Impact of Ad Libitum Versus Programmed Drinking on Endurance Performance: A Systematic Review with Meta-Analysis

Area of Science:

• Exercise Physiology
• Sports Nutrition
• Hydration Strategies

Background:

• Ongoing debate exists regarding optimal hydration strategies for athletes during exercise.
• Recent studies compare the effects of ad libitum (ALD) and programmed drinking (PD) on endurance performance (EP).

Purpose of the Study:

• To determine if one drinking strategy (ALD or PD) offers a significant advantage in endurance performance.
• To systematically review and meta-analyze existing research on ALD versus PD in athletes.

Main Methods:

• Systematic review and meta-analysis of crossover controlled trials.
• Searched PubMed and SPORTDiscus databases for relevant studies.
• Included studies with controlled settings, exercise duration ≥ 1 hour, euhydrated state, specific fluid intake criteria, and controlled electrolyte/carbohydrate composition.

Main Results:

• Seven publications with eight effect estimates were analyzed, involving 82 subjects in cycling and running exercises.
• Mean fluid consumption was significantly higher with PD (1073 mL/h) than ALD (505 mL/h).
• Despite lower fluid intake and greater dehydration with ALD, endurance performance was not significantly different between ALD and PD.

Conclusions:

• Both ALD and PD strategies similarly impact 1-2 hour cycling or running performances under moderate to high intensity and temperate to warm conditions.
• The observed minor performance improvement with ALD is considered trivial.
• Hydration strategy may have less impact on performance than previously thought for these specific exercise conditions.