Posted: February 2, 2007

Athletics: Weekly Mileage - Mileage, Too Little and Too Much?

How important is your weekly mileage? Well for marathoners, it should be more than 40 miles per week. Amateur marathon runners who run less than 40 miles per week during training often show signs of cardiac dysfunction after the race and some of these abnormalities may persist for up to a month after they cross the finish line, a study shows. "Running less than 40 miles per week prior to running a marathon leads to temporary heart muscle weakness and increased pressure in the lung arteries," Dr. Malissa J. Wood told Reuters Health. "Individuals who consistently ran greater than 45 miles per week showed no such signs of damage after completing the marathon." The findings are based on a study of 20 amateur athletes who ran the 2003 Boston Marathon and underwent echocardiography (ultrasound imaging of the heart) prior to, immediately after, and about one month after running the 26-mile race. Several follow-up studies with a greater number of runners are currently underway. And for all runners, more than 60 miles per week can cause problems. This month's Running Times (Letters) has a report that a Dr. Nieman and a few other researchers have studied how "excessive" mileage affects the immune system. What current research indicates is that "...runners who trained more than 60 miles per week doubled their chances of getting sick in the days and weeks following the race." When the immune system is stressed, inflammation results. Scientists/researchers are just now beginning to understand the connection between inflammation and many diseases, such as heart disease, cancer and arthritis. When inflammation occurs it is a sign that the immune system is breaking down. If you have a copy of the March 2007 Running Times I suggest you read the letter "How much mileage is too much?" on page 6. Some doctors have been saying for years that the Ironman is causing havoc with people's immune systems but nobody wants to hear that message so it has never really gotten out. Now it appears that it takes even less stress to cause serious immune system problems. Subscribe to the Runner's Web Weekly Digest

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