title: Isometric training with maximal co-contraction instruction does not increase co-activation during exercises against external resistances.
abstract: The present investigation verified that strength is improved by a training programme consisting of repetitions of maximal isometric voluntary co-contractions without increasing co-activations during contractions against external resistances. Ten participants performed 12 training sessions (four sets of 6 × 4 second maximal isometric co-contraction of the elbow flexor and extensors, 3 days a week for 4 weeks). Surface electromyograms of triceps and biceps brachii were collected during maximal voluntary isometric elbow flexion and extension against a force transducer. Maximal voluntary isometric force increased significantly after training, by 13.8 ± 6.0% (extension) and 9.6 ± 9.5% (flexion), but the observed increases in EMG of agonist muscles during maximal voluntary contraction were not significant. No significant changes in the levels of co-activation of the elbow flexors and extensors were observed. No significant change was observed for all the parameters in a control group of ten participants. These results indicated that the strength improvements after co-contraction training occur without increases in co-activation level.
authors.affiliation: a Université Paris Ouest Nanterre La Défense , CeRSM (EA 2931), UFR STAPS , Nanterre , France.
authors.forename: Tarak
authors.initials: T
authors.lastname: Driss
authors.forename: Virgile
authors.initials: V
authors.lastname: Serrau
authors.forename: David George
authors.initials: DG
authors.lastname: Behm
authors.forename: Ethelle
authors.initials: E
authors.lastname: Lesne-Chabran
authors.forename: Armande
authors.initials: A
authors.lastname: Le Pellec-Muller
authors.forename: Henry
authors.initials: H
authors.lastname: Vandewalle
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D004550:Elbow / Q000502:physiology; D004576:Electromyography; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D055070:Resistance Training / Q000379:methods*; D055815:Young Adult