Estudo comparativo da utilização da fotobiomodulação e do ultrassom de baixa frequência sobre o contorno corporal: ensaio clínico controlado, randomizado, duplo cego

Abstract

Photobiomodulation (PBM), low-frequency ultrasound (LOFU) and muscle electrostimulation have been investigated for localized fat reduction. However, there is no consensus on the best parameters for the application of these therapeutic resources. Indeed, randomized controlled trials combining these techniques are scarce. Thus, the aim of this study was to compare the effectiveness of this techniques association to body contouring in the abdominal region. This controlled, randomized, double-blind, single-center clinical trial was based on the use of infrared LED (830 ± 20 nm; 71 mW/cm²; 127.8 J/cm²) and LOFU (30 kHz/3MHz; 25 W/cm²) alone or together, associated with muscle electrostimulation (2500 Hz, 30 bps, 50%), applied in this order. Seventy-nine female participants were recruited, aged between 25 and 45 years, with BMI between 18.5 and 27.5 kg/m², who were distributed among the following four groups: (A) PBM + LOFU sham + muscle electrostimulation; (B) PBM sham + LOFU + muscle electrostimulation; (C) combined treatment + muscle electrostimulation; (D) combined treatment sham + muscle electrostimulation. The treatment protocol consisted of eight sessions, held twice a week for 4 weeks. There were obtained anthropometric data (body mass, height, BMI, waist circumference, waist-hip ratio and adipometry), bioimpedance, psychometric variables relating to quality of life (WHOQOL-BREF) and body self-image (BSQ-34), photographic records for comparison between before and after and degree of satisfaction with the treatment at the end of the protocol. Finally, control information related to eating habits and level of physical activity performed during the treatment period was also collected. Data were analyzed based on the intention-to-treat principle. A significance level of 5% was adopted for statistical analysis. It was found that all groups presented a reduction in abdominal circumference (A: -1.47 ± 0.69 cm, P=0.036; B: -2.59 ± 0.69 cm, P < 0.001; C: -1.87 ± 0.76 cm, P=0.017), except Group D. The evaluation of skinfolds in the treatment region (abdominal and suprailiac) indicated that none of the groups demonstrated a significant decrease after the interventions, however the comparison of the observed differences indicated that the active combined treatment (Group C) stood out with a greater difference than the groups that received the treatments alone. The bioimpedance exam identified that Group B showed a gain in lean mass (2.35 ± 1.12 kg, P=0.040), a decrease in fat percentage (-3.73 ± 1.72%, P=0.035) and increased basal metabolic rate (BMR) (71.60 ± 33.93 kcal, P=0.039), while Group C showed loss of lean mass (-2.84 ± 1.22 kg, P=0.023) and decreased BMR (-85.91 ± 37.04 kcal, P=0.024). The waist-hip ratio was reduced in all groups (A: -0.023 ± 0.007, P=0.003; B: -0.019 ± 0.007; P=0.010; C: -0.019 ± 0.008; P=0.024), except in Group D. No correlations were found between eating habits and physical activity, which suffered a significant reduction after treatments. The quality-of-life assessment indicated that Group B (LOFU) showed improvement in the Physical domain when compared to the groups that received PBM (A: 1.97 points, CI = 0.17 to 3.77), active combined treatment (C: 2.36 points, CI = 0.50 to 4.22) and sham combined treatment (D: 2.84 points, CI = 1.00 to 4.68). In the self-image assessment, Group B was the only one that showed a significant reduction in scores again (-12.70 ± 4.46 points; P = 0.006). It was concluded that, among the treatments evaluated, LOFU showed the greatest effectiveness in improving body contour, while the combination of PBM and LOFU did not generate a synergistic effect. Although well tolerated, the treatments in the investigated dosimetric parameters generate subtle and almost imperceptible results in most of the treated participants. Finally, it is clear that the combination of treatments aiming for a synergistic effect, common in clinical practice, will not always generate better results than treatments carried out alone.