Date of Graduation


Document Type


Degree Name

Bachelor of Science

Degree Level



Health, Human Performance and Recreation


Kavouras, Stavros

Committee Member/Reader

Ganio, Matthew

Committee Member/Second Reader

McDermott, Brendon



Introduction: Hypohydration exceeding 2% of body mass (bm), affected by heat and thirst level, leads to decreased athletic performance. Both physiological and psychological factors of dehydration have an impact on an athlete’s perceived performance. However, it is unclear whether the effects of psychological, physiological, or both have a negative impact on athletic performance caused by mild hypohydration. Purpose: The purpose of this study was to determine if mild hypohydration affects exercise performance in trained cyclists while blinding their hydration state. Methodology: Eleven competitive male cyclists participated in two blinded experimental trials, hypohydrated and euhydrated states by intra-venous infusions. The experimental criterium simulation test includes cycling through 3 sets of 20-minute steady state followed by a 5km race. Results: During the 5km time trial, the hypohydrated trial (39.0±0.5°C) resulted in significantly higher core temperatures compared to the euhydrated trial (38.5±0.2°C; P<0.05). Cycling speed was significantly faster in the euhydrated vs. the hypohydrated trial (27.3±0.1 vs. 26.2±0.7 km×h-1; P<0.05) due to greater cycling power output (304±6 vs. 286±10 W; P<0.05). Conclusion: Overall, the study found that mild hypohydration led to impairment in exercise performance in the heat compared to euhydration, when subjects were unaware of their hydration state. These responses might have been a response of great heat strain and/or cardiovascular impairment.


cycling, heat stress, male, hydration, dehydration, thirst