title: Effect of prior experience and task stability on the intrinsic muscle activity of the thumb.
abstract: Manual techniques involving the use of the thumb are commonly employed by physical therapists for treating patients with vertebral disorders. The demands on the intrinsic muscles of the thumb in these manual tasks are very different from those of the pinch tasks. The aim of this study was to investigate the influence of clinical experience and different mobilization techniques on the electromyographic activity (EMG) of thumb intrinsic muscles. Fifteen participants without exposure to manual techniques (the Novice Group) and fifteen physical therapists with at least 3 years of orthopaedic experience (the Experienced Group) participated. Each participant exerted thumb tip forces with 3 different posterioanterior (PA) glide techniques including unsupported, with digital support and with thumb interphalangeal joint supported by the index finger. The exerted force was increased from 25% to 100% maximum force at 25% increments on a 6 component load cell. The thumb tip force and EMG activity of four intrinsic muscles (flexor pollicis brevis, adductor pollicis, abductor pollicis brevis, first dorsal interosseus) were recorded with surface electrodes. Both experience and technique influenced intrinsic muscle activity of the thumb. While participants of both groups generated the same magnitude of force, experienced participants generated less intrinsic muscle activity while performing PA glide through practice. However, novice participants increased activity of the intrinsic muscles in accordance with the stability status of the technique. PA glide with thumb interphalangeal joint supported by the index finger was a more stable technique as evidenced by smallest relative errors of thumb tip force.
authors.affiliation: Department of Physical Therapy, Tzu Hui Institute of Technology, Nanchou Hsian, Ping Tung, Taiwan; Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Meng-Tzu
authors.initials: MT
authors.lastname: Hu
authors.affiliation: Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Fong-Chin
authors.initials: FC
authors.lastname: Su
authors.affiliation: Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Institute of Allied Health Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan. Electronic address: arthsu@mail.ncku.edu.tw.
authors.forename: Ar-Tyan
authors.initials: AT
authors.lastname: Hsu
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002983:Clinical Competence; D004576:Electromyography; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D059825:Physical Therapists; D013647:Task Performance and Analysis; D013933:Thumb / Q000502:physiology*
keywords: Electromyography; Joint mobilization; Muscles; Thumb