Jogger's Ills

Perils on the path to fitness

Paul Zarmunsky. 40. of Englewood.

N.J., runs ten miles a day to keep fit.

He thus had reason to expect that the doctor who gave him his annual physical would marvel at his fat-free midsection and low heart rate. Instead, the doctor seemed more interested in the results of Zarmunsky's laboratory tests, one of which showed the abnormal presence of protein, red blood cells and other substances in his urine. This condition can be an indication of nephritis, a potentially serious kidney disease. It can also be a sign of an apparently benign condition that is likely to become more common as increasing numbers of Americans take up jogging and running. When a second test 48 hours after the first turned out normal, Zarmunsky's doctor diagnosed his condition as "jogger's kidney," or athletic pseudonephritis, a transient problem caused not by disease but by prolonged exercise.

Dr. Robert Johnson of Knox College in Galesburg, Ill., who helped conduct a 1970 medical study of several hundred athletes, figures that large numbers of the country's estimated 10 million joggers and runners suffer at some time from athletic pseudonephritis, especially if they exercise strenuously for an hour or more at a time. The problem, says Johnson, is that many doctors are unaware of the phenomenon and may order up expensive tests instead of the simple follow-up exam that would show the condition to be pseudonephritis. "Doctors are used to studying people who have been lying down in bed," says Johnson. "They are not always familiar with the effects of exercise."

Why does vigorous and prolonged exrcise cause pseudonephritis? Under normal conditions, some 20% of the blood pumped from the heart flows to the kidneys for filtration and removal of wastes. Exercise causes the body to shunt more blood to the muscles, reducing the flow to the kidneys by as much as 50%. But the kidneys continue to work at the same rate and apparently filter more protein out of a smaller volume of blood. Exercise also seems to cause constriction of the efferent arterioles, the vessels that lead out of the glomeruli, the kidney's filtration units. The result is a backup that increases pressure in the glomeruli and makes them more permeable, allowing proteins and blood cells to pass through the glomerular membranes and ultimately into the urine.

Jogger's kidney usually cures itself within 48 hours, but whether it can lead to more permanent kidney damage remains to be determined. David Jeffrey Fletcher, a second-year medical student at Chicago's Rush Medical College, is setting up a five-year study of long-distance runners to find the answer to this question. Until he does, says Researcher Gilbert Gleim of the Institute of Sports Medicine at Manhattan's Lenox Hill Hospital. fitness freaks should keep on running or jogging. The known benefits of such exercise, he says, far outweigh any known disadvantages. sb sb sb Jogger's kidney is not the only problem plaguing those involved in the great American running boom. An even more exotic ailment is "jogger's nipples," an irritation caused by the rubbing of a runner's shirt against skin. This condition, which afflicts not only women who jog braless but also men, can be prevented by covering the nipples with Band-Aids before a long run or by coating them liberally with petroleum jelly to reduce friction. Failure to take such precautions can leave the nipples raw. bleeding and quite painful.

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