Plastic changes induced by muscle focal vibration: A possible mechanism for long-term motor improvements

Effect of tibialis anterior focal muscle vibration for gait rehabilitation in hemiplegic individuals during the subacute phase after stroke: the NEUROVIB-AVC study protocol - a multicentric randomised controlled trial

INTRODUCTION

Gait recovery remains one of the most determining factors in social participation for poststroke individuals, in whom ankle dorsiflexor function is closely related to gait speed. Focal muscle vibration has shown promising neurophysiological and clinical effects in neuromotor recovery. However, it remains to be determined whether tibialis anterior focal muscle vibration applied to the paretic limb could improve walking speed when implemented in early rehabilitation after stroke occurrence.

METHODS AND ANALYSIS

This study describes a multicentric randomised controlled trial in which 70 participants will be randomly assigned in a 1:1 ratio to the tibialis anterior focal muscle vibration group or the sham group, in addition to their conventional rehabilitation. Participants will receive 100 Hz vibration/sham for 30 min, five times per week, for 8 weeks. The primary outcome will be gait speed, as assessed through a 10 m walking test and will be compared between groups at the end of the intervention. Secondary outcomes will include gait abilities, neuromuscular clinical evaluations and neurophysiological measures. Outcomes will be assessed at baseline and across five visits during and after the intervention, until 16 weeks of follow-up.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the French Ethics Committee 'Protection des Personnes Nord Ouest III' in 30 May 2023 (IDRCB: 2023-A00489-36). The results will be published in a peer-reviewed journal and presented at scientific conferences.

TRIAL REGISTRATION NUMBER

NCT05945212.

Effect of proprioceptive neuromuscular facilitation and focal vibration in older adults with osteoarthritis after total knee arthroplasty: A randomized clinical trial study

BackgroundPostoperative balance disorders in older adults after total knee arthroplasty (TKA) due to osteoarthritis are commonly attributed to proprioceptive joint deficits. Both Proprioceptive Neuromuscular Facilitation (PNF) and Focal Vibration (FV) can improve balance and proprioception.AimTo examine the combination of a PNF exercise program and quadriceps tendon FV in older adults after TKA due to osteoarthritis.MethodsNinety older adults who underwent TKA were randomly assigned to three groups of 30. The PNF Group followed a 6-week PNF exercise program starting four weeks post-surgery. The PNF + FV Group followed the same PNF program combined with FV applied to the rectus femoris and vastus medialis. The control group received instructions for a home-based exercise program. Pain (Numeric Pain Rating Scale; NPRS), knee range of motion (ROM), functional ability (Knee Injury and Osteoarthritis Outcome Score, KOOS), joint position sense (JPS), postural sway (force platform), and balance (Timed Up-and-Go; TUG test, Berg Balance Scale; BBS) were evaluated at baseline, six weeks, and six months post-intervention. A two-way repeated measures ANOVA analysis was applied with significance set at p < .05.ResultsThe PNF + FV group showed significant improvements compared to the control group in NPRS, KOOS, TUG, BBS, displacement parameters, and absolute error scores (p < .05). The PNF + FV group showed earlier improvements compared to the PNF group, indicating faster adjustments due to the combined effect of PNF and FV. Additionally, the PNF + FV group showed greater improvement in TUG, BBS, KOOS sport, anterior-posterior displacement distance, and absolute error scores at 25° compared to the PNF group (p < .05). PNF exercises improved knee ROM (p < .05) with no additional effect from FV.ConclusionsA 6-week protocol combining PNF exercises and FV significantly improved balance, knee joint position sense, knee functional ability, and pain intensity in older adults after TKA due to osteoarthritis. These findings suggest faster and more effective rehabilitation, potentially reducing postoperative disorders and future injury risks. Further research is needed to investigate the combination of FV and PNF.

The Effects of Sensory Electrical Stimulation and Local Vibration on Motor Learning and Motor Function

Sensory afferent inputs play a crucial role in neuromuscular control. Enhancing sensory input through electrical or mechanical stimulation of the limbs may improve motor function and facilitate motor learning. This scoping review synthesizes literature investigating the effects of sensory electrical stimulation (SES) and local vibration (LV) on motor function and learning in both healthy individuals and those with musculoskeletal or neurological disorders. The findings suggest that SES can enhance motor learning and improve motor function. Furthermore, its efficacy is maximized when combined with rehabilitation programs and motor training rather than being used as a stand-alone intervention. Similarly, LV applied to muscle or tendon regions enhances proprioceptive input, thereby improving motor control and learning. The clinical benefits of LV, like those of SES, can be augmented by incorporating it into motor training regimens. Future research should focus on optimizing stimulation parameters and determining the most effective integration strategies for rehabilitation programs to maximize therapeutic outcomes.

Neck muscle fatigue disrupts self-motion perception

The effect of neck muscle fatigue induced by prolonged isometric contraction of the neck extensor muscles on self-motion perception was studied. The magnitude of self-motion perception was assessed by evaluating the tracking of a remembered earth-fixed visual target during passive symmetric and asymmetric sinusoidal horizontal body rotation. The trunk was rotated on a stationary head for examining the role of neck proprioception and the whole-body for that of the vestibular system. To induce neck extensor muscle fatigue, participants held their head extended against a load for several minutes. Perceptual responses were examined before and during neck muscle fatigue. It was found that the perception of the movement was diminished by neck muscle fatigue as shown by a reduction of the amplitude of the tracking during trunk rotation. This suggests that fatigue affects the motion perception when the neck proprioceptive system was activated by the rotation. This effect has been observed only during slow rotation, while the responses remained unmodified during fast rotation. In contrast, neck muscle fatigue did not affect the tracking when rotation activated only the vestibular system. Furthermore, neck muscle fatigue abolished the effect of tonic head deviation on perceptual responses to whole-body rotation. Therefore, neck muscle fatigue alters the self-motion perception reducing the ability of the proprioceptive system to signal slow trunk rotations and the position of the head relative to the trunk during body movements.

