The effect of a high (H) and a low (L) rate of post-exercise fluid consumption on plasma volume and fluid balance restoration was investigated. Eight well-trained cyclists were dehydrated at 3% of body weight (BW) by cycling at 28 °C. During the recovery period, they ingested a carbohydrate-electrolyte solution in a volume equivalent to 120% of BW loss. Randomly, they ingested 60%, 40%, and 20% in the 1 st, 2nd, and 3rd hours of the recovery period, respectively (H), or 24% · h−1 during 5 hours (L). BW loss was similar for both trials and resulted in a total drink intake of 2.6 ± 0.1 kg. Urine output in H exceeded significantly that of L in the 2nd and 3rd hours. This was reversed in the 5th and 6th hours. Plasma volume and fluid balance increased more rapidly in H compared to L. After 6 hours this difference disappeared. It is concluded that H results in a faster rate of plasma volume and fluid balance restoration compared to L, despite a temporary large urine output.
The authors are with the Department of Human Biology at Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.