[Purpose] The purpose of this study was to investigate the difference in onset timing
between the vastus medialis and lateralis among the different knee alignments, as well as
the best isokinetic angular velocity for an isokinetic concentric contraction. [Subjects]
Fifty-two adults (20 with genu varum, 12 genu valgum, and 20 controls) were enrolled in
this study. Subjects with > 4 cm between the medial epicondyles of the knee were placed
in the genu varum group, whereas subjects with > 4 cm between the medial malleolus of
the ankle were placed in the genu valgum group. [Methods] Surface electromyography was
used to measure the onset times of the vastus medialis and vastus lateralis during
concentric contractions at 30, 60, and 90°/sec. [Results] The vastus lateralis showed more
delayed firing than the vastus medialis in the genu varum group, whereas vastus medialis
firing was delayed more than that of the vastus lateralis in the genu valgum group. No
differences in onset timing were observed between the vastus medialis and lateralis
according the different angular velocities during concentric contractions in all three
groups. [Conclusion] Genu varum and valgum affect quadriceps firing. Therefore, selective
rehabilitation training of the quadriceps femoris should be considered to prevent pain or
knee malalignment deformities.
[Purpose] This study examined the relationship between the center of pressure (COP)
displacement time during the stance subphases and dynamic balance ability when elderly
cross obstacles 0, 10, and 40 cm in height. [Subjects] Fifteen older adults were enrolled
in this study (≥65 years of age). [Methods] An F-Scan System was used to measure the COP
displacement time when subjects crossed obstacles 0, 10, and 40 cm in height, and the
Dynamic Gait Index, Berg Balance Scale, and Four Square Step Test were used to measure
dynamic balance ability. [Results] The Dynamic Gait Index, Berg Balance Scale, and Four
Square Step Test were correlated with each other. Dynamic balance tests were correlated
with the COP displacement time during the stance phase. At obstacle heights of 10 and
40 cm during loading response and at all heights during pre-swing, there were correlations
with dynamic balance ability. However, dynamic balance ability did not affect the COP
displacement time during mid-stance and terminal stance. [Conclusion] People with a lower
dynamic balance ability show a larger COP displacement time during loading response and
pre-swing. Therefore, dynamic balance ability can be predicted by measuring the COP
displacement time.
[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.
[Purpose] We investigated the difference in onset time between the vastus medialis and
lateralis according to knee alignment during stair ascent and descent to examine the
effects of knee alignment on the quadriceps during stair stepping. [Subjects] Fifty-two
adults (20 with genu varum, 12 with genu valgum, and 20 controls) were enrolled. Subjects
with > 4 cm between the medial epicondyles of the knees were placed in the genu varum
group, whereas subjects with > 4 cm between the medial malleolus of the ankle were
placed in the genu valgum group. [Methods] Surface electromyography was used to measure
the onset times of the vastus medialis and vastus lateralis during stair ascent and
descent. [Results] The vastus lateralis showed more delayed firing than the vastus
medialis in the genu varum group, whereas vastus medialis firing was more delayed than
vastus lateralis firing in the genu valgum group. Significant differences in onset time
were detected between stair ascent and descent in the genu varum and valgum groups.
[Conclusion] Genu varum and valgum affect quadriceps firing during stair stepping.
Therefore, selective rehabilitation training of the quadriceps femoris should be
considered to prevent pain or knee malalignment deformities.
This study was conducted to investigate the effects on muscle thickness and balance ability after performing plank exercise on various surface types. Methods: In this study, there were thirty healthy participants. Participants were randomly distributed into three groups, a control group (n= 10), sling group (n= 10), and ball group (n= 10). All participants performed plank exercises three times a week for four weeks. Plank exercises consisted of five sets of 30 seconds each with a one minute break between each set. Muscle thickness of the transverse abdominis (TrA), internal oblique (IO), and external oblique (EO) was measured using an ultrasound diagnostic apparatus and balance was measured using I-balance. Results: Evaluation of muscle thickness revealed that the IO and EO muscle of the ball group changed significantly relative to the control group (p< 0.05). However, there were no significant changes in balance. Conclusion: The results revealed that performing plank exercise on a ball is more effective among various types of surfaces.
Purpose: This study was to investigate the differences abdominal muscles activities of according to hip adductor contraction levels 20% (mild), 50% (moderate), and 70% (strong) of MVIC on during bilateral lower extremity raising exercise on supine. Methods: The subjects of the study were a total of 39 persons including 23 healthy males and 16 females, who performed bilateral lower extremity raising exercise in 20%, 50%, 70% MVIC hip contraction. Muscle activities were measured by using S-EMG in RA (rectus abdominis), IO (internal oblique), and EO (external oblique). Results: Muscle activity of the internal oblique abdominal muscle and external oblique abdominal muscle, their activities were also greatest with the adductor contraction size at 70% and there was statistically significant difference when compared with the adductor contraction size at 20% and 50% (p< 0.05). As for the rectus abdominis muscle according to the size of contraction of the adductor was greatest at 70%, without statistically significant difference (p> 0.05). Conclusion: bilateral lower extremity raising with strong hip joint adductor contraction was effective exercise to strengthen abdominal muscles. If subjects could not perform strong hip adductor contraction, moderate contraction is effective abdominal muscle contraction exercise. The contraction size of the adductor is small, weak contraction may trigger middle level contraction and therefore appropriate application of the exercise program of bilateral leg raising may result in great effect as a lumbar stabilization exercise.
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