Sarcopenia is a musculoskeletal disorder characterized by reduced strength and muscle mass in aging. Photobiomodulation through LED Therapy (LEDT, acronym for Light Emitting Diode Therapy) can influence the components of the mitochondrial respiratory pathway by converting electromagnetic energy into biochemistry, with increased synthesis of adenosine triphosphate (ATP) and growth factors. On the other hand, Neuromuscular Electrical Stimulation (NMES, acronym for Neuromuscular Electrical Stimulation), provides artificial muscle stimuli to replace voluntary stimuli in physical exercise, with muscle hypertrophy responses.

To analyze therapeutic responses in muscle thickness and functional tests in elderly women with the simultaneous association of NMES to photobiomodulation through LEDT during a four-week program aimed at the prevention and treatment of sarcopenia.

The study participants were selected and comprised of 20 sedentary women with an average age of 60 years. The participants were randomly distributed into two groups (G1 and G2). In G1, the participants were treated with NMES (carrier frequency of 2500 Hz; 3 channels and electrodes with a diameter of 7 cm; frequency of 50 Hz, on/off time of 6/18 s in the first week, evolving to 10/30 s in the second week, 12/30 s in the third week and 15/30 s in the fourth week; with 20 minutes of therapy per session). G2 simultaneously associated NMES (similar parameters) and LEDT (set of 10 LEDs coupled to each NMES electrode, totaling 60 LEDs, power of 30 mW/LED, with a wavelength of 830 nm, application time of 180 s and total energy of 324 J in the quadriceps femoris muscle). The electrophotostimulated muscles were the vastus lateralis, vastus medialis and rectus femoris, with a stimulation frequency of three times a week. The analysis of ultrasound scans of the quadriceps femoris and functional tests such as the time up and go (TUG), walking speed and the sit-to-reach test were performed before and at the end of the therapeutic intervention.

Therapeutic interventions through NMES alone or associated with LEDT demonstrated a significant increase in muscle thickness after one month of therapy in all quadriceps femoris muscles. The NMES promoted an increase in the flexibility of the hamstring muscles of the volunteers, observed in the sit and reach test. Neuromuscular electrical stimulation demonstrated a significant increase in TUG tests and gait speed. G2 showed no significant difference in responses to optimize the increase in muscle thickness and muscle functions through the TUG tests and gait speed in relation to the isolated use of NMES.

Electrophototherapy promoted an increase in quadriceps femoris muscle thickness and significant improvements in functional tests. However, the simultaneous association of NMES to LEDT did not demonstrate a significant difference in the supplementation of muscle functions during physical exertion in relation to the isolated use of NMES.

NMES may prevent and rehabilitate sarcopenia by increasing muscle thickness, improving gait speed and neuromuscular coordination.