title: Validity of the twitch interpolation technique for the assessment of quadriceps neuromuscular asymmetries.
abstract: This study examined the validity of the twitch interpolation technique for evaluating side-to-side asymmetries in quadriceps neuromuscular function. Fifty-six subjects with a wide range of asymmetries (19 healthy, 24 with unilateral and 13 with bilateral anterior cruciate ligament reconstruction) took part in the study. Supramaximal electrical paired stimuli were delivered to the quadriceps muscle during and immediately after a maximal voluntary contraction (MVC) of the knee extensors (twitch interpolation technique). MVC torque, voluntary activation and resting doublet-evoked torque were measured separately for the two sides, and percent side-to-side asymmetries were calculated for each parameter. MVC torque asymmetry was plotted against voluntary activation asymmetry and doublet-evoked torque asymmetry, and a multiple regression analysis was also conducted. Significant positive correlations were observed between MVC torque asymmetry and both voluntary activation asymmetry (r=0.40; p=0.002) and doublet-evoked torque asymmetry (r=0.53; p<0.001), and their relative contribution to MVC torque asymmetry was comparable (r=0.64; p<0.001). These results establish the validity of the twitch interpolation technique for the assessment of neuromuscular asymmetries. This methodology could provide useful insights into the contribution of some neural and muscular mechanisms that underlie quadriceps strength deficits.
authors.affiliation: Neuromuscular Research Laboratory, Schulthess Clinic, Zurich, Switzerland.
authors.forename: Nicola Angelo
authors.initials: NA
authors.lastname: Maffiuletti
authors.affiliation: Rehabilitation Research Laboratory 2rLab, Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Manno, Switzerland. Electronic address: marco.barbero@supsi.ch.
authors.forename: Marco
authors.initials: M
authors.lastname: Barbero
authors.affiliation: Rehabilitation Research Laboratory 2rLab, Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Manno, Switzerland.
authors.forename: Corrado
authors.initials: C
authors.lastname: Cescon
authors.affiliation: Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, SUPSI, Landquart, Switzerland; University College Physiotherapy, Thim Van Der Laan AG, Landquart, Switzerland.
authors.forename: Ron
authors.initials: R
authors.lastname: Clijsen
authors.affiliation: Rehabilitation Research Laboratory 2rLab, Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Manno, Switzerland.
authors.forename: Matteo
authors.initials: M
authors.lastname: Beretta-Piccoli
authors.affiliation: Rehabilitation Research Laboratory 2rLab, Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Manno, Switzerland.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Schneebeli
authors.affiliation: Neuromuscular Research Laboratory, Schulthess Clinic, Zurich, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Preiss
authors.affiliation: Ars Medica Clinic, Gravesano, Switzerland.
authors.forename: Danilo
authors.initials: D
authors.lastname: Togninalli
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction / Q000009:adverse effects / Q000639:trends; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D052097:Quadriceps Muscle / Q000502:physiology*; D015203:Reproducibility of Results; D004561:Transcutaneous Electric Nerve Stimulation / Q000379:methods / Q000592:standards*; D055815:Young Adult
keywords: Activation; Contractility; Strength; Weakness