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Sweat and sodium losses in NCAA football players: a precursor to heat cramps?
Int J Sport Nutr Exerc Metab 2005; 15(6):641-52IJ

Abstract

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. Ad libitum 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.

Authors+Show Affiliations

Gatorade Sports Science Institute, Barrington, IL 60010, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16521848

Citation

Stofan, John R., et al. "Sweat and Sodium Losses in NCAA Football Players: a Precursor to Heat Cramps?" International Journal of Sport Nutrition and Exercise Metabolism, vol. 15, no. 6, 2005, pp. 641-52.
Stofan JR, Zachwieja JJ, Horswill CA, et al. Sweat and sodium losses in NCAA football players: a precursor to heat cramps? Int J Sport Nutr Exerc Metab. 2005;15(6):641-52.
Stofan, J. R., Zachwieja, J. J., Horswill, C. A., Murray, R., Anderson, S. A., & Eichner, E. R. (2005). Sweat and sodium losses in NCAA football players: a precursor to heat cramps? International Journal of Sport Nutrition and Exercise Metabolism, 15(6), pp. 641-52.
Stofan JR, et al. Sweat and Sodium Losses in NCAA Football Players: a Precursor to Heat Cramps. Int J Sport Nutr Exerc Metab. 2005;15(6):641-52. PubMed PMID: 16521848.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Sweat and sodium losses in NCAA football players: a precursor to heat cramps? AU - Stofan,John R, AU - Zachwieja,Jeffrey J, AU - Horswill,Craig A, AU - Murray,Robert, AU - Anderson,Scott A, AU - Eichner,E Randy, PY - 2006/3/9/pubmed PY - 2006/3/29/medline PY - 2006/3/9/entrez SP - 641 EP - 52 JF - International journal of sport nutrition and exercise metabolism JO - Int J Sport Nutr Exerc Metab VL - 15 IS - 6 N2 - 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. Ad libitum 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. SN - 1526-484X UR - https://www.unboundmedicine.com/medline/citation/16521848/Sweat_and_sodium_losses_in_NCAA_football_players:_a_precursor_to_heat_cramps DB - PRIME DP - Unbound Medicine ER -