Seifert, J. G., Luetkemeier, M. J., White, A. T., & Mino, L. M. (1998). The physiological effects of beverage ingestion during cross country ski training in elite collegiate skiers. Canadian Journal of Applied Physiology, 23, 66-73.

Two studies were conducted to assess the effects of forms of fluid ingestion on blood in cross-country skiing.

The first investigation was conducted at ski training. Skiers (N = 6) drank water frequently. Body weight, plasma and urine osmolality, and plasma protein decreased significantly. The volume of excreted urine increased significantly.

The second study compared two groups of five skiers ingesting 2.5 ml/kg/BW of fluid, one being water, the other a carbohydrate/electrolyte solution. The CHO/electrolyte group produced less urine and had smaller decreases in plasma osmolality and protein than the water-group.

It was concluded that the free ingestion of water at cross-country ski training was inadequate to minimize fluid balance disruption. Plain water ingestion also diluted the plasma and increased urine excretion. On the other hand, a CHO/electrolyte solution minimized fluid balance disruption probably by maintaining osmotic balance in the plasma.

Implication. When exercising in the cold, and in particular during cross-country skiing, the intake of carbohydrate/electrolyte fluids is important for sustaining fluid balance. The consumption of water alone does not maintain that balance.

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