Background: Passive straight leg raising (PSLR) is the common clinical test to measure of hamstring muscle length. Hip flexion angle contributes to change the lumbopelvic rotation during PSLR. Pressure biofeedback unit (PBU) is commonly used to detect lumbopelvic movement during lower limb movements. Thus, there may be the relationship between pressure of PBU and lumbopelvic motion during PSLR. Objects: The objective of this study was to determine the relationship between pressure of PBU and lumbopelvic motion during PSLR. Methods: Thirty two subjects participated in this study. A three-dimensional motion analysis system were used to measure the lumbopelvic angle during PSLR, while recording the pressure of PBU according to angle of PSLR by 10 degree increments. Pearson product moment correlations and linear regression analysis were used to describe the relationship between variables. Results: The results showed that there was a significant relationship between the lumbopelvic and angle of PSLR (Pearson’s r=.83, p<.05), between the pressure of PBU and angle of PSLR (Pearson’s r=.75, p<.05), and between lumbopelvic motion and pressure of PUB (Pearson’s r=.83, p<.05). Linear regression equation using lumbopevic angle as an independent factor was as follows: Pressure of PBU = 47.35 + (2.55 × angle of lumbopelvic motion) (R2=.69, p<.05). Conclusion: Results of the present study indicate that pressure of PBU can be used to indirectly detect the amounts of lumbobevic motion during muscle length test or stretching of hamstring.

The purposes of this study were to compare the electromyographic activities from the rectus femoris, vastus medialis oblique portion, vastus medialis longitudinal portion, and vastus lateralis during straight leg raising (SLR) and quadriceps setting (QS) exercise and to determine which exercise is more effective to selectively strengthen the vastus medialis. Thirty two healthy subjects <19 men, 13 women) participated in the study. All participants performed SLR and QS exercises while electromyographic activity was recorded from EMG surface electrodes. Statistical analysis demonstrated significantly greater values for the vastus medialis oblique portion, vastus medialis longitudinal portion, and vastus lateralis activities during QS exercise than for those during SLR exercise. However, the rectus femoris muscle activity between SLR and QS exercises was not significantly different. The ratios of vastus lateralis to vastus medialis during SLR and QS exercise were not significantly different. These results show that QS exercise is more effective for strengthening the quadriceps muscle on the whole than the SLR exercise. As for selective methods of strengthening vastus medialis specifically, both SLR and QS exercises are useful.

The purpose of this study was to investigate which of 4 positions produced the highest action potential in the rectus femoris muscle of normal adult subjects. Testing was performed in supine with the right leg performing a simple straight leg raise with the knee fully extended. The left leg, however, was placed in 4 different positions: 1. Full support with flexion. 2. Flexed on the plinth with knee flexion and foot flat. 3. Same as N0.2 but with knee flexion. 4. Left leg hanging over the end of the plinth with knee flexion, hip flexion and no foot support. This study was designed to compare the level of electromyographic activity of the rectus femoris under 4 positions. Fourty-three healthy young adults performed three trials of each exercise condition in random order in the supine position. Electromyographic activity was recorded from surface electrodes. Rectus femoris action potentials in all 4 positions were significantly different. The highest action potential at the end of movement of the right leg occurred with the left leg hanging over the end of the plinth with knee flexion. It is therefore recommended the straight leg raising be performed with the contralateral leg flexed at over the end of the supporting surface to obtain a maximum rectus femoris isometric contraction.