• The Journal of Korean Physical Therapy
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• v.28 no.2
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• pp.65-70
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• 2016

Purpose: The aim of this study was to determine the effects of electromyographic (EMG)-Biofeedback using closed kinetic chain exercise (EB-CKCE) on quadriceps angle (Q-angle) and quadriceps muscle activation and muscle activation ratio in subjects with patellofemoral pain syndrome and to provide fundamental information on rehabilitation exercise in patellofemoral pain syndrome. Methods: Thirty participants who met the criteria were included. The subjects were randomly divided into three groups: control group (Group I, n=10), semi-squat exercise group (Group II, n=10), and EMG-Biofeedback using closed kinetic chain exercise group (Group III, n=10). Intervention was provided to each group for eight weeks (three times per week; 30 minutes per day). Subjects were measured on Q-angle and quadriceps muscle activation. Results: Significant difference in Q-angle and quadriceps muscle activation was observed in groups II and III compared with control group I (p<0.01). Results of post-hoc analysis showed a significant difference in Q-angle and quadriceps muscle activation in on group III compared with groups I and II. Conclusion: Findings of this study suggest that closed kinetic chain exercise using EMG-Biofeedback that provides real-time biofeedback information on muscle contraction may have a beneficial effect on improvement of Q-angle and quadriceps muscle activation in patellofemoral pain syndrome.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.20 no.2
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• pp.9-14
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• 2014

Background: This study aims to examine correlations between quadriceps angle, lower extremity muscle strength and leg length discrepancy. Methods: This study selected 96 healthy women university students as the subjects of research. Quadriceps angle, lower extremity muscle strength and leg length discrepancy were measured. The statistical analysis of the data SPSS/window (version 12.0) were analyzed using the pearson correlation analysis. Results: There were negative correlations between the muscle strength of the right hamstring muscles and the right quadriceps angle in supine and standing positions. Functional leg length discrepancy of left and right quadriceps angle in supine and standing position showed positive correlations. Conclusions: The quadriceps angle affect the knee. An abnormal angle caused weakening of balance. Muscle strength, leg length discrepancy, and affected lower extremity alignment and knee function. These conclusions may prevent exercise limitation or disorders in the subjects and treating the patients with knee injury or patellofemoral pain syndrome with basic therapy intervention.

• The Journal of Korean Physical Therapy
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• v.35 no.2
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• pp.53-57
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• 2023

Purpose: The purpose of this study was to compare the changes in the muscle activation of the quadriceps muscle (rectus femoris, vastus lateralis, vastus medialis) during the stand-to-sit (StandTS) movement according to the plantar flexion angle of the ankle joint. Methods: A total of 22 healthy young females participated in this study. During the StandTS under the three conditions (plantarflexion angle 0°, 20°, and 45° of the ankle), electromyography (EMG) data (% maximum voluntary iso¬metric contraction) of the rectus femoris, vastus lateralis, and vastus medialis were recorded using a wireless surface EMG system. Results: There was a significant difference in the muscle activation of rectus femoris, vastus lateralis, and vastus medialis according to the plantar flexion angle (0°, 20°, and 45°) of the ankle. The muscle activation of the quadriceps was the highest at a 45° angle of plantarflexion and the lowest at 0°. One-way repeated ANOVA was used to analyze the muscle activation data of the lower extremity muscles according to the angle of the ankle joint. Conclusion: Based on the results of our study, it was confirmed that the muscle activity of the quadriceps can be increased even in the StandTS movement, which involves the eccentric contraction of the quadriceps muscle. This suggests that maintaining a plantar flexion posture for a long time, say by wearing high-heeled shoes, can quickly cause muscle fatigue in the lower-limb muscles, which can cause a decrease in balance ability leading to falls.

