Change in the Order of Activation of Lower Limb Muscles Relative to Spinal Extensors During the Janda Test and Change in Postural Balance in Patients with LBP After Muscle Energy Techniques

<b>Background:</b> The aim of this study was to investigate change in the order activation of leg muscles in relation to the spinal extensors during the Janda test and change postural balance in patients with low back pain (LBP) after muscle energy techniques (METs). <b>Methods:</b> The study included fifteen men (mean age 41.9 years) working on an assembly line. The activity and recruitment of the following muscles: biceps femoris (BF), gluteus maximus (GM) and erector spinae (ES) were measured with the use of surface electromyography (sEMG) during the prone hip extension (PHE) test. Pain levels and postural balance were analysed. <b>Results</b>: MET translated into a reduction in muscle activation time in both the left and right side of the body (<i>p</i> < 0.001). The change was observed in the following muscles: BF (<i>p</i> = 0.003) and GM (<i>p</i> = 0.004). A reduction in pain was obtained post application of the MET therapy (<i>p</i> < 0.001). It was observed that after the therapy, along with the later activation time of the GM muscle, the range of motion of the COP along the <i>x</i>-axis increased (<i>p</i> = 0.0368). Increased activation time of the RES (<i>p</i> = 0.0411) and the LES (<i>p</i> = 0.0350) muscles influenced a decrease in the COP range of motion along the <i>x</i>-axis. <b>Conclusions</b>: The use of MET in people with LBP improves the sequence of activation of the ES, GM and BF muscles, affects postural balance, allows for the restoration of muscle balance in the lumbar spine and lower limbs, and reduces pain.