How important are those last few reps? by Terrence Riley
Bodybuilding legends like Arnold Schwarzenegger emphasized the importance of chasing that pump by training until you literally cannot do another repetition. Many of us gym rats understand this concept to be “going to failure.” Failure involves performing as many reps as possible to create maximal muscle damage while optimizing muscle growth potential. Under normal circumstances going to failure is done at every workout and every set. But does this allow for optimal muscle growth or is there a better method to utilize during your workout? Recently, bringing each set to failure has been called into question and is now claimed by some members of the fitness community as an unnecessary tax on the body. If true, it would mean the years of advice from bodybuilding and sport legends are slightly misguided. Let’s look at the state of the research and what evidence can be gleaned from either lifting method.
Completing a set short of failure, while seemingly intuitive, can be a bit ambiguous in the literature making it a difficult parameter to study. Interpreting the moment a repetition has “failed” usually refers to the inability to complete a full concentric contraction. But, how many reps constitutes a pre-failure set? Many studies comparing muscle growth resulting from pre-failure and failure sets allow the participants to subjectively anticipate when they might fail. That can either mean the participant still has 3 reps before failure or no reps at all. Research hasn’t yet delineated the optimal pre-failure rep range and stopping before failure hasn’t quite resulted in many straightforward answers.
A recent meta-analysis by Davies et al. (2016) looked at the current research comparing pre-failure and failure sets on muscular strength. The conclusion saw no significant difference between pre-failure and failure training, however, sub-group comparisons suggested some slight distinctions. The groups that stopped their workout prior to failure saw some significant strength benefits when the participants were experienced or worked with compound movements. In contrast, the studies that controlled for volume did not show a significant difference since volume can be a relevant contributor to muscle strength, thus muddy the results. Muscle stimulation does not seem to differ between groups either when comparing failure sets to non-failure sets under heavier or lighter loads.2 Therefore, muscular stimulation - via EMG testing – and strength levels don’t seem to be a differentiating factor in strength gains in either training method.1,3 So why does this debate over training to failure continue? There doesn’t seem to be any distinction between going all out in a workout and stopping so you have more reps left in the tank
The more important interpretation of the data is that going to failure isn’t necessary for muscular adaptations or strength gains. The long held belief that failure at each workout and each set elicits a greater muscle building effect just doesn’t seem true based on the data. There is essentially no difference in the amount of strength that can be gained or stimulation of the muscle.
There are some benefits to stopping before failure that have anecdotal rather than scientific evidence, though, some interesting secondary data support these benefits.1 Stopping before failure allows a consistent level of performance throughout the workout. Many might feel completely fatigued after the first set of the first workout that goes to failure. A traditional rep scheme might look something like 8reps (to failure) – 6reps – 4reps or 18 total repetitions. Had the exerciser stopped before failure they might have been more consistent or 6rep - 6rep -6rep sets. This scheme has the same number of total reps (18reps) but the exerciser might have greater control of the movement thus making the lift much safer. This effect can transfer to other movements as well. Going from a static military press to a seated dumbbell should press after going to failure allows the lifter to handle a greater load, with more control, and potentially more volume1 (assuming all things equal).
While going to failure and pre-failure workouts show no significant differences in performance, the data still needs to be studied under many other scenarios to tease out any distinction between the two. The benefits in either direction seem to be too nuanced or slight to say one is greater than the other. If you were to ask for a recommendation, I’d say include both. Use training to failure like a tool. For any workouts that are similar in nature save the failure set till the very last reps in that movement (like Military/seated DB press example above). This will allow you to feel consistently strong throughout your workout and avoid poor form especially under heavier loads. Don’t worry too much about the pump from the workout, rather, empty the tank at the end of your routine to get the best of both worlds.