Focal muscle vibration and action observation: a combined approach for muscle strengthening

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.

Effects of prolonged vibration to the flexor carpi radialis muscle on intracortical excitability

Prolonged local vibration (LV) can induce neurophysiological adaptations thought to be related to long-term potentiation or depression. Yet, how changes in intracortical excitability may be involved remains to be further investigated as previous studies reported equivocal results. We therefore investigated the effects of 30 min of LV applied to the right flexor carpi radialis muscle (FCR) on both short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). SICI and ICF were measured through transcranial magnetic stimulation before and immediately after 30 min of FCR LV (vibration condition) or 30 min of rest (control condition). Measurements were performed during a low-intensity contraction (n = 17) or at rest (n = 7). No significant SICI nor ICF modulations were observed, whether measured during isometric contractions or at rest (p = 0.2). Yet, we observed an increase in inter-individual variability for post measurements after LV. In conclusion, while intracortical excitability was not significantly modulated after LV, increased inter-variability observed after LV may suggest the possibility of divergent responses to prolonged LV exposure.

Sensory Stimulation of the Triceps Surae Muscle Complex Modulates Spinal Reflex Responses-A Comparison between Tapotement Massage and Repetitive Peripheral Magnetic Stimulation (rPMS)

BACKGROUND

The reduction of muscular hypertonia is important in the treatment of various diseases or rehabilitation. This study aims to test the efficacy of a 5 Hz mechanical muscle stimulation (tapotement massage) in comparison to a 5 Hz repetitive peripheral magnetic stimulation (rPMS) on the neuromuscular reflex response.

METHODS

In a randomized control trial, 15 healthy volunteers were administered with either 5 Hz rPMS, tapotement massage, or rPMS sham stimulation. The posterior tibial nerve was stimulated with rPMS and sham stimulation. The Achilles tendon was exposed to a mechanically applied high-amplitude 5 Hz repetitive tendon tapotement massage (rTTM). The tendon reflex (TR) was measured for the spinal response of the soleus muscle.

RESULTS

After rPMS, there was a reduction of the TR response (-9.8%, p ≤ 0.034) with no significant changes after sham stimulation. Likewise, TR decreased significantly (-17.4%, p ≤ 0.002) after Achilles tendon tapotement intervention.

CONCLUSIONS

These findings support the hypothesis that both afferent 5 Hz sensory stimulations contributed to a modulation within the spinal and/or supraspinal circuits, which resulted in a reduction of the spinal reflex excitability. The effects could be beneficial for patients with muscle hypertonia and could improve the functional results of rehabilitation programs.

Immediate effects of local muscle vibration on static and dynamic balance control in individuals with chronic ankle instability

OBJECTIVES

To investigate the immediate effects of local muscle vibration (LMV) on static and dynamic balance control in individuals with and without chronic ankle instability (CAI).

DESIGN

Quasi-experimental study.

SETTING

Research laboratory.

PARTICIPANTS

Twenty-six individuals with CAI and 26 healthy controls.

MAIN OUTCOME MEASURES

Center of pressure variables (mean total velocity and displacement in anteroposterior (AP) and mediolateral (ML) directions) during single-leg standing with eyes open and eyes closed and also reach distances in anterior (ANT), posteromedial (PM), and posterolateral (PL) directions of the modified star excursion balance test (MSEBT) were assessed before and after LMV.

RESULTS

Statistical analyses showed a significant decrease in mean total velocity and displacement in AP direction from before to after LMV in eyes open condition for both individuals with CAI (p = 0.025, p = 0.041, respectively) and healthy controls (p = 0.001, p = 0.003, respectively). Similar results were observed in eyes closed condition for both individuals with CAI (p < 0.001, p < 0.001, respectively) and healthy controls (p = 0.040, p = 0.014, respectively). The results also showed increased reach distances in ANT (p < 0.001), PM (p < 0.001), and PL directions (p < 0.001) in all participants after LMV.

CONCLUSION

Our results suggest that LMV may be a useful tool in rehabilitation of static and dynamic balance deficits in individuals with CAI.

Effectiveness of Focal Muscle Vibration in the Recovery of Neuromotor Hypofunction: A Systematic Review

Adequate physical recovery after trauma, injury, disease, a long period of hypomobility, or simply ageing is a difficult goal because rehabilitation protocols are long-lasting and often cannot ensure complete motor recovery. Therefore, the optimisation of rehabilitation procedures is an important target to be achieved. The possibility of restoring motor functions by acting on proprioceptive signals by unspecific repetitive muscle vibration, focally applied on single muscles (RFV), instead of only training muscle function, is a new perspective, as suggested by the effects on the motor performance evidenced by healthy persons. The focal muscle vibration consists of micro-stretching-shortening sequences applied to individual muscles. By repeating such stimulation, an immediate and persistent increase in motility can be attained. This review aims to show whether this proprioceptive stimulation is useful for optimising the rehabilitative process in the presence of poor motor function. Papers reporting RFV effects have evidenced that the motor deficits can be counteracted by focal vibration leading to an early and quick complete recovery. The RFV efficacy has been observed in various clinical conditions. The motor improvements were immediate and obtained without loading the joints. The review suggests that these protocols can be considered a powerful new advantage to enhance traditional rehabilitation and achieve a more complete motor recovery.