title: Water and sodium intake habits and status of ultra-endurance runners during a multi-stage ultra-marathon conducted in a hot ambient environment: an observational field based study.
abstract: BACKGROUND
  Anecdotal evidence suggests ultra-runners may not be consuming sufficient water through foods and fluids to maintenance euhydration, and present sub-optimal sodium intakes, throughout multi-stage ultra-marathon (MSUM) competitions in the heat. Subsequently, the aims were primarily to assess water and sodium intake habits of recreational ultra-runners during a five stage 225 km semi self-sufficient MSUM conducted in a hot ambient environment (Tmax range: 32°C to 40°C); simultaneously to monitor serum sodium concentration, and hydration status using multiple hydration assessment techniques.
  
  
  METHODS
  Total daily, pre-stage, during running, and post-stage water and sodium ingestion of ultra-endurance runners (UER, n = 74) and control (CON, n = 12) through foods and fluids were recorded on Stages 1 to 4 by trained dietetic researchers using dietary recall interview technique, and analysed through dietary analysis software. Body mass (BM), hydration status, and serum sodium concentration were determined pre- and post-Stages 1 to 5.
  
  
  RESULTS
  Water (overall mean (SD): total daily 7.7 (1.5) L/day, during running 732 (183) ml/h) and sodium (total daily 3.9 (1.3) g/day, during running 270 (151) mg/L) ingestion did not differ between stages in UER (p < 0.001 vs. CON). Exercise-induced BM loss was 2.4 (1.2)% (p < 0.001). Pre- to post-stage BM gains were observed in 26% of UER along competition. Pre- and post-stage plasma osmolality remained within normal clinical reference range (280 to 303 mOsmol/kg) in the majority of UER (p > 0.05 vs. CON pre-stage). Asymptomatic hyponatraemia (<135 mmol/L) was evident pre- and post-stage in n = 8 UER, corresponding to 42% of sampled participants. Pre- and post-stage urine colour, urine osmolality and urine/plasma osmolality ratio increased (p < 0.001) as competition progressed in UER, with no change in CON. Plasma volume and extra-cellular water increased (p < 0.001) 22.8% and 9.2%, respectively, from pre-Stage 1 to 5 in UER, with no change in CON.
  
  
  CONCLUSIONS
  Water intake habits of ultra-runners during MSUM conducted in hot ambient conditions appear to be sufficient to maintain baseline euhydration levels. However, fluid over-consumption behaviours were evident along competition, irrespective of running speed and gender. Normonatraemia was observed in the majority of ultra-runners throughout MSUM, despite sodium ingestion under benchmark recommendations.
authors: Department of Health Professions, Coventry University, Priory Street, Coventry, CV1 5FB, United Kingdom. ricardo.costa@coventry.ac.uk
authors: Ricardo J S
authors: RJ
authors: Costa
authors: Ana
authors: A
authors: Teixeira
authors: Luis
authors: L
authors: Rama
authors: Abigail J M
authors: AJ
authors: Swancott
authors: Lisa D
authors: LD
authors: Hardy
authors: Benjamin
authors: B
authors: Lee
authors: Vera
authors: V
authors: Camões-Costa
authors: Samantha
authors: S
authors: Gill
authors: Jessica P
authors: JP
authors: Waterman
authors: Emily C
authors: EC
authors: Freeth
authors: Edel
authors: E
authors: Barrett
authors: Joanne
authors: J
authors: Hankey
authors: Slawomir
authors: S
authors: Marczak
authors: Encarna
authors: E
authors: Valero-Burgos
authors: Volker
authors: V
authors: Scheer
authors: Andrew
authors: A
authors: Murray
authors: Charles D
authors: CD
authors: Thake
mesh_terms: D000328:Adult; D058070:Asymptomatic Diseases / Q000628:therapy; D001834:Body Water; D015331:Cohort Studies; D004326:Drinking; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance; D010953:Plasma Volume; D012420:Running / Q000502:physiology*; D012982:Sodium, Dietary / Q000008:administration & dosage* / Q000097:blood*; D014882:Water-Electrolyte Balance
chemical_list: D012982:Sodium, Dietary