PURPOSE: This study compared the effects of three different clamshell exercises (CLAM) on the gluteus medius (GMED), quadratus lumborum (QL), anterior hip flexor (AHF), gluteus medius/quadratus lumborum ratio, and gluteus medius/anterior hip flexor ratio by studying the activities of participants wi...
PURPOSE: This study compared the effects of three different clamshell exercises (CLAM) on the gluteus medius (GMED), quadratus lumborum (QL), anterior hip flexor (AHF), gluteus medius/quadratus lumborum ratio, and gluteus medius/anterior hip flexor ratio by studying the activities of participants with GMED weakness. METHODS: Eleven subjects with weak GMED participated in this study. Subjects performed CLAM under three different conditions (standard, and modified 1 and 2). Surface electromyography was then used to measure the muscle activity and one-way repeated-measures analysis of variance was used to assess the statistical significance of the measured variables. RESULTS: GMED and the QL muscle activities did not differ significantly between the standard CLAM and the modified CLAM with the 2 different foot positions (F=4.74, P=.02; F=4.57, P=.02, respectively). AHF activity was significantly different in the two different foot positions when compared to the standard CLAM (F=11.17, P=.00). However, there was no significant difference between the AHF activities for the two different foot positions (P=.09). Finally, GMED/QL and GMED/AHF ratios were not significantly different between the three different CLAM exercises (F=.63, P=.55; F=.82, P=.45, respectively). CONCLUSION: Modified CLAM can be recommended as a good method to minimize AHF activity while maintaining GMED activity in subjects with weak GMED.
PURPOSE: This study compared the effects of three different clamshell exercises (CLAM) on the gluteus medius (GMED), quadratus lumborum (QL), anterior hip flexor (AHF), gluteus medius/quadratus lumborum ratio, and gluteus medius/anterior hip flexor ratio by studying the activities of participants with GMED weakness. METHODS: Eleven subjects with weak GMED participated in this study. Subjects performed CLAM under three different conditions (standard, and modified 1 and 2). Surface electromyography was then used to measure the muscle activity and one-way repeated-measures analysis of variance was used to assess the statistical significance of the measured variables. RESULTS: GMED and the QL muscle activities did not differ significantly between the standard CLAM and the modified CLAM with the 2 different foot positions (F=4.74, P=.02; F=4.57, P=.02, respectively). AHF activity was significantly different in the two different foot positions when compared to the standard CLAM (F=11.17, P=.00). However, there was no significant difference between the AHF activities for the two different foot positions (P=.09). Finally, GMED/QL and GMED/AHF ratios were not significantly different between the three different CLAM exercises (F=.63, P=.55; F=.82, P=.45, respectively). CONCLUSION: Modified CLAM can be recommended as a good method to minimize AHF activity while maintaining GMED activity in subjects with weak GMED.
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문제 정의
However, the AHF activity was significantly lower during the two modified CLAM exercises than in the standard CLAM. Nevertheless, to our knowledge, this is the first study to compare the GMED, QL, and AHF activities and the GMED/QL and GMED/AHF activity ratios during different CLAM exercises in participants with GMED weakness. The results of the current study partially supported the research hypotheses.
가설 설정
The purpose of this study was to compare the GMED, QL, and AHF muscle activities and the GMED/QL and GMED/AHF muscle activity ratios between the standard CLAM and modified CLAM 1 and 2 (with two different foot positions) among participants with gluteus medius weakness. We hypothesized that the GMED, QL, and AHF activities would be different during both modified CLAM 1 and 2 in contrast to during the standard CLAM among these participants.
제안 방법
To minimize any potential learning effect, all participants performed one practice set of each exercise before the data collection and were instructed by the principal investigator on how to perform the exercises {PI, JeongSeomGyeul (JSG)}. During all the trials, the investigators gave oral feedback to correct the errors, as well as to assist in maintenance of the proper tempo.
The participants were instructed to draw lots to randomize the exercise order to avoid learning effects or fatigue. Each participant performed all the exercises with the weak GMED side for both the lower extremities. A metronome was set at one beat per second to ensure that each participant performed the exercises at a standard speed.
This result is similar with respect to the findings of a previous study that showed the standard CLAM does not produce high activation of the GMED and activates the TFL and AHF to a greater extent, and that the AHF is more active than the TFL and GMED [15]. In addition, in this study, two different foot positions in the modified CLAM were designed to reduce the AHF activity without enhancing the GMED activity. Although gluteus maximus activity was not investigated in this study, it is possible that the gluteus maximus activity would have been increased during the modified CLAM exercises via reciprocal inhibition.
0 (SPSS, Chicago, IL, USA) was used for all statistical analyses. One-way, repeated-measures analysis of variance was used to assess the statistical significance of the GMED, QL, and AHF EMG activities, as well as the GMED/AHF and GMED/QL EMG activity ratios during the CLAM with different foot positions. The level of significance was set at .
An investigator applied traction to the test leg, directly opposing the line of the QL. The mean of the MVIC values estimated from the two trials for 5 seconds with a 3-minute rest between the contractions was used for MVIC data analysis. The participants had a 3-minute rest between muscle tests [29].
The target bar was positioned such that the top of the weak side’s knee touched the bar when the angle between the top leg and the horizontal plane became 25°. The participants were instructed not to tip it backward and to hold the pelvis in a neutral position, and this was monitored visually and using a stabilizer pressure bio-feedback unit (Chattanooga Group, Inc, Hixson, TN, USA). This unit composed of an inflatable air bag linked to a pressure gauge.
