The peripheral sensory system is critical to regulating motor plasticity and motor recovery. Peripheral electrical stimulation (ES) can generate constant and adequate sensory input to influence the excitability of the motor cortex. The aim of this proof of concept study was to assess whether ES prior to each hand function training session for eight weeks can better improve neuromuscular control and hand function in chronic stroke individuals and change electroencephalography-electromyography (EEG-EMG) coherence, as compared to the control (sham ES). We recruited twelve subjects and randomly assigned them into ES and control groups. Both groups received 20-minute hand function training twice a week, and the ES group received 40-minute ES on the median nerve of the affected side before each training session. The control group received sham ES. EEG, EMG and Fugl-Meyer Assessment (FMA) were collected at four different time points. The corticomuscular coherence (CMC) in the ES group at fourth weeks was significantly higher (p = 0.004) as compared to the control group. The notable increment of FMA at eight weeks and follow-up was found only in the ES group. The eight-week rehabilitation program that implemented peripheral ES sessions prior to function training has a potential to improve neuromuscular control and hand function in chronic stroke individuals.

Background: Electrical stimulation (ES) in the periphery can induce brain plasticity and has been used clinically to promote motor recovery in patients with central nervous system lesion. Electroencephalogram (EEG) and electromyogram (EMG) are readily applicable in clinical settings and can detect real-time functional connectivity between motor cortex and muscles with EEG–EMG (corticomuscular) coherence. Objective: The purpose of this study was to determine whether EEG–EMG coherence can detect changes in corticomuscular control induced by peripheral ES. Methods: Fifteen healthy young adults and 15 stroke survivors received 40-min electrical stimulation session on median nerve. The stimulation (1-ms rectangular pulse, 100 Hz) was delivered with a 20-s on–20-s off cycle, and the intensity was set at the subjects’ highest tolerable level without muscle contraction or pain. Both before and after the stimulation session, subjects performed a 20-s steady-hold thumb flexion at 50% maximal voluntary contraction (MVC) while EEG and EMG were collected. Results: Our results demonstrated that after ES, EEG–EMG coherence in gamma band increased significantly for 22.1 and 48.6% in healthy adults and stroke survivors, respectively. In addition, after ES, force steadiness was also improved in both groups, as indicated by the decrease in force fluctuation during steady-hold contraction (−1.7% MVC and −3.9%MVC for healthy and stroke individuals, respectively). Conclusions: Our results demonstrated that EEG–EMG coherence can detect ES-induced changes in the neuromuscular system. Also, because gamma coherence is linked to afferent inputs encoding, improvement in motor performance is likely related to ES-elicited strong sensory input and enhanced sensorimotor integration.

Patients with bilateral vestibular hypofunction (BVH) often suffer from imbalance, gait problems, and oscillopsia. Noisy galvanic vestibular stimulation (GVS), a technique that non-invasively stimulates the vestibular afferents, has been shown to enhance postural and walking stability. However, no study has investigated how it affects stability and neural activities while standing and walking with a 2 Hz head yaw turning. Herein, we investigated this issue by comparing differences in neural activities during standing and walking with a 2 Hz head turning, before and after noisy GVS. We applied zero-mean gaussian white noise signal stimulations in the mastoid processes of 10 healthy individuals and seven patients with BVH, and simultaneously recorded electroencephalography (EEG) signals with 32 channels. We analyzed the root mean square (RMS) of the center of pressure (COP) sway during 30 s of standing, utilizing AMTI force plates (Advanced Mechanical Technology Inc., Watertown, MA, USA). Head rotation quality when walking with a 2 Hz head yaw, with and without GVS, was analyzed using a VICON system (Vicon Motion Systems Ltd., Oxford, UK) to evaluate GVS effects on static and dynamic postural control. The RMS of COP sway was significantly reduced during GVS while standing, for both patients and healthy subjects. During walking, 2 Hz head yaw movements was significantly improved by noisy GVS in both groups. Accordingly, the EEG power of theta, alpha, beta, and gamma bands significantly increased in the left parietal lobe after noisy GVS during walking and standing in both groups. GVS post-stimulation effect changed EEG activities in the left and right precentral gyrus, and the right parietal lobe. After stimulation, EEG activity changes were greater in healthy subjects than in patients. Our findings reveal noisy GVS as a non-invasive therapeutic alternative to improve postural stability in patients with BVH. This novel approach provides insight to clinicians and researchers on brain activities during noisy GVS in standing and walking conditions in both healthy and BVH patients.

