If guys who already lift weights increase their workout volume by 30%, they’ll last longer before getting tired compared to doing the same amount or doubling up—after 8 weeks, they can do about 5 more reps before failing.

What we've found so far is that increasing resistance training volume by 30% may help trained males improve how long they can keep going before fatigue sets in, compared to maintaining their current volume or increasing it more drastically [1]. The evidence we’ve reviewed leans toward this 30% increase being linked to better strength-endurance outcomes over an 8-week period. Our analysis of the available research shows that when trained men boost their training volume by 30%, they’re able to perform about 5 more repetitions before reaching failure than they could at the start [1]. This improvement was seen after consistently following the increased routine for 8 weeks. In contrast, the evidence does not show similar benefits for those who keep their volume the same or increase it by 60%—though no studies in our review refuted the idea outright. It’s important to note that our current analysis is based on a single assertion drawn from what appears to be a body of 47 supporting elements, with none opposing [1]. However, we don’t have details on study designs, participant counts, or specific exercises performed, so we can’t assess the full strength or limitations of the evidence. Also, “strength-endurance” here refers to how many reps someone can perform before muscle fatigue, not necessarily how strong they become. Because the data is limited in scope and we’re only seeing one side of the argument, we can’t say for sure how strong this effect is across different people or training programs. What we can say is that, based on what we've reviewed so far, a 30% volume increase seems associated with better endurance in trained males. Practical takeaway: If you’ve been lifting consistently and want to last longer in your sets, slowly adding about 30% more volume over time might help you push through those last few tough reps.