• Journal of Veterinary Science
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• v.21 no.5
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• pp.69.1-69.11
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• 2020

Background: An inappropriate Q angle may affect the biomechanics of the canine patellofemoral joint. Objectives: The purpose of this study was to evaluate the effects of changes in quadriceps angle (Q angle) on patellofemoral joint pressure distribution in dogs. Methods: Eight stifles were positioned at 45, 60, 75, 90, 105, and 120° of flexion in vitro, and 30% body weight was applied through the quadriceps. Patellofemoral contact pressure distribution was mapped and quantified using pressure-sensitive film. For the pressure area, mean pressure, peak pressure, medial peak pressure, and lateral peak pressure, differences between groups according to conditions for changing the Q angle were statistically compared. Results: Increases of 10° of the Q angle result in increases in the pressure area (P = 0.04), mean pressure (P = 0.003), peak pressure, and medial peak pressure (P ≤ 0.01). Increasing the Q angle by 20° increases the pressure area (P = 0.021), mean pressure (P ≤ 0.001), peak pressure (P ≤ 0.01), and medial peak pressure (P ≤ 0.01) significantly, and shows higher mean (P ≤ 0.001) and peak pressures than increasing by 10°. Decreasing the Q angle increases the mean pressure (P = 0.013), peak pressure, and lateral peak pressure (P ≤ 0.001). Conclusions: Both increases and decreases in the Q angle were associated with increased peak patellofemoral pressure, which could contribute to the overloading of the cartilage. Therefore, the abnormal Q angle should be corrected to the physiologically normal value during patellar luxation repair and overcorrection should be avoided.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.16 no.1
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• pp.1-8
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• 2010

Purpose : This study aimed to examine the relationships among five clinical measures for functional alignment of the lower extremity. Methods : Thirty healthy subjects (15 males and 15 females) were recruited for the study. The five clinical measures of functional alignment of the lower extremity included navicular drop, quadriceps angle, internal rotation of hip, and anterior and lateral pelvic tilt angles. The level of navicular drop was calculated by the difference between the height of the navicular bone in the sitting (non-weight bearing) and standing (weight bearing) positions. The quadriceps angle and internal rotation of hip were measured using a standard goniometer with photographic markers while the subjects were lying in a prone position on a table with their knee at $90^{\circ}$ flexion. Anterior and lateral pelvic tilt angles were determined using a inclinometer. Results : Correlation and a simple linear regression analysis were used to assess relationships between the clinical measures. There were significant correlations between navicular drop and quadriceps angle (p<.05), between navicular drop and internal rotation of hip (p<.05), and between quadriceps angle and internal rotation of hip (p<.01). In simple linear regression analysis, the navicular drop appeared to be a factor affecting the quadriceps angle and internal rotation of hip (p<.05). The findings suggest that navicular drop has a great impact on lower extremity alignment. Conclusion : This study might help us to examine lower extremity function and clarify its role as a potential injury risk factor.

• The Journal of Korean Physical Therapy
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• v.12 no.1
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• pp.9-13
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• 2000

The purpose of this study was to determine the overflow effect and cross training effect of isometric quadriceps training that performed in specific angle of unilateral let. Ten healthy students with an average age of 24 years$(24.1\pm1.3)$, were participated in this study. Then 5 subjects in each group were chosen at random to train using only right quadriceps muscle two time per day(group 2), five times a week and the other 5 subjects(group 1) were chosen to train one times per day, five times a week for 2 weeks at only 50 degrees (contract 6 seconds, rest 10 seconds, 3 sets). Before and after the training, isometric quadriceps muscle testing of the both leg was Performed at three different angles, 60, 50 and 40 degrees respectively by BHN-COM (isokinetic dynamometer) in sitting position. The data was analyzed with paired t-test to determine significant difference between before and after training. In this study, we have found that the isometric quadriceps muscle training on specific angle of right side produced overflow effect In healthy subjects. However, increasing the peak torque of specific angle(training angle) of trained limb did not have an effect on increasing the peak torque of contralateral limb. These results demonstrate that the cross training effect did nut found in this study but a alight increase of peak torque of the untrained limb would recognized the possibility of cross training effect.

• Journal of The Korean Society of Integrative Medicine
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• v.2 no.1
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• pp.15-21
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• 2014

Purpose : The aim of this study was to find out differences between muscle activity of quadriceps according to hip angle. Method : 40 healthy adults produced maximum isometric muscle contraction of quadriceps femoris and each part of the quadriceps femoris were measured with a surface EMG in hip joint angle of $90^{\circ}$, $135^{\circ}$, $180^{\circ}$. Result : There was no significant difference between muscle activity of vastus medialis and lateralis according to hip angle. But there was significant difference in muscle activity of rectus femoris and the muscle activity was maximum at 135 degrees of hip angle. Conclusion : In conclusion, maximum muscle activation of rectus femoris is affected by hip angle, and the findings from this study may be helpful for physical therapists in selecting hip position when instructing patients to do Q-setting exercise. So, we suggest that patients perform Q-setting exercise at 135 degrees of hip angle for the best result.

