Muscle deconditioning, characterized by a loss of muscle mass and strength, is a frequent consequence of prolonged lower limb unloading. Beyond muscle mass loss, reduced neural drive contributes significantly to strength decline, highlighting the need for interventions targeting neuromuscular function during immobilization. Focal muscle vibration (FMV) has shown promise in modulating neuromuscular excitability by activating muscle spindle afferents and inducing cortical adaptations. Chronic use of FMV has been associated with significant strength gains and improved neural command. This makes FMV an effective rehabilitation tool. Its simplicity and non-invasiveness further make it a practical countermeasure.
This study hypothesizes that a 10-day FMV protocol can induce neural adaptations to limit strength loss during unilateral lower limb suspension, offering a novel strategy against neuromuscular function decline.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
42
focal muscle vibration sessions, using small and portable vibrator devices.
The control group will not receive any intervention.
Centre Hospitalier Universitaire
Saint-Etienne, France
RECRUITINGIsometric force measurement
Maximal isometric force (% decrease) in knee extension of the immobilized leg will be evaluated
Time frame: Day 1, 7, 14, 28, 33
Maximum voluntary force measurement
Maximum voluntary force (Nm) in knee extension, assessed in isometric (for the immobilized leg and also for the contralateral leg), concentric (+60°/s and +180°/s) and eccentric (-60°/s) conditions.
Time frame: Day 1, 7, 14, 28, 33
Jumping performance measurement
Jumping performance (height, in cm), assessed in vertical jump tests (Squat Jump and Counter Movement Jump).
Time frame: Day 1, 7, 14, 28, 33
Postural balance measurement
Postural balance performance (displacement of center of pressure, in mm), assessed in a unipodal postural balance test performed on a strength platform
Time frame: Day 1, 7, 14, 28, 33
Neuromuscular fatigue measurement
Neuromuscular fatigue (decrease in maximum voluntary force (in %), assessed during a fatigue protocol consisting of quadriceps muscle contractions at incremental force levels.
Time frame: Day 1, 7, 14, 28, 33
Force-velocity-endurance measurement
Force-velocity-endurance profile, assessed during an effort performed on a cycloergometer at linearly decreasing power values.
Time frame: Day 1, 7, 14, 28, 33
Voluntary activation level evaluation
Voluntary activation level (in %), determined by the force increment obtained following stimulation during a maximal voluntary isometric contraction.
Time frame: Day 1, 7, 14, 28, 33
Cortico-spinal excitability measurement
Cortico-spinal excitability, assessed by electromyographic responses (motor evoked potentials, in mV) evoked by transcranial magnetic stimulation (TMS).
Time frame: Day 1, 7, 14, 28, 33
Spinal excitability evaluation
Spinal excitability (i.e. spinal reflexes, in mV), assessed by recording EMG responses evoked by electrical stimulation of the lumbar vertebrae.
Time frame: Day 1, 7,14 , 28, 33
Cortical activation of sensorimotor areas measurement
Cortical activation of sensorimotor areas, assessed by recording the electroencephalographic (EEG) signal during submaximal isometric contractions.
Time frame: Day 1, 7, 14, 28, 33
Muscle volume measurement
Muscle volume will be assessed by ultrasound of the thigh muscles (in cm2).
Time frame: Day 1, 7, 14, 28, 33
Determination of plasma molecular markers of bone and muscle remodeling
Assessment of blood factors of nerve (BDNF) and muscle remodeling (circulating steroids, insulin, GH, IGF-1, myostatin, activinA, follistatin).
Time frame: Day 1, 7, 14, 28, 33
Determination of plasma molecular markers of bone and muscle remodeling
Evaluation of bone remodeling factors by bAP, CTx, P1NP and Trap5b assays
Time frame: Day 1, 7, 14, 28, 33
Plasma molecular markers of thrombotic risk evaluation
Plasma molecular markers of thrombotic risk will be assessed by blood sampling followed by assay of HSP47 and D-dimer factors.
Time frame: Day 1, 7, 14, 28, 33
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