title: Body Mass Changes Across a Variety of Running Race Distances in the Tropics.
abstract: BACKGROUND
  Current 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.
  
  
  METHODS
  A 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.
  
  
  RESULTS
  In 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.
  
  
  CONCLUSIONS
  Approximately 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.
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Desmond Wei
authors.initials: DW
authors.lastname: Tan
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Si Hui
authors.initials: SH
authors.lastname: Yap
authors.affiliation: National University Hospital Sports Centre, National University Health System, Singapore, Singapore.
authors.forename: Mingchang
authors.initials: M
authors.lastname: Wang
authors.affiliation: Defence Medical & Environmental Research Institute, DSO National Laboratories, Singapore, Singapore.
authors.forename: Priscilla Weiping
authors.initials: PW
authors.lastname: Fan
authors.affiliation: Defence Medical & Environmental Research Institute, DSO National Laboratories, Singapore, Singapore.
authors.forename: Ya Shi
authors.initials: YS
authors.lastname: Teo
authors.affiliation: Department of Orthopaedics, Tan Tock Seng Hospital, Singapore, Singapore.
authors.forename: Priathashini
authors.initials: P
authors.lastname: Krishnasamy
authors.affiliation: National University Hospital Sports Centre, National University Health System, Singapore, Singapore.
authors.forename: Lingaraj
authors.initials: L
authors.lastname: Krishna
authors.affiliation: School of Health Sciences, Oakland University, Rochester, MI USA.
authors.forename: Tamara
authors.initials: T
authors.lastname: Hew-Butler
authors.affiliation: Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore ; Defence Medical & Environmental Research Institute, DSO National Laboratories, Singapore, Singapore ; Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
authors.forename: Jason Kai Wei
authors.initials: JK
authors.lastname: Lee