What we've found so far is that the evidence leans toward a specific type of resistance training—designed to build up lactic acid—possibly increasing rectus femoris muscle size more than traditional resistance training in professional bodybuilders over four weeks, especially in those whose muscles don’t typically respond well to training [1].
Our analysis of the available research shows that all 52.0 supporting assertions point to this approach, which we refer to as lacto-resistance training, having a potential edge in muscle growth for the rectus femoris, a key quadriceps muscle [1]. These findings are based on studies suggesting that when training triggers higher lactic acid accumulation, it may create a stronger signal for muscle growth in certain individuals [1]. This could be particularly relevant for professional bodybuilders who have reached a plateau with standard training methods [1].
However, we want to be clear: our current analysis is based on a single assertion that aggregates 52.0 supporting points, with no studies refuting the idea [1]. We have not found any evidence that contradicts this pattern, but the total number of distinct studies or the quality of those studies isn’t specified in what we’ve reviewed so far. That means we can’t yet determine how strong or reliable this pattern is over time.
We also don’t have enough information to say how this effect might vary by training volume, diet, or individual metabolism. Since this is just one assertion with aggregated support, our understanding is still limited.
In everyday terms: if you're a professional bodybuilder and your legs aren’t responding to usual training, trying a routine that increases lactic acid buildup might help stimulate more muscle growth in the rectus femoris—but this is based on early signals, not a final conclusion. We’ll update our analysis as more evidence becomes available.
2 items of evidenceView full answer