Electromyographic fatigue characteristics of the quadriceps in patellofemoral pain syndrome

This study compared the fatigue characteristics of the vastus medialis oblique (VMO), vastus lateralis (VL) and rectus femoris (RF) muscles. Ten healthy subjects with 10 patients with patellofemoral pain syndrome (PFPS) performed an isometric leg press for 60 seconds at 60% MVIC with data collected using surface EMG. The power spectrum was analyzed and the extracted median frequency normalised to calculate a linear regression slope for each muscle. A repeated measures ANOVA revealed no significant differences, neither between the groups (P=0.592) nor the muscles (P=0.434). However, the slopes for the VMO and VL were different between the two groups with similar slopes for the RF. There was much larger variability of MF values in the PFPS group. The VMO:VL ratio calculated from these slopes for the healthy subjects was 1.17 and for the PFPS group was 1.78. These results may indicate unusual features in the fatigue indices of the quadriceps in PFPS.     

髌股关节疼痛及其临床治疗的研究

概述过去十年作者在实验室进行有关髌股关节及髌股关节疼痛综合征(PFPS)的研究,研究了正常人髌股关节的几个指标及PFPS患者的康复成效。研究结果反映股内侧肌(VMO)对于控制髌股关节的压力分布所发挥的力学作用、下肢方位对促进VMO募集的影响,以及髌骨叩压、股四头肌的疲劳恢复与生物反馈辅助对PFPS康复治疗的作用。     

Contribution of components of the quadriceps femoris muscle for producing external torque in patients with patellofemoral pain syndrome

IntroductionDifferent muscular activities of the quadriceps components for producing necessary torque may change in patients with patellofemoral pain syndrome (PFPS). The aim of the current study, therefore, was to assess the contribution of each component of the quadriceps femoris muscle for producing external torque in patients with PFPS.MethodTwelve females with PFPS (24.7 ± 2.3 years) and twelve healthy matched females (25.4 ± 2.4 years) performed three consecutive knee flexion and extension movements with maximum effort at 45°/s and 300°/s using a Biodex system 3 dynamometer. Simultaneously, electromyographic (EMG) activities of the vastus medialis oblique (VMO), RF (rectus femoris) and vastus lateralis (VL) muscles were recorded using a DataLog instrument. Standard multiple regressions were used to assess the ability of EMG activities of the VMO, RF and VL muscles to predict normalized quadriceps femoris isokinetic concentric and eccentric torques at 45°/s and 300°/s in the normal and patient groups.ResultsIn the normal group, the VL and the VMO were the good predictors of quadriceps concentric torque at 45°/s and 300°/s, respectively. The VL and the RF were the good predictors of quadriceps eccentric torque at 300°/s in the patient group. No other conditions showed a considerable prediction for quadriceps torque in the normal or patient group.ConclusionFemales with PFPS differ with normal females in terms of the contribution of each component of the quadriceps femoris for producing external torque. Training the VMO for concentric contraction at both high and low velocities should be included in the management of the patients with PFPS.     

Outcomes of a weight-bearing rehabilitation program for patients diagnosed with patellofemoral pain syndrome

OBJECTIVE: To determine the effects of a weight-bearing rehabilitation program on quadriceps and gluteus medius electromyographic activity, pain, and function in subjects diagnosed with patellofemoral pain syndrome (PFPS). DESIGN: Pretest and posttest 6-week intervention study. SETTING: Musculoskeletal research laboratory. PARTICIPANTS: Fourteen subjects diagnosed with PFPS and 14 healthy control subjects volunteered to participate in this study. No subjects withdrew from the study because of adverse effects. INTERVENTION: Subjects diagnosed with PFPS participated in a 6-week rehabilitation program. The rehabilitation program consisted of weight-bearing exercises that focused on strengthening the quadriceps and hip abductor musculature. MAIN OUTCOME MEASURES: Electromyographic onsets of the vastus medialis oblique (VMO) and vastus lateralis and onset and duration of the gluteus medius were collected during a stair-stepping task that was performed during the pretest and posttest. A visual analog scale (VAS) and Functional Index Questionnaire (FIQ) were administered at pretest and posttest and each week of the intervention. RESULTS: Vastus lateralis and VMO onset timing differences (vastus lateralis electromyographic onset minus VMO electromyographic onset) and VAS and FIQ scores significantly improved for patients diagnosed with PFPS. Vastus lateralis and VMO onset timing in the PFPS group were significantly different from those in the control group at baseline and were not significantly different from the control group after the intervention. We did not find differences in gluteus medius onsets or duration of activity. CONCLUSIONS: Subjects diagnosed with PFPS responded favorably and quickly to a therapeutic exercise program that incorporated quadriceps and hip musculature strengthening. The efficacy of the therapeutic exercise program used in this study should be further investigated in a larger subject population.     

