Comparison of the knee valgus angle, leg muscle activity, and vastus medialis oblique/vastus lateralis ratio during a single leg squat on flat and declined surfaces in individuals with patellofemoral pain syndrome

Article type: Research Article

Authors: Yoon, Tae-Lim^a | Kim, Ki-Song^{b; *} | Cynn, Heon-Seock^c

Affiliations: [a] Department of Physical Therapy, College of Health Science, Cheongju University, Cheongwon-gu, Cheongju, Chungbuk, Korea | [b] Department of Physical Therapy, College of Biohealth Science, Hoseo University, Baebang-eup, Asan-si, Chungnam, Korea | [c] Applied Kinesiology and Ergonomic Technology Lab Laboratory, Department of Physical Therapy, The Graduate School, Yonsei University, Baekwoon-kwan, Wonju, Kangwon-do, Korea

Correspondence: [*] Corresponding author: Ki-Song Kim, Department of Physical Therapy, College of Biohealth Science, Hoseo University, 20 Hoseo-ro, 79 gil, Baebang-eup, Asan-si, Chungnam, 336-795, Korea. Tel.: +82 10 3410 0816; Fax: +82 41 540 9975; E-mail:kskim68@hoseo.edu

Abstract: BACKGROUND: The knee valgus angle and knee muscles activity on a declined surface have not yet provided enough biomechanical analyses and treatment guidelines for patellofemoral pain syndrome (PFPS) patients OBJECTIVE: The purpose of this study was to investigate the knee valgus angle, leg muscle activity, and the vastus medialis oblique (VMO)/vastus lateralis (VL) muscles ratio during a single leg squat (SLS) on a declined surface in individuals with PFPS. METHODS: Fifteen young adults with PFPS (9 men, 6 women; height, 168.6 ± 7.3 cm; weight, 62.4 ± 17.9 kg; age, 22.7 ± 2.8 y; body mass index, 22.7 ± 2.8) participated in this study. Knee valgus angle and leg muscle activity and VMO/VL ratios were collected in subjects with PFPS during SLS on flat and declined surfaces. RESULTS: During the SLS, the knee valgus angle was significantly increased on the declined surface than the flat surface (p< 0.05). Also, significantly higher EMG activity in the rectus femoris (RF), VMO, and VL muscles when doing the SLSs were present during the SLSs on the declined surface (p< 0.05). CONCLUSIONS: The results of this study suggest that significantly increased knee valgus angles and muscle activity of RF, VMO, and VL during SLSs occur on a declined surface. Therefore, individuals with PFPS should be cautious when stepping down on a declined surface, such as downhill terrain on a mountain.

Keywords: EMG, knee exercise, PFPS, video analysis

DOI: 10.3233/IES-160636

Journal: Isokinetics and Exercise Science, vol. 24, no. 4, pp. 341-347, 2016