title: Is eccentric exercise-induced torque decrease contraction type dependent?
abstract: OBJECTIVE
  This study was designed to determine whether torque decrease following an acute eccentric exercise is contraction type dependent.
  
  
  METHODS
  Ten active males performed an exercise session consisting of five sets of ten maximal eccentric muscle actions of the elbow flexors. Before and immediately after the exercise, maximal voluntary eccentric (-60 degrees.s-1; Ecc60), isometric (0 degrees.s-1; Iso) and concentric (60 degrees.s-1; Con60 and 240 degrees.s-1; Con240) torque were measured. In order to distinguish central from peripheral factors involved in torque decrement, activation level (twitch interpolation technique), myoelectrical activity (RMS) of biceps brachii, as well as electrically evoked M-wave and peak twitch torque (Pt) were recorded.
  
  
  RESULTS
  The eccentric exercise induced a significant torque reduction (P < 0.01), whatever the muscular contraction type [mean (SD): -22.3 (8.1)% for Ecc60; -20.8 (11.2)% for Iso; -18.5 (6.1)% for Con60 and -12.5 (8.9)% for Con240]. Relative torque decrement was however significantly less for Con240 compared with Ecc60, Iso, and Con60 (P < 0.05). Torque decreases were associated with a reduction of both M-wave amplitude (P < 0.01) and Pt (P < 0.001), probably related to an impairment of the excitation-contraction coupling. Concurrently, activation level was reduced (P < 0.01), therefore indicating the occurrence of central fatigue, as also confirmed by RMS decreases for all the conditions (P < 0.05), except Con240.
  
  
  CONCLUSIONS
  An acute eccentric exercise induced a significant voluntary maximal torque reduction during eccentric, isometric, and concentric muscle actions ascribed to both peripheral and central failure of force production capacity. It can be concluded that eccentric exercise-induced torque decrease is not contraction type dependent.
authors.affiliation: Laboratoire de Biomécanique et de Physiologie, Institut National des Sports et de L'Education Physique (I.N.S.E.P.), Paris, France. anne.michaut@insep.fr
authors.forename: Anne
authors.initials: A
authors.lastname: Michaut
authors.forename: Michel
authors.initials: M
authors.lastname: Pousson
authors.forename: Nicolas
authors.initials: N
authors.lastname: Babault
authors.forename: Jacques
authors.initials: J
authors.lastname: Van Hoecke
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D004550:Elbow / Q000502:physiology; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D019415:Torque