First Study to Demonstrate Ergogenic Effects of Metformin - 14% Increased Time to Exhaustion in Standardized Supra-Maximal Cycling Test With 500mg of Ordinary Metformin
|With the publication of Learsi's latest paper the list of things metformin can do for you has just gotten been expanded with another item: Doping!|
All tests were performed twice once with a placebo supplement and once with 500mg of metformin. Both, the placebo and the metformin supplement were ingested 60 minutes before the supramaximal test, in order to investigate the hypothesis that metformin would increase anaerobic capacity and performance during high-intensity, short-duration exercise.
The authors, Learsi et al. (2015), based this hypothesis on the fact that metformin inhibits aerobic pathway energy production and so the glycolytic energy system could be overloaded during ATP production for muscle contraction.
Is this really the first study? Yes, it is the first to prove metformin's ergogenic effects in humans. It's yet not the first human study to test the ergogenic effects of metformin. 2008 Johnson et al. made the mistake to assume that taking metformin would affect the VO2max, or ventilatory threshold. Just like Gudat et al. before them, Johnson et al. simply missed the most straight forward practical measure of exercise performance, i.e. total time to exhaustion, while focusing on things like VO2 (Johnson et al. 2008) or lactate (Gudat et al. 1997) which are nice to explain increases in performance, but - if we are honest - still irrelevant, when all that really counts is how fast you run, how long you cycle or how hard you hit.While many of the variables they assessed didn't change, the already hinted at 14% increase in maximal endurance (see headline) is something that may make the difference between winning an Olympic medal and placing fourth or worse.
|Figure 2: Changes in time to exhaustion and EPOC, both stat. significantly w/ metformin (Learsi. 2015).|
- Gudat, U., G. Convent, and L. Heinemann. "Metformin and exercise: no additive effect on blood lactate levels in healthy volunteers." Diabetic medicine 14.2 (1997): 138-142.
- Johnson, S. T., et al. "Acute effect of metformin on exercise capacity in active males." Diabetes, Obesity and Metabolism 10.9 (2008): 747-754.
- Learsi, et al. "Metformin improves performance in high-intensity exercise, but not anaerobic capacity." in healthy male subjects." Clin Exp Pharmacol Physiol. 2015 Aug 7. doi: 10.1111/1440-1681.12474. [Epub ahead of print]