[Effect of knee isokinetic extension training with maximum lateral tibial rotation on vastus amplitudes in patellofemoral pain syndrome patients]

Objective: Patellofemoral pain syndrome [PFPS] is one of the most common knee chronic disorders especially among females that is closely related to forces imbalance of vastus medial is oblique [VMO] and vastus lateral is [VL] muscles. The purpose of study was to examine the effect of knee isokinetic extension in maximum lateral tibia rotation on VMO and VL amplitudes in PFPS patients

Materials and Methods: Thirty-six women with PFPS participated voluntarily in this study and were randomly placed in one of three groups included the VMO selective isokinetic strengthening exercise, quadriceps general strengthening and control groups. Each exercise was performed for 8 weeks. Muscle RMS of VMO and VL and VMO/VL RMS ratio were recorded and calculated before and after training using of an 8-channels electromyography system. Data analysis was made by analyses of variance with repeated measures

Results: In baseline, VMO amplitude was less than VL in all groups [P0.05]. Yet, after interventions, VMO amplitude and VMO/VL amplitude ratio were more in selective group than in general and control groups [P

Conclusion: According to the study results, isokinetic extension training with maximum lateral tibia rotation and in close to knee full extension can be recommended as an appropriate training for improving VMO/VL electrical activity ratio and decreasing imbalance between lateral and medial vastus muscles amplitudes in patients with PFPS

[Comparison of electromyographic activity pattern of knee two-joint muscles between youngs and olders in gait different speeds]

Objective: In recent years, it has been focused much attention on gait analysis. Factors such as speed, age and gender affect gait parameters. The purpose of the present study was to compare the electromyographic activity pattern of knee two-joint muscles between younger and older subjects in different gait speeds

Materials and Methods: The method of current study was analytical cross-sectional method in which 15 healthy young men and 15 old men, were selected conveniently. Electromyographic activity of rectus femoris, biceps femoris, semitendinus and gastrocenemius were recorded during walking with preferred [100%], slow [80%] and fast [120%] speeds in a 10 meter walkway. Normalized RMSs of muscles were compared using RM-ANOVA and Tokey's tests by SPSS 18 software

Results: According to results, RMSs of rectus femoris in midstance [P<0.01] and gastrocenemius in loading response [P=0.02] phases in all walking speeds were higher in older subjects than in younger ones, and it increased with speed in both age groups [P<0.01]. Biceps femoris RMS in terminal stance at 80% speed, was lower in older subjects than in younger ones [P=0.01] and it increased with walking speed [P=0.01]. Semitendinus activity in loading and midstance phases at 120% speed was higher in older subjects than in younger ones [P<0.01], and it increased with speed in both age groups in swing phase [P<0.05]

Conclusion: According to the results, older subjects have more muscle co-contraction around knee at high speed in midstance phase than younger subjects. These age-related changes in muscle activity, leads to increase in joint stiffness and stability during single support, and probably play a role in reducing push off power at faster speeds

Muscular response of females with Kyphosis in balance recovery from Postural Perturbation

Purpose: This study aimed to determine muscular response in balance recovery after postural perturbation among females with increased thoracic kyphosis

Methods: This is a quasi-experimental study. A total of 12 female students with thoracic kyphosis [>40 degrees] and 12 matched controls were selected to participate in the study. Each subject underwent unexpected perturbation from anterior, posterior, right, and left directions with eyes open and eyes closed conditions while standing on a movable plate, triggered by a weight equivalent to 10% of the subjects' body weight. Then, the electromyography activity of some selected muscles was measured. SPSS version 19.0 and Analysis of variance [ANOVAs] with repeated measures were used for data analyses [P<0.05]

Results: Significant effects after perturbation were observed with regard to the activation of rectus femoris [P<0.001], biceps femoris [P<0.001], tibialis anterior [P<0.005], gastrocnemius medialis [P=0.032], and gluteus maximus [P<0.001]. Whereas, no impact was seen in activities of erector spinae [P=0.461] and rectus abdominal muscles [P=0.224]. Also the results showed increase in muscles activities when the eyes is closed compared to open eyes condition [P<0.05]. Activities of all muscles were significantly higher in kyphotic group in comparison with control group. However, these differences were statistically significant regarding gastrocnemius medialis [P=0.007], gluteus maximus [P=0.033], and rectus abdominus [P=0.010]

Conclusion: Proximal muscles activity was higher in kyphotic subjects than normal subjects during balance recovery after postural perturbation

Dynamics study of ankle joint during quiet standing balance control with emphasis on dominant and non-dominant lower limb

Purpose: The present study aimed to evaluate the effect of dominant lower limb on the correlation between some of the dynamic variables of ankle joint and center of mass during quiet standing balance control

Methods: Twelve healthy females with no known neurological or musculoskeletal disorders,4with the mean age of 26 +/- 3.5 years, participated in this study. Motion analysis system, force4platform and Visual3D software were utilized in order to measure and compute the research variables. The relationship between research variables was evaluated using Pearson's correlation coefficient. T test and One-way ANOVA were used to examine the effect of dominant leg on the correlations

Results: Findings indicated the correlation between ankle joint moment and center of mass displacement [r=0.95] was higher than the correlation between ankle angular displacement and center of mass displacement [r=0.84]. It seems that the leg factor [dominance and nondominance] does not influence the correlation of angular displacement of ankle joint and center of mass displacement. However, it influenced the correlation between ankle joint moment and center of mass displacement

Conclusion: Therefore according to the present study it can be said that the kinetic variables of ankle joints are more important than kinematic variables for the prediction of center of mass displacement. In addition, it is suggested that in order to evaluate the lower extremity dynamics, during balance control, dominant and non-dominant lower limbs of the subjects be noticed too