A study on muscle activity and ratio of the knee extensor depending on the types of squat exercise

Abstract

[Purpose] For preventing the patellofemoral pain syndrome, this study aims to suggest a proper squat method, which presents selective muscle activity of Vastus Medialis Oblique and muscle activity ratios of Vastus Medialis Oblique/Vastus Lateralis by applying squat that is a representative weight bearing exercise method in various ways depending on the surface conditions and knee bending angles. [Subjects and Methods] An isometric squat that was accompanied by hip adduction, depending on the surface condition and the knee joint flexion angle, was performed by 24 healthy students. The muscle activity and the ratio of muscle activity were measured. [Results] In a comparison of muscle activity depending on the knee joint flexion angle on a weight-bearing surface, the vastus medialis oblique showed a significant difference at 15° and 60°. Meanwhile, in a comparison of the muscle activity ratio between the vastus medialis oblique and the vastus lateralis depending on the knee joint flexion angle on a weight-bearing surface, significant differences were observed at 15° and 60°. [Conclusion] An efficient squat exercise posture for preventing the patellofemoral pain syndrome is to increase the knee joint bending angle on a stable surface. But it would be efficient for patients with difficulties in bending the knee joint to keep a knee joint bending angle of 15 degrees or less on an unstable surface. It is considered that in future, diverse studies on selective Vastus Medialis Oblique strengthening exercise methods would be needed after applying them to patients with the patellofemoral pain syndrome.

Intrarater reliability of measuring the patella position by ultrasonography in weight-bearing condition

“…Patients with patellofemoral pain syndrome often complain of discomfort in the initial range of knee flexion while ascending or descending stairs 3 ) . According to the results of a recent study, significant muscle imbalance was noted in knee flexion at 15° and 60° in a weight-bearing condition in participants with patellofemoral pain syndrome 6 ) . Elias and White 1 ) suggested that imaging studies of patellofemoral tracking should focus on the initial range of knee flexion.…”

“…Imbalanced forces on the patella, which are generated by the surrounding soft tissue, such as vastus medialis oblique weakness and iliotibial band or lateral retinaculum tightness, will cause malalignment of patella. Changes in lower limb alignment also cause patella maltracking, such as femoral or tibial rotation and excessive subtalar joint pronation 1 , 5 , 6 , 7 , 8 , 9 ) . Patella malalignment and maltracking may increase contact pressures on the lateral facet of the patella 7 ) , which damages cartilage and surrounding soft tissues, and causes pain, apprehension, and giving way 1 ) .…”

Morphometric analysis of vastus medialis oblique muscle and its influence on anterior knee pain

“…Motor point stimulation and anatomical dissection clearly showed that VM distal fibers were attached directly to the medial aspect of the patella that contributes to dynamic medial patellar stabilization and opposing its lateral dislocation [ 28 ]. Altered muscle activity and weaknesses in VMO cause mal-tracking of the patella and subsequent damage to surrounding structures and aching pain [ 29 ]. In the current research, the oblique fibers of VM are not only involved in the medial border of the patella, but additionally, they have a minor area of direct continuity with the patellar tendon.…”

“…Providing support for this hypothesis are data from human studies in which quadriceps muscle dysfunction may precede degenerative changes [ 40 ]. Patients with PFPS were found to have a lower muscle activity ratio between VM and VL muscles than healthy subjects [ 29 ]. Engelina et al [ 2 ] added that VMO angle may be a contributory factor in a subset of PFPS, especially in patients who have patellar instability.…”

Centro de presión y patrones de actividad muscular durante la ejecución de una sentadilla monopodal isométrica realizada sobre una superficie esponjosa en mujeres jóvenes sanas

“…No obstante, la sentadilla monopodal analizada, correspondió a una ejecución dinámica sobre una superficie estable. También, distintos autores han analizado la sentadilla sobre superficies inestables, debido a que presentan buenos resultados en la mejora del desempeño de la fuerza 13,14 . Sin embargo, estos estudios no identifican la actividad muscular cuando la sentadilla se realiza de manera monopodal e isométrica, sobre una superficie inestable.…”