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

Purpose The aim of this study was to investigate change in the order activation of legs muscles in relation to the spinal extensors during the Janda test and change postural balance in patients with LBP (low back pain) after FRS and ERS muscle energy techniques (MET). Methods The study included fifteen men (mean age 41.9 years) with chronic non-specific low back pain syndrome, working on an assembly line in the automotive industry. 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 hip extension (PHE) test. Pain levels and postural balance were analysed. Results MET translated into a reduction of muscle activation time in both the left and right side of the body (p<0.001). The change was observed in the following muscles: BF (p = 0.003) and GM (p = 0.004). A reduction in pain was obtained thanks to the MET therapy (p<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 x-axis increased (p = 0.0368). Increased activation time of the RES (p = 0.0411) and the LES (p = 0.0350) muscles influenced a decrease in the COP range of motion along the x-axis. Conclusion The use of segmental muscle energy techniques in individuals with LBP improves the activation sequence of the ES, GM and BF muscles, which has an impact on postural balance. Diagnosis of the level and type of dysfunction used in MET enables restoration of muscle balance in the lumbar spine and lower limbs and reduction of pain.