646 MEP179 – What do upper-extremity physical performance tests measure? Insights from an electromyographical study

AbstractBackground Upper-extremity physical performance tests (PPTs) are frequently employed for athletic screening because they are easily administered in field settings. Knowledge of muscle activity during PPT execution could enhance our understanding of the mechanisms underlying their performance and enable clinicians to select appropriate PPTs for their athletes' specific needs.Objective To evaluate the electromyographical (EMG) requirements associated with four upper-extremity PPTs.Design cross-sectional descriptive study.Setting Laboratory.Participants Thirty asymptomatic overhead athletes. Interventions Four PPTs (Y-Balance Test – Upper Quarter (YBT-UQ), Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST), Upper Limb Rotation Test (ULRT) and Shoulder Endurance Test (SET)) were evaluated using surface EMG on both sides.Main Outcome Measurements Muscle activity in upper (UT), middle (MT), and lower (LT) trapezius, serratus anterior (SA), infraspinatus (IS) and, posterior deltoid (PD).Results During YBT-UQ performance on both sides, the supporting hand showed high SA activity levels (range: 51 – 94%MVIC) during all reach directions while IS was most active when supporting the superolateral reach (range: 92 – 129%MVIC). For the reaching arm, SA was most active (range: 46 – 83%MVIC). During the CKCUEST, all muscles were moderate to highly active, with SA (range: 64 – 87%MVIC) and IS (range: 42 – 85%MVIC) being the most active ones in both moving and supporting arms. Moderate to high activity was recorded for all muscles on both sides during the ULRT. For the SET, muscle activity progressively increased with increasing speed for both sides.Conclusion This study provides specific EMG-based insights which allow clinicians to increase their understanding of PPT performance, enhancing appropriate PPT selection for athletic screening. Moreover, this knowledge can guide clinical decision-making concerning which muscles may need additional strengthening if the athlete fails testing and lead to more sport-specific and muscle-specific rehabilitation strategies to get athletes ready for return to sport.