title: Test-retest reliability of v-wave responses in the soleus and gastrocnemius medialis.
abstract: This study was designed to assess the reliability of the first volitional (V) wave, which can be used as a measure of efferent neural drive, while also reflecting reflex excitability. Ten subjects volunteered for one familiarization session followed by an experimental test session and an identical retest session spaced 3 to 8 days apart. V-waves were evoked in the tibial nerve during plantar flexion maximal voluntary isometric contractions (MVCs). Test-retest reliability was assessed using the intraclass correlation coefficient (ICC), along with standard error of measurement and 95% confidence intervals for the following variables: MVC force, surface electromyogram activity (EMG), and the peak-to-peak V-wave amplitude in soleus (SOL) and gastrocnemius medialis (GM). The superimposed M-wave (MSUP) accompanying V-wave stimulation was also obtained for normalization purposes. Substantial reliability was documented for V/MSUP in both SOL (ICC = 0.86) and GM (0.90), as well as for the non-normalized V-wave in SOL (0.92). Moderate reliability was displayed for the non-normalized V-wave response in GM (0.78). Substantial reliability was also established for EMG/MSUP (>0.82) and MVC force (0.98). This study provides novel evidence that V-wave responses can be consistently measured in the SOL and GM, thus advocating its continued use in future research.
authors.affiliation: Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway. gerdmas@alumni.ntnu.no
authors.forename: Gerd Marie
authors.initials: GM
authors.lastname: Solstad
authors.forename: Marius S
authors.initials: MS
authors.lastname: Fimland
authors.forename: Jan
authors.initials: J
authors.lastname: Helgerud
authors.forename: Vegard Moe
authors.initials: VM
authors.lastname: Iversen
authors.forename: Jan
authors.initials: J
authors.lastname: Hoff
mesh_terms: D004558:Electric Stimulation; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000294:innervation*; D009664:Norway; D015588:Observer Variation; D012018:Reflex; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013979:Tibial Nerve / Q000502:physiology*; D014836:Volition; D055815:Young Adult