Glycerol, An Overlooked Ergogenic Supplement? 10-12g of Glycerol May Increase Lean Mass Without Training. Plus: Effects on Adrenals & AST + Lactate Response to Exercise

Interestingly, the study at hand suggests that glycerol may make you more musclar, even if you don't life. Crazy, but true (photo by awesomebody).

As a SuppVersity reader the potential ergogenic effect of the backbone of triglycerides are no news to you. The number of studies investigating the effects of glycerol on exercise performance and/or the adaptive response to exercise is yet low. Against that background, even a rodent study like the one by Eric Francelino Andrade from the Federal University of Lavras is worth its own SuppVersity article, I guess.

In said study, the Brazilian researchers evaluated the training adaptation and physical performance parameters in rats orally supplemented with glycerol,glucose, or saline, and submitted to moderate aerobic exercise.
Thirty male rats were trained for 6 weeks and administered the supplements during the last 4 weeks of the experiment. Animals were distributed in a completely randomized factorial 2 × 3 design (with or without exercise and 3 substrates) and received 864 mg/kg body of either glucose or glycerol in solution.

For human beings this equals human equivalents of 140mg/kg or ~10-12g of both, glucose and glycerol, for an adult. If this amount of glycerol had the same effects on humans at it did on the rodents in the study at hand, this would mean that it would lead to non-significant increases in lean body mass, even if the men and women who take it, were not working out.

Figure 1: Overview of the study design (top) and changes in protein content (~lean mass) and fat content of the carcass of trained and untrained rodents in the glycerol, glucose and saline groups at the end of the study period (Andrade. 2014)

The data from the rodent study at hand does yet also suggest that glycerol may at the same time non-significantly inhibit the lean mass gains that occur in response to aerobic training.

Glycerol as an adrenal supplement?

In contrast to the previously cited changes in lean body mass, which are not the result of a simple increase in body water (that's the beauty of actually cutting your "hairy subjects" open - you don't have to use BIA or DEXA scans to measure their lean mass), the effects on the weight of the adrenals of the animals was statistically significant in both, the trained and the non-trained rodents.

Figure 2: Organ weights (top row) and lactate (middle row) and aspartate aminotransferase (AST | lower row) levels at the end of the study period and after workouts, respectively (Andrade. 2014)

In the exercise trained rodents, there was also a significant reduction in the protein oxidation marker AST in both, the glucose and glycerol group. An obvious sign that both, pure glucose and the polyol (sugar alcohol) compound were used as alternative fuel during the exhaustive workouts, with the latter providing greater reductions in lactate build-up than the former.
References:

• Andrade, Eric Francelino, et al. "Adaptation to physical training in rats orally supplemented with glycerol." Canadian journal of physiology and pharmacology 93.999 (2014): 1-7.
• Decaux, Guy, et al. "Low plasma bicarbonate level in hyponatremia related to adrenocorticotropin deficiency." The Journal of Clinical Endocrinology & Metabolism 88.11 (2003): 5255-5257.
• Easton, Chris, Stephen Turner, and Yannis P. Pitsiladis. "Creatine and glycerol hyperhydration in trained subjects prior to exercise in the heat." International journal of sport nutrition and exercise metabolism 17.1 (2007): 70-91.
• Montner, P., et al. "Pre-exercise glycerol hydration improves cycling endurance time." International Journal of Sports Medicine 17.01 (1996): 27-33. 
• Von Duvillard, Serge P., et al. "Fluids and hydration in prolonged endurance performance." Nutrition 20.7 (2004): 651-656.