IMPROVE study protocol, investigating post-stroke local muscle vibrations to promote cerebral plasticity and functional recovery: a single-blind randomised controlled trial.

INTRODUCTION: Spasticity is a frequent disabling consequence following a stroke. Local muscle vibrations (LMVs) have been proposed as a treatment to address this problem. However, little is known about their clinical and neurophysiological impacts when used repeatedly during the subacute phase post-stroke. This project aims to evaluate the effects of a 6-week LMV protocol on the paretic limb on spasticity development in a post-stroke subacute population. METHODS AND ANALYSIS: This is an interventional, controlled, randomised, single-blind (patient) trial. 100 participants over 18 years old will be recruited, within 6 weeks following a first stroke with hemiparesis or hemiplegia. All participants will receive a conventional rehabilitation programme, plus 18 sessions of LMV (ie, continuously for 30 min) on relaxed wrist and elbow flexors: either (1) at 80 Hz for the interventional group or (2) at 40 Hz plus a foam band between the skin and the device for the control group.Participants will be evaluated at baseline, at 3 weeks and 6 weeks, and at 6 months after the end of the intervention. Spasticity will be measured by the modified Ashworth scale and with an isokinetic dynamometer. Sensorimotor function will be assessed with the Fugl-Meyer assessment of the upper extremity. Corticospinal and spinal excitabilities will be measured each time. ETHICS AND DISSEMINATION: This study was recorded in a clinical trial and obtained approval from the institutional review board (Comité de protection des personnes Ile de France IV, 2021-A03219-32). All participants will be required to provide informed consent. The results of this trial will be published in peer-reviewed journals to disseminate information to clinicians and impact their practice for an improved patient's care. TRIAL REGISTRATION NUMBER: Clinical Trial: NCT05315726 DATASET: EUDRAct.

Local vibration induces changes in spinal and corticospinal excitability in vibrated and antagonist muscles.

Local vibration (LV) applied over the muscle tendon constitutes a powerful stimulus to activate the muscle spindle primary (Ia) afferents that project to the spinal level and are conveyed to the cortical level. This study aimed to identify the neuromuscular changes induced by a 30-min LV-inducing illusions of hand extension on the vibrated flexor carpi radialis (FCR) and the antagonist extensor carpi radialis (ECR) muscles. We studied the change of the maximal voluntary isometric contraction (MVIC, experiment 1) for carpal flexion and extension, motor-evoked potentials (MEPs, experiment 2), cervicomedullary motor-evoked potentials (CMEPs, experiment 2), and Hoffmann's reflex (H-reflex, experiment 3) for both muscles at rest. Measurements were performed before (PRE) and at 0, 30, and 60 min after LV protocol. A lasting decrease in strength was only observed for the vibrated muscle. The reduction in CMEPs observed for both muscles seems to support a decrease in alpha motoneurons excitability. In contrast, a slight decrease in MEPs responses was observed only for the vibrated muscle. The MEP/CMEP ratio increase suggested greater cortical excitability after LV for both muscles. In addition, the H-reflex largely decreased for the vibrated and the antagonist muscles. The decrease in the H/CMEP ratio for the vibrated muscle supported both pre- and postsynaptic causes of the decrease in the H-reflex. Finally, LV-inducing illusions of movement reduced alpha motoneurons excitability for both muscles with a concomitant increase in cortical excitability.NEW & NOTEWORTHY Spinal disturbances confound the interpretation of excitability changes in motor areas and compromise the conclusions reached by previous studies using only a corticospinal marker for both vibrated and antagonist muscles. The time course recovery suggests that the H-reflex perturbations for the vibrated muscle do not only depend on changes in alpha motoneurons excitability. Local vibration induces neuromuscular changes in both vibrated and antagonist muscles at the spinal and cortical levels.

Effect of dietary n-3 PUFA supplementation on the muscle transcriptome in older adults.

Dietary fish oil-derived n-3 PUFA supplementation can increase muscle mass, reduce oxygen demand during physical activity, and improve physical function (muscle strength and power, and endurance) in people. The results from several studies conducted in animals suggest that the anabolic and performance-enhancing effects of n-3 PUFA are at least in part transcriptionally regulated. The effect of n-3 PUFA therapy on the muscle transcriptome in people is unknown. In this study, we used muscle biopsy samples collected during a recently completed randomized controlled trial that found that n-3 PUFA therapy increased muscle mass and function in older adults to provide a comprehensive assessment of the effect of n-3 PUFA therapy on the skeletal muscle gene expression profile in these people. Using the microarray technique, we found that several pathways involved in regulating mitochondrial function and extracellular matrix organization were increased and pathways related to calpain- and ubiquitin-mediated proteolysis and inhibition of the key anabolic regulator mTOR were decreased by n-3 PUFA therapy. However, the effect of n-3 PUFA therapy on the expression of individual genes involved in regulating mitochondrial function and muscle growth, assessed by quantitative RT-PCR, was very small. These data suggest that n-3 PUFA therapy results in small but coordinated changes in the muscle transcriptome that may help explain the n-3 PUFA-induced improvements in muscle mass and function.

Fish oil-derived n-3 PUFA therapy increases muscle mass and function in healthy older adults.

BACKGROUND: Age-associated declines in muscle mass and function are major risk factors for an impaired ability to carry out activities of daily living, falls, prolonged recovery time after hospitalization, and mortality in older adults. New strategies that can slow the age-related loss of muscle mass and function are needed to help older adults maintain adequate performance status to reduce these risks and maintain independence. OBJECTIVE: We evaluated the efficacy of fish oil-derived n-3 (ω-3) PUFA therapy to slow the age-associated loss of muscle mass and function. DESIGN: Sixty healthy 60-85-y-old men and women were randomly assigned to receive n-3 PUFA (n = 40) or corn oil (n = 20) therapy for 6 mo. Thigh muscle volume, handgrip strength, one-repetition maximum (1-RM) lower- and upper-body strength, and average power during isokinetic leg exercises were evaluated before and after treatment. RESULTS: Forty-four subjects completed the study [29 subjects (73%) in the n-3 PUFA group; 15 subjects (75%) in the control group]. Compared with the control group, 6 mo of n-3 PUFA therapy increased thigh muscle volume (3.6%; 95% CI: 0.2%, 7.0%), handgrip strength (2.3 kg; 95% CI: 0.8, 3.7 kg), and 1-RM muscle strength (4.0%; 95% CI: 0.8%, 7.3%) (all P < 0.05) and tended to increase average isokinetic power (5.6%; 95% CI: -0.6%, 11.7%; P = 0.075). CONCLUSION: Fish oil-derived n-3 PUFA therapy slows the normal decline in muscle mass and function in older adults and should be considered a therapeutic approach for preventing sarcopenia and maintaining physical independence in older adults. This study was registered at clinicaltrials.gov as NCT01308957.