title: Electromechanical delay components during skeletal muscle contraction and relaxation in patients with myotonic dystrophy type 1.
abstract: The electromechanical delay during muscle contraction and relaxation can be partitioned into mainly electrochemical and mainly mechanical components by an EMG, mechanomyographic, and force combined approach. Component duration and measurement reliability were investigated during contraction and relaxation in a group of patients with myotonic dystrophy type 1 (DM1, n = 13) and in healthy controls (n = 13). EMG, mechanomyogram, and force were recorded in DM1 and in age- and body-matched controls from tibialis anterior (distal muscle) and vastus lateralis (proximal muscle) muscles during maximum voluntary and electrically-evoked isometric contractions. The electrochemical and mechanical components of the electromechanical delay during muscle contraction and relaxation were calculated off-line. Maximum strength was significantly lower in DM1 than in controls under both experimental conditions. All electrochemical and mechanical components were significantly longer in DM1 in both muscles. Measurement reliability was very high in both DM1 and controls. The high reliability of the measurements and the differences between DM1 patients and controls suggest that the EMG, mechanomyographic, and force combined approach could be utilized as a valid tool to assess the level of neuromuscular dysfunction in this pathology, and to follow the efficacy of pharmacological or non-pharmacological interventions.
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Via Colombo 71, 20133 Milan, Italy. Electronic address: fabio.esposito@unimi.it.
authors.forename: Fabio
authors.initials: F
authors.lastname: Esposito
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Via 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 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 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 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 Colombo 71, 20133 Milan, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Monti
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Via Colombo 71, 20133 Milan, Italy; IRCCS Policlinico San Donato, Piazza Malan 2, 20097 San Donato, Milanese (MI), Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Bet
authors.affiliation: IRCCS Policlinico San Donato, Piazza Malan 2, 20097 San Donato, Milanese (MI), Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Fossati
authors.affiliation: Department of Biomedical Sciences for Health, University of Milan, Via Colombo 71, 20133 Milan, Italy; IRCCS Policlinico San Donato, Piazza Malan 2, 20097 San Donato, Milanese (MI), Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Meola
mesh_terms: D061725:Accelerometry; D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D009126:Muscle Relaxation / Q000502:physiology*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009223:Myotonic Dystrophy / Q000473:pathology*; D011601:Psychophysics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017603:Signal Detection, Psychological; D055815:Young Adult
keywords: Electromyogram; Latency; MMG; Mechanomyogram; Muscle weakness; Myotonia