Nuevos beneficios de la electroestimulación como agente terapéutico físico

Abstract

This Doctoral Thesis aims to explore new benefits of electrostimulation as a physical therapeutic agent. The experimental work includes two research projects that have been carried out in parallel. The first one, carried out on experimental animals, aimed the evaluation of neuromuscular electrostimulation (NMES) as a therapeutic agent for the improvement of the functional properties of the muscle. And the second one, on volunteer participants, aimed the evaluation of transcranial direct current stimulation (tDCS) as a therapeutic agent for the treatment of overweight. The objective of the first study was to analyse the effects of NMES training on the structure, function, oxidative capacity and vascularization of skeletal muscle using a mouse model. The left tibialis anterior muscle in experimental mice was electrically stimulated while the right muscle was kept as a control. The stimulated limb was subjected to daily sessions of surface NMES (100 Hz) for two weeks. NMES training increased muscle mass, mean fiber cross-sectional area, maximal strength, and rate of strength development, with no effect on muscle oxidative profile. These results demonstrate that the NMES induced muscle hypertrophy and instigated an improvement in the contractile properties of the tibialis anterior muscle in this experimental model. Likewise, we demonstrate that electrostimulation promotes muscular adaptation similar to that which occurs with voluntary exercise, seen through the tendency to transition of myosin heavy chain isoforms and the increase in satellite cells. Therefore, this animal model seems to be suitable for the study of hypertrophic processes induced by electrical stimulation of the muscle. The second study suggested that high body mass index (BMI) is associated with neurocognitive deficiencies that contribute to overeating and interfere with efforts to lose weight. Non-invasive neuromodulation represents a novel, affordable, and scalable approach to improve neurocognitive function in this setting. The purpose of this second study was to examine whether transcranial direct current stimulation applied to the prefrontal cortex, in combination with a hypocaloric diet, could improve weight loss. The study was carried out on 38 women with a BMI of 25 to 35 kg / m2 who underwent a parallel intervention, with active cases and case controls, randomized, double-blind studi of 4 weeks duration, during which they received eight sessions of tDCS (n = 18 controls, n = 20 active) in combination with a diet (20 kcal / kg / day). We assess longitudinal changes in body weight, appetite, and food craving. Furthermore, we examined the contribution of cognitive-executive processes through computerized food-modified tasks. Our results allowed us to observe that the active group experienced more reduction in body weight than the control group throughout the study and a significant weekly weight loss. The components of subjective appetite and food craving showed a trend towards a greater reduction in the active group. These changes paralleled significant improvements in task performance in the active group, particularly in a dual task that required inhibitory control and working memory. No significant adverse effects were observed. Our results provide a proof of concept that validates the use of prefrontal cortex-directed tDCS, combined with diet, in middle-aged women with excess body weight, paving the way for larger studies evaluating clinical efficacy and effects to long term of this intervention.