Acute influence of aerobic physical exercise on procalcitonin

Sir, Although the new guidelines of the American College of Sports Medicine (ACSM) and American Heart Association (AHA) emphasizes that physical activity above the recommended minimum amount provides additional health benefits [1], debate continues regarding the intensity of activity required for good health, as excessive strains of exercise might overwhelm advantageous changes and, particularly, induce a state of systemic inflammation [2]. We read with interest the article of Papassotiriou et al. who concluded that a prolonged endurance exercise results in severe stimulation of inflammatory mediators followed by muscle and liver damage, but does not induce procalcitonin (PCT) secretion [3]. This is surprising since PCT is produced as part of the systemic response to circulating cytokines, and is currently considered a helpful marker in bacterial infection and sepsis due to its virtual absence in health, induction in sepsis and a half-life suitable for daily monitoring of disease progress [4]. Moreover, the only time points available for PCT measurements in the study of Papassotiriou et al. were the end of the race and 48 h thereafter. To further investigate PCT metabolism in sportsmen, ten healthy trained Caucasian males, (mean age: 47 years, range: 37–64 years), who had been engaged in specific endurance training for at least 5 years, performed a 21 km, half-marathon run under subintensive conditions (78 ± 3% VO2 max). Baseline blood samples (pre-run) were collected at fast, 30 min before the participants warmed up, after (post-run), and 3 h, 6 h and 24 h after the run. PCT was measured by an immunoluminometric assay (Vidas Brahms, bioMerieux, Marcy l'Etoile, France). The lowest concentration of PCT detectable by this technique is 0·05 μg L. The intraand interassay CV are < 5% and < 7%, respectively. Data are presented as mean ± standard error of mean (SEM). Statistical significance was defined as P < 0·05. The paired observation Student’s t-test was used to analyse time-course changes. PCT values significantly increased over the pre-run values (0·05 ± 0·00 μg L) 3 h after the run (0·09 ± 0·02 μg L; P = 0·02) and continued to increase 6 h (0·19 ± 0·04 μg L; P < 0·01) and to 24 h thereafter (0·021 ± 0·06 μg L; P = 0·03) (Fig. 1). The variation throughout the study period was statistically significant by one-way analysis of variance (P < 0·01). Results of our investigation attest that a subintensive aerobic activity in healthy, middle-aged, trained individuals acutely influence PCT levels, in agreement with the previous finding that PCT concentrations start to rise at 4 h, peak at 6 h and reach plateau at 8–24 h [4]. In agreement with our findings, Papassotiriou et al. did not find a statistical variation of PCT immediately after the race. However, PCT measurements were unavailable until 48 h afterward. In this period, PCT increases are more likely to occur, as reflected in previous observations [4] and confirmed in our investigation. Since PCT values were about to reach a plateau at 24 h, we cannot rule out, however, (we have no data after 24 h), that PCT levels 48 h after a subintensive aerobic activity may return to values comparable to those before the run.