Muscles activation in the movement pattern during hip joint extension.

The aim of the study was to determine the order of muscle recruitment during the active hip joint extension in particular positions in young healthy adults during two different testing positions. First position – the subjects were asked to lie lateral on a therapeutic table with pelvis stabilization, the tested lower extremity at neutral position suspended in Universal Exercise Unit (UEU) in accordance with kinesiotherapeutic rules to exclude the force of gravity and to ensure a facilitation conditions. Second position – the subjects were asked to lie prone on therapeutic table with pelvis stabilization, feet shoulder–width apart, arms at their sides and head was in mild line in standardized test position for prone hip extension testing. Subjects were instructed to perform hip extension at their natural speed, repeating five trials of each movement from starting position with 5–s rest between every trial. Subjects were given a 5–min rest period between the positions. All subjects presented right–leg dominance, defined according to which leg they used for kicking. The lower extremity subjected to measurement was chosen randomly as follows: 36 right and 28 left lower extremities were tested. We performed a one–stage simple randomisation using a computer–generated random numbers, which were hidden in sequentially numbered envelopes and then selected by subjects. The researcher, who allocated the participants into the study, marking one of two cards with "X" for the left or with "Y" for the right lower extremity. The measurement was performed by a dual–channel sEMG NeuroTrac MyoPlus device integrated with computer software for digital analysis and report creation. All electrodes were placed in pairs with distance of 1.5–2.0 cm from each other and parallel to the muscle fibers over the centre part of the GM and HMG muscles’ bellies according to recommendations of the Surface Electromyography for the Non-Invasive Assessment of Muscles (SENIAM) and International Society of Electrophysiology and Kinesiology (ISEK). Functional sEMG activity of the GM and HMG were recorded in real–time to analyse the order of muscle activation pattern. Recruitment time was considered necessary time to attain 75% value of the average muscle activation during hip extension in two positions. The mean onset of muscle activity for each set was calculated from the five trials within that set in both positions separately. Mean values of resting and functional GM and HMG muscles’ bioelectrical activity were given according to the Root Mean Square (RMS) algorithm expressed in microvolts.