High incidence of hyponatremia in rowers during a four-week training camp.
OBJECTIVE
To investigate the incidence of hyponatremia and its relationship to plasma copeptin, a surrogate marker for arginine vasopressin (AVP) during 28 days of high-volume rowing training.


METHODS
Thirty rowers from the German junior national team (21 male) were studied during a training camp. Serum sodium ([Na(+)]), osmolality, and copeptin were measured before the beginning of the camp (day 0), and at days 7, 13, 18, 24, and 28. Daily fluid intake, body weight, urine parameters, and training volume were recorded.


RESULTS
Seventy percent of the rowers developed hyponatremia at least once. At day 18, training volume and incidence of hyponatremia (43%) were highest. [Na(+)] decreased from 143 ± 9 mmol·L(-1) (day 0) to 135 ± 5 mmol·L(-1) (day 18, P < .01). Hyponatremia was correlated significantly with weight gain compared with the previous day (P < .01). Copeptin decreased from day 0 to 28 (male: 6.7 ± 2.8 to 3.6 ± 1.7 pmol·L(-1); P < .05; female: 4.8 ± 1.1 to 3.2 ± 1.5 pmol·L(-1); P < .05), being only partially suppressed. Relative fluid intake per body surface area increased from day 7 (male: 2.79 ± 0.78 L·m(-2); female: 2.20 ± 0.70 L·m(-2)) to day 28 (3.88 ± 0.69 L·m(2) and 2.65 ± 0.93 L·m(-2); P < .05). No athlete developed symptomatic hyponatremia.


CONCLUSIONS
Prolonged high-volume rowing training can lead to a high incidence of hyponatremia. Overdrinking and inadequate suppression of AVP contribute to its development.
Division of Sports and Rehabilitation Medicine, Department of Internal Medicine II, University of Ulm, Germany; Department of Orthopedics, Medical Faculty, University of Düsseldorf, Germany.
Constantin Ulrich
CU
Mayer
Division of Sports and Rehabilitation Medicine, Department of Internal Medicine II, University of Ulm, Germany.
Gunnar
G
Treff
Department of Internal Medicine I, Endocrine Unit, University Hospital, University of Wuerzburg, Germany; IFB Adiposity Diseases, Leipzig University Medical Center, Germany.
Wiebke Kristin
WK
Fenske
Department of Internal Medicine I, Endocrine Unit, University Hospital, University of Wuerzburg, Germany.
Katja
K
Blouin
Division of Sports and Rehabilitation Medicine, Department of Internal Medicine II, University of Ulm, Germany. Electronic address: juergen.steinacker@uni-ulm.de.
Jürgen Michael
JM
Steinacker
Department of Internal Medicine I, Endocrine Unit, University Hospital, University of Wuerzburg, Germany; Comprehensive Heart Failure Center, University of Wuerzburg, Germany.
Bruno
B
Allolio
D000293:Adolescent; D056352:Athletes; D015415:Biomarkers / Q000097:blood; D004327:Drinking Behavior; D005260:Female; D005858:Germany; D006020:Glycopeptides / Q000097:blood; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D015994:Incidence; D008297:Male; D013177:Sports / Q000502:physiology*
D015415:Biomarkers; D006020:Glycopeptides; C048197:copeptins
Copeptin; Exercise-associated hyponatremia; Prolonged exercise; Vasopressin