C-Reactive Protein Serum Concentrations in Well-Trained Athletes*

Abstract

Previously it had been shown that there is a sharp increase in C-reactive protein (CRP) serum concentration during the first few days after severe exercise. To evaluate the effect of physical training on the CRP levels, a sensitive enzyme immunoassay was developed and used to assess the basal CRP concentrations in 356 male and 103 female athletes, who trained at least 4 times per week in various disciplines, in 45 male and 40 female untrained controls, and in 35 elderly coronary patients. In male athletes the lowest CRP values were found in swimmers (median: 102 ng/ml, n = 59), which were significantly lower (P < 0.001) than those of male controls (median: 502 ng/ml, n = 45). The CRP concentrations in rowers (median: 260 ng/ml, n = 108) were also significantly lower (P < 0.01) than in the control group. CRP levels in middle- and long-distance runners (median: 315 ng/ml, n = 53), racing cyclists (median: 620 ng/ml, n = 111), and soccer players (median: 660 ng/ml, n = 25) did not differ significantly from those of the controls. In female athletes the lowest CRP concentrations were also found in swimmers (median: 110 ng/ml, n = 49), which were significantly lower (P < 0.001) than those of the female controls (median: 396 ng/ml, n = 40). Female middle- and long-distance runners (n = 36) and female rowers (n = 18) had median CRP values of 250 and 285 ng/ml, respectively.

This results suggest that training induces a suppressive effect upon CRP, respqnsible for the low serum levels in athletes (particularly swimmers) when compared to controls. CRP has a broad bacteriostatic action, hence low CRP levels intensively training athletes could be implicated in an increased susceptibility for infections.

Key words

C-reactive protein - inflammation - exercise - training