Article Title



K. Johnson1, C. Connolly2, P. Nilssen1, T. Miller3, W. D. Hiller2

1Washington State University, College of Education, Pullman, WA

2Washington State University, Elson S. Floyd College of Medicine, Spokane, WA

3Virginia Tech Carilion School of Medicine, Roanoke, VA

Exercise-associated muscle cramps (EAMC) is a common condition in ultra-endurance athletic events. Despite its high incidence, the etiology and risk factors are not fully understood. PURPOSE: The purpose of this study was to explore trends in Ironman-distance triathletes, that presented to the medical tent during competition with muscle cramping as well as those who returned with subsequent cramping after initial treatment. METHODS: Medical records (n=10,553) from the 1989-2019 Ironman World Championship (Kona, HI) were reviewed. Independent samples t-tests were run and odds ratios were calculated to compare athletes with cramping (n=2,859) to those without (n=7670). The same analyses were used to compare those who returned to the tent with muscle cramps (n=377) to those who had muscle cramps and did not subsequently return with mucscle cramps (n=2248). RESULTS: Triathletes who presented with muscle cramps were more likely to have a history of previously reporting to the medical tent with muscle cramps within the same race compared to those presenting without muscle cramps (OR 2.40; 95% CI = 1.91-3.03). Triathletes who presented with muscle cramps had slightly higher serum sodium (140 +/- 7 vs. 139 +/- 7 mEq/L, p = .007) and potassium (4.3 +/- 0.7 vs. 4.2 +/- 0.6 mEq/L, p < .001) concentrations than those without muscle cramps. Dehydration was more common in triathletes with muscle cramps (OR 1.63; 95% CI = 1.49-1.78) compared to those without. Male triathletes were much more likely to present with muscle cramps than female triathletes (29 vs. 22%, p < .001). For those returning to the medical tent with muscle cramps, faster race completion time was associated with increased risk of returning with muscle cramps (11.0 +/- 1.9 vs. 11.4 +/- 1.8 hours, p < .001). CONCLUSION: Our findings from nearly 30 years of elite ultra-endurance data indicate that muscle cramps are likely to be a reoccurring issue throughout the race and are more common among males. We confirm that electrolyte abnormalities are not associated with muscle cramps during ultra-endurance competition. Our finding that dehydration is associated with muscle cramps is somewhat contradictory to current literature.

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