等尺性運動におけるフィードバックの効果

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Isometric exercise is one of the commonly used physiotherapeutic modalities for muscle strengthening. Under verbal command from a physiotherapist the patient is asked to make the maximum voluntary effort to contract a muscle or a muscle group. One cannot, however, exactly know whether the muscle or the muscle group is contracting maximally. The purpose of this investigation was to determine whether one would exert maximum contraction of the hip abductors (HA) using visual digital dynamometric feedback (VDDF) and if each contraction would be consistent over a series of trials in comparison to the traditional method of isometric contraction only. The subjects consisted of 20 healthy female college students with their age ranging from 18 to 22 (mean 20.1±2.4) years old, height from 151 to 170 (mean 158.7±4.9) cm, and weight from 43 to 67 (mean 51.9±6.5) kg. A cuff was fitted around each ankle joint of the subjects lying supine. The sensor of a digital dynamometer was attached between the cuffs to measure in kg the maximum isometric tension bilaterally of HA. Each hip was in approximately 10 degrees of abduction. Using each subject as her own control, we measured the subjects' HA tension under two experimetal conditions. Each subject in the isometric alone (1) group contracted HA maximally for 3 seconds, followed by a 30-second rest, and repeated it 5 times. Each subject in the isometric contraction (F) group with VDDF performed the exercise in the same way, but was allowed to watch the dynamometer reading. The result showed that the average maximum tension of HA for Group I was 9.79±0.49kg as opposed to 10.57±0.49kg for Group F. The difference between these groups was approximately 0.8kg which was statistically significant. Furthermore, regarding the average maximum tension for each trial. Group F consistently achieved a stronger contraction. The maximum HA tention at each trial fluctuated widely in Group I compared to Group F. However, a one-way analysis of variance revealed no significant differences in the fluctuations amongst the trials. The visual cues from the digital dynamometer encouraged the subjects in Group F to achieve greater tension. We can therefore hypothesize that isometric contraction with VDDF consistently sustains maximum contraction. In other words, VDDF appears to have enabled the subjects to produce overflow at synapses of the motor end-plates by a possible increase in the number of motor units recruited. Usually, both auditory and visual biofeedback are employed to commence training. One may eventually discard either one of them depending on one's purpose and the patient's condition. Possible advantages of VDDF are : 1) signal presentation in the form of numbers; 2) easy and simple fitting of cuffs; and 3) no need for electrodes/leads and exposure of the skin over the target muscle or muscle group. At present, biofeedback instrumentation for exercise therapy includes EMG, electrogoniometry, and pressure transducers. The result of this investigation may provide a rationale for the addition of VDDF to the repertoire of biofeedback therapy.
日本バイオフィードバック学会の論文
1991-06-01

等尺性運動におけるフィードバックの効果

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