title: Electromechanical delay components during relaxation after voluntary contraction: reliability and effects of fatigue.
abstract: BACKGROUND
  Fatigue effects on total relaxation delay (R-DelayTOT ) components and measurement reliability were investigated.
  
  
  METHODS
  Electromyogram (EMG), force (F), and mechanomyogram (MMG) were recorded during maximum voluntary contraction from the biceps brachii muscle before and after fatigue. The delays between EMG cessation and onset of F decay (R-EMD), between F decay and onset of MMG largest displacement (MMG p-p) (R-Δt F-MMG), from the beginning to the end of MMG p-p (R-Δt MMGp-p ), and from the end of MMG p-p to F cessation (R-Δt MMG-Fend ) were calculated.
  
  
  RESULTS
  R-DelayTOT lasted 366 ± 10 ms. R-EMD, R-Δt F-MMG, R-Δt MMGp-p , and R-Δt MMG-Fend accounted for 6%, 8%, 59%, and 27% of R-DelayTOT , respectively. After fatigue, R-DelayTOT , R-EMD, R-Δt F-MMG, and R-Δt MMGp-p increased by 38%, 22%, 40%, 40%, and 38%, respectively (P<0.05). Reliability was very high (0.853-0.960).
  
  
  CONCLUSIONS
  R-Δt MMGp-p was the main contributor to R-DelayTOT . Fatigue affected all R-DelayTOT contributors, with a smaller effect on R-EMD.
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Via G. Colombo 71, 20133, Milan, Italy.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Cè
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Via G. Colombo 71, 20133, Milan, Italy.
authors.forename: Susanna
authors.initials: S
authors.lastname: Rampichini
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Via G. Colombo 71, 20133, Milan, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Venturelli
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Via G. Colombo 71, 20133, Milan, Italy.
authors.forename: Eloisa
authors.initials: E
authors.lastname: Limonta
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Via G. Colombo 71, 20133, Milan, Italy.|Center of Sport Medicine, Don Gnocchi Foundation, Milan, Italy.
authors.forename: Arsenio
authors.initials: A
authors.lastname: Veicsteinas
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Via G. Colombo 71, 20133, Milan, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Esposito
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology; D004576:Electromyography; D016552:Ergometry; D005221:Fatigue / Q000503:physiopathology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D009213:Myography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D055815:Young Adult
keywords: electromyogram; force; latency; mechanomyogram; myotonia