Altered vastii recruitment when people with patellofemoral pain syndrome complete a postural task

OBJECTIVE: To investigate the recruitment of the vastus medialis obliquus (VMO) and vastus lateralis during voluntary tasks that challenge the stability of the knee and to evaluate whether there is a change in the coordination of the postural response by the central nervous system in subjects with patellofemoral pain syndrome (PFPS). DESIGN: Cross-sectional. SETTING: University laboratory in Australia. PARTICIPANTS: Thirty-seven subjects with PFPS and 37 asymptomatic sex-matched controls. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Recordings of electromyographic activity of the VMO, vastus lateralis, tibialis anterior, and soleus were made by using surface electrodes. Subjects rose onto their toes (rise task) or rocked back on their heels (rock task) in a visual choice-reaction time task. Electromyographic onsets were determined by using a computer algorithm and were verified visually. RESULTS: Our results confirm that, in asymptomatic subjects, contraction of the VMO and vastus lateralis occurs as part of the feed-forward postural response associated with ankle movements in standing, and the contraction of these separate heads of the quadriceps group occurs simultaneously. However, when subjects with PFPS perform identical tasks, the electromyographic onset of the vastus lateralis occurs before that of the VMO. CONCLUSION: These findings indicate a difference in motor control in subjects with PFPS. They also support the hypothesized relation between changes in the timing of activity of the vastii and PFPS and provide the theoretic rationale to support physiotherapy treatment commonly used in the management of PFPS.     

Vastus medialis obliquus and vastus lateralis activity in open and closed kinetic chain exercises in patients with patellofemoral pain syndrome: an electromyographic study

OBJECTIVES: To evaluate the electromyographic activities of vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles in open and closed kinetic chain exercises in subjects with patellofemoral pain syndrome (PFPS). DESIGN: Case-controlled study. SETTING: Rehabilitation science center in a tertiary medical center. PARTICIPANTS: Ten patients with bilateral knee pain diagnosed with PFPS and 10 healthy volunteers. INTERVENTIONS: Subjects performed open kinetic chain exercise on an isokinetic dynamometer and closed kinetic chain exercise by squat-to-stand and stand-to-squat tasks. Surface electromyography was done for the VMO and VL muscles. MAIN OUTCOME MEASURES: VMO/VL ratios were calculated after normalization of muscle activities. RESULTS: The VMO/VL ratios of PFPS subjects were significantly lower than were those of unimpaired subjects during knee isokinetic closed kinetic chain exercises (p = .047). However, there was no statistical difference in VMO/VL ratio between subjects with and without PFPS during closed kinetic chain exercises (p = .623). Maximum VMO/VL ratio was obtained at 60 degrees knee flexion in closed kinetic chain exercise. CONCLUSION: In closed kinetic chain exercises, more selective VMO activation can be obtained at 60 degrees knee flexion. Maximal VMO/VL ratio was observed at this knee flexion angle, and muscle contraction intensity was also greatest.     

Temporal activity of vastus medialis obliquus and vastus lateralis in symptomatic knee osteoarthritis

OBJECTIVE: Knee osteoarthritis has a major impact on quadriceps function, yet its effect on the specific temporal recruitment of vastus medialis obliquus and vastus lateralis is unknown. The aim of this study was to determine the electromyographic onset of vastus medialis obliquus activity relative to that of vastus lateralis in individuals with symptomatic knee osteoarthritis and in an asymptomatic control group during the functional task of stair climbing. DESIGN: Cross-sectional, comprising 41 participants with symptomatic knee osteoarthritis and 33 controls matched for age, sex, and body mass. RESULTS: No significant differences were detected in the timing of onset of vastus medialis obliquus relative to that of vastus lateralis between the osteoarthritis and control groups. Radiographic osteoarthritis severity, presence of patellofemoral joint disease, and pain intensity did not seem to influence the temporal relationship of the vastii in the osteoarthritis group. CONCLUSION: The presence of symptomatic, radiographic knee osteoarthritis is not associated with deficits in the temporal recruitment of vastus medialis obliquus and vastus lateralis during stair climbing. This implies that selective retraining of the individual components of the quadriceps is not indicated in rehabilitation programs for patients with this disease.     

