***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    ***EXAMPLES*** 
    Input: The purpose of this study was to compare the effect of an open-stance cycling protocol ( OSCP ) with the traditional cycling foot position ( TCFP ) for preferential vastus medialis oblique ( VMO ) muscle activation , measured by surface electromyography ( SEMG ) , and preferential VMO activation as defined by achieving significantly increased VMO/VL ( vastus lateralis muscle ) ratio values . Forty subjects of both sexes participated , 18 symptomatic with patellofemoral pain and 22 control subjects ; ages ranged from 18 to 60 years ( mean 5 28.7 ± 8 years ) . The OSCP and TCFP were ridden in r and omized order while SEMG recordings were taken of the VMO and VL muscles , collecting the mean of peak amplitudes to calculate VMO/VL ratio values . The SEMG readings were taken 4 times per testing session with r and omized resistance and a consistent cycling cadence of 85 rpm . The OSCP  displayed preferential VMO activation for all subject groups ( F = 40.47 , p = 0.0001 ) , and this study revealed a protocol that effectively treats patellofemoral pain Strengthening of the vastus medialis oblique ( VMO ) has been advocated as a treatment for patellofemoral pain syndrome ( PFPS ) , as weakness of this component of the quadriceps is postulated to contribute to malalignment of the patella . This study investigated the  surface electromyographic activity ( EMG ) of the VMO relative to the vastus lateralis ( VL ) during five isometric exercises in eight PFPS female subjects and 19 controls . The area under the EMG curve of each muscle was normalized to the EMG area acquired while subjects performed a submaximal isometric contraction ( 50 % of maximum voluntary contraction ) , and the " normalized " outcome measure was expressed as a proportion ( VMO : VL ) . A two-factor repeated measures analysis of variance indicated no differences in the VMO : VL proportion between the control group and PFPS participants across the five exercises ( p > .05 ) . The VMO : VL proportions  for medial tibial rotation and knee extension combined and knee extension alone were significantly greater than for the other three exercises ( p < 0.005 ) . Hip adduction or the combination of hip adduction and knee extension did not result in greater recruitment of the VMO compared with the VL A prospect i ve study of 20 normal subjects was undertaken to determine the effect of three ankle positions ( active dorsiflexion , active plantar flexion , natural or rest position ) on comfort and facilitation of quadriceps contraction in isometric strengthening in a supine position with the hip and knee fully extended . Surface EMG activity was found to be greatest for the vastus lateralis followed by the vastus medialis and least for the rectus femoris . Equal facilitation was apparent with either active ankle dorsiflexion or plantar flexion . Both were superior to the natural ( rest ) position . In situations where isometric quadriceps exercises are required , the authors recommend either active ankle dorsiflexion or plantar flexion to facilitate quadriceps strengthening . The choice between the two positions should be based on patient comfort OBJECTIVE The purpose of this study was to investigate the effect of hip adduction on the activity of the Vastus Medialis Obliquus ( VMO ) and Vastus Lateralis Longus ( VLL ) muscles during semisquat exercises . METHODS Twenty female subjects , divided into two groups comprising healthy and patellofemoral pain syndrome ( PFPS ) subjects ( ten volunteers for each group ) , performed three double-leg semisquat exercise trials with maximum hip adduction isometric contraction ( DLSS-HA ) and three double-leg semisquat exercise trials without hip adduction ( DLSS ) . The normalized electromyographic muscle data were analysed using Repeated Measure ANOVA ( p < or=0.05 ) . RESULTS The electrical activity of both VMO and VLL muscles was significantly greater during DLSS-HA exercise than during DLSS ( p=0.0002 ) for both groups . Additionally , an independent Repeated Measure ANOVA revealed that the electric activity of the VLL muscle was significantly greater ( p=0.0149 ) than that of the VMO muscle during DLSS exercises only for the PFPS group . However , no differences were found during DLSS-HA exercises . CONCLUSIONS Although there was no preferential VMO muscle activation , the association of hip adduction with squat exercise promoted a greater balance between the medial and lateral portions of the quadriceps femoris muscle and could be indicated for the conservatory treatment of PFPS patients . The association of isometric hip adduction with isometric semisquat exercises produced a more overall quadriceps activity and could be indicated for clinical rehabilitation or muscle strengthening programs Lam PL , Ng