title: Validity of trunk extensor and flexor torque measurements using isokinetic dynamometry.
abstract: This study aimed to evaluate the validity and test-retest reliability of trunk muscle strength testing performed with a latest-generation isokinetic dynamometer. Eccentric, isometric, and concentric peak torque of the trunk flexor and extensor muscles was measured in 15 healthy subjects. Muscle cross sectional area (CSA) and surface electromyographic (EMG) activity were respectively correlated to peak torque and submaximal isometric torque for erector spinae and rectus abdominis muscles. Reliability of peak torque measurements was determined during test and retest sessions. Significant correlations were consistently observed between muscle CSA and peak torque for all contraction types (r=0.74-0.85; P<0.001) and between EMG activity and submaximal isometric torque (r ⩾ 0.99; P<0.05), for both extensor and flexor muscles. Intraclass correlation coefficients were comprised between 0.87 and 0.95, and standard errors of measurement were lower than 9% for all contraction modes. The mean difference in peak torque between test and retest ranged from -3.7% to 3.7% with no significant mean directional bias. Overall, our findings establish the validity of torque measurements using the tested trunk module. Also considering the excellent test-retest reliability of peak torque measurements, we conclude that this latest-generation isokinetic dynamometer could be used with confidence to evaluate trunk muscle function for clinical or athletic purposes.
authors.affiliation: French National Institute of Sport (INSEP), Research Department, Laboratory Sport, Expertise and Performance, Paris, France. Electronic address: gael.guilhem@insep.fr.
authors.forename: Gaël
authors.initials: G
authors.lastname: Guilhem
authors.affiliation: French National Institute of Sport (INSEP), Research Department, Laboratory Sport, Expertise and Performance, Paris, France; CETAPS UPRES EA 3832, Faculty of Sports Sciences, University of Rouen, Mont Saint Aignan Cedex, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Giroux
authors.affiliation: French National Institute of Sport (INSEP), Research Department, Laboratory Sport, Expertise and Performance, Paris, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Couturier
authors.affiliation: Neuromuscular Research Laboratory, Schulthess Clinic, Zurich, Switzerland.
authors.forename: Nicola A
authors.initials: NA
authors.lastname: Maffiuletti
mesh_terms: D000328:Adult; D004576:Electromyography / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D053581:Muscle Strength Dynamometer / Q000592:standards*; D018482:Muscle, Skeletal / Q000502:physiology*; D015203:Reproducibility of Results; D019415:Torque; D060726:Torso / Q000502:physiology*; D055815:Young Adult
keywords: Cross sectional area; EMG; Erector spinae; GRRAS; Muscle strength; Rectus abdominis