表面肌电仪对髌股疼痛综合征患者膝关节肌电活动的分析

目的利用表面肌电仪分析髌股疼痛综合征患者康复训练前后股内侧斜肌（VMO）和股外侧肌（VL）肌电活动的变化。方法26例髌股疼痛综合征患者随机分为神经肌电生物反馈训练组（A组）和单纯训练组（B组）各13例，均接受相同的家庭训练，但A组患者在神经肌电生物反馈仪配合下进行训练。所有患者在开始训练前和训练8周后，利用表面肌电仪对VMO和VL的神经肌肉电活动进行连续6h评定，同时对膝关节疼痛程度进行评定。结果治疗后，B组患者的VMO／VL神经肌电比率与治疗前比较差异无显著性意义（P〉0．05），而A组患者的VMO／VL神经肌电比率与治疗前比较差异有显著性意义（P〈0．05）。结论采用神经肌电生物反馈仪配合髌股疼痛综合征患者的康复训练可促进股内侧斜肌的募集。     

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

[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.Key words: Electromyography, Quadriceps muscle, Isometric contraction     

Comparison of vastus medialis obliquus: vastus lateralis muscle integrated electromyographic ratios between healthy subjects and patients with patellofemoral pain

The purpose of this study was to compare vastus medialis obliquus:vastus lateralis muscle (VMO:VL) integrated electromyographic (IEMG) ratios of healthy subjects and patients with unilateral patellofemoral pain (PFP) under isotonic and isometric quadriceps femoris muscle contraction conditions. Subjects ranging in age from 18 to 35 years (mean = 28.06, SD = 5.97) were assigned to one of three groups on the basis of type of knee condition. In group 1, which consisted of seven healthy control subjects with no history of knee pathology, both knees were tested. In group 2, which consisted of nine patients with unilateral PFP, only the painful knee was tested. In group 3, which consisted of the same nine patients who comprised group 2, only the nonpainful knee was tested. Nonnormalized and normalized VMO:VL IEMG ratios were computed for ascending stairs, descending stairs, submaximal isometric contraction, and maximal isometric contraction (nonnormalized only). A two-way analysis of variance for repeated measures indicated VMO:VL ratios for isotonic stair-climbing activities were significantly greater than VMO:VL ratios for isometric contractions. Nonnormalized VMO:VL ratios in group 1 were significantly greater than nonnormalized VMO:VL ratios in the other two groups. Patients with PFP may have abnormal VMO:VL activation patterns, and isotonic quadriceps femoris muscle exercise may elicit more favorable muscle activation patterns than isometric exercise for patients with PFP.     

闭链与开链运动对髌股疼痛综合征股四头肌作用的表面肌电图研究

摘要 目的：利用表面肌电图(sEMG)对髌股疼痛综合征（patellofemoral pain syndrome, PFPS）患者双足半蹲伴或坐位伸膝动作下股四头肌进行评估,比较不同开链与闭链动作对股四头肌的作用差异。 方法：PFPS病例组及正常对照组各30例,分别在双足半蹲以及坐位伸膝动作时检测股外侧肌(vastus lateralis, VL)及股内斜肌（vastus medialis oblique, VMO）表面肌电图,分析时域、频域指标,比较其平衡关系。 结果：病例组双足半蹲动作与坐位伸膝动作时各肌电指标的VL/VMO比值在时域、频域指标均有显著性差异,在坐位单侧完全伸膝动作时VL/VMO肌电比值大于双足半蹲动作且>1。 结论：VL、VMO表面肌电指标在双足半蹲动作时较坐位单侧完全伸膝动作时更接近平衡,提示适当屈膝时的闭链运动能够更有选择性地激发VMO,这为PFPS的康复治疗的动作选择提供参考。     

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

[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.Key words: Quadriceps muscle, Genu varum, Genu valgum     

Electromyographic activity of the quadriceps components during the final degrees of knee extension

An imbalance in the recruitment patterns of the quadriceps muscle has been implicated in patellofemoral knee pain; however ambiguity remains in the normal recruitment patterns of this muscle. We investigated the activity of the quadriceps muscle during the final degrees of knee extension, specifically in the medial and lateral components. Sixteen healthy subjects (age; 22.5 (± 3.4) years, body mass; 67.5 (± 12.1) kg and height; 173.9 (± 10.4) cm) participated.Torque and electromyographic (EMG) activity of the quadriceps muscle were measured during isokinetic and isometric knee extensions. Torque and EMG activity reduced in all component muscles during the final degrees of isokinetic extension, but this did not occur during isometric contractions at similar angles. Normalised activity of rectus femoris (RF) was greater than that of vastus lateralis (VL) and vastus medialis obliquus (VMO) during the final degrees of isokinetic knee extension at 30°/sec; there were no differences between any component muscles at the higher velocities. VMO:VL and vastus medialis longus (VML):VL ratios were unchanged during knee extensions, except that VML:VL ratio increased significantly during the final degrees of extension at 30°/sec. Future work should compare these results with people with anterior knee pain, and explore this further during activities of daily living.     

