title: Strength training, but not endurance training, reduces motor unit discharge rate variability.
abstract: This study evaluates and compares the effects of strength and endurance training on motor unit discharge rate variability and force steadiness of knee extensor muscles. Thirty sedentary healthy men (age, 26.0±3.8yrs) were randomly assigned to strength training, endurance training or a control group. Conventional endurance and strength training was performed 3days per week, over a period of 6weeks. Maximum voluntary contraction (MVC), time to task failure (at 30% MVC), coefficient of variation (CoV) of force and of the discharges rates of motor units from the vastus medialis obliquus and vastus lateralis were determined as subjects performed 20% and 30% MVC knee extension contractions before and after training. CoV of motor unit discharges rates was significantly reduced for both muscles following strength training (P<0.001), but did not change in the endurance (P=0.875) or control group (P=0.995). CoV of force was reduced after the strength training intervention only (P<0.01). Strength training, but not endurance training, reduces motor unit discharge rate variability and enhances force steadiness of the knee extensors. These results provide new insights into the neuromuscular adaptations that occur with different training methods.
authors.affiliation: Polytechnic Institute of Guarda, Av. Dr. Francisco Sá Carneiro, n. 50, 6300-559, Portugal; Research Center in Sports Sciences, Health and Human Development (CIDESD), Quinta de Prados, 5001-801 Vila Real, Portugal. Electronic address: cvilacha@ipg.pt.
authors.forename: Carolina
authors.initials: C
authors.lastname: Vila-Chã
authors.affiliation: Institute for Neurorehabilitation Systems, Bernstein Center for Computational Neuroscience, University Medical Center Göttingen, Georg-August University, Von-Siebold-Str. 6, Göttingen, Germany; Pain Clinic, Center for Anesthesiology, Emergency and Intensive Care Medicine, University Hospital Göttingen, Robert-Koch-Str. 40, Göttingen, Germany.
authors.forename: Deborah
authors.initials: D
authors.lastname: Falla
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D007717:Knee / Q000502:physiology; D007719:Knee Joint / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D052097:Quadriceps Muscle / Q000502:physiology; D011999:Recruitment, Neurophysiological / Q000502:physiology*; D055070:Resistance Training / Q000379:methods; D055815:Young Adult
keywords: Discharge rate variability; Endurance training; Force steadiness; Strength training