Rowing Performance After Dehydration: An Effect of Method

Purpose: To investigate whether mild hypohydration in lightweight rowers compromises rowing performance despite a two-hour rehydration window. Methods: Experienced varsity rowers [11 male (82.3 ± 26.2 kg, age = 21.3 ± 4.0 years, height = 184.7 ± 2.4 cm) and three female (62.1 ± 11.8 kg, 2.3 ± 4.2 years, 166.4 ± 16.2 cm)] performed a 2000 m rowing ergometer time trial and visuomotor battery twice: once euhydrated and once after mild dehydration. Weight loss (−1.68 ± 0.23% body mass reduction) was achieved through a combination of 12 h (abstinence) of fluid and food restriction and sauna exposure. Results: Participants were significantly slower on the 2000 m rowing trial in the hypohydration condition than in the euhydration condition (+2.44 ± 4.5 s, p < 0.05). Hierarchical linear regression analyses revealed that this rowing performance decrement was explained by hypohydration achieved overnight through fluid abstinence (r2 = 0.504, p < 0.01) but not by hypohydration achieved in the sauna (r2 = 0.025, n.s.), corroborating our previous finding. This analysis also revealed a relationship between hypohydration-related rowing performance decrements and hypohydration-related changes in visuomotor function (r2 = 0.310, p < 0.01). Conclusions: These findings suggest that rowing time trial performance can be negatively affected by relatively small changes in hydration status and that the method by which hypohydration is achieved is important. Rowing performance losses were explained by hypohydration due to prolonged fluid abstinence and by hypohydration-related changes to neural control of movement. Performance losses were not related to rapid sauna-based fluid loss.