Muscle-training effect associated with scaler operation

Abstract

Objective: In this study, since the gripping of the scaler is based on the gripping of the writing instrument, we examined the effect of training of the correct writing instrument’s gripping motion on the operation of the scaler. Methods: Training of holding a pen with a grip was performed in subjects whose thumb did not properly contact with the pen. In the measurement of EMG, we measured the first dorsal interdigital muscle and the flexor pollicis brevis muscle in the scaler manipulation and measured the daily grasping and correct grasping motion, the forearm rotational motion of the scaler operation and the finger flexion exercise before and after the training went. Results: RMS of the flexor pollicis brevis muscle significantly increased during usual and proper pen-holding motions and that of the first dorsal interosseous muscle significantly increased in scaler operation. In addition, the flexor pollicis brevis muscle activity level in scaler significantly decreased operation during bending and extending the fingers after training. It was suggested that training of positioning and the way of applying the force of the thumb could be performed leading to a reduction of the muscle activity level by daily use of writing instruments with a grip. Discussion: A strong correlation was noted between proper pen-holding motion operation and scaler operation-induced forearm rotation and RMS of the flexor pollicis brevis muscle, suggesting that holding a pen with a grip serves as training strengthening the flexor pollicis brevis muscle.