title: Metabolic reaction after concentric and eccentric endurance-exercise of the knee and ankle.
abstract: OBJECTIVE
  Power training plays an essential part in many sport disciplines. The importance of eccentric power training remains a matter of controversial discussion. The objective of this study was therefore to investigate the difference in metabolic reaction between eccentric and concentric stress in comparable work.
  
  
  METHODS
  Sixty-four men between 22 and 60 yr of age performed maximum isokinetic 1-min endurance tests of the knee and ankle each in concentric (180 degrees.s-1) and eccentric (60 degrees.s-1) modes with comparable total area of contraction-time curve (NS). Higher strength values (mean peak torque, P < 0.01), lower fatigue (fatigue index, P < 0.001), lower increase in lactate (P < 0.01), and lower ammonia production (P < 0.01) were found in eccentric than in concentric exercise, independent of the joint. The eccentric form of stress showed lower decrease and thus age-dependence in maximum strength and in fatigue than the concentric form.
  
  
  RESULTS
  The results permit the conclusion that eccentric exercise leads to less fatigue and lower lactate and ammonia reaction than concentric exercise in comparable work levels. Variable visco-elastic properties of the muscle fibers themselves with additive passive strength in eccentric mode is considered as the cause.
  
  
  CONCLUSIONS
  It remains uncertain whether the lower metabolic stress might be useful during the training process. A greater scope of training and increased number of training stimuli might be applied in primarily eccentric forms of exercise.
authors.affiliation: Department of Sports Medicine, Medical Clinic and Policlinic, Eberhard-Karls-University, 72074 Tübingen, Germany. thomas.horstmann@uni-tuebingen.de
authors.forename: T
authors.initials: T
authors.lastname: Horstmann
authors.forename: F
authors.initials: F
authors.lastname: Mayer
authors.forename: J
authors.initials: J
authors.lastname: Maschmann
authors.forename: A
authors.initials: A
authors.lastname: Niess
authors.forename: K
authors.initials: K
authors.lastname: Roecker
authors.forename: H H
authors.initials: HH
authors.lastname: Dickhuth
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000641:Ammonia / Q000378:metabolism; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D008875:Middle Aged; D018763:Muscle Fatigue / Q000502:physiology*; D014891:Weight Lifting / Q000502:physiology*
chemical_list: D019344:Lactic Acid; D000641:Ammonia