Body Mass Changes Across a Variety of Running Race Distances in the Tropics.

Desmond Wei Tan,Priscilla Weiping Fan,Lingaraj Krishna,Priathashini Krishnasamy,Si Hui Yap,Jason Kai Wei Lee,Tamara Hew-Butler,Ya Shi Teo,Mingchang Wang

doi:10.1186/s40798-016-0050-3

Abstract

BackgroundCurrent literature evaluating body mass (BM) changes across a variety of running race distances is limited. The primary objective of this study was to profile the range of BM changes across race distances. The secondary objective was to evaluate the prevalence of exercise-associated hyponatremia (EAH) in runners admitted to the on-site medical tent following participation of race events of different distances.MethodsA total of 1934 runners across seven footrace categories (10-, 21-, 25-, 42-, 50-, 84-, and 100-km) were included in the study. One thousand eight hundred eighty-seven runners had their BM measured before and after each race. Blood sodium concentrations were measured from the remaining 47 symptomatic runners admitted to the on-site medical tents and did not complete the race.ResultsIn terms of hydration status, 106 (6 %) were overhydrated, 1377 (73 %) were euhydrated, and 404 (21 %) were dehydrated. All race distances exhibited similar percentage of overhydrated runners (5 % in 10 km, 3 % in 21 km, 5 % in 25 km, 6 % in 42 km, 8 % in 50 km, 7 % in 84 km, and 6 % in 100 km). Forty-seven runners were admitted to the medical tents. Eight (17 %) were diagnosed with EAH (4 from 42 km, 2 from 84 km, 2 from 100 km), 38 (81 %) were normonatremic, and 1 (2 %) was hypernatremic. The % ΔBM across all races ranged from −8.0 to 4.1 % with a greater decrement noted in the 42-, 50-, 84-, and 100-km categories.ConclusionsApproximately 3–8 % runners had increased post-race BM, suggesting overhydration regardless of race distance. Symptomatic EAH was seen at race distances at or above 42 km, where BM changes demonstrated the widest range of values.

Highlights

Current literature evaluating body mass (BM) changes across a variety of running race distances is limited
It has been previously shown that male and female runners underestimate sweat losses by roughly 50 % after a 60-min run in the heat [2]. Such underestimations of fluid replacement needs have sparked recommendations suggesting that athletes drink above the dictates of thirst, which has resulted in an overestimation of fluid requirements, weight gain, and fluid overload hyponatremia [3]
A study by Hoffman et al [10] revealed that of exercise-associated hyponatremia (EAH) with dehydration as measured by mass loss was more predominant than EAH with overhydration as measured by mass gain in 161-km ultramarathoners in Northern California

Summary

Introduction

Current literature evaluating body mass (BM) changes across a variety of running race distances is limited. The secondary objective was to evaluate the prevalence of exercise-associated hyponatremia (EAH) in runners admitted to the on-site medical tent following participation of race events of different distances. It has been previously shown that male and female runners underestimate sweat losses by roughly 50 % after a 60-min run in the heat [2] Such underestimations of fluid replacement needs have sparked recommendations suggesting that athletes drink above the dictates of thirst, which has resulted in an overestimation of fluid requirements, weight gain, and fluid overload hyponatremia [3]. Other risk factors reported to cause EAH include prolonged exercise exceeding 4 h, low pace racing, low body mass, female gender, and hot environments [3, 11]

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