Abstract
Background: It is important that the load of the repaired rotator cuff tendon must not be heavy. However, the load of the rotator cuff muscles in activities of daily living are not quantified. The purpose of this study was to quantify the electromyographic activities of supraspinatus (SSP) and infraspinatus (ISP) muscles in activities of daily living (ADL), and to select safe ADL in the repaired rotator cuff muscles.
Methods: We examined wire EMG of SSP and surface EMG of ISP of dominant side in 5 asymptomatic males. Their average age was 26.8 years old. We examined the integration of EMG by manual muscle test of elevation and external rotation. The peak of it reached for one second was defined as the maximal voluntary contraction (MVC). The EMG activities of each ADL were divided by MVC. This was %MVC. We tested 12 kinds of ADL.
Results: Each ADL : %MVC of SSP, %MVC of ISP. Writing : 3.6, 3.7. Drinking from a glass : 8.3, 8.5. Eating with chopsticks : 8.4, 6.5. Brushing teeth : 10.2, 7.1. Washing face : 16.1, 11.7. Squeezing towel : 9.8, 16.9. Shampoo with head down : 13.7, 9.9. Shampoo with head up : 20.8, 14.0. Cutting with kitchen knife : 6.9, 8.4. Dishwashing : 3.4, 7.3. Vacuuming : 10.3, 10.7. Hanging the wash : 21.3, 24.1.
Conclusion: The 0-20%MVC range was judged a low load. The activities on a desk were under 10%MVC and safe. Shampoo with head up and Hanging the wash were over 20%MVC. These were risky activities for repaired rotator cuff. We should educate patients about doing ADL on hanging arm position.
