title: Muscle contractile properties by surface electrodes compared with those by needle electrodes.
abstract: We measured the contractile properties of the first dorsal interosseous muscle by surface electrodes and needle electrodes during submaximal voluntary contraction. Twenty-seven single motor units were recorded from 5 volunteers by surface electrodes, which were confirmed by subsequent needle electrode recordings. Twitch tension ranged from 0.6 to 10.0 g with a mean of 3.7 g based on an averaging method triggered by surface myoelectric signals, and the tension calculated from the needle myoelectric signals ranged from 0.8 to 11.7 g with a mean of 3.6 g. Rise time ranged from 33.9 to 81.6 msec with a mean of 49.4 msec for the surface electrode recordings, and from 33.0 to 73.2 msec with a mean of 50.8 msec for the needle electrode recordings. The obtained data of surface electrode recordings indicated a high correlation with that of the needle electrode recordings, r = 0.92 (P < 0.001) for twitch tension and r = 0.91 (P < 0.001) for rise time. We also found a positive correlation between threshold force and twitch tension (by surface electrodes: r = 0.71, P < 0.05; by needle electrodes: r = 0.77, P < 0.05). Our studies indicate that it is possible to record single motor units by non-invasive surface electrodes provided that the unit has a threshold force of less than 2 kg.
authors.affiliation: Department of Physiology and Biomechanics, National Institute of Fitness and Sports, Kagoshima, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Fujimoto
authors.forename: H
authors.initials: H
authors.lastname: Nishizono
mesh_terms: D000328:Adult; D004566:Electrodes; D004576:Electromyography / Q000295:instrumentation*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D009132:Muscles / Q000502:physiology; D009339:Needles; D011930:Reaction Time / Q000502:physiology