ABSTRACT
Background: Patients often need to use their arms to assist with functional activities, but after open heart surgery pushing with the arms is limited to minimize force across the healing sternum. Objectives: The main purposes of this study were to determine: 1) how accurately patients can estimate arm weight bearing with 10 lb or less of force and 2) if feedback training is effective for improving ability to estimate arm force and reduce pectoralis major muscle contraction during functional activities. Materials and Methods: An instrumented walker was used to measure arm force during functional mobility tasks including walker ambulation and sit-stand transfers. Pectoralis major muscle electromyography (EMG) activity was measured simultaneously in study participants (n = 21). After baseline testing, study participants underwent a brief session of visual and auditory concurrent feedback training. Data analyses included t-tests, ANOVA, and Pearson correlations (P<0.05). Results: Results showed that self-selected arm force was greater than 10 lb for all tasks (11.7-19.0 lb) but after feedback training, it was significantly lower (8.3-9.8 lb). During most trials (67%), study participants used more than 12 lb of arm force. Pectoralis major muscle EMG values were less than 10% of maximal voluntary contractions and were reduced (2.7-3.3%) after feedback training. Conclusions: Results indicate that patients may not be able to accurately estimate upper extremity force used during weight bearing activities, and that visual and auditory feedback improves accuracy. Activation of the pectoralis major muscle during arm weight bearing is minimal, suggesting minor force occurs across the sternum. An instrumented walker and feedback training appear to be very clinically useful for patients recovering from open heart surgery.