Increased urinary excretion of hydroxyproline in runners training in urban areas

In this study, the authors investigated urinary excretion of hydroxyproline in 120 subjects to test the hypothesis that physical activity is associated with increased exposure to pollution derived from traffic exhaust. The study population comprised active noncompetitive runners (i.e., 21.1% trained < 2.5 hr/wk, 20% trained for 2.5-5.0 hr/wk, and 54.4% trained > 5 hr/wk) who lived in Genoa, an urban area of Northern Italy. The mean hydroxyproline value (24.39 +/- 8.38 standard deviation] mg/24 hr x m2) in a group of 69 runners who trained in tracks and streets located in downtown Genoa was higher (p < .05) than the mean value recorded in a group of 21 runners (13.33 +/- 2.51 mg/24 hr x m2) who trained mainly in a rural environment of Genoa. The difference was even greater (p < .01) when a third comparable group of 30 nonrunners was considered (mean = 12.54 +/- 3.41 [standard deviation] mg/24 hr x m2). In the urban environment, urinary levels of hydroxyproline were correlated significantly with intensity and frequency of running, but they were unrelated to smoking status.