Original Research
Changes in Blood Electrolytes and Plasma Volume in National Football League Players During Preseason Training Camp

Athletic Training & Sports Health Care  Vol. 1   No. 6   November/December 2009

By Sandra Fowkes Godek, PhD, ATC; Arthur R. Bartolozzi, MD

ABSTRACT

Blood samples were drawn from 6 National Football League players for baseline measures and then prior to morning practice on days 3, 5, and 9. Mean blood sodium level was lower on days 3 (136.9±0.6 mmol·L^-1) and day 5 (138.1±0.6 mmol·L^-1) compared to baseline (140.4±0.4 mmol·L^-1) and day 9 (140.3±0.4 mmol·L^-1). Mean blood potassium level was higher on day 5 (4.16±0.13 mmol·L^-1) and day 9 (4.36±0.08 mmol·L^-1) compared to baseline (3.77±0.15 mmol·L^-1). Mean plasma volume was lower on day 3 (-4.9%±2.4%) compared to day 5 (4.5%±1.9%), and mean mass (days 2 through 9) was below baseline before and after practices. Blood sodium level declined by day 3 of preseason and was maintained at low normal levels at the expense of contracted plasma volume. Increased resting blood potassium levels on days 5 and 9 indicated rhabdomyolysis. Increased consumption of sodium is important for professional football players to maintain plasma volume during the first week of preseason.

AUTHORS

Dr Fowkes Godek is from the Heat Illness Evaluation Avoidance & Treatment Institute, West Chester University, West Chester, and Dr Bartolozzi is from 3B Orthopaedics, Pennsylvania Hospital, Philadelphia, Pa.

Originally submitted January 16, 2009.

Accepted for publication September 30, 2009.

The authors have no financial or proprietary interest in the materials presented herein.

The authors thank the athletic training staff and players from this NFL team for allowing them to conduct this study. This study was partially funded by a faculty development grant from West Chester University.

Address correspondence to Sandra Fowkes Godek, PhD, ATC, Sports Medicine Department, West Chester University, 755 South New Street, West Chester, PA 19383; e-mail: sfowkesgod@wcupa.edu.

doi:10.3928/19425864-20091019-03