A Soft Robotic Sleeve for Physiotherapy: Improving Elbow Rehabilitation in Baseball Pitchers.

BACKGROUND AND PURPOSE

Throwing a baseball involves intense exposure of the arm to high speeds and powerful forces, which contributes to an increasing prevalence of arm injuries among athletes. Traditional rigid exoskeletons and rehabilitation equipment frequently lack portability, safety, ergonomic design, and affordability. Traditional rehabilitation approaches frequently require therapist monitoring, resulting in therapy delays. This paper describes a Pneumatic Artificial Muscle (PAM) based soft robotic sleeve designed for upper limb rehabilitation, with an emphasis on elbow flexion and extension in baseball pitchers.

METHODS

The experiment included five healthy male baseball pitchers aged 20-24 with no history of upper limb injuries, ensuring their suitability for testing the effectiveness of the PAM-based sleeve in supporting elbow flexion and extension specific to baseball pitching. The effectiveness of the PAM-based soft sleeve was evaluated utilizing a pre-post design that included surface electromyography (sEMG). Participants were tested for muscle activation and range of motion both with and without the device. The sleeve has two operational modes: Active Surge Flex Mode, which detects movement intention using sEMG and delivers targeted help, and Steady Passive Mode, which allows repetitive flexion and extension without intentional muscle activation.

RESULTS

The PAM-based sleeve reduced muscle activation in both triceps and biceps, with reductions of approximately 40% (p < 0.05) and 60% (p < 0.05), respectively. When activated based on assistance thresholds, triceps and biceps EMG amplitudes were further reduced by 30% (p < 0.05) and 50% (p < 0.05), respectively. The flexion angle remained consistent between 70 and 90°, indicating smooth and controlled movements. The Co-Contraction Index (CCI) decreased from 0.31 to 0.12, highlighting a reduction in unnecessary muscle co-activation, thereby improving movement efficiency.

DISCUSSION

The PAM-based soft robotic sleeve provides a convenient and effective upper limb rehabilitation solution that is specifically designed for baseball pitchers. The sleeve reduces the physical strain of pitchers by reducing muscle activation in both the biceps and triceps, as well as decreasing the Co-Contraction Index (CCI). Its portability, convenience of use, and potential to improve muscle efficiency make it an effective tool for improving rehabilitation outcomes.