Patellofemoral pain syndrome (PFPS) ranks among the most prevalent factors causing anterior knee pain. Quadriceps exercises such as forward lunges are important to treat PFPS. Aim: We in-vestigated whether there is a muscle activity difference between the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles and the center of pressure (CoP) among three hip posi-tions: hip adduction forward lunge (HADF), hip neutral forward lunge (HNEF), and hip abduc-tion forward lunge (HABF) in healthy subjects. Method: This was a randomized controlled pilot study that included twenty healthy volunteers. CoP was measured using a “Wii Balance Board” from Nintendo and VMO and VL muscle activity were measured via wireless surface electro-myography. Results: CoP outcomes showed significant differences among the three positions in position, sum distance, range, and max distance. VMO and VL muscle activity and the ratio of VMO/VL significantly differed among the three positions. Conclusions: Although VMO and VL muscle activity increased in HADF and HABF, excessive change in CoP occurred in the two posi-tions. The change in the CoP during HADF and HABF may result in valgus, varus, and loading of the knee joint, which may worsen PFPS. The HNEF is recommended for quadriceps strengthening in healthy subjects and PFPS patients.