Plasma and Salivary C-Reactive Protein Responses to Marathon Running: A Systematic Review and Meta-Analysis of Moderating Factors

Purpose: Running exercise induces a robust acute‑phase inflammatory response, yet the magnitude and moderators of C‑reactive protein (CRP) elevation remain unclear, with no prior quantitative synthesis distinguishing plasma from salivary measurements. Method: A systematic search of PubMed/MEDLINE, Scopus, Web of Science, and Google Scholar was performed from inception to February ۲۰۲۶. Eligible studies reported CRP levels before and after running exercise of any distance in runners. Random-effects meta-analyses pooled standardized mean differences (SMDs), with subgroup analyses and meta-regression examining age, BMI, and race distance. Results: Thirty studies (۱,۲۴۷ runners; ۷۲% male) were included. Endurance running significantly increased plasma CRP (SMD=۱.۲۰۷, ۹۵%CI:۰.۶۸۸–۱.۷۲۶; p=۰.۰۰۱) and in the single study with salivary CRP data (three distance subgroups), salivary CRP increased (SMD=۱.۲۳۰, ۹۵%CI:۰.۱۳۶–۲.۳۲۴; p=۰.۰۲۸). Age significantly moderated the response: older runners (>۴۸ years) showed a four‑fold greater effect (SMD=۱.۶۴۲) than younger runners (SMD=۰.۴۰۲; Q=۲۲.۸۷۳, p<۰.۰۰۱). Race distance was a dominant moderator: ultra‑marathons (>۱۰۰ km) elicited a nine‑fold larger surge (SMD=۳.۵۷۷) versus standard marathons (SMD=۰.۴۰۴; Q=۱۸.۶۹۵, p<۰.۰۰۱). BMI did not significantly moderate CRP elevation (Q=۱.۰۷۶, p=۰.۵۸۴). Substantial heterogeneity (plasma: I²=۹۱.۹۹%; salivary: I²=۷۳.۳۶%) and publication bias (plasma: Egger's p=۰.۰۰۳) were observed. Conclusion: Running exercise significantly elevates plasma and salivary CRP, with age and race distance as potent moderators. BMI does not influence the acute CRP response. Clinicians should avoid general population cutoffs (>۳ mg/L) during acute recovery. Salivary CRP requires further validation before clinical adoption. Standardized sampling at ۲۴‑۴۸ hours post‑race is essential for peak detection.

کلیدواژه ها:

C‑reactive protein ، marathon running ، ultra‑marathon ، Inflammation ، Meta‑analysis ، aging