Functional Resistance Training With Viscous and Elastic Devices: Does Resistance Type Acutely Affect Knee Function?

Objective: Functional resistance training (FRT) during walking is an emerging approach for rehabilitating individuals with neuromuscular or orthopedic injuries. During FRT, wearable exoskeleton/braces can target resistance to a weakened leg joint; however, the resistive properties of the training depend on the type of resistive elements used in the device. Hence, this study was designed to examine how the biomechanical and neural effects of functional resistance training differ with viscous and elastic resistances during both treadmill and overground walking. Methods: Fourteen able-bodied individuals were trained on two separate sessions with two devices that provided resistance to the knee (viscous and elastic) while walking on a treadmill. We measured gait biomechanics and muscle activation during training, as well as kinematic aftereffects and changes in peripheral fatigue and neural excitability after training. Results: We found the resistance type differentially altered gait kinetics during training—elastic resistance increased knee extension during stance while viscous resistance primarily affected swing. Also, viscous resistance increased power generation while elastic resistance could increase power absorption. Both devices resulted in significant kinematic and neural aftereffects. However, overground kinematic aftereffects and neural excitability did not differ between devices. Conclusion: Different resistance types can be used to alter gait biomechanics during training. While there were no resistance-specific changes in acute neural adaptation following training, it is still possible that prolonged and repeated training could produce differential effects. Significance: Resistance type alters the kinetics of functional resistance training. Prolonged and repeated training sessions on patients will be needed to further measure the effects of these devices.