Validity of trunk extensor and flexor torque measurements using isokinetic dynamometry

• Published in: Journal of electromyography and kinesiology Vol. 24; no. 6; pp. 986 - 993
• Main Authors: Guilhem, Gaël, Giroux, Caroline, Couturier, Antoine, Maffiuletti, Nicola A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2014; Elsevier
• Subjects: Adult; Biomechanics; Cross sectional area; Electromyography - standards; EMG; Erector spinae; Female; GRRAS; Human health and pathology; Humanities and Social Sciences; Humans; Life Sciences; Male; Mechanics; Muscle strength; Muscle Strength Dynamometer - standards; Muscle, Skeletal - physiology; Physical Medicine and Rehabilitation; Physics; Rectus abdominis; Reproducibility of Results; Sport; Sport physiology; Tissues and Organs; Torque; Torso - physiology; Young Adult; Muscle strength; Erector spinae; Rectus abdominis; GRRAS; EMG; Cross sectional area; muscle strength; erector spinae; cross sectional area; rectus abdominis
• ISSN: 1050-6411; 1873-5711; 1873-5711
• DOI: 10.1016/j.jelekin.2014.07.006

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.