• Physical Therapy Korea
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• v.6 no.1
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• pp.1-14
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• 1999

The quadriceps angle (Q angle) has been used to reflect the quadriceps muscle's force on the patella in the frontal plane. Previous investigations of the Q angle and it's relationship to knee disorders have yield equivocal results. The purpose of this study was to analyze the factors related to the Q angle and it's relation to other variables such as leg length, body weight, CTA (calcaneus to tibia angle), TOA (toe out angle), and pelvic width in normal subjects. The participants were 60 students (30 men and 30 women) who had no orthopedic and neurological impairments, aged from 20 to 29 years of age, with an average age of 22.1 years. Prior to participation, each subject was informed of the procedures of the experiment from a researcher and assistant researchers. The equipment used in this study were modified standard goniometer, ruler, marking pen, and Martin apparatus for pelvic width. In order to determine the statistical significance of the experiment, regression analysis, independent t-test, and Pearson correlation were used at the 0.05 level. The results were as follows: 1) It was found that the Q angle of women is greater than that of men's from both knees. 2) There was no significant difference between right and left quadriceps angle. 3) The Q angle decreased as the body weight (leg length) shifted from low to high. 4) It seems that factors related to the Q angle were body weight, CTA, and pelvic width, but there was no significant difference at the 0.05 level.

• PNF and Movement
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• v.17 no.2
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• pp.311-319
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• 2019

Purpose: This study was conducted to determine the structural change in knees caused by quadriceps angle and the muscle activity in lower limbs. Indirect intervention was provided by using taping for stability in the ankle joints, which affected patellofemoral pain. Methods: The subjects in this study were 20 patients with patellofemoral pain who visited ${\bigcirc}{\bigcirc}{\bigcirc} $ Hospital in Busan. The visual analogue scale measured the dynamic quadriceps angle and the degree of pain felt by the patients while walking down stairs, which was a known factor of patellofemoral pain. In addition, muscle activities in the rectus femoris, vastus lateralis, vastus medialis, tibialis anterior, peroneus longus, and biceps femoris, which affect the knees and ankles, were measured using surface electromyography. The muscle activities were converted into %RVC for this study. The data obtained in this study were analyzed with the Wilcoxon signed-rank test using the SPSS Ver. 25.0 statistical program. The significance level ${\alpha}$ was 0.05. Results: The study results showed that the pain and dynamic quadriceps angle were significantly reduced statistically when applying the calcaneus fixation taping (p<0.05). Muscle activity in the lower limbs was significantly decreased in the vastus medialis, vastus lateralis, and tibialis anterior (p<0.05). Conclusion: The summary of the study results verified that the calcaneus fixation taping reduced the pain and dynamic quadriceps angle by providing stability in the ankle joints. It also produced efficient movement due to the difference in lower-limb muscle activity.

• Physical Therapy Korea
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• v.12 no.1
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• pp.45-54
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• 2005

The quadriceps-angle (Q-angle) and the ratio of hamstring/quadriceps (H/Q) are important for the stability of the knee and for protection from excessive stress. The aim of this study was to examine the association between Q-angle and H/Q ratio with and without knee osteoarthritis. We compared knee osteoarthritis patients with symptom-free women. The mean age of the patients in the arthritis group (25 women, osteoarthritis) was 59.7 years. The non-arthritis group consisted of 25 women with a mean age of 55.2 years. Of the 25 women with osteoarthritis, 5 had the condition in their left knee, 5 had it in their right knee, and 15 had it on both sides. There was no significant difference in the knee Q-angle of the left and right knees of the arthritis group and the non-arthritis-group (p>.05). The strength of all the muscles around the involved right knee in the arthritis group was significantly weaker than that of the non-arthritis group (p<.05). However, in the left knee, only the strength of the knee extensors and internal rotators was significantly weaker than that of the non-arthritis group (p<.05). The Q-angle was not associated with the H/Q ratio and internal rotators/external rotators ratio of the involved knee in the arthritis group (p>.05). Neither was the Q-angle associated with the pain level of an involved knee in the arthritis group (p>.05). The knee pain was not associated with the H/Q ratio of the involved knee in the arthritis group (p>.05). The Q-angle was not associated with the ratio of H/Q and pain level of the involved knee in the osteoarthritis women.