Mechanisms underlying exercise-induced muscle fatigue and recovery are dependent on peripheral changes at the muscle level and improper control of motoneurons by the central nervous system. In this study, we analyzed the effects of muscle fatigue and recovery on the neuromuscular network through the spectral analysis of electroencephalography (EEG) and electromyography (EMG) signals. A total of 20 healthy right-handed volunteers performed an intermittent handgrip fatigue task. In the prefatigue, postfatigue, and postrecovery states, the participants contracted a handgrip dynamometer with sustained 30% maximal voluntary contractions (MVCs); EEG and EMG data were recorded. A considerable decrease was noted in EMG median frequency in the postfatigue state compared with the findings in other states. Furthermore, the EEG power spectral density of the right primary cortex exhibited a prominent increase in the gamma band. Muscle fatigue led to increases in the beta and gamma bands of contralateral and ipsilateral corticomuscular coherence, respectively. Moreover, a decrease was noted in corticocortical coherence between the bilateral primary motor cortices after muscle fatigue. EMG median frequency may serve as an indicator of muscle fatigue and recovery. Coherence analysis revealed that fatigue reduced the functional synchronization among bilateral motor areas but increased that between the cortex and muscle.

Background and objectives: Respiratory muscle fatigue is one of the important factors limiting sports performance due to the metaboreflex. This reflex will cause a decrease in blood flow to the extremities and accelerate exercising limb fatigue. Previous studies found that inspiratory muscle training (IMT) can effectively enhance the respiratory muscle endurance and reduce fatigue during long-duration exercise or aerobic exercise, thereby enhancing athletic performance. However, the mechanism between inspiratory muscle strength, change of limb blood flow and sports performance still requires investigation, especially in short-duration exercise, anaerobic or both aerobic and anaerobic exercise. The purpose of this study was to investigate the effects of 4-week inspiratory muscle training on respiratory muscle strength, limb blood flow change rate and sports performance in recreational 800-m college runners. Materials and Methods: Twenty healthy 800-m college runners randomized into the IMT group (11 subjects) and control group (9 subjects). IMT consisted of 30 inspiratory efforts twice daily, 5 days a week, with intensity at 50%, 60%, 70% and 80% of maximum inspiratory pressure (MIP) for 4 weeks, while a control group kept 50% of MIP for 4 weeks. An 800-m trial test, limb blood flow change rate by using Impedance Plethysmography, and MIP were as the outcome measured variables and be evaluated. All measured variables were assessed before and after 4-week IMT training. Two-way ANOVA was conducted for statistical analysis. Results: The results showed significantly interaction between groups and pre-posttest. IMT group significantly decreased limb blood flow change rate from 19.91 ± 11.65% to 9.63 ± 7.62% after received the IMT training program (p < 0.05). The MIP significantly improved from 112.95 ± 27.13 cmH₂O to 131.09 ± 28.20 cm H₂O in IMT group, and the 800-m trial test also shorted the running time from 162.97 ± 24.96 s to 156.75 ± 20.73 s. But the control group no significantly changed in MIP and 800-m trial test. Conclusions: Our results indicated that the 4-week IMT training (twice a day, 5 days a week) significantly improves participants’ inspiratory muscle strength, 800-m running performance and decreases the limb blood flow change rate.

Foot orthoses (FOs) are commonly used as interventions for individuals with flatfoot. Advances in technologies such as three-dimensional (3D) scanning and 3D printing have facilitated the fabrication of custom FOs. However, few studies have been conducted on the mechanical properties and biomechanical effects of 3D-printed FOs. The purposes of this study were to evaluate the mechanical properties of 3D-printed FOs and determine their biomechanical effects in individuals with flexible flatfoot. During mechanical testing, a total of 18 FO samples with three orientations (0°, 45°, and 90°) were fabricated and tested. The maximum compressive load and stiffness were calculated. During a motion capture experiment, 12 individuals with flatfoot were enrolled, and the 3D-printed FOs were used as interventions. Kinematic and kinetic data were collected during walking by using an optical motion capture system. A one-way analysis of variance was performed to compare the mechanical parameters among the three build orientations. A paired t-test was conducted to compare the biomechanical variables under two conditions: walking in standard shoes (Shoe) and walking in shoes embedded with FOs (Shoe+FO). The results indicated that the 45° build orientation produced the strongest FOs. In addition, the maximum ankle evertor and external rotator moments under the Shoe+FO condition were significantly reduced by 35% and 16%, respectively, but the maximum ankle plantar flexor moments increased by 3%, compared with the Shoe condition. No significant difference in ground reaction force was observed between the two conditions. This study demonstrated that 3D-printed FOs could alter the ankle joint moments during gait.