Effectiveness of the open and closed kinetic chain exercises in the treatment of the patellofemoral pain syndrome

The aim of this study was to analyze the therapeutic effects of the open kinetic chain (OKC) and closed kinetic chain (CKC) exercises to treat the patellofemoral syndrome (PFSD). For this, 24 volunteers, bearers of the PFSD were randomly divided in two groups: group I (n = 12) performed the OKC exercises; group II (n = 12) performed the CKC exercises. Both groups were submitted to eight consecutive weeks of treatment consisting of three weekly sessions performed in alternate days. To analyze the activation pattern of the vastus medialis oblique (VMO) and the vastus lateralis (VL) muscles, the electromyographic signals (EMG) were collected using bipolar surface electrodes quantified by the root mean square (RMS) normalized by the maximal voluntary isometric contraction of the quadriceps. The pain intensity and the functionality of the volunteers were assessed using scales. The analysis of the amounts of the VMO/VL ratio in both groups I and II showed no significant differences as to the pre- and post-treatment times in the concentric (p > 0.05) and eccentric (p > 0.05) phases of the OKC and CKC exercises. Despite of this, the VMO muscle presented a lower activation rate compared to the VL in the eccentric phase of the CKC exercise. It was found significant increases in the functionality (p 0,05) e excêntrica (p > 0,05) dos exercícios em CCA e CCF. Apesar disso, o músculo VMO apresentou menor taxa de ativação em relação ao VL na fase excêntrica do exercício em CCF. Foram encontrados aumentos significativos na funcionalidade (p 0,05) y excéntricas (el p > 0,05) de los ejercicios en CCA y CCC. A pesar de eso, el músculo VMO presentó un punto de activación más pequeño respecto a VL en la fase excéntrica del ejercicio en CCF. En ellos se encontraron aumentos significantes en la funcionalidad (p < 0,05) y en la reducción de la intensidad del dolor (p < 0,05) entre veces de tiempo y post-tratamiento en ambos grupos, sin embargo, el de grupo II se mostraron superiores al grupo I en estas dos variables. Los resultados de este estudio sugieren que, de acuerdo con las condiciones experimentales usadas, los ejercicios en CCA y CCC no provocaron los cambios en los modelos de activación EMG de los músculos VMO y VL, sin embargo, ellos promovieron mejora de la funcionalidad y reducción de la intensidad del dolor después de ocho semanas de intervención, y los ejercicios en CCC eran superiores al de en CCA.667