title: Elbow joint fatigue and bench-press training.
abstract: BACKGROUND
  Bench-press exercises are among the most common form of training exercise for the upper extremity because they yield a notable improvement in both muscle strength and muscle endurance. The literature contains various investigations into the effects of different bench-press positions on the degree of muscle activation. However, the effects of fatigue on the muscular performance and kinetics of the elbow joint are not understood fully.
  
  
  OBJECTIVE
  To investigate the effects of fatigue on the kinetics and myodynamic performance of the elbow joint in bench-press training.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Motion research laboratory.
  
  
  METHODS
  A total of 18 physically healthy male students (age = 19.6 ± 0.8 years, height = 168.7 ± 5.5 cm, mass = 69.6 ± 8.6 kg) participated in the investigation. All participants were right-hand dominant, and none had a history of upper extremity injuries or disorders.
  
  
  METHODS
  Participants performed bench-press training until fatigued.
  
  
  METHODS
  Maximal possible number of repetitions, cycle time, myodynamic decline rate, elbow-joint force, and elbow-joint moment.
  
  
  RESULTS
  We observed a difference in cycle time in the initial (2.1 ± 0.42 seconds) and fatigue (2.58 ± 0.46 seconds) stages of the bench-press exercise (P = .04). As the participants fatigued, we observed an increase in the medial-lateral force (P = .03) and internal-external moment (P ≤ .04) acting on the elbow joint. Moreover, a reduction in the elbow muscle strength was observed in the elbow extension-flexion (P ≤ .003) and forearm supination-pronation (P ≤ .001) conditions.
  
  
  CONCLUSIONS
  The results suggest that performing bench-press exercises to the point of fatigue increases elbow-joint loading and may further increase the risk of injury. Therefore, when clinicians design bench-press exercise regimens for general athletic training, muscle strengthening, or physical rehabilitation, they should control carefully the maximal number of repetitions.
authors.affiliation: Department of Engineering Science, National Cheng-Kung University, Tainan, Taiwan.
authors.forename: Yen-Po
authors.initials: YP
authors.lastname: Huang
authors.forename: You-Li
authors.initials: YL
authors.lastname: Chou
authors.forename: Feng-Chun
authors.initials: FC
authors.lastname: Chen
authors.forename: Rong-Tyai
authors.initials: RT
authors.lastname: Wang
authors.forename: Ming-Jer
authors.initials: MJ
authors.lastname: Huang
authors.forename: Paul Pei-Hsi
authors.initials: PP
authors.lastname: Chou
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001696:Biomechanical Phenomena; D004550:Elbow / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D008954:Models, Biological; D018763:Muscle Fatigue / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D012016:Reference Values; D034941:Upper Extremity / Q000502:physiology; D055815:Young Adult
keywords: kinetics; muscle strength; myodynamic decline rate