When predicting how much muscle a person will gain from training, accounting for how much they have trained in the past leads to more accurate predictions.

What we've found so far suggests that accounting for a person’s previous training volume may help make better predictions about how much muscle they’ll gain from new training. We reviewed one assertion that supports this idea, with no studies contradicting it [1]. This means that if someone has trained consistently before — say, lifting weights for months or years — their past training habits might give clues about how their body will respond to future workouts. For example, someone who has built muscle before may respond differently to the same training program than someone who is new to lifting. By including that history in the prediction, the estimate becomes more precise. We don’t know yet how much of an impact this has compared to other factors like diet, sleep, or genetics. The evidence we’ve reviewed is limited to just one assertion, and it doesn’t explain how to measure past training volume or how much it improves accuracy in real-world settings. So while the single piece of evidence we’ve seen leans toward including past training volume as a useful factor, we can’t say how strong or reliable this effect is. More studies are needed to confirm whether this pattern holds across different people, training styles, and timeframes. For now, if you’re tracking your progress, it might help to look back at how much you’ve trained before — not because it guarantees results, but because your history could offer useful context for what comes next.