No case of exercise-associated hyponatraemia in top male ultra-endurance cyclists: the 'Swiss Cycling Marathon'.

Rüst, Christoph; Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas

The prevalence of exercise-associated hyponatraemia (EAH) has been investigated in endurance athletes such as runners and Ironman triathletes, but not in ultra-endurance road cyclists. We assessed fluid intake and changes in body mass, urine specific gravity and plasma sodium concentration ([Na]) in 65 ultra-endurance road cyclists in a 720-km ultra-cycling marathon, the 'Swiss Cycling Marathon'. The cyclists lost 1.5 (1.7)% body mass ( P < 0.01). No athlete developed EAH. Fluid intake was associated with the change in plasma [Na] ( r = −0.32, P < 0.05) and the change in body mass ( r = −0.30, P < 0.05). The change in plasma [Na] was related to post-race plasma [Na] ( r = 0.63, P < 0.0001). To conclude, ad libitum fluid intake in ultra-endurance cyclists in a single-stage ultra-endurance road cycling race showed no case of EAH. Future studies regarding drinking behaviour in different ultra-endurance disciplines might give insights into why the prevalence of EAH is different in the different disciplines.

SWITZERLAND; ENDURANCE athletes; CYCLISTS; SODIUM content of drinking water; CYCLING competitions; MARATHONS (Sports)

European Journal of Applied Physiology, 2012, Vol 112, Issue 2, p689

1439-6319

Academic Journal

10.1007/s00421-011-2024-y