If you've spent much time around serious weightlifters, you've probably overheard a few general rules of thumb about what it takes to build muscle. One of the most common beliefs is that you need to train to failure—as in, terminating a set only when it’s physically impossible to move the weight any further. Failure isn’t just the last rep you think you can do, either; it’s the point where your muscles throw in the towel and you literally fail to complete a full repetition.
You might also hear that stimulating gains in size and strength is an on-off phenomenon, much like turning on a light. And that reaching momentary muscular failure is what it takes to "flick the switch" from off to on. If you stop short of failure, the idea goes, the growth mechanism hasn’t been triggered, and you’ve not given your muscles a clear reason to adapt and grow.
Is training to failure the best way to get stronger?
The truth, however, is that reaching failure is not a requirement for building bigger, stronger muscles. You’ll do just as well to leave a few reps in the tank. In fact, some studies show that avoiding failure in your workouts will deliver faster gains in strength and power. Here’s a closer look at the science and what it all means for you.
Back in 2006, Spanish researcher Mikel Izquierdo ran a study comparing failure with not-to-failure training. Izquierdo and his colleagues rounded up 42 physically active men and assigned them to one of two groups. The failure group did three sets of six to ten reps on the bench press and squat. Group two did the same exercises using the same amount of weight. But to avoid reaching failure, they cut their reps in half and did twice as many sets. Instead of doing three sets of ten, for example, they did six sets of five.
The result? After almost three months of training, both the failure and not-to-failure groups increased the maximum amount of weight they could bench press and squat by around 20 percent. Strength gains in both groups were almost identical.
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When scientists from Australia’s University of Sydney pulled together all the research on the effect of failure versus not-to-failure training, they found that both methods delivered very similar strength gains. In fact, there was a small advantage with not-to-failure training. Even trained participants got stronger faster when their workouts required steering clear of failure.
To quote the researchers directly:
“Trained athletes are able to tolerate high training stresses, and it has been suggested that failure training might provide an extra stimulus to increase muscular strength, since strength gains tend to slow down or even plateau following long-term training. However, the findings from this review showed that trained participants responded more favorably to non-failure compared with failure training, suggesting that regular failure training may be too demanding for strength athletes.”
Does training to failure give you bigger muscles?
It doesn’t matter if you hit muscle failure, or cut a set short knowing that you could have cranked out another rep or two. Your muscles will still grow at much the same rate.
That was the conclusion of a team of Brazilian scientists, who compared the effects of failure versus not-to-failure training on muscle growth. One group of participants was instructed to lift to failure, while the other group stopped with a few reps to spare. After 12 weeks, ultrasound scans showed similar rates of muscle growth in both groups. Whether they trained to failure or not, their gains were no different.
Research carried in the Scandinavian Journal of Medicine and Science in Sports shows much the same result. Test subjects—a group of men in their twenties—trained their biceps three times a week for three months. Some of the men trained to failure, while the others left one or two reps in the tank at the end of each set.
Both the failure and not-to-failure groups ended the study with bigger, stronger biceps. But the researchers could find no significant difference in the rate of muscle growth between them.
So are there any benefits to training to failure?
Building muscle takes a lot of hard work and effort, and you may end up failing on some of your work sets whether you planned to or not. Doing so, however, will give you no better gains than finishing each set feeling like you could grind out another rep or two. While muscle fatigue plays a role in stimulating growth, it’s not necessary to take a set to failure in order to create that fatigue.
If you could take a look inside your muscles at the point where you hit failure, you wouldn’t spot any growth mechanisms being triggered, or muscle-building switches being flicked. In fact, there’s nothing magical or special about reaching the point in a set where you’re no longer able to lift the weight.
All that’s happened is that the amount of force produced by the various muscles involved in moving the bar from point A to point B—not all of which are fatigued to the same extent—is no longer sufficient to move the bar past a certain point.
In the bench press, for example, failure is the point when, after lowering the bar to your chest, you can’t get it back to the starting position. While your chest, triceps and shoulders are experiencing high levels of fatigue, they haven’t really “failed” in the sense that they’re still capable of doing more work.
Once you hit the point where you’re unable to lift the bar, you’ll still be able to lower it under control. And when you’re unable to lower it under control, you’ll still be able to hold it in place, if only very briefly. It’s only when you’re not able to support the weight that you can say you’ve pushed a muscle to its “true” limit, or at least the limits available consciously.
Is it safe to train to failure?
Towards the latter stages of a set, the build-up of fatigue can easily lead to a breakdown in technique. During the last few reps of a squat, for example, when your lungs are locked in a desperate struggle for oxygen, and it feels like someone has taken a blowtorch to your quads, maintaining proper form can be extremely difficult.
It’s not so much of a problem with exercises like the leg extension or dumbbell curl, which don’t require a great deal of skill to perform. But training to failure on big compound lifts like the squat and deadlift, where technique is paramount, isn’t a great idea. Your form can start to break down before you hit failure, increasing the risk of tears, strains and other bad things happening to your body.
Other than a drop in speed, your last rep should look much the same as the first. Don’t allow a set to go beyond the point where your form goes down the drain. Far better to leave a couple of reps in the tank than end up with an injury that keeps you out of action for months.
When you reach failure during a set, it’s a sign that you’re pushing yourself hard and generating a large amount of muscle fatigue. Stimulating growth does require that you reach a certain threshold of effort, and pushing yourself to the limit is one sign you’ve crossed that threshold.
There’s very little evidence, however, to suggest that intentionally training to failure needs to be the focus of your workouts, or that doing so is necessary for building bigger, stronger muscles.
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