Passive knee exoskeletons in functional tasks: Biomechanical effects of a SpringExo coil-spring on squats

Abstract

Passive wearable exoskeletons are desirable as they can provide assistance during user movements while still maintaining a simple and low-profile design. These can be useful in industrial tasks where an ergonomic device could aid in load lifting without inconveniencing them and reducing fatigue and stress in the lower limbs. The SpringExo is a coil-spring design that aids in knee extension. In this paper, we describe the muscle activation of the knee flexors and extensors from seven healthy participants during repeated squats. The outcome measures are the timings of the key events during squat, flexion angle, muscle activation of rectus femoris and bicep femoris, and foot pressure characteristics of the participants. These outcome measures assess the possible effects of the device during lifting operations where reduced effort in the muscles is desired during ascent phase of the squat, without changing the knee and foot kinematics. The results show that the SpringExo significantly decreased rectus femoris activation during ascent (−2%) without significantly affecting either the bicep femoris or rectus femoris muscle activations in descent. This implies that the user could perform a descent without added effort and ascent with reduced effort. The exoskeleton showed other effects on the biomechanics of the user, increasing average squat time (+0.02 s) and maximum squat time (+0.1 s), and decreasing average knee flexion angle (−4°). The exoskeleton has no effect on foot loading or placement, that is, the user did not have to revise their stance while using the device.

Wearables for Biomechanical Performance Optimization and Risk Assessment in Industrial and Sports Applications

“…Results indicated that an exoskeleton significantly reduced the required mechanical energy for tasks, which can help improve worker performance by reducing fatigue [ 6 ]. Based on a series of exoskeleton-based studies, researchers have demonstrated that this assistive-based technology improves both range of motion [ 16 , 17 ] and muscle fatigue or activation [ 16 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ].…”

“…As wearable technologies for industry advance in the realm of biomechanical task assessment, these systems will need to communicate through a layered data structure that integrates collected data throughout the workers’ environment to optimize performance and ensure worker health as a holistic system [ 46 ]. As smart factories continue to develop, advancements in industrial wearable devices will play an essential role in optimizing worker performance through those task components previously mentioned such as range of motion [ 16 , 17 ] and muscle fatigue or activation [ 16 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ].…”

Repetitive Stress Injury In The Lower Extremity Due To Foot Stances During Weight Squats

“…It's important to understand how anthropometrics and fatigue affect the kinematics of the lower extremities during squats in order to create customised training plans and injury prevention techniques. Research into joint range of motion during squats based on stance width and anthropometrics, as well as studies into the effects of fatigue on lower extremity kinematics, offer important insights for improving training methods and reducing injury (Bengtsson et al, 2018;Escamilla, 2001;Escamilla et al, 2001;Hidayah et al, 2021;Milner et al, 2007) (Salem & Powers, 2001).…”

A Compatible Design of a Passive Exoskeleton to Reduce the Body–Exoskeleton Interaction Force

“…Given the assistant method of the passive exoskeleton, the elastic element has been used to assist human movement through combining the characteristics of human movement [31]. For example, Hidayah [32] used a coil-spring to assist knee extension. Walsh [19] designed a mechanical exoskeleton that has ankle and hip springs and a knee variable damper to bear a load.…”