Sweat and Sodium Losses in NCAA Football Players: A Precursor to Heat Cramps?

Click name to view affiliation

John R. Stofan
Search for other papers by John R. Stofan in
Current site
Google Scholar
PubMed
Close
,
Jeffrey J. Zachwieja
Search for other papers by Jeffrey J. Zachwieja in
Current site
Google Scholar
PubMed
Close
,
Craig A. Horswill
Search for other papers by Craig A. Horswill in
Current site
Google Scholar
PubMed
Close
,
Robert Murray
Search for other papers by Robert Murray in
Current site
Google Scholar
PubMed
Close
,
Scott A. Anderson
Search for other papers by Scott A. Anderson in
Current site
Google Scholar
PubMed
Close
, and
E. Randy Eichner
Search for other papers by E. Randy Eichner in
Current site
Google Scholar
PubMed
Close
Restricted access

This observational study was designed to determine whether football players with a history of heat cramps have elevated fluid and sodium losses during training. During a “two-a-day” training camp, five Division I collegiate football players (20.2 ± 1.6 y, 113 ± 20 kg) with history of heat cramps (C) were matched (weight, age, race and position) with a cohort of teammates (19.6 ± 0.6 y, 110 ± 20 kg) who had never cramped (NC). Change in body weight (adjusted by fluid intake) determined gross sweat loss. Sweat samples (forearm patch) were analyzed for sodium and potassium concentrations. Adlibitum fluid intake was measured by recording pre- and post-practice bottle weights. Average sweat sodium loss for a 2.5-h practice was projected at 5.1 ± 2.3 g (C) vs. 2.2 ± 1.7 g (NC). When averaged across two practices within the day, fluid intake was similar between groups (C: 2.6 ± 0.8 L vs. NC: 2.8 ± 0.7 L), as was gross sweat loss (C: 4.0 ± 1.1 L vs. NC: 3.5 ± 1.6 L). There was wide variability in the fluid deficit incurred for both C and NC (1.3 ± 0.9 vs. 0.7 ± 1.2%) due to fluid intake. Sweat potassium was similar between groups, but sweat sodium was two times higher in C versus NC (54.6 ± 16.2 vs. 25.3 ± 10.0 mmol/L). These data indicate that sweat sodium losses were comparatively larger in cramp-prone football players than in NC. Although both groups consumed sodium-containing fluids (on-field) and food (off-field), both appeared to experience an acute sodium deficit at the end of practices based on sweat sodium losses. Large acute sodium and fluid losses (in sweat) may be characteristic of football players with a history of heat cramping.

Stofan, Zachwieja, Horswill, and Murray are with the Gatorade Sports Science Institute, Barrington, IL, 60010. Anderson is with the University of Oklahoma, Norman, OK, 73019. Eichner is with the Health Sciences Center, University of Oklahoma, Oklahoma City, OK, 73126

  • Collapse
  • Expand