Investigation of muscular activation levels around the scapula and shoulder in body-weight-bearing exercises

The importance of neuromuscular exercise training in shoulder rehabilitation was well-established. This study was planned to determine the muscular activation levels and activation rates of the scapula and shoulder girdle in various variations of the plank exercises, in which the body weight is carried on the arms. Twenty-one asymptomatic, physically active males (Age:266,5 years, BMI:24,42,4 kg/m²) were included in the study. A total of ten distinctive plank exercises were applied. Exercises were varied with alterations made by alterating the plane of motion, the elbow joint position and load-bearing condition (four-point, three-pod and two-point) and performed by all participants in random order. During all exercises, the activation levels of the upper trapezius (UT), middle trapezius (LT), lower trapezius (LT), serratus anterior (SA), infraspinatus (IS), biceps brachii (BB) and triceps brachii (TB) muscles were measured by a surface electromyography. Findings of this study showed that, in all plank variations SA showed moderate (%20-40 MVIC) to higher (%40-60 MVIC) muscular activation. While observed BB activation was at low level (<%20 MVIC) during all exercises, TB activation increased to moderate level (%20-40 MVIC) in the variations that the support decreased. UT/MT, UT/LT and UT/SA ratios were low (<1) during plank with shoulder external rotation resistance and side plank exercise. However, high plank exercise with toe touch resulted in an increased activation in the UT. As a result of this study, it was observed that there were differences in shoulder and scapular muscle activations between plank variations performed at varied support level and motion plane. It was concluded that spesific variations of plank exercise should be used in shoulder rehabilitation based on spesific requirements and needs of the individual programs.