GYF : Activation of the quadriceps muscle during semisquatting with different hip and knee positions in patients with anterior knee pain . Am J Phys Med Rehabil 2001;80:804–808 . Objective We measured the surface electromyographic activities of vastus medialis obliquus and vastus lateralis in 16 subjects with patellofemoral joint pain syndrome . Design Each subject performed bilateral static knee extension exercises at 60 % of his or her maximal voluntary effort under different combinations of hip rotation ( 30 degrees of medial rotation , neutral , 45 degrees of lateral rotation ) and knee flexion ( 20 and 40 degrees ) in a st and ing position . The ratio of surface-integrated electromyographic signals of vastus medialis obliquus over vastus lateralis was calculated for each of the six conditions . Because of significant interaction of hip rotation and knee flexion in the two-way analysis of variance , data were analyzed separately with paired t tests for the effect of knee positions and one-way repeated measures analysis of variance for hip positions . Results At 20 degrees of knee flexion , there was no significant difference among the three hip positions , whereas at 40 degrees of knee flexion , medial rotation of the hip result ed in significantly higher vastus medialis obliquus over vastus lateralis activity ratio than lateral rotation ( P < 0.05 ) . Conclusions There was relatively more activation of vastus medialis obliquus than vastus lateralis at 40 degrees of semisquat with the hip medially rotated by 30 degrees . This finding has clinical implication s for training the vastus medialis obliquus in patients with patellofemoral joint pain syndrome The purpose of this study was to determine whether various positions of the lower extremity affect the muscle activity of the vastus medialis obliquus ( VMO ) differently during both open and closed kinetic chain exercise conditions among patients with patellofemoral pain syndrome ( PFPS ) . Patients who presented with symptoms consistent with PFPS completed a series of open kinetic chain and closed kinetic chain exercises in which  VMO activity was measured and compared . Statistical analysis revealed that there is less than a 0.001 % ( open kinetic chain ) or 0.005 % ( closed kinetic chain ) chance that all positions activate the VMO equally . In open kinetic exercise , maximum VMO activity was achieved with terminal knee extension with medial tibial rotation . During closed kinetic exercises , squats with external rotation were preferred for maximum VMO activation . Therefore , our results highlight the importance of including both the open and closed kinetic chain exercises into rehabilitation programs for patients with PFPS Nondriving intersegmental knee moment components ( i.e. , varus/valgus and internal/external axial moments ) are thought to be primarily responsible for the etiology of overuse knee injuries such as patellofermoral pain syndrome in cycling because of their relationship to muscular imbalances . However the relationship between these moments and muscle activity has not been studied . Thus the four primary objectives of this study were to test whether manipulating the inversion/eversion foot angle alters the varus/valgus knee moment ( Objective 1 ) and axial knee moment ( Objective 2 ) and to determine whether activation patterns of the vastus medialis oblique ( VMO ) , vastus lateralis ( VL ) , and tensor fascia latae ( TFL ) were affected by changes in the varus/valgus ( Objective 3 ) and axial knee moments ( Objective 4 ) . To fulfill these objectives , pedal loads and lower limb kinematic data were collected from 15 subjects who pedaled with five r and omly assigned inversion/eversion angles : 10 deg and 5 deg everted and inverted and 0 deg ( neutral ) . A previously described mathematical model was used to compute the nondriving intersegmental knee moments throughout the crank cycle . The excitations of the VMO , VL , and TFL muscles were measured with surface electromyography and the muscle activations were computed . On average , the 10-deg everted position decreased the peak varus moment by 55 % and decreased the peak internal axial moment by 53 % during the power stroke ( crank cycle region where the knee moment is extensor ) . A correlation analysis revealed that the VMO/VL activation ratio increased significantly and the TFL activation decreased significantly as the varus moment decreased . For both the VMO/VL activation ratio and the TFL activation , a path analysis indicated that the varus/valgus moment was highly correlated to the axial moment but that the correlation between muscle activation and the varus moment was due primarily to the varus/valgus knee moment rather than the axial knee moment . The conclusion from these results is that everting the foot may be beneficial towards either