Using biofeedback to optimize scapular muscle activation ratios during a seated resisted scaption exercise

Area of Science:

• Biomechanics
• Sports Medicine
• Rehabilitation Science

Background:

• Muscle activation impairments are linked to shoulder pathologies like subacromial impingement syndrome (SIS) and rotator cuff injuries.
• Individuals with SIS often exhibit increased upper trapezius (UT) activation and reduced serratus anterior (SA) and lower trapezius (LT) activation, impacting muscle activation ratios (UT/SA, UT/LT).
• Targeted exercise and electromyography (EMG) biofeedback are crucial for shoulder rehabilitation, aiming to restore optimal muscle activation patterns.

Purpose of the Study:

• To compare the effects of three biofeedback types (visual EMG, auditory, verbal cues) on shoulder muscle activation ratios during a seated resisted scaption exercise.
• To investigate the efficacy of different biofeedback modalities in altering the UT/SA and UT/LT muscle activation ratios in healthy individuals.
• To address a literature gap concerning the effectiveness of various biofeedback methods beyond visual EMG for shoulder rehabilitation.

Main Methods:

• Fifteen healthy subjects performed a seated resisted scaption exercise under three randomized biofeedback conditions: visual EMG, auditory, and verbal cues.
• Baseline muscle activation data was collected and compared to real-time muscle activation during each biofeedback trial.
• Electromyography (EMG) was used to measure the activation of the upper trapezius (UT), serratus anterior (SA), and lower trapezius (LT) muscles.

Main Results:

• All tested biofeedback types (visual EMG, auditory, verbal cues) demonstrated improvements in both UT/SA and UT/LT muscle activation ratios.
• Visual EMG biofeedback resulted in a statistically significant improvement in the UT/LT muscle activation ratio (p < 0.05).
• These findings indicate that various forms of biofeedback can positively influence scapular muscle activation patterns.

Conclusions:

• Biofeedback interventions show promise for improving muscle activation ratios during shoulder exercises.
• Visual EMG biofeedback appears particularly effective in modulating the UT/LT ratio, suggesting its potential in clinical applications.
• These results support the integration of biofeedback as a component in rehabilitation programs aimed at preventing or treating shoulder pain and related injuries.