Glycerol

Effective for hyperhydration and thermoregulation during prolonged exercise in heat; limited utility outside of endurance sport contexts.

A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.

Meta-analyses show glycerol hyperhydration can reduce heart rate and core temperature during exercise in the heat, with small improvements in endurance performance. Effects are most pronounced in hot conditions and prolonged exercise lasting over 60 minutes.

• Expands plasma volume for improved thermoregulation
• May improve endurance performance in heat
• Reduces cardiovascular strain during prolonged exercise

Typical loading protocol: 1-1.5 g/kg body weight with 25-30 mL water per gram of glycerol, consumed 60-120 minutes before exercise.

• Bloating and GI discomfort
• Headache
• Nausea

Can cause headache, bloating, and nausea. Banned by WADA from 2010-2018 but currently permitted. Not suitable for those with kidney disease.

Benefits are specific to endurance exercise in hot conditions. Negligible benefit for short-duration or thermoneutral exercise. Requires specific loading protocols.

• Energy40
• Recovery35