Delayed onset of electromyographic activity of vastus medialis obliquus relative to vastus lateralis in subjects with patellofemoral pain syndrome

OBJECTIVE: To determine whether electromyographic (EMG) onsets of vastus medialis obliquus (VMO) and vastus lateralis (VL) are altered in the presence of patellofemoral pain syndrome (PFPS) during the functional task of stair stepping. DESIGN: Cross-sectional. SETTING: University laboratory. PATIENTS: Thirty-three subjects with PFPS and 33 asymptomatic controls. INTERVENTIONS: Subjects ascended and descended a set of stairs-2 steps, each 20-cm high-at usual stair-stepping pace. EMG readings of VMO and VL taken on middle stair during step up (concentric contraction) and step down (eccentric contraction). MAIN OUTCOME MEASURES: Relative difference in onset of surface EMG activity of VMO compared with VL during a stair-stepping task. EMG onsets were determined by using a computer algorithm and were verified visually. RESULTS: In the PFPS population, the EMG onset of VL occurred before that of VMO in both the step up and step down phases of the stair-stepping task (p <.05). In contrast, no such differences occurred in the onsets of EMG activity of VMO and VL in either phase of the task for the control subjects. CONCLUSION: This finding supports the hypothesized relationship between changes in the timing of activity of the vastimuscles and PFPS. This finding provides theoretical rationale to support physiotherapy treatment commonly used in the management of PFPS.     

Differences in onset timing between the vastus medialis and lateralis during concentric knee contraction in individuals with genu varum or valgum

[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.Key words: Quadriceps muscle, Genu varum, Genu valgum     

Quadriceps muscle activity in women runners with and without patellofemoral pain syndrome.

The purpose of this study was to determine whether there was a difference in the electromyographic (EMG) patterns of the quadriceps muscles in women runners diagnosed with patellofemoral pain syndrome (PFPS) compared to the quadriceps activity of women runners free of knee pain and with normal lower extremity alignment. Linear envelope EMGs from vastus medialis, vastus lateralis, and rectus femoris, together with a footswitch signal, were recorded as each subject ran on a treadmill at 80% of their normal running pace and at 12km/h. Each stride period was normalized to 100%, then the linear envelopes for ten trials were ensemble averaged to achieve a mean ensemble for each muscle from each subject. Subsequently, the ensembles for each subject were normalized by dividing by the maximum EMG per cycle; they were then averaged across subjects to obtain the grand mean ensembles of each muscle for each group. Comparisons between the experimental and control groups at both speeds showed that nowhere during the stride cycle did the mean EMG levels of the two groups differ by more than two standard deviations. It was concluded that any changes in the running pattern of the runners with patellofemoral pain syndrome could not be detected by changes in the EMG patterns.     

Effect of Weight-bearing Therapeutic Exercise on the Q-angle and Muscle Activity Onset Times of Elite Athletes with Patellofemoral Pain Syndrome: A Randomized Controlled Trial

[Purpose] The purpose of this study was to determine the effect of a weight-bearing therapeutic exercise program for elite athletes diagnosed as having patellofemoral pain syndrome (PFPS). [Subjects] The subjects were 34 elite athletes from the Seoul T Center. They were randomly allocated to three groups: an elastic band exercise group (EBG), a sling exercise group (SEG), or a control group (CG). [Methods] Therapeutic exercises were performed 3 times a week for 8 weeks. The visual analogue scale (VAS) hamstring length, and static and dynamic Q angles were used to test the exercise effect of the exercises, as well as the onset time of electromyographic activity of vastus medialis oblique (VMO) and vastus lateralis (VL). [Results] Decrease of the dynamic Q-angle in EBG was significant and significantly greater than that in CG. The decrease in VAS in SEG was significant and significantly greater than that in CG. There were significant differences in the VL and VMO activity onset times in SEG between pre- and post-test, and their differences between pre- and post-test were also significantly different. [Conclusion] Weight-bearing therapeutic exercise is hoped that clinicians will use this information for better implementation of effective exercise methods for elite athletes with PFPS.Key words: Electromyographic onset time, Patellofemoral pain syndrome, Q-angle     

