Glycerol

What it is

Glycerol is a sugar alcohol that draws and holds water in the body through its osmotic properties. Taken with a large fluid load before exercise, it expands total body water (hyperhydration), which can help athletes resist dehydration in heat or long events.

Benefits

Increases body-water retention by roughly a liter and can improve endurance and heat tolerance when dehydration would otherwise exceed about 2% of body weight; performance findings are mixed across studies. Typical protocol is about 1-1.2 g per kg body weight with a large volume of fluid.

When to take it

Take with the prescribed fluid load roughly 60-120 minutes before exercise to allow hyperhydration to develop. Most useful when in-event fluid intake will be insufficient.

Side effects

Can cause bloating, nausea, and gastrointestinal discomfort, and sometimes headache from fluid shifts; tolerability varies by individual and dose. Banned-list status has changed over time, so competitive athletes should check current rules.

Sources

• Hyperhydrating with glycerol: implications for athletic performance (PubMed)
• Effects of glycerol hyperhydration on the running economy of long-distance runners: a randomized crossover clinical trial (PMC)

Products containing Glycerol

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