Two weeks of a cheap, beet-associated compound was linked to roughly 16% higher bench throw power on day one of a hard testing block. That is the headline from a small 2010 crossover trial of betaine supplementation in resistance-trained men. The results are interesting, but they come with caveats, and the lifters who benefited most were the ones doing upper-body work.
What Is Betaine (TMG)?
Betaine, also called trimethylglycine (TMG), is a compound found in foods such as beets, spinach and wheat. It is also sold as a standalone supplement. Betaine has long been discussed in sports nutrition circles as a possible ergogenic aid, which is why Lee and colleagues set out to test it directly on strength and power outcomes. Their paper, "Ergogenic effects of betaine supplementation on strength and power performance," appeared in the Journal of the International Society of Sports Nutrition in 2010.
The Crossover Design
The study enrolled twelve men (mean age 21 ± 3 years, body mass 79.1 ± 10.7 kg) who had at least three months of resistance training behind them. The design was balanced, randomized, double-blind and crossover. Each man completed two 14-day trials, one on betaine and one on placebo, separated by a 14-day washout.
Before and after each 14-day block, participants did two consecutive days (D1 and D2) of a standardized, high-intensity strength/power resistance exercise challenge. It included bench press, squat and jump tests. Because every lifter acted as his own control, a crossover like this reduces the noise from individual differences in strength and training history. The consecutive-day format also let the researchers look at how well performance was maintained under accumulated fatigue.
Power and Force Results
The bench press numbers drew the most attention. After 14 days of betaine, bench throw power was 1779 ± 90 W on D1 and 1788 ± 34 W on D2. Pre-supplementation values were 1534 ± 30 W and 1498 ± 29 W, and the placebo condition produced 1374 ± 128 W and 1523 ± 39 W. By simple arithmetic, the D1 figure is about 16% above the pre-supplementation value, which is where the headline comes from. The D2 gain over baseline works out to roughly 19%. The differences were statistically significant (p < 0.05).
Isometric bench press force followed a similar pattern. It reached 2922 ± 297 N on D1 and 2503 ± 28 N on D2 after betaine, versus 2345 and 2423 N before supplementation and 2175 and 2128 N on placebo. The D1 jump is large. The D2 gain over baseline is much smaller, so the force benefit looks bigger on the first day than the second.
Lower-body measures moved too, though the paper frames the effect as weaker there. Compared with pre-supplementation, vertical jump power and isometric squat force increased on both days after betaine. The authors concluded that betaine increased power, force and the maintenance of those measures in selected tests, with effects more apparent in the smaller upper-body muscle groups.
What Didn't Improve
Not everything moved. Jump squat power did not differ, and neither did the number of bench press or squat repetitions. For lifters, this matters. The benefits showed up in power and maximal force expression, not in rep endurance or in every power test. If your goal is more reps at a given load, this study offers no support for betaine.
Dose and Timing
Per the full text (PMC2915951), participants took 1.25 g of betaine twice daily, for 2.5 g per day, mixed in a sports drink, for 14 days. This is a modest dose, and the protocol was a daily regimen rather than a single pre-workout hit. The study design supports twice-daily use over two weeks, not a one-off acute dose.
Caveats
The sample was twelve young men over a short trial, so this is early-stage evidence. The results may not carry over to women, older lifters, elite athletes or longer training phases. Some of the reported variability also looks uneven. For example, a few standard deviations are very small next to others, and the D2 isometric force gain over baseline is modest. That is a reason to read the numbers cautiously rather than treat any single percentage as a promise. Importantly, the trial measured performance in a test setting, not long-term muscle or strength gains from training.
Practical Takeaways for Lifters
- Think power, not reps. The signal was in bench throw power and isometric force, while rep counts and jump squat power were unchanged.
- Upper body looked like the sweet spot. The authors noted the effects were more apparent in smaller upper-body muscle groups.
- Match the protocol if you experiment. The tested dose was 1.25 g twice daily (2.5 g/day) in a drink for 14 days.
- Keep expectations realistic. One small crossover is a reason for further research, not a guarantee. Training, sleep and food still do the heavy lifting.
Source
Lee EC, et al. Ergogenic effects of betaine supplementation on strength and power performance. J Int Soc Sports Nutr. 2010. DOI: 10.1186/1550-2783-7-27. PubMed: 20642826.
