What "Train to Failure" in Weight Training Means

Failure doesn't ever sound like a good thing, but when it comes to weight training and bodybuilding, training to failure is often the goal. Many training programs use the term, which may also be noted as AMRAP—as many reps as possible. But what exactly does it mean and why is it recommended?

Short for "concentric failure," failure is the point at which whatever part of your body you're working out literally gives out and you physically can’t complete another repetition with good form. If doing another rep is possible, you haven't reached muscle failure.

Here's how it works in real life: Let's say your training program calls for three sets of 10 reps of barbell curls. In weight-training program language that's 3×10 arm curls. Training to failure means selecting a weight that's heavy enough so that the last rep taxes you to the point that you struggle to complete it in that set. This is called 10RM (repetition maximum), or the most weight you can lift for a defined number of exercise movements.

Muscles fail when they use up their supply of ATP, the energy that fuels contraction, and lactic acid builds up in the muscle. The muscle needs a few minutes to flush out the lactic acid and create more ATP. Hence the reason it's possible to do a set of 10 bicep curls to failure and then do another set shortly thereafter.

Most average Joes and Janes don't train to complete failure and they probably shouldn't, if for no other reason that training to failure hurts. It's really hard to reach muscle failure every single time you do an exercise. It taxes your body and your mind, and it's very difficult to push yourself like that unless you're motivated by competition. Those who train this way are usually bodybuilders, powerlifters, people involved in competitive strength training, or people working to build larger muscles.

Whether people should strength train to failure is a contentious topic. Many believe, "no pain, no gain," and think that the discomfort of the failure point is a signal of the stress on the muscle that will drive increases in strength and muscle size. But research on this is mixed. A review article from 2016 found that highly trained people experienced slightly greater increases in muscle strength and muscle mass when lifting heavy weight to failure compared to without failure. However, a 2017 study on active young women found that training to failure doesn't provide any additional gains in muscle strength and muscle mass.

Advanced trainers might also use training to failure to break through a plateau, and one research review from 2007 found that this strategy sometimes does help experienced lifters get to the next level of training. This could be because when you push yourself, your body secretes more muscle-building, fat-fighting hormones and recruits more muscle fibers than you would if you cut your sets short.

Despite the potential pros, researchers worry about the potential cons to training to failure. For instance, one study found that exclusively using the technique drastically increased resting levels of the stress hormone cortisol and suppressed anabolic growth factors. This seems to indicate that taking every set to absolute failure may actually hinder long-term growth.

Another concern is that overdoing it may result in using the improper form when performing exercises. If you're struggling with a move while using a challenging weight you may not be able to focus on the correct technique. The combination of using poor technique and overtaxing the muscles might lead to injury. It may also lead to overtraining, especially when used over long periods rather than for a shorter cycle of training. Hence the reason some researchers advise advance lifters to consider training to failure only occasionally, rather than making it a regular part of their workout.  

Another option is to train to what's called technical failure. Unlike with absolute failure, when you can't lift that barbell and do that curl at all, technical failure is when you perform a set with the correct form on each repetition until you're unable to maintain proper form. When you reach this point in a workout, the set is over. The difference is that the set is over, regardless of the number of prescribed reps, once you reach the point of technical failure. You should then rest until you can do the next set to failure as well. You can manipulate the rest period between sets or the weight you lift to reach the ideal failure point for you.

If you decide to train to failure, consider working with a trainer who can help you set up a program designed to do so strategically and appropriately. The last thing you want is to end up paying a cost for (training to) failure.