Briefly, subjects were instructed to push their feet against a wall at about 10% of the maximal contraction while they were performing the CLAM [16,17]. The purpose of this study was to compare the GMED, QL, and AHF muscle activities and the GMED/QL and GMED/AHF muscle activity ratios between the standard CLAM and modified CLAM 1 and 2 (with two different foot positions) among participants with gluteus medius weakness. We hypothesized that the GMED, QL, and AHF activities would be different during both modified CLAM 1 and 2 in contrast to during the standard CLAM among these participants.
This study examined the effects of the modified CLAM on the EMG amplitude of the GMED, QL, AHF activities, as well as the GMED/QL and GMED/AHF ratios in the participants with weak GMED. Our results showed that the AHF muscle activity significantly decreased during the modified CLAM when compared to that during the standard CLAM.
This study excluded the participants with past or present musculoskeletal, neurological, or cardiopulmonary diseases, shortness of iliotibial band and calf muscles, and limited ROM of the hip, knee, and ankle joints that could interfere with side-lying position. Overweight or obese participants were also excluded, as fatty tissue could interfere with EMG signals, acting as a low-pass filter [24].
This study was conducted to investigate whether the GMED, QL, and AHF activities and the GMED/QL and GMED/AHF muscle activity ratios differed between the standard CLAM and 2 modified CLAM exercises performed by participants with GMED weakness. The GMED and QL activities and the GMED/QL and GMED/AHF activity ratios were not significantly different among the three types of CLAM.
The EMG amplitude of each exercise was expressed as a percentage of the average MVIC value for each muscle (% MVIC) because this has been reported to be the most credible method of EMG normalization for hip abduction exercises [3]. To calculate the muscle activity ratios of the GMED/AHF and GMED/QL, the normalized GMED amplitude was divided by the normalized AHF and QL amplitudes, respectively.
The mean value was used for data analysis [32]. To minimize any potential learning effect, all participants performed one practice set of each exercise before the data collection and were instructed by the principal investigator on how to perform the exercises {PI, JeongSeomGyeul (JSG)}. During all the trials, the investigators gave oral feedback to correct the errors, as well as to assist in maintenance of the proper tempo.
An investigator applied inferior force to the ankle while keeping the hip with the other hand. To obtain the MVIC values for the AHF, an investigator stabilized the opposite iliac crest with the participants assuming a supine position on the treatment table. The quadriceps of the test leg stabilized the knee in extension, after which the hip was flexed in a position of slight abduction and slight lateral rotation.
To obtain the MVIC values for the GMED, the participants assumed a side-lying position on the treatment table with the knee flexed at 90° for stability and the test leg up and the bottom hip flexed at 45°.
To perform the modified CLAM 2, the participants remained in the modified CLAM 1 position and pushed both the heels and metatarsal heads against the wall at about 10% of the maximal contraction while maintaining neutral ankle position (Fig. 3), separated their knees, and rotated the weak limb upward keeping their feet together.
대상 데이터
05. Eleven participants (7 males, 4 females) with weak GMED that were selected through manual muscle testing participated in this study. Table 1 indicates the demographic information of the participants.
Surface EMG data were collected by using a Tele-Myo DTS EMG instrument with a wireless telemetry system (Noraxon, Inc., Scottsdale, AZ, USA) at a sampling rate of 1000 Hz. A digital band-pass filter (Lancosh FIR), which filtered the raw signals, was between 20 and 450 Hz, and a common mode rejection ratio of 92 dB at 60 Hz was obtained.
성능/효과
, Scottsdale, AZ, USA) at a sampling rate of 1000 Hz. A digital band-pass filter (Lancosh FIR), which filtered the raw signals, was between 20 and 450 Hz, and a common mode rejection ratio of 92 dB at 60 Hz was obtained. Myo-Research Master Edition 1.
Contrary to the research hypothesis, the GMED activity did not increase during the two modified CLAM exercises when compared to the standard CLAM. This result is similar with respect to the findings of a previous study that showed the standard CLAM does not produce high activation of the GMED and activates the TFL and AHF to a greater extent, and that the AHF is more active than the TFL and GMED [15].
Third, the upward movement of the pelvis during the exercises was not well controlled. Fourth, the strength of the push at about 10% of the maximal contraction was not measured. Further studies should determine the long-term effects on the GMED and QL muscle activities in different foot positions in subjects with GMED weakness.
This study examined the effects of the modified CLAM on the EMG amplitude of the GMED, QL, AHF activities, as well as the GMED/QL and GMED/AHF ratios in the participants with weak GMED. Our results showed that the AHF muscle activity significantly decreased during the modified CLAM when compared to that during the standard CLAM. Therefore, this finding signifies that the modified CLAM can be recommended as a good method to minimize the AHF activity while maintaining the GMED activity in subjects with weak GMED.
The AHF activity was significantly lower during the two modified CLAM exercises than in the standard CLAM (by 38.41% and 26.49% for CLAM 1 and 2, respectively).These results support our research hypothesis, and may be explained by the mechanism of reciprocal inhibition.
5. The GMED/QL and GMED/AHF ratios were not significantly different among all types of CLAM (F=.63, P=.55; F=.82, P=.45, respectively).
Second, this study is a cross-sectional study; therefore, the long-term effects of different foot conditions on the muscles that were investigated cannot be determined. Third, the upward movement of the pelvis during the exercises was not well controlled. Fourth, the strength of the push at about 10% of the maximal contraction was not measured.
후속연구
Fourth, the strength of the push at about 10% of the maximal contraction was not measured. Further studies should determine the long-term effects on the GMED and QL muscle activities in different foot positions in subjects with GMED weakness.
First, the age range of the participants was limited to 18-24years; therefore, our outcomes may not be generalized to the population belonging to other age groups. Second, this study is a cross-sectional study; therefore, the long-term effects of different foot conditions on the muscles that were investigated cannot be determined. Third, the upward movement of the pelvis during the exercises was not well controlled.
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