COMPARISON OF HIP AND KNEE STRENGTH AND NEUROMUSCULAR ACTIVITY IN SUBJECTS WITH AND WITHOUT PATELLOFEMORAL PAIN SYNDROME

Purpose/Background:

Historically, patellofemoral pain syndrome (PFPS) has been viewed exclusively as a knee problem. Recent findings have suggested an association between hip muscle weakness and PFPS. Altered neuromuscular activity about the hip also may contribute to PFPS; however, more limited data exist regarding this aspect. Most prior investigations also have not concurrently examined hip and knee strength and neuromuscular activity in this patient population. Additional knowledge regarding the interaction between hip and knee muscle function may enhance the current understanding of PFPS. The purpose of this study was to compare hip and knee strength and electromyographic (EMG) activity in subjects with and without PFPS.

Methods:

Eighteen females with PFPS and 18 matched controls participated in this study. First, surface EMG electrodes were donned on the gluteus medius, vastus medialis, and vastus lateralis. Strength measures then were taken for the hip abductors, hip external rotators, and knee extensors. Subjects completed a standardized stair-stepping task to quantify muscle activation amplitudes during the loading response, single leg stance, and preswing intervals of stair descent as well as to determine muscle onset timing differences between the gluteus medius and vastii muscles and between the vastus medialis and vastus lateralis at the beginning of stair descent.

Results:

Females with PFPS demonstrated less strength of the hip muscles. They also generated greater EMG activity of the gluteus medius and vastus medialis during the loading response and single leg stance intervals of stair descent. No differences existed with respect to onset activation of the vastus medialis and vastus lateralis. All subjects had a similar delay in gluteus medius onset activation relative to the vastii muscles.

Conclusion:

Rehabilitation should focus on quadriceps and hip strengthening. Although clinicians have incorporated gluteus medius exercise in rehabilitation programs, additional attention to the external rotators may be useful.Level of Evidence: 4     

Effects of Open and Closed Kinetic Chains of Sling Exercise Therapy on the Muscle Activity of the Vastus Medialis Oblique and Vastus Lateralis

[Purpose] The muscle strength of the quadriceps muscle is critical in patellofemoral pain syndrome. The quadriceps muscle supplies the power for dynamic patellar movement, and the vastus medialis oblique (VMO) and vastus lateralis (VL) enable the patella to stabilize during tracking. We followed the theories about open and closed kinetic chain exercises to design two exercises, sling open chain knee extension (SOCKE) exercise and sling closed chain knee extension (SCCKE) exercise. The purpose of our study was to research the changes in quadriceps muscle activity during both exercises. [Methods] Electromyographic analysis was used to explore the different effects of the two exercises. The MVC% was calculated for the VMO and VL during exercise for analysis. [Results] We found that the mean MVC% values of the VMO and VL during the SOCKE exercise were higher than those during the SCCKE exercise. The ratio of the VMO to VL was 1.0 ± 0.19 during the SOCKE exercise and 1.11 ± 0.15 during the SCCKE exercise. [Conclusions] The SOCKE exercise is targeted at quadriceps muscle training and has a recruitment effect on the VMO. The beneficial effect of the SOCKE exercise is better than that of the SCCKE exercise.Key words: Patellofemoral pain syndrome, Sling exercise therapy, Electromyography     

Differences of quadriceps activity during inline lunge by using FMS assessment

[Purpose] This study assessed the exercise capacity of healthy adults while performing the inline lunge exercise by using Functional Movement Screen (FMS). Compared the difference in muscle activity of the quadriceps according to the exercise capacity. [Participants and Methods] Thirty two healthy participants (12 males, 20 females) participated in this study. The surface electromyography (sEMG) was used to measure the electrical activities for the vastus medialis (VM), rectus femoris (RF), vastus lateralis (VL) of quadriceps. [Results] Both groups had significant difference when sitting up and getting up during the inline lunge. In scores 3 group, vastus medialis showed higher muscle activity than vastus lateralis. On contrary, in scores 2 group, vastus lateralis had higher muscle activity than vastus medialis. [Conclusion] Therefore, this study suggests that inline lunge can help to strengthen the quadriceps effectively by showing the difference of quadriceps activity according to exercise capacity.Key words: Inline lunge, Muscle activity, Functional movement screen