O efeito do método Mckenzie nos parâmetros neuromusculares, amplitude de movimento, flexibilidade e na dor lombar crônica de bombeiros militares

Abstract

The occupational activities of firefighters involve significant physical strain, both during fire situations, rescue, and victim transport, as well as in administrative sectors, where 40% of firefighters report musculoskeletal injuries and chronic low back pain (LBP). The McKenzie Method (MDT) is a physiotherapy technique aimed at increasing joint mobility in the spine and reducing low back pain. The objective of this research was to analyze the effect of MDT on neuromuscular parameters, flexibility, and symptoms of chronic low back pain in firefighters. The study consisted of two groups: one received the McKenzie Method intervention (MDT Group, n=8, 41 ± 7 years, 27.4 ± 2.3 kg/m²), and the control group performed daily 20 minutes in the Fowler’s position (Control Group, n=5, 38 ± 8 years, 27.0 ± 2.9 kg/m²). The MDT group received daily instructions and exercises to be performed at home or in the workplace. The exercises were individually prescribed based on the evaluation (classification) by MDT and repeated four times per day, with 10 repetitions per set. The following variables were analyzed (PRE and POST) over a 12-week period: peak torque (PT) and rate of force development (RFD) of trunk flexor and extensor muscles and hip extensor muscles; quantification of the level of electromyographic activation (RMS) during maximum voluntary isometric contraction (MVIC) of the rectus abdominis (RA), right (RO) and left (LO) internal obliques, lumbar erector spinae (LES), and right (RGM) and left (LGM) gluteus maximus; muscle activation level and pattern of the RA, RO, LO, LES, RGM, and LGM during a perturbation; lumbar range of motion, hamstring flexibility, sciatic nerve tension, and pain using the visual analog scale (VAS). Data underwent standard descriptive analysis, and normality and homogeneity were tested using the Levene and Shapiro-Wilk tests. A two-way repeated measures ANOVA was used to verify the influence of the McKenzie Method on the variables. Hedges’ (g) effect size was calculated, and the variables were tested at a significance level of p<0.05. In the analysis of lumbar range of motion, there was an increase in the extension angle in the MDT group (p=0.043; g=1.56). For trunk extensor peak torque, the MDT group showed a 23% gain (p=0.002; g=1.41), while the control group showed a 17% reduction (g=0.60). The MDT group had a 66% increase in trunk extensor RFD (p=0.006; g=3.56), and a 50% increase in trunk flexor RFD (p=0.013; g=1.88). Electromyographic activation of the lumbar erector spinae during MVIC indicated an interaction (p=0.0001) and a main effect of the intervention (p=0.002) for the MDT group (g=1.21). In the perturbation test, an interaction was observed for the lumbar erector spinae (MDT group had a 33% increase, p=0.011, g=1.50), right internal oblique (MDT group had a 40% increase, p=0.020; g=2.40), and left internal oblique (MDT group had a 20% increase, p=0.001; g=1.12) in muscle activation during the perturbation. The VAS pain scale showed a score of 7.2 (±1.5) points for the control group and 6.2 (±2.5) points for the MDT group. During the intervention, the groups reported scores of 6.4 (±1.6) in the control group and 5.2 (±2.8) in the MDT group, and by the end of the intervention, both groups significantly reduced their scores to 1.4 (±0.8) points (p=0.004) in the control group and 1.7 (±1.7) points (p=0.004) in the MDTgroup. The MDT reduced low back pain, increased trunk extensor strength, improved the rate of force development of the trunk extensor and flexor muscles, and was able to modify the activation level of the trunk stabilizers during perturbation in firefighters.