Muscle Failure: The Key to Muscle Growth

Definition, risks and benefits of training to failure

Training to failure has become a popular term in the bodybuilding and athletic community recently. Whereas some studies champion non-failure workouts, true bodybuilders swear by this method. Mainstream medicine seems to agree, with even notable publications such as “Current Medical Diagnosis and Treatment” stating that failure is necessary for maximal hypertrophy.

The definition

The “proper” medical definition of training to failure is training to muscular failure, that is, until the nervous and muscular systems can no longer muster the force to overcome a specific load.

But that definition is flawed due to a number of reasons. Firstly, how can a regular person judge when they’ve reached that limit? Well, if you’ve reached a point when you can no longer do any more reps at the same weight, that would be the point of muscular failure. On the other hand, consistently doing reps until that point is not truly “training to failure” (confused yet?).

Muscles are split up into motor units, that is a group of muscle cells innervated by a single neuron. But not all motor units are made equal. There are motor units which are usually called in first to perform a particular movement, and then there are those which barely participate in the normal setting. True training to failure means that ALL motor units need to fail. Since some motor units will be the first to fatigue, that means overall muscular failure will be reached with a good number of motor units still not failing. This is the core problem facing those who choose to work out this way.

So, how can we make sure we reach “true” failure? The best way to do that is going beyond the point of usual muscle failure. This is done by simply reaching “normal” failure at a specific load and then either having someone spot you, or quickly reducing the weight and continuing for a number of reps, at a lower weight, until muscle failure kicks in again (doing a forced set). This way we make sure that even those inactive motor units get the maximum exercise.

The benefits and the risks

The benefits are quite simple – you can expect faster hypertrophy by training to failure, and research has proven that it might increase growth hormone and testosterone levels post workout. The risks and the questions surrounding training to failure are, on the other hand, manifold:

  • Usually training to failure is very hard to do on compound exercises such as squats, deadlifts and rows. Due to the many muscle groups involved in these, there is no physical way to gauge if every single one of them is at failure. Not only that, according to your conditioning your body might give out before reaching muscle failure.
  • There is no agreement on how often you should go to failure. Usually the recommendation is to keep failure confined to the last set of any particular exercise you are doing.
  • Too many forced reps are, on a whole, bad for your health. These lead to higher levels of stress hormones in your circulation and might damage your muscular tissues.
  • There is no consensus on how many forced reps you should do after reaching failure.

The bottom line 

Training to failure is an effective and, if used properly, safe way to ensure maximum muscle growth. The experience of numerous well-known athletes and bodybuilders can be codified into two basic recommendations:

  • Training to failure should be confined to the last set of any particular exercise. Forced reps are needed to reach maximum muscle failure, so having a partner or reducing weights is immensely helpful.
  • One should judge the level and frequency of training to failure on an individual basis. There is no logic behind training to injury, that only harms your health while having negligible gains.