Abstract
Purpose: This study aimed to investigate changes in muscle damage during the course of a 217-km mountain ultramarathon (MUM). In an integrative perspective, inflammatory response and renal function were also studied.Methods: Six male ultra-runners were tested four times: pre-race, at 84 km, at 177 km, and immediately after the race. Blood samples were analyzed for serum muscle enzymes, acute-phase protein, cortisol, and renal function biomarkers.Results: Serum creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST) increased significantly throughout the race (P < 0.001, P < 0.001; P = 0.002, respectively), and effect size (ES) denoted a large magnitude of muscle damage. These enzymes increased from pre-race (132 ± 18, 371 ± 66, and 28 ± 3 U/L, respectively) to 84 km (30, 1.8, and 3.9-fold, respectively); further increased from 84 to 177 km (4.6, 2.9, and 6.1-fold, respectively), followed by a stable phase until the finish line. Regarding the inflammatory response, significant differences were found for C-reactive protein (CRP) (P < 0.001) and cortisol (P < 0.001). CRP increased from pre-race (0.9 ± 0.3 mg/L) to 177 km (243-fold), cortisol increased from pre-race (257 ± 30 mmol/L) to the 84 km (2.9-fold), and both remained augmented until the finish line. Significant changes were observed for creatinine (P = 0.03), urea (P = 0.001), and glomerular filtration rate (GFR) (P < 0.001), and ES confirmed a moderate magnitude of changes in renal function biomarkers. Creatinine and urea increased, and GFR decreased from pre-race (1.00 ± 0.03 mg/dL, 33 ± 6 mg/dL, and 89 ± 5 ml/min/1.73 m2, respectively) to 84 km (1.3, 3.5, and 0.7-fold, respectively), followed by a plateau phase until the finish line.Conclusion: This study shows evidence that muscle damage biomarkers presented early peak levels and they were followed by a plateau phase during the last segment of a 217-km MUM. The acute-phase response had a similar change of muscle damage. In addition, our data showed that our volunteers meet the risk criteria for acute kidney injury from 84 km until they finished the race, without demonstrating any clinical symptomatology.
Highlights
Ultramarathons are foot race competitions comprising longer distances than a marathon and performed on a variety of terrains (Wu et al, 2004; Vernillo et al, 2016)
Significant increases were observed for Creatine kinase (CK) [F(3,15) = 105.55; P < 0.001; η2 = 0.95; large], lactate dehydrogenase (LDH) [F(3,15) = 27.062; P < 0.001; η2 = 0.84; large], and AST [F(1.09,5.48) = 26.977; P = 0.002; η2 = 0.84; large], denoting marked muscle damage during the competition
Post hoc analysis denoted no changes from pre-race (1; no soreness) to the first checkpoint (3 ± 1; slight soreness) (P > 0.05), high reports of muscle soreness were observed from pre-race to the second checkpoint (7 ± 1; sore) (P < 0.05), followed by a stable phase from the second checkpoint to post-race (6 ± 1; sore) (P > 0.05)
Summary
Ultramarathons are foot race competitions comprising longer distances than a marathon and performed on a variety of terrains (Wu et al, 2004; Vernillo et al, 2016). It is difficult to generalize these findings in ultramarathons, given races range from 50 km through beyond 1,600 km, are performed on a mostly flat road or on varying terrains, and may occur in a single-stage or multi-days (Fallon et al, 1999; Wu et al, 2004; Mastaloudis et al, 2006; Miyata et al, 2008; Vernillo et al, 2016) Each of these characteristics may influence muscle damage during these competitions (Peake et al, 2005; Brancaccio et al, 2008; Banfi et al, 2012; Saugy et al, 2013).
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