do you do if you are already ill?

He also has guidelines that are useful for coaches and athletes facing illness, including of course the proviso that one should consult a physician first:

  • If symptoms are from the neck up (e.g. nasal congestion) supervised exercise should be fine.
  • If symptoms are body wide such as fever, chills and muscle aches exercise should be avoided until symptoms are completely gone.
  • Trying to exercise out an illness can lead to “post-viral fatigue syndrome” that can persist for months or years.

While Dr. Nieman indicates that safe exercise levels are an individual thing, he gives the following guidelines, that are not much beyond the common sense approach taken by athletes and coaches. These include getting adequate sleep, and eating a well-balanced diet.

There are a few interesting points though that you can apply to your training:

Applications to Training

Using sports drinks (OK, he is sponsored by Gatorade) before, during and after heavy training. This is often overlooked by rowers and coaches since most rowing does not get into the zone that could result in complete carbohydrate depletion (“bonking”) which generally requires several hours of steady work. However, Nieman reports that “ingestion of carbohydrate beverages during prolonged and intense exercise keeps blood sugar levels up and stress hormones low, resulting in better immune system functioning.”

He also notes that athletes should “avoid rapid weight loss” which obviously applies to lightweight rowers who take significant health risks when they try to make weight too quickly – actually endangering their ability to compete if they induce sickness.

Read the complete text of this article at:The Gatorade Sport Science Institute

A related blog entry by Canadian Kip MCDaniel