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 a repetition fails due to inadequate muscular strength.

Training to failure is a controversial topic. Some proponents of High Intensity Training—such as Mike Mentzer, Arthur Jones and Ellington Darden—advise training to failure on every set. Other experts believe that this will lead to overtraining, and suggest training to failure only on the last set of an exercise. Because when bodybuilders workout to failure, this strongly increases cortisol levels in the body, reduces Insulin-like growth factor 1, peripheral nervous system and central nervous system, and also stress and testosterone, which reduces the secretion.

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% 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% of their maximum.

When the athlete has reached initial failure (i.e. fails to perform a further repetition), the exercise can be continued by making the exercise easier (change of posture, switching to lower weight) or by recruiting help (from a spotting partner or by involving another bodypart).

This of course increases the risk of overtraining and safety issues have to be kept in mind regarding posture.

Working out your Repetition Max (such as your 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 reps can be used, for instance a 10RM or 15RM, in fact your 10RM weight will be much more useful for you in terms of training for hypertrophy than your 1RM. Some say it can be performed with a much lower risk of joint injury (due to the lower weight), while others say a 1RM is safer because failure occurs due to absolute inability of your muscles to perform at the attempted weight rather than due to fatigue. Your 10RM would be the weight at which you can do 10 repetitions, but fail to fully perform the 11th rep - whether that be from loss of form or just natural inability.

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Wikipedia