Electromyography study of muscle fatigue during isometric exercises in swimmers and non-swimmers.

摘要

The use of electromyography (EMG) techniques offer strong evaluation of musculature fatigue during activity in different exercises. Studies show that EMG can be used to monitor fatigue patterns in muscles composing the upper extremities and thoracic areas of the human body by analyzing median frequency values. Advances in muscle fatigue research have been critical for improving rehabilitation programs for patients with musculoskeletal conditions. Despite these developments, many collegiate athletes are still at high risk for muscle injury on and off the playing field. Therefore, in order to help reduce injury numbers, it is important that current research focus on the fatigue rates over time in muscles involved for critical movements within specific sports. This study tested fatigue patterns in muscles of the posterior shoulder and lower lumbar using surface EMG (sEMG). Thirty one female subjects between the ages of 18--23 (11 swimmers and 23 non-swimmers) with no previous shoulder problems recorded in the past year were evaluated. Seven different muscles were tested including the posterior deltoid (PD), upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), infraspinatus (INF), serratus anterior (SA), and the erector spinae (ES). Two isometric exercises were conducted with the subject's dominant arm at horizontal abduction of the shoulder joint at 90° ("T"), and at horizontal abduction of the shoulder joint at 135° ("Y"). The slope of the median frequency was used to evaluate the muscle fatigue of all seven muscles studied. Results demonstrate that the muscles of non-swimmers fatigue more rapidly than those of the swimmers, but only at the 90° position. Results also show that there is significant difference in fatigue rates in the two groups in the UT and LT at 135°, and the PD at 90°. These findings will help specialists develop appropriate rehabilitation programs for collegiate swimmers focusing on muscles involved in the recovery and reach phases of a swimming stroke. This could ultimately aid in producing stronger collegiate swimmers and fewer shoulder related injuries.