Glycerol with IV fluids and hydration in athletes
What it found
In nine endurance-trained men, adding glycerol to oral fluid alongside intravenous fluid led to the greatest fluid retention after dehydration.
The same combination also restored plasma volume the most.
What they found
Studies in people
Plasma volume restoration
Plasma volume came back the most with IV fluid plus oral glycerol, then IV fluid alone, then oral glycerol, then oral fluid alone.
Urine volume
Urine volume was lower in both trials that used IV fluid compared with the oral-only trial.
Fluid retention
The mix of IV fluid and oral glycerol led to the greatest fluid retention of all four rehydration methods.
Stress hormones
IV fluid, with or without glycerol, led to lower aldosterone levels during rehydration and the performance test, and lower cortisol levels during rehydration.
What the authors conclude
“IV with oral glycerol resulted in the greatest fluid retention.”
Also in their conclusions
- They report that the IV conditions led to greater fluid retention than oral fluid alone.
- They also found that the IV conditions led to lower levels of fluid regulatory and stress hormones compared with both oral conditions.
How it was done
Athletes use intravenous saline to rehydrate as fully as possible. The authors wanted to see whether adding oral glycerol could reduce the urine losses that come with intravenous rehydration.
Nine endurance-trained men lost 4% of their bodyweight through dehydration. They then rehydrated with 150% of the fluid lost, using four different mixes of oral fluid, intravenous fluid and glycerol, in a randomised order, before a cycling performance test.
What it can’t tell you
- We summarised it from the abstract only.
- This was a small trial in nine endurance-trained men, so the results may not apply to other people.
- The study cannot show whether these rehydration mixes affect long-term health or performance outside this cycling test.
Who paid
- Authors work at
- The University of Queensland, Australia
The paper
- Title
- Hydration and endocrine responses to intravenous fluid and oral glycerol
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- van Rosendal SP, Strobel NA, Osborne MA, Fassett RG, Coombes JS (2015). Hydration and endocrine responses to intravenous fluid and oral glycerol. Scandinavian journal of medicine & science in sports. doi:10.1111/sms.12367PubMed 25943662DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error