Effects of an active exoskeleton on the muscle activity of the erector spinae and biceps femoris muscles during lifting with symmetric stoop and squat technique.

Introduction: Active exoskeletons are increasingly used to reduce muscle activity and support lifting tasks. However, the effectiveness of exoskeletons can vary depending on the lifting technique. This study investigates the effects of a commercially available active exoskeleton (Apogee) on muscle activity during two different lifting techniques: stoop and squat. Methods: 17 healthy young adults (8 male, 9 female) participated in the study. Muscle activity was measured in the M. erector spinae (MES) and M. biceps femoris (MBF) using EMG while lifting a 15 kg box in four conditions: 1) without exoskeleton, 2) exoskeleton in passive mode, 3) 50% support and 20% counterforce, 4) 100% support and 60% counterforce. Results: The MBF activity was 29% lower during the squat technique compared to the stoop technique (F Discussion: The results indicate that the exoskeleton provides greater benefits during the stoop technique, where the lifting motion primarily involves hip extension. The reduction in muscle activity supports the potential of exoskeletons in reducing muscle load and preventing work-related musculoskeletal disorders (MSDs). However, the squat technique showed limited improvements, suggesting that exoskeletons may need to be adapted for different lifting tasks. Future exoskeletons should aim to dynamically adjust their support based on the specific lifting technique to maximize effectiveness.