Study of the activation and oxygenation of multifidus and gluteus medius muscles during stretching of the lower limb posterior chain: Comparison between two different executions techniques

Background. Ischiocrural (IC) stretching procedures may result in different involvement of the posterior kinetic chain and of the lumbar spine. Objective. The aim of the study was to evaluate homolateral muscle activation and hemodynamic changes in the Multifidus (MM) and Gluteus medius (GM) muscles in healthy subjects during monolateral IC stretching by using two different execution techniques: technique A (TA: forward bending of the torso, hands in Open Kinetic Chain (OKC), leg stretched) and technique B (TB: forward bending of the torso, leg stretched with knee joint angle of 20°, hands in Closed Kinetic Chain (CKC). Methods. A total of 12 recreationally active males (35-24±4.2 years) and 14 recreational-ly active females (26-22±2.3 years) volunteered to participate in the study and randomly performed TA and TB stretching of 20 s in two subsequent sessions one week apart. During execution, hemodynamic parameters obtained with near infrared spectroscopy (NIRS), namely total hemoglobin (tHb) and tissue oxygen index (TOI%), as indicators of blood flow and oxygen extraction respectively, were detected from homolateral MM, and myoelectric parameters obtained with surface bipolar electromyography (sEMG), namely root mean square (RMS) as indicator of muscle activation, were detected from homolateral GM and MM. Percentage of change (Δ%) was calculated from the beginning and the end of the 20 s recording divided into 5 s epochs for all the parameters measured. Results. All along the 20 s procedure, compared to TB, TA stretching produced higher muscle activation both in MM and GM muscles (p<0.001), and lower tHB% change combined with higher % oxygen extraction in MM (p