A Study on the Differences of Quadriceps Femoris Activities by Knee Alignment during Isometric Contraction

Abstract

[Purpose] This study attempted to identify how genu varum or valgum affects the electromyographic activities of the vastus medialis, vastus lateralis, and rectus femoris during knee isometric contraction. [Subjects] Fifty-two healthy young adults were enrolled in this study. They were enrolled and classified into three groups by knee alignment conditions: the genu varum, genu valgum, and control groups. [Methods] The electromyographic activity ratio of the vastus medialis to the vastus lateralis and rectus femoris were calculated using the percentage of maximum voluntary contraction. The participants contracted their quadriceps during isometric contraction at 30 and 60° of knee flexion. [Results] The genu varum group had more activity in the vastus medialis than in the vastus lateralis and rectus femoris, whereas the genu valgum group had more activity in the vastus lateralis and rectus femoris than in the vastus medialis. There was a significant difference in the muscle activity ratio between the vastus medialis and vastus lateralis by angle of knee flexion degree only in the genu valgum. There were no significant differences in any of the three groups in terms of the muscle activity ratio of the vastus medialis to the rectus femoris by angle of knee flexion. [Conclusion] The quadriceps femoris was used for different strategies according to knee alignment during isometric contraction at 30 and 60°. This study suggests that rehabilitation training programs used to strengthen the quadriceps should consider the knee alignment conditions of the target subjects.

Differences in onset time between the vastus medialis and lateralis during stair stepping in individuals with genu varum or valgum

“…Previous studies 10 , 11 , 12 ) reported that genu varum and valgum are common knee malalignment problems that affect the cross-sectional area, onset time, and activation of the vastus medialis and lateralis. Knee malalignment leads to imbalance between the vastus medialis and lateralis.…”

“…Knee malalignment leads to imbalance between the vastus medialis and lateralis. In particular, studies that investigated the differences in contraction onset time between the vastus medialis and lateralis during isometric and isokinetic concentric exercise show that genu varum delays the vastus lateralis and genu valgum delays the vastus medialis 11 , 12 ) .…”

Effect of knee alignment on the quadriceps femoris muscularity: Cross-sectional comparison of trained versus untrained individuals in both sexes

“…The anatomical cross-sectional areas (ACSAs) of VL, VM and VI were reportedly greater in untrained men with a larger quadriceps femoris angle (Q-angle) compared to ones who had a smaller Q-angle, whereas the ACSA of the RF was similar for the two different Q-angle groups [ 6 ]. The percent ACSAs of VL and RF to the total quadriceps femoris were greater in the untrained men with genu valgum (i.e., large Q-angle [ 8 ]) than with genu varum, and vice versa for that of VM [ 7 ]. Although there are some discrepancies between the previous studies [ 6 , 7 ], the findings suggest that Q-angle affects each muscle size of the quadriceps femoris in untrained individuals: there may be an association between Q-angle and the quadriceps femoris muscularity.…”

The immediate effects of foot pressure based insole on ankle dorsiflexion range of motion, postural sway, and muscle activation in healthy adults with genu varum

“…Therefore, this posture affects muscle activation and strength in the lower extremities. A previous study showed that the genu varum group had more muscle activity in the vastus medialis than in the vastus lateralis and rectus femoris [24]. The vastus medialis/vastus lateralis ratio was also significantly higher in with genu varum than in values for both genu valgum and normal knee alignment [25].…”

“…Previous studies only reported the effects of applying a lateral wedge for genu varum with ankle DFROM [26], postural sway [12], or muscle activation [24]. However, there are no studies that investigated the combination of ankle DFROM, postural sway, and muscle activation.…”