Training to failure
In weight training, training to failure is repeating an exercise (such as the bench press) to the point of momentary muscular failure, i.e. the point where the neuromuscular system can no longer produce adequate force to overcome a specific workload. "Current Medical Diagnosis and Treatment" states that training to failure is necessary for maximal hypertrophic response. Resistance. A 2010 study concluded that training to failure with "lower loads" with more repetitions can be "more beneficial" for muscle building than using higher loads with fewer repetitions. In this study, participants who trained to failure with a weight equal  to 30 per cent of their single repetition maximum (1RM) had higher levels of muscle-building proteins 24 hours after their training session than participants who trained to failure with a weight that was 90 per cent of their maximum. Initial failure. When the athlete has reached initial failure (i.e. fails to perform a further repetition), rather than ending the current set, the exercise can be continued by making the exercise easier (switching to another similar exercise e.g. pull-ups to chin-ups, switching to another (correct) form of the same exercise, switching to lower weight) or by recruiting help  (from a spotting partner or by involving another body part). The athlete may also choose to use the rest-pause method or other advanced techniques. Repetition maximum. Determining a repetition maximum (RM; such as 1RM) must be done to true failure, so this also can be considered a form of training to failure. Though 1RM is the most popular and commonly used, any number of repetitions can be used, for instance a 10RM or 15RM. A 10RM weight is more useful in terms of training for hypertrophy than a 1RM. There is less consensus as to why a 10RM is  actually safer; it may be because a 10RM can be performed with a much lower risk of joint injury (due to the lower weight), but also potentially because failure occurs due to absolute inability of the muscles to perform at the attempted weight (rather than due to fatigue). A 10RM would be the weight at which a person can do 10 repetitions, but fail to fully perform the 11th. Types of failure. There are multiple types of failure that can be reached before ending a set. They are listed here in order of increasing intensity. When determining repetition maximum, form  failure should be used. Training past form failure can cause joint and muscle injury and should never be attempted. Beginners should train to pre-failure or tempo failure, while focusing on maintaining proper form. Stages of failure in high-intensity training. High-intensity training (HIT) is a form of strength training that involves brief, infrequent, intense workouts at a low volume of repetitions and sets. HIT distinguishes three stages of muscle failure. The first stage consists of normal repetitions performed in a slow, controlled manner until no further repetitions can be completed (failure). The second stage consists of a controlled  static hold until failure. The third stage consists of negative repetitions performed in a slow, controlled manner until failure. After all three stages of failure are reached the muscle is considered thoroughly exhausted and the set is complete.