RESUMEN
Muscle strength is essential for autonomy in daily activities and performance in sports activities. Yet, conventional strength training is challenging during recovery from pathological conditions. This study investigates a novel combined intervention employing Focal Muscle Vibration (FMV) and Action Observation (AO) to enhance muscle strength. Twenty-seven healthy volunteers (18 females and 9 males, aged 22 to 42 years) were enrolled for an intervention-control study comparing 2 groups: the intervention group received AO treatment with FMV on the right leg, and the control group underwent only FMV on the right leg. This design allowed the comparison of four conditions: FMV+AO (intervention group, right leg), AO alone (intervention group, left leg), FMV alone (control group, right leg), and no-treatment NT (control group, left leg). The treatment, conducted five times a week (Mon-Fri) for two weeks, involved a 20-minute session of FMV on the right quadriceps, coupled, for the intervention group, with the observation of a gym training video. The assessments of Maximum Voluntary Contraction (MVC), and fatigue coefficient (FC) expressed at knee extension bilaterally were measured at the beginning (T0), after the first week (T1), at the end of treatment (T2), and one-week post-intervention for the follow-up (T3). The FMV+AO group demonstrated a significant improvement in MVC over time, reaching statistical significance at T2 and maintaining the gain at T3. In contrast, all the other conditions demonstrated milder MVC increases without statistical significance. FC did not differ significantly in any condition. The combination of FMV and AO optimized muscle strengthening, offering insights for targeted treatments in various settings.
RESUMEN
The loss of a hand disrupts the sophisticated neural pathways between the brain and the hand, severely affecting the level of independence of the patient and the ability to carry out daily work and social activities. Recent years have witnessed a rapid evolution of surgical techniques and technologies aimed at restoring dexterous motor functions akin to those of the human hand through bionic solutions, mainly relying on probing of electrical signals from the residual nerves and muscles. Here, we report the clinical implementation of an interface aimed at achieving this goal by exploiting muscle deformation, sensed through passive magnetic implants: the myokinetic interface. One participant with a transradial amputation received an implantation of six permanent magnets in three muscles of the residual limb. A truly self-contained myokinetic prosthetic arm embedding all hardware components and the battery within the prosthetic socket was developed. By retrieving muscle deformation caused by voluntary contraction through magnet localization, we were able to control in real time a dexterous robotic hand following both a direct control strategy and a pattern recognition approach. In just 6 weeks, the participant successfully completed a series of functional tests, achieving scores similar to those achieved when using myoelectric controllers, a standard-of-care solution, with comparable physical and mental workloads. This experience raised conceptual and technical limits of the interface, which nevertheless pave the way for further investigations in a partially unexplored field. This study also demonstrates a viable possibility for intuitively interfacing humans with robotic technologies.