Chronic Effects of Wide-pulse Neuromuscular Electrostimulation on Neuromuscular and Functional Properties in Healthy Subjects

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.

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.

Eligibility Criteria:
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)