Background: Prolonged standing during work causes a lower extremity pain and disorders. Patellofemoral pain syndrome (PFPS) is one of the common diagnoses of the knee pain. Although the etiology of PFPS is not completely understood, it is considered to be multifactorial. Objects: The purpose of this study was to investigate difference in strength of knee muscles, quadriceps:hamstring muscles strength ratio (Q:H ratio), asymmetry ratio of knee muscles strength and dorsiflexion range of motion (ROM) between standing workers with and without PFPS. Methods: Twenty-eight standing workers with PFPS and 26 age-, height-, and weightmatched standing workers without PFPS participated in this study. A tension sensor measured knee muscle strength, and motion sensor measured dorsiflexion ROM. The asymmetry ratio of knee muscles was calculated by a specific formula using the knee muscles strength of the dominant side and the sound side. An independent t-test was used to identify significant differences in the strength, ROM, Q:H ratio, and asymmetry ratio between the PFPS and normal groups. Results: The standing worker with PFPS have significantly lower dorsiflexion ROM (p < 0.000) and higher asymmetry ratio of the hamstring muscles strength (p < 0.000) compare to the standing worker without PFPS. No significant differences were seen in the strength of quadriceps muscle and hamstring muscles, Q:H ratio, and asymmetry ratio of quadriceps muscle strength. Conclusion: There was a significant difference in the asymmetry ratio of the isometric hamstring muscle strength. This finding suggests that the asymmetry ratio of isometric hamstring muscle strength may be more important than measuring only the hamstring muscle strength of the PFPS side. Furthermore, the results of this study showed a significant difference in dorsiflexion ROM between the standing industrial workers with and without PFPS. Dorsiflexion ROM and isometric hamstring muscle strength should be considered when evaluating the subjects with PFPS.

This study was designed to identify the effect of various decline boards and postures of lower extremities on surface electromyographic (EMG) activity of knee muscles during isometric single-leg decline squat exercises. The subjects were twenty young male adults who had not experienced any knee injury and their Q-angles were within a normal range. They were asked to perform single-leg decline squat exercises in five various conditions. The EMG activities of the gluteus maximus (GM), vastus lateralis (VL), vastus medialis (VMO), tibialis anterior (TA), and gastrocnemius (GCM) muscles were recorded in five various single-leg decline squat exercises by surface electrodes and normalized by maximal voluntary isometric contraction (MVIC) values. The normalized EMG activity levels were compared using one-way ANOVA with repeated measures. The results of this study were as follows: 1) Exercises 2 and 4 produced significantly greater EMG activity of VMO than did exercise 1 (<.05/10), 2) The VMO/VL ratio of EMG activity of exercise 4 was the highest, producing a significantly greater ratio than exercise 1 (<.05/10). These results show that single-leg lateral oblique decline squat exercise is the best exercise for selective strengthening of VMO, and the posture of the contralateral leg does also affect strengthening of VMO, but we'll need to research patellofemoral joint compression for clinical application of single-leg lateral oblique decline squat exercises.

The purpose of this study was to assess the effect of rehabilitation exercise and neuromuscular electrical stimulation on a visual analysis scale and functional visual analysis scale regarding functional capacity. A total of 7 consecutive patients with the complaint of patellofemoral pain syndrome who received this diagnosis from a sports medicine physician were recruited to assess the effect of rehabilitation exercise and neuromuscular electrical stimulation (NMES) on Visual Analog Scale (VAS) and Functional Visual Analog Scale (FVAS), functional capacity patients with patellofemoral pain syndrome. The exercise rehabilitation consisted of a complex training program requiring five treatments a week for eight weeks. The training program consisted of four phases, and each lasted for two weeks. Statistical analyses were one-way ANOVA with repeated measures. The results were as follows: (1) There were significant differences in the VAS and FVAS during 8-weeks of rehabilitation exercise and neuromuscular electrical stimulation (p<.01). (2) There were no significant differences in the functional capacity during 8-weeks of rehabilitation exercise and neuromuscular electrical stimulation (p<.05). In conclusion, at the end of the eight weeks of this rehabilitation program and neuromuscular electrical stimulation, a significant reduction was found in VAS and FVAS, but there was no significant difference in functional capacity at the end of the treatment.