‘You have to take every single set to failure bro, that’s the only way the muscle gets bigger and stronger!’
I’m sure a phrase articulated in a manner similar to this has been uttered to you many times so far in your lifting journey. Walk into most local gyms, and this seems that this is a unanimously held belief. With little exception. Training to failure on every single set certainly seems to be pretty commonplace in the training programs of many. Nevertheless, the question is, is it the most optimal way to train? Does training to failure maximise recovery from training, facilitate the most amount of muscle and strength gain, and promote longevity in the gym?
The Size Principle
The main physiological mechanism used to rationalise the benefits of training to failure is the size principle. During a heavy set, lower threshold motor units composed of type I slow twitch or Type IIA fast twitch fibres are recruited. As consecutive reps are performed, thee lower threshold fibres fatigue, which results in the recruitment of higher threshold motor units composed predominantly of type IIX fast twitch fibres. Once all available motor units have fatigued, muscular failure occurs. The theory concludes, therefore, that training to failure will allow a lifter to maximise motor unit recruitment, and thus gain the most amount of muscle and strength.
Taking a look at the research, what does it tell us?
This study was incredibly revealing. It was a meta-analysis comparing four studies that compared a training to failure vs a non-training to failure intervention. Because many of the studies on the topic have a low sample size and therefore struggle to reach real-world validity (10-15 participants on average), pooling the results of all the studies together in this way is an excellent method of drawing more significant conclusions from the data.
The results found that despite the higher levels of discomfort and physical effort exerted when training to failure, non-failure training leads to similar gains in muscle strength, as long as training volume (reps x sets x weight) was equated between groups. The meta analysis observed that in two of the studies, training volume was not equated (the non-failure group ended up achieving greater training volumes) and this resulted in the non-failure group gaining slightly more strength, which reveals the first primary benefit that exists of not training to failure:
More training volume can be accumulated
While significant increases in muscular strength can be achieved with relatively low training volumes, performing higher training volumes has been shown to result in higher levels of strength than lower volumes. Performing consecutive sets to failure with a specific load has been shown to significantly reduce the number of repetitions possible in subsequent sets (I’m sure you know this to be true you’re your own training). Terminating sets shy of failure allows a lifter to accumulate more total workload in a single session, because they have not elicited as much fatigue from training all the way to failure; this allows performance to be sustained.
This increased training volume adds up over time. More training volume = more muscle recruitment + more opportunity to build technical efficiency = more strength gain long term.
Expanding upon the idea of more opportunity to build technical efficiency, we come to the second benefit of not training to failure:
Enhanced movement quality
There is evidence to suggest that dynamic 1RM’s (heavy squats/bench press and deads) are disproportionately greater compared to isometric strength. This suggests that factors such as learning of a movement/exercise and co-ordination of muscle groups plays a role in the expression of strength with a barbell. Consistently performing sets to failure increases the risk of developing faulty movement and technique, particularly on technically demanding compound lifts like squats and deadlifts. This could hugely limit a lifters potential for generating force, particularly if they are training to failure very frequently. Not to mention the enhanced injury risk associated with less efficient movement patterns. Not only does staying away from failure give you more opportunity to practice technique, but it also gives you more opportunity to practice technique in a less fatigued state, a benefit that adds up over time, both from an injury prevention and strength development stand point.
This study tested 10 resistance-trained males and compared the recovery capacity of ‘to failure’, ‘low volume, not to failure’ and ‘high volume, not to failure’ training sessions over a 72 hour period. The study was a crossover design, meaning each participant completed each training session in a randomised order over a four-week period. Interestingly, the researchers used both blood measures and numerous performance measures (barbell velocity and countermovement jump height) to assess recovery capacity, giving this study huge practical application.
The results showed that bench press performance was suppressed for 24-48 hours, and squat and countermovement jump height were suppressed up to 24 hours after participants trained to failure. Additionally, Cortisol and Ammonia was higher in the failure group post training, and Creatine Kinase (an indirect measure of muscle damage) took the longest to return to baseline after participants trained to failure, indicating that training to failure elicits a bigger fatigue debt than staying away from failure, and diminishes a muscles ability to produce high levels of force for longer.
