Healthy Volunteers
Conditions
Keywords
Wide-pulse, Training, Strength gain, Neuromuscular adaptations, Neuromuscular electrostimulation
Brief summary
Neuromuscular electrostimulation (NMES) is a technique used in the clinical and training fields to increase the strength of a muscle group.The recent use of wide-pulse (WP) stimulations allows, in addition to the direct activation of the muscle fibers, the use of sensory pathways. This more global solicitation of the neuromuscular system (i.e. information going back to the spinal cord and even to the brain) prejudges more nervous adaptations and therefore a greater functional benefit. The first aim of this study is to evaluate and compare the force gains induced by 2 NMES training programs (CONV, WP) applied on knee extensors in healthy subjects for 6 weeks.The second aim is to understand the neuromuscular adaptations involved in these gains, as well as the functional benefit resulting from these improvements.
Detailed description
Neuromuscular electrostimulation (NMES) is a technique used in the clinical and training fields to increase the strength of a muscle group. The conventional (CONV) parameters of NMES induces a direct activation of the muscle fibers located close to the stimulation electrodes. This means that the neuromuscular system is not fully solicited, which limits its adaptation. The recent use of wide-pulse (WP) stimulations allows, in addition to the direct activation of the muscle fibers, the use of sensory pathways. This more global solicitation of the neuromuscular system (i.e. information going back to the spinal cord and even to the brain) prejudges more nervous adaptations and therefore a greater functional benefit. The first aim of this study is to evaluate and compare the force gains induced by 2 NMES training programs (CONV, WP) applied on knee extensors in healthy subjects for 6 weeks. The second aim is to understand the neuromuscular adaptations involved in these gains, as well as the functional benefit resulting from these improvements. To consolidate the benefit of NMES programs, a control (CONT) modality is used as a reference and is representative of a sedentary behaviour regularly observed in our populations. The CONV modality allows us to compare with the current clinical application and the majority of the literature on the adaptations induced by NMES training. Finally, the WP modality aims to assess the possible benefits linked to the use of wide-pulses during the application of NMES. A clinical transfer will then be envisaged to confirm the interest and benefits of this type of program. We hypothesise that nervous adaptations will be increased by the use of WP NMES, leading to greater gains in strength and functional benefits than with CONV NMES.
Interventions
DEVICEWide-pulse neuromuscular electrostimulation (WP NMES)
The WP NMES program consists of electrical stimulation trains of 1000 symmetrical biphasic pulses (1 ms, 100 Hz). The duration of a train is of 10 s and the rest between trains is of 30 s. A WP NMES session includes 30 evoked contractions. The stimulation intensity is monitored online and adjusted to the highest tolerable by the subjects.During the stimulation, subjects are seated with the knee joint fixed a 60° angle. Three self-adhesive electrodes are placed over the right thigh. The positive electrodes, measuring 25 cm² (5 x 5 cm), are placed as close as possible to the motor point of the vastus lateralis and vastus medialis muscles. The negative electrode, measuring 50 cm² (10 x 5 cm), is placed 5-7 cm below the inguinal ligament. Electrical stimulations are delivered by a stimulator BioStim (Mazet Santé).
DEVICEConventional neuromuscular electrostimulation (CONV NMES)
The CONV NMES program consists of electrical stimulation trains of 500 symmetrical biphasic pulses (0.2 ms, 50 Hz). The duration of a train is of 10 s and the rest between trains is of 30 s (duty cycle: 1/3). A WP NMES session includes 30 evoked contractions. The stimulation intensity is monitored online and adjusted to the highest tolerable by the subjects. During the stimulation, subjects are seated with the knee joint fixed a 60° angle. Three self-adhesive electrodes are placed over the right thigh. The positive electrodes, measuring 25 cm² (5 x 5 cm), are placed as close as possible to the motor point of the vastus lateralis and vastus medialis muscles. The negative electrode, measuring 50 cm² (10 x 5 cm), is placed 5-7 cm below the inguinal ligament. Electrical stimulations are delivered by a stimulator BioStim (Mazet Santé).
DEVICEControl (CONT) modality
Control (CONT) modality is used as a reference and is representative of a sedentary behaviour regularly observed in our populations.
Sponsors
Centre Hospitalier Universitaire de Saint Etienne
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Intervention model description
Evaluating and comparing the force gains induced by 2 NMES training programs (CONV, WP) applied on knee extensors in healthy subjects for 6 weeks. Understanding the neuromuscular adaptations involved in these gains, as well as the functional benefit resulting from these improvements. To consolidate the benefit of NMES programs, a control (CONT) modality is used as a reference and is representative of a sedentary behaviour regularly observed in our populations. The CONV modality allows us to compare with the current clinical application and the majority of the literature on the adaptations induced by NMES training. Finally, the WP modality aims to assess the possible benefits linked to the use of wide-pulses during the application of NMES.
Eligibility
Sex/Gender
MALE
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* Affiliates or beneficiaries of a social security scheme * Having freely given their written consent
Exclusion criteria
* Disease or surgery resulting in a locomotor disorder, within 6 months prior to the study * Chronic neurological, motor or psychic diseases * Taking neuro-active substances likely to alter cortico-spinal excitability (hypnotics, antiepileptics, psychotropic drugs, muscle relaxants) for the duration of the study * Contraindication to neuromuscular electrostimulation * Contraindication to magnetic stimulation * Participation at the same time in another interventional experiment or having participated in such a study within 30 days prior to this study * Sports (\>10 hours per week or strength training of the lower limbs)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Maximal voluntary contraction (MVC) of the knee extensor muscle measurement | week 6 | Maximal isometric force (maximal voluntary contraction, MVC) of the knee extensor muscle |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Cortico-spinal excitability measurement | week 6 | The quantification of cortico-spinal excitability (i.e. motor evoked potentials, in mV) will be evaluated by recording the electromyographic responses (surface EMG) evoked by transcranial magnetic stimulation |
| Spinal excitability measurement | week 6 | The quantification of spinal excitability (i.e. spinal reflex, in mV) will be evaluated by recording the EMG responses evoked by electrical stimulation in the lumbar vertebrae. The quantification of spinal excitability (i.e. spinal reflex, in mV) will be evaluated by recording the EMG responses evoked by electrical stimulation in the lumbar vertebrae. |
| Voluntary activation measurement (%) | week 6 | The level of voluntary activation will be determined by the force increment obtained following stimulation performed during a condition of the muscle in a state of maximum contraction. |
| Jump performances measurement | week 6 | The performance of jumps (height, in cm; length, in cm) will be evaluated during various tests of vertical (Squat Jump and Counter Movement Jump) and horizontal (Single Hop and Triple Hop) jumps. |
| Postural balance performances measurement | week 6 | The postural balance performance (displacement of the center of pressure, in mm) will be evaluated during a unipodal postural balance test performed on a force platform. |
| Muscular endurance measurement | week 6 | Muscle endurance (number of contractions performed before failure) will be assessed during a fatigue protocol consisting of performing quadriceps muscle contractions at incremental strength levels. |
Countries
France
Outcome results
None listed