Electromyographic Analysis of the Supraspinatus and Infraspinatus Muscles During Activities of Housework

Abstract

The purpose of this study was to evaluate muscle activation levels of supraspinatus (SSP) and infraspinatus (ISP) muscles during various activities of housework by electromyogram (EMG), and to decide the range of activity for patients after rotator cuff repair.
Eight normal volunteers, five male and three female, aged 25 to 43 years old, were studied. We evaluated muscle activation levels of SSP and ISP muscles by EMG during 13 various activities of housework; holding a frying pan, using a kitchen knife, pouring hot water. Also the % maximal voluntary contraction (%MVC) of each movement was compared. The SSP muscle showed greater activity (%MVC>20) during holding a frying pan (containing a 1kg weight) with one hand(21.6%MVC). Also the ISP muscle showed greater activity (%MVC>20) during holding a frying pan (containing a 0.5kg or 1kg weight) with one hand(22.8,31.7%MVC) and pouring hot water with the kettle with one hand(34.3%MVC). Both muscles showed lesser activity(%MVC<20) during using a kitchen knife.
The evaluation of SSP muscle and ISP muscle activities of housework by EMG was useful to classify movement of housework into various categories by muscle activation and to decide the patient activity level after rotator cuff repair.