To advance our knowledge on the motor system during cyclic gait observation, we aimed to explore the effects of gaze fixation on corticospinal excitability evaluated by single-pulse transcranial magnetic stimulation (TMS). Fourteen healthy adult volunteers watched a video of a demonstrator walking on a treadmill under three different conditions: (1) observing the right lower limb, (2) observing the right ankle joint, and (3) observing the right lower limb on a video focused on the area below the knee. In each condition, motor-evoked potentials elicited by TMS in the tibialis anterior (TA) muscle were measured synchronously with the demonstrator’s initial contact and toe-off points. Directing visual attention to the ankle joint and focusing on its movements caused corticospinal facilitation in the TA muscle compared with watching the video without any visual fixation. In addition, phase-dependent differences in corticospinal excitability between the initial contact and toe-off points were only detected when the visibility range was restricted to below the knee. Our findings indicated that motor resonance during cyclic gait observation is modulated by visual attention and motion visibility in different activation manners.

Objective: The study aimed to determine the relationship between knee extension torque induced by repetitive peripheral magnetic stimulation and the characteristics of the participants. Design: This was a basic study with noninvasive intervention. Knee extension torque induced by repetitive peripheral magnetic stimulation (repetitive peripheral magnetic stimulation–induced torque) and maximum voluntary contraction were measured. Stepwise method of multiple regression was performed to determine the factors affecting repetitive peripheral magnetic stimulation–induced torque at 100% intensity and repetitive peripheral magnetic stimulation–induced torque divided by maximum voluntary contraction (percent maximum voluntary contraction). Subcutaneous fat thickness, vastus lateralis muscle thickness measured by ultrasound, maximum voluntary contraction, and mean power frequency of electromyography during maximum voluntary contraction were selected as independent variables. Results: Repetitive peripheral magnetic stimulation was applied to the right vastus lateralis of 30 young healthy adults (average age, 21.1 ± 0.3 yrs). In the multiple regression analysis, repetitive peripheral magnetic stimulation–induced torque (P < 0.001) was shown to be independently and significantly associated with maximum voluntary contraction (β = 0.510), subcutaneous fat thickness (β = −0.358), and vastus lateralis muscle thickness (β = 0.208), while percent maximum voluntary contraction value (P < 0.05) was independently and significantly associated with vastus lateralis muscle thickness (β = 1.059). Conclusions: Repetitive peripheral magnetic stimulation–induced torque decreases with thicker subcutaneous fat and increases with stronger maximum voluntary contraction or with thicker muscle.

Objective: To investigate the factors that induce strong contractions during repetitive peripheral magnetic stimulation (rPMS) and compare the muscle torque induced by two stimulators (Stim A and Stim B) with different coil properties.Methods: rPMS was applied to the right vastus lateralis of 30 healthy young adults. Stim A contained a 10.1 cm2 rectangular iron core coil, while Stim B contained a 191 cm2 round coil. The knee extensor torque (KET) induced by rPMS at 30 Hz was measured isometrically and divided by the maximum voluntary contraction (MVC) to obtain a relative value of MVC (%MVC). KET at 100% intensity of Stim A (A100%, 1.08 T) was compared to those at 100% or 70% intensity of Stim B (B100%, 1.47 T vs. B70%, 1.07 T). Additionally, we conducted a comprehensive literature search for studies that measured the KET during rPMS.Results: Both the mean values of %MVC using B100% and B70% were significantly greater than that using A100%. Furthermore, the KET induced by Stim B was found to be larger than that described in previous reports, unless booster units were used to directly stimulate the main trunk of the femoral nerve.Conclusion: Stim B induced a stronger muscle contraction force than Stim A did. This may be because the larger the coil area, the wider the area that can be stimulated. Additionally, a circular coil allows for deeper stimulation.

Kamiue M, Tsubahara A, Ito T, Koike Y. Effects of repetitive peripheral magnetic stimulation on knee joint extensor strength in older persons receiving day services. Jpn J Compr Rehabil Sci 2024; 15: 49-57.Objective: To verify the effects of repetitive peripheral magnetic stimulation (rPMS) on knee joint extensor strength and motor ability in older adults receiving day services.Methods: Thirty Hz rPMS using Talent Pro® was applied to the bilateral vastus lateralis, vastus medialis, and rectus femoris of 12 older persons (mean age 83.8 ± 4.5 years) attending a day service center and receiving functional training by a physical therapist. The intervention was performed for 20 minutes per day, three times per week, for a total of 4 weeks. Evaluations before and after the intervention included maximum voluntary contraction (MVC), knee extensor torque induced by rPMS (rPMS-induced torque), pain (visual analog scale: VAS), thigh circumference, comfortable 5-m walking time, 30-second chair-stand test (CS-30), Timed-Up-and-Go Test (TUG), and Functional Reach Test (FRT). MVC and rPMS-induced torque were measured using the μ-Tas F-1®.Results: MVC significantly increased in both lower limbs after the intervention (right/left: 72.4 ± 23.5 Nm/72.9 ± 23.0 Nm) compared with immediately before the intervention (right/left: 59.9 ± 17.2 Nm/64.5 ± 21.0 Nm). No significant changes were observed in MVC between one month before the intervention and immediately before the start of the intervention, and between the end of the intervention and one month after the end of the intervention. rPMS-induced torque, TUG, and CS-30 improved significantly after the intervention compared with immediately before the intervention.Conclusion: Intervention using rPMS increases MVC- and rPMS-induced torque and improves motor ability in older adults. Because rPMS is a simple means of increasing muscle strength, it is expected to be widely used in the future.

Kamiue M, Tsubahara A, Ito T. Effects of repetitive peripheral magnetic stimulation on a patient with severe lower limb muscle weakness due to coronavirus disease-2019. Jpn J Compr Rehabil Sci 2024; 15: 27-33.Introduction: A patient developed severe lower limb muscle weakness and gait disturbance after receiving mechanical ventilation in the intensive care unit (ICU) due to coronavirus disease 2019 (COVID-19). We describe the effect of repetitive peripheral magnetic stimulation (rPMS) to strengthen his lower limb muscles.Case: A 70-year-old man was mechanically ventilated due to COVID-19-related breathing difficulties. He was weaned off mechanical ventilation after 54 days, and the tracheostomy was closed after 225 days. However, his lower limbs remained significantly weak, and he was wheelchair-bound for daily activities. Despite approximately 6 months of functional training at a day-service center, his physical function and movement abilities did not improve. Therefore, 30-Hz rPMS was applied to both quadriceps for 20 minutes/day, three times a week, for 4 weeks (12 times). Knee extensor torque (KET) during maximum voluntary contraction (MVC) was greater after (right: 42.1 Nm, left: 40.7 Nm) than before the intervention (right: 33.7 Nm, left: 36.2 Nm). Before the intervention, KET induced by rPMS (rPMS-induced torque) was 0 Nm on both sides, the 30-second chair stand test (CS-30) was challenging to perform, and the walking item score of the Functional Independence Measure (FIM) was 2 points (endurance 30 m). Post-intervention, rPMS-induced torque was 6.5 Nm on the right and 4.7 Nm on the left side, CS-30 could be performed once, and the FIM walking score was improved to 6 points (endurance 60 m).Discussion: The use of rPMS improved lower limb muscle strength in a patient who developed ICU-acquired muscle weakness after COVID-19.