title: The EMG activity-acceleration relationship to quantify the optimal vibration load when applying synchronous whole-body vibration.
abstract: OBJECTIVE
  To date are lacking methodological approaches to individualizing whole-body vibration (WBV) intensity. The aim of this study was: (1) to determine the surface-electromyography-root-mean-square (sEMG(RMS))-acceleration load relationship in the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), lateral gastrocnemius (LG) muscles during synchronous WBV, and (2) to assess the reliability of the acceleration corresponding to the maximal sEMG(RMS).
  
  
  METHODS
  Twenty-five sportsman voluntarily took part in this study with a single-group, repeated-measures design. All subjects postured themselves in an isometric half-squat during nine trials in the following conditions: no vibrations and random vibrations of different acceleration loads (from 0.12 to 5.72 g).
  
  
  RESULTS
  The sEMG(RMS) were dependent on the acceleration loads in the VL (p = 0.0001), LG (p = 0.0001) and VM (p = 0.011) muscles; while RF was not affected by the acceleration loads (p = 0.508). The comparisons among the sEMG(RMS)-accelerations relationships revealed a significant difference between the LG and the others muscles (p = 0.001). No significant difference was found between the different thigh muscles (p > 0.05). The intra-class correlation coefficient ranged from 0.87 to 0.99 for the measurements performed on the LG, VL and VM.
  
  
  CONCLUSIONS
  The sEMG(RMS)-acceleration relationship in the VL, VM and LG is a reliable test to individualize the WBV intervention.
authors.affiliation: Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Italy. Electronic address: riccardo.digiminiani@univaq.it.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Di Giminiani
authors.affiliation: Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Masedu
authors.affiliation: University eCampus, Novedrate, COMO, Italy; Tunisian Research Laboratory "Sport Performance Optimization" National Center of Medicine and Science in Sports (CNMSS), Tunis, Tunisia.
authors.forename: Johnny
authors.initials: J
authors.lastname: Padulo
authors.affiliation: Department of Biomechanics, Faculty of Physical Education and Sport Sciences, Semmelweis University, Budapest, Hungary.
authors.forename: Jozsef
authors.initials: J
authors.lastname: Tihanyi
authors.affiliation: Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Valenti
mesh_terms: D000054:Acceleration; D000328:Adult; D004576:Electromyography / Q000379:methods*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D014732:Vibration
keywords: Dose–response; Exercise test; Individualization; Internal–external load; Methods; Reliability