title: Sweat rates, sweat sodium concentrations, and sodium losses in 3 groups of professional football players.
abstract: BACKGROUND
  Sweat sodium losses have never been reported in a large cohort of American football players.
  
  
  OBJECTIVE
  To compare sweat rates (SwtRs), sweat sodium concentrations (SwtNa(+)), and sodium losses in 3 groups of players (backs and receivers [BK], linebackers and quarterbacks [LB/QB], and linemen [LM]) to determine if positional differences and, therefore, size differences exist.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  Data were collected during practices in the second week of 2 consecutive training camps. The wet bulb globe temperature was 78.5 degrees F +/- 3.5 degrees F (25.9 degrees C +/- 1.9 degrees C).
  
  
  METHODS
  Eighteen BK, 12 LB/QB, and 14 LM volunteered.
  
  
  METHODS
  Sterile sweat patches were applied to the right forearm after the skin was appropriately cleaned. The patches were removed during practice, placed in sterile tubes, centrifuged, frozen, and later analyzed by flame photometry.
  
  
  METHODS
  Sweat rate, SwtNa(+), and sodium loss. We calculated SwtR by change in mass adjusted for urine produced and fluids consumed divided by practice time in hours.
  
  
  RESULTS
  Other than age, physical characteristics were different among groups (P < .001). The SwtR was different among groups (F(2,41) = 7.3, P = .002). It was lower in BK (1.42 +/- 0.45 L/h) than in LB/QB (1.98 +/- 0.49 L/h) (P < .05) and LM (2.16 +/- 0.75 L/h) (P < .01), but we found no differences between SwtRs for LB/QB and LM. The SwtNa(+) was not different among groups (BK = 50 +/- 16 mEq/L, LB/QB = 48.2 +/- 23 mEq/L, and LM = 52.8 +/- 25 mEq/L) and ranged from 15 to 99 mEq/L. Sweat sodium losses ranged from 642 mg/h to 6.7 g/h, and findings for group comparisons approached significance (P = .06). On days when players practiced 4.5 hours, calculated sodium losses ranged from 2.3 to 30 g/d.
  
  
  CONCLUSIONS
  The BK sweated at lower rates than did the midsized LB/QB and large LM, but LB/QB sweated similarly to LM. Sweat sodium concentration and daily sodium losses ranged considerably. Heavy, salty sweaters require increased dietary consumption of sodium during preseason.
authors.affiliation: HEAT Institute, West Chester University, PA 19383, USA. sfowkesgod@wcupa.edu
authors.forename: Sandra Fowkes
authors.initials: SF
authors.lastname: Godek
authors.forename: Chris
authors.initials: C
authors.lastname: Peduzzi
authors.forename: Richard
authors.initials: R
authors.lastname: Burkholder
authors.forename: Steve
authors.initials: S
authors.lastname: Condon
authors.forename: Gary
authors.initials: G
authors.lastname: Dorshimer
authors.forename: Arthur R
authors.initials: AR
authors.lastname: Bartolozzi
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005440:Fluid Therapy; D005538:Football / Q000502:physiology*; D006801:Humans; D020896:Hypovolemia; D008297:Male; D012964:Sodium / Q000032:analysis*; D013546:Sweating / Q000502:physiology*; D014869:Water Intoxication; D014882:Water-Electrolyte Balance; D015431:Weight Loss
chemical_list: D012964:Sodium