If an athlete’s force producing capacity is suppressed for longer periods of time, this will further diminish the amount of training volume they can accumulate over the course of a training session/training week/training block (as discussed earlier, this is a detriment to strength gain). These findings also have implications for athletes that are competing on a regular basis or are in the middle of a season. Training to failure simply creates a larger recovery debt, and could negatively effect performance on the field, on the court or on the track… The last thing a competitive athlete wants! But even so, if you are a non-competitive athlete who’s goal is to get stronger at the main compound lifts, training to failure may not be the best approach to take, at least not on a frequent basis.
Are There Advantages to Training to Failure?
Training to failure definitely has a place in a training program. Programming AMRAP (as many reps as possible) sets involves a lifter taking a certain percentage of their max and performing repetitions until they reach failure, and can be utilised very effectively in a strength training program for a number of reasons. It provides a gauge of progress for athletes, as 1RM’s can be estimated from completing them (most accurately with loads 85% and above) – This can be a huge motivator for a lifter, it gives them a tangible goal in the near future to work towards, which often results in a huge incentive to work hard throughout a training cycle to perform well in the upcoming AMRAP set.
Additionally, training to failure can allow a lifter to increase their training density. In other words, do more total workload in less time. This time efficiency can be a big positive for lifters with busy schedules who may have limited time to train. In these instances, training to muscle failure for a limited number of sets may result in the ability to accumulate more training volume than if they had performed more sets and stayed away from failure.
Does Training To Failure Build More Muscle?
What about muscle mass? We know from previous research that increasing the cross sectional area of a muscle can create the potential for more force production, and is actually the main driver of strength gain after a lifter reaches a certain experience level. Is there any benefit to training to failure for maximising muscle mass?
In this study, subjects who trained to the point of muscular failure gained the same amount of muscle as those who terminated a set just before the point of failure. That being said, the authors’ definitions of ‘failure vs not failure’ are somewhat sketchy. The term ‘volitional failure’ was used to define the group that didn’t achieve failure, which from the way it was described implied that subjects stopped performing repetitions when they didn’t feel another rep was in the tank. This is literally what most people would describe as ‘hitting failure’. Therefore, it appears that the ‘failure’ group literally performed reps until they actually failed to perform another repetition. Thus, it appears that if training to muscular failure does have benefits on muscle gain, it should be defined as the point in which a lifter doesn’t feel they can perform another repetition as oppose to performing repetitions until you they are physically incapable of performing another.
More research needs to be conducted on this topic – comparing a group stopping just shy of failure (1-3 reps) to a group going all the way to failure would be helpful. This will give a much better indication as to whether training to failure maximises muscle hypertrophy (muscle gain).
Take Home Messages?
Training to muscular failure does not appear to have any advantage over staying shy of failure for maximising strength gain
Staying shy of failure allows a lifter to accumulate more training volume, and just as importantly, a higher quality of training volume, leading to more strength long term
The time course of recovery is longer when training to failure, which has subsequent effects on performance for the rest of the session/subsequent sessions. This can hinder training volume accumulation and thus hinder strength
Training to failure definitely has psychological and practical advantages in many contexts, and should not be demonised altogether, but rather used intelligently and ideally infrequently.
It remains to be seen if training to failure is superior for muscular hypertrophy, however it appears that training to the point where you actually fail to complete another repetition has no advantages.
I think body part split training, in which muscle groups were only trained once per week, has traditionally been so popular because of the popularity in training to failure. Training muscles once a week was the only conceivable way that lifters could recover from the unbelievable muscle damage accumulated in one session when taking every set to complete failure. Modern research has shown that training body parts more frequently is superior for strength and hypertrophy, and as a result, the ‘must train to failure’ theory doesn’t fit in the new model. There are certainly instances in training to failure is a great option, but for the vast majority of training, as long as the weights are heavy and challenging, staying 1-3 reps from failure on most sets is advantageous for strength development, recovery and longevity.