by Chris Shugart
What Builds More Muscle?
What works best, training to absolute failure or leaving a couple of reps in the tank? A new study answers that question, finally.
As muscle nerds, we love digging into the research and debating the best training methods. But when we step back and take a cleansing breath, we notice something: there are muscular people on every side of every lifting debate. Golly, it’s almost as if the particulars don’t matter all that much, as long as you’re lifting weights, training hard, eating lots of protein, and being consistent.
Of all the debatable ideas about hypertrophy, failure training is near the top of the list. There are entire systems based around either training to absolute failure or stopping a couple of reps short. Both methods even have studies to back them up.
That’s why I like this new study which basically says, “It doesn’t matter much; do what you like.” Let’s dig into it.
First, Let’s Define Some Terms
- Absolute Failure: You do an exercise for 10 reps. You just barely get 10, but you try for one more and only get it halfway. In nerd terms, it’s called “training to momentary muscular failure.”
- Near Failure: You do an exercise for 8 solid reps. It gets tough at rep 8 and you stop, even though you could grind out 1 or 2 more. You don’t hit failure; you leave a couple in the tank. In nerd-speak, this is called “RIR” or reps in reserve.
The New Study
In most hypertrophy studies, researchers gather up some people and divide them into two groups. Half trains one way and the other half trains another away, and then they compare the results. But what if you get some genetically lucky (or unlucky) folks in one group? It throws off the results.
In this study, the researchers avoided that pitfall by using a “within-subjects design.” They took 18 experienced lifters – men and women – and had each train one leg to failure and the other leg to near failure.
All subjects did unilateral leg presses and leg extensions for 8 weeks (16 workouts) with a few days between each session. One leg was randomly assigned to the failure condition and the other to the near-failure condition.
Load was set at 8-10 RM on the leg press and 10-12 RM on the extensions. Set volume was identical between the two legs and increased halfway through the study to ensure progressive overload. The starting leg was alternated each workout to keep it fair. Failure sets were, well, taken to failure, and near-failure sets were stopped one or two reps short.
All subjects were prescribed a calorie-surplus diet with 1.1 grams of protein per pound of body weight. The researchers used before-and-after ultrasound scans of the quads to measure hypertrophy.
Which Leg Got Bigger?!
Eh, they were pretty much the same.
In Dr. Bill Campbell’s analysis in his Body by Science newsletter, he summed it up like this:
“When both muscles (rectus femoris and vastus lateralis) were combined, the average gain in muscle mass was nearly identical, with about a 7% increase in muscle hypertrophy.”
Training to near failure was a tiny bit better at building muscle in the rectus femoris (+7.5% vs. +6%). Training to absolute failure was a tiny bit better for increasing muscle mass in the vastus lateralis (+8% vs. +6.5%). In short, it all kinda evened out in the end.
The researchers concluded that both styles promote hypertrophy.
What Can We Learn?
Two quick caveats: First, training to total failure causes more neuromuscular fatigue and muscle damage, so recovery between workouts is important. Second, leaving one or two reps in the tank on each set means ONE or TWO reps, not six. No sandbagging.
The moral of the story? Lift challenging weights. If you feel like it, go to failure on certain exercises. If you don’t, then don’t; just get close to failure. It just doesn’t matter all that much when it comes to building size. And here in the real world, experienced lifters are probably using a little of both styles anyway, even if they don’t realize it.
In short, don’t worry your pretty little head about it.
References
- Refalo, et al. “Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve in resistance-trained individuals.” J Sports Sci. 2024 Feb 23:1-17. doi: 10.1080/02640414.2024.2321021.