preventing or ameliorating patellofemoral pain syndrome in cycling PURPOSE To investigate the effect of physical therapy treatment on the timing of electromyographic ( EMG ) activity of the vasti in individuals with patellofemoral pain syndrome ( PFPS ) . METHODS Sixty-five ( 42 female , 23 male ) participants aged 40 yr or less ( 29.2 + /- 7.8 yr ) diagnosed with PFPS . Participants were r and omly allocated into physical therapy treatment ( McConnell-based ) or placebo groups . Treatment programs were st and ardized and consisted of six-treatment sessions over 6 wk . Vastus medialis oblique ( VMO ) and vastus lateralis ( VL ) EMG activity  was recorded with surface electrodes during a stair-stepping task and onsets of EMG activity  were measured pre- and post-treatment . RESULTS Before treatment , the EMG onset of VL occurred before that of VMO in both participant groups . After physical therapy intervention , there was a reduction in symptoms , and this improvement was associated with a significant change in the time of onset of VMO EMG compared with that of VL in both phases of the stair-stepping task . After physical therapy treatment , the onset of VMO preceded VL in the eccentric phase and occurred at the same time in the concentric phase of the stair-stepping task . There was no change in time of EMG onset in the placebo group . CONCLUSION This study demonstrates that a " McConnell"-based physical therapy treatment regime for PFPS alters the motor control of VMO relative to VL in a functional task and this is associated with a positive clinical outcome The clinical application of EMG requires that the recorded signal is representative of the muscle of interest and is not contaminated with signals from adjacent muscles . Some authors report that surface EMG is not suitable for obtaining information on a single muscle but rather reflects muscle group function [ J. Perry , C.S. Easterday , D.J. Antonelli , Surface versus intramuscular electrodes for electromyography of superficial and deep muscles . Physical Therapy 61 ( 1981 ) 7 - 15 ] . Other authors report however , that surface EMG is adequate to determine individual muscle function , once guidelines pertaining to data acquisition are followed [ D.A. Winter , A.J. Fuglev and , S.E. Archer . Cross-talk in surface electromyography : theoretical and practical estimates . Journal of Electromyography and Kinesiology 4 ( 1994 ) 15 - 26 ] . The aim of this study was to determine whether surface EMG was suitable for monitoring rectus femoris ( RF ) activity during static contractions . Five healthy subjects , having given written informed consent , participated in this trial . Surface and fine wire EMG from the rectus femoris and the vastus lateralis ( VL ) muscles were recorded simultaneously during a protocol of static contractions consisting of knee extensions and hip flexions . Ratios were used to quantify the relationship between the surface EMG amplitude value and the fine wire EMG amplitude value for the same contraction . The results showed that hip flexion contractions elicited RF activation only and that knee extension contractions elicited fine wire activity in VL only . When the relationship between RF surface and RF fine wire electrodes was compared for hip flexion and knee extension contractions , it was observed that for all subjects , there was a tendency for increased RF surface activity in the absence of RF fine wire activity during knee extensions . It was concluded that the activity recorded by the RF surface electrode arrangement during knee extension consisted of EMG from the vastii , i.e. , cross-talk and that vastus intermedius was the most likely origin of the erroneous signal . Therefore it is concluded that for accurate EMG information from RF , fine wire electrodes are necessary during a range of static contractions PURPOSE This study aim ed to examine whether a physical therapy intervention , design ed to reduce pain and improve the neuromotor control result ed in greater improvements in stance-phase knee flexion during stair ambulation in individuals with patellofemoral pain . The relationship between changes in stance-phase knee flexion and changes in pain , disability , and onset timing of individual vasti activity was also examined . METHODS Forty participants aged 40 yr or younger diagnosed with patellofemoral pain were r and omly allocated to a physical therapy ( N = 21 ) or placebo ( N = 19 ) treatment group . Stance-phase knee flexion was measured in two dimensions using a PEAK movement analysis system during stair ambulation . Individuals were divided into those with improvements in onset of vastus medialis obliquus ( V 
    Output:
    
These reported principally that altering lower limb joint orientation or the addition of a co-contraction does not preferentially enhance VMO activity over VL .