title: Effect of Training Leading to Repetition Failure on Muscular Strength: A Systematic Review and Meta-Analysis.
abstract: BACKGROUND
  It remains unclear whether repetitions leading to failure (failure training) or not leading to failure (non-failure training) lead to superior muscular strength gains during resistance exercise. Failure training may provide the stimulus needed to enhance muscular strength development. However, it is argued that non-failure training leads to similar increases in muscular strength without the need for high levels of discomfort and physical effort, which are associated with failure training.
  
  
  OBJECTIVE
  We conducted a systematic review and meta-analysis to examine the effect of failure versus non-failure training on muscular strength.
  
  
  METHODS
  Five electronic databases were searched using terms related to failure and non-failure training. Studies were deemed eligible for inclusion if they met the following criteria: (1) randomised and non-randomised studies; (2) resistance training intervention where repetitions were performed to failure; (3) a non-failure comparison group; (4) resistance training interventions with a total of ≥3 exercise sessions; and (5) muscular strength assessment pre- and post-training. Random-effects meta-analyses were performed to pool the results of the included studies and generate a weighted mean effect size (ES).
  
  
  RESULTS
  Eight studies were included in the meta-analysis (combined studies). Training volume was controlled in four studies (volume controlled), while the remaining four studies did not control for training volume (volume uncontrolled). Non-failure training resulted in a 0.6-1.3% greater strength increase than failure training. A small pooled effect favouring non-failure training was found (ES = 0.34; p = 0.02). Significant small pooled effects on muscular strength were also found for non-failure versus failure training with compound exercises (ES = 0.37-0.38; p = 0.03) and trained participants (ES = 0.37; p = 0.049). A slightly larger pooled effect favouring non-failure training was observed when volume-uncontrolled studies were included (ES = 0.41; p = 0.047). No significant effect was found for the volume-controlled studies, although there was a trend favouring non-failure training. The methodological quality of the included studies in the review was found to be moderate. Exercise compliance was high for the studies where this was reported (n = 5), although limited information on adverse events was provided.
  
  
  CONCLUSIONS
  Overall, the results suggest that despite statistically significant effects on muscular strength being found for non-failure compared with failure training, the small percentage of improvement shown for non-failure training is unlikely to be meaningful. Therefore, it appears that similar increases in muscular strength can be achieved with failure and non-failure training. Furthermore, it seems unnecessary to perform failure training to maximise muscular strength; however, if incorporated into a programme, training to failure should be performed sparingly to limit the risks of injuries and overtraining.
authors.affiliation: Discipline of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, 75 East Street, Lidcombe, Sydney, NSW, 2141, Australia.
authors.forename: Tim
authors.initials: T
authors.lastname: Davies
authors.affiliation: Discipline of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, 75 East Street, Lidcombe, Sydney, NSW, 2141, Australia.
authors.forename: Rhonda
authors.initials: R
authors.lastname: Orr
authors.affiliation: Discipline of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, 75 East Street, Lidcombe, Sydney, NSW, 2141, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Halaki
authors.affiliation: Discipline of Exercise and Sport Science, Faculty of Health Sciences, The University of Sydney, 75 East Street, Lidcombe, Sydney, NSW, 2141, Australia. daniel.hackett@sydney.edu.au.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hackett
mesh_terms: D005221:Fatigue; D006801:Humans; D053580:Muscle Strength / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*