Introduction: Patellofemoral pain syndrome (PFPS) is one of the most common orthopaedic problems of the knee joint. Muscular weakness considered as a risk factor of this syndrome. Muscular weakness can alter LOWER EXTREMITY kinematics and lead to this syndrome. Also according to the kinetic chain, weakness in one motor segment can influence other motor segments. So the aim of this study was to determine the association between muscular strengths of both LOWER EXTREMITY and trunks MUSCLES and PFPS.Materials and Methods: 40 women participated in this study (20 subjects with PFPS and 20 as controls). In both groups isometric strengths of the LOWER EXTREMITY and LOWER trunk MUSCLES were evaluated with Nicholas hand-held dynamometer and then compared with each other.Results: There was a significant decrease in strength of the hip abductors, adductors, external rotators, flexors and extensors, quadriceps, ankle plantarflexors, dorsiflexors, flexor and lateral flexors of the trunk in patients with PFPS.Conclusion: Our results indicate that decrease in strength of the hip and trunk MUSCLES is associated with the knee injury. It seems strengthening of MUSCLES of these areas to be effective in preventing the injury, reducing the risk of more injury and treatment of patients with this syndrome.

Background and Aim: The purpose of the present study was to investigate the effect of core MUSCLES’ fatigue on landing mechanic and LOWER EXTREMITY function. Materials and Methods: In the present semi-experimental study, 18 female students were randomly selected from among the students at Razi University. First, pretests were administered. Y-test was used to measure dynamic balance, square & lateral hop tests was used to measure LOWER EXTREMITY function, and weight bearing dorsiflexion ROM and Landing Error Scoring System-Real Time as well as Kinova and AutoCAD Software were used to assess landing mechanic. After the pretest, we perfromed core MUSCLES fatigue protocol and then the posttest was conducted. For data analysis, K-S and Levine’ s test and paired sample t-test were run. The statistical significance was set at 0. 05. Results: The results showed that after core MUSCLES fatigue, among studied factors, landing error scores (P=0. 001), weight bearing dorsiflexion ROM (P=0. 002), dynamic balance (P=0. 02), and knee flexion angle (P=0. 03) decreased in contact time. Discussion: According to the results, it can be stated that the core MUSCLES fatigue that accrues in sports competitions could result in the prevalence of LOWER EXTREMITY injuries. So, core strengthening protocol can be effective in preventing injuries in the LOWER EXTREMITY.

Shock absorption and reducing the Rate of Loading (ROL) during daily activities are considered as a reason for reducing the rate of injuries. Since, skeletal MUSCLES utilize as shock absorber during weight bearing tasks, the purpose of this study was to examine the relationship between the maximum torques of LOWER EXTREMITY MUSCLES with the ROL during single leg drop landing. 33 men subjects (23±2years and 73±3 Kg) from Tarbiyat Moallem University of Tehran volunteered in this study. Maximum torque of LOWER EXTREMITY MUSCLES and the Ground Reaction Forces (GRF) were measured by the Biodex system and force plate (AMTI), respectively. The Pearson correlation used to analyses the data at the a£0.05 threshold. The mean torque of the quadriceps, hamstring, plantar flexors, dorsi flexors, invertors and evertors muscled were 2.70, 1.75, 0.77, 0.43, 0.43, 0.40 Nm respectively, and the mean ROL was 519/60 N/ms. Significant correlations wasn't seen between maximum torque of LOWER EXTREMITY MUSCLES with ROL. Due to results of this study it seem that quadriceps, hamstring, plantar flexors, dorsiflexors, invertors and evertors MUSCLES have no role in decreasing the ROL in single leg drop landing.

Purpose: Less attention has been paid to the electromyographic activity of the LOWER EXTREMITY MUSCLES, which is considered as an essential part of the kinetic studies on the gait of mentally retarded individuals. Hence, the study aims at determining the surface electromyography characteristics of the LOWER EXTREMITY MUSCLES of mentally retarded adolescents during walking.Methods: It is a causal-comparative study. Fifteen mentally retarded and 15 normal adolescents with an age range of 10 to 14 years participated in this study. To record the activities of vastus medialis, vastus lateralis, biceps femoris, semi-tendinosus, tibialis anterior, long peroneal, medial gastrocnemius, and soleus MUSCLES, sEMG was employed during the stance phase of gait. For the data analysis, an independent sample t-test was conducted using SPSS version 18.Results: The results revealed that the mentally retarded adolescents had higher level of biceps femoris muscle activity in the heel contact sub-phase (P=0.016) compared to the normal group.Also, the vastus medialis (P=0.015) and the long peroneal (P=0.026) MUSCLES showed higher EMG activity. Furthermore, their vastus lateralis (P=0.039) and Soleus (P=0.002), and vastus medialis (P=0.045) MUSCLES demonstrated higher and LOWER activities, respectively. The cