Prescribed drinking leads to better cycling performance than ad libitum drinking

Costas N. Bardis, Stavros A. Kavouras, J. D. Adams, Nickos D. Geladas, Demosthenes B. Panagiotakos, Labros S. Sidossis

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Drinking ad libitum during exercise often leads to dehydration ranging from j1% to j3% of body weight. Purpose: This article aimed to study the effect of a prescribed hydration protocol matching fluid losses on a simulated 30-km criterium-like cycling performance in the heat (31.6-C T 0.5-C). Methods: Ten elite heat-acclimatized male endurance cyclists (30 T 5 yr, 76.5 T 7.2 kg, 1.81 T 0.07 m,V O2peak = 61.3 T 5.2 mLIminj1Ikgj1, body fat = 10.5% T 3.3%, Powermax = 392 T 33 W) performed three sets of criterium-like cycling, which consisted of a 5-km cycling at 50% power max followed by a 5-km cycling all out at 3% grade (total 30 km). Participants rode the course on two separate occasions and in a counterbalanced order, during either ad libitum drinking (AD; drink water as much as they wished) or prescribed drinking (PD; drink water every 1 km to much fluid losses). To design the fluid intake during PD, participants performed a familiarization trial to calculate fluid losses. Results: After the exercise protocol, the cyclist dehydrated by j0.5% T 0.3% and j1.8% T 0.7% of their body weight for the PD and AD trial, respectively. The mean cycling speed for the third bout of the 5-km hill cycling was greater in the PD trial (30.2 T 2.4 kmIhj1) compared with the AD trial (28.8 T 2.6 kmIhj1) by 5.1% T 4.8% (P G 0.05). Gastrointestinal, mean skin, and mean body temperatures immediately after the last hill climbing were greater in the AD compared with the PD trial (P G 0.05). Overall, sweat sensitivity during the three climbing bouts was lower in the AD (15.6 T 5.7 gIWj1Imj2) compared with the PD trial (22.8 T 3.4 gIWj1Imj2, P G 0.05). Conclusion: The data suggested that PD to match fluid losses during exercise in the heat provided a performance advantage because of lower thermoregulatory strain and greater sweating responses.

Original languageEnglish (US)
Pages (from-to)1244-1251
Number of pages8
JournalMedicine and science in sports and exercise
Issue number6
StatePublished - Jan 1 2017
Externally publishedYes


  • Dehydration
  • Fluid Balance
  • Gastrointestinal Temperature
  • Sweating
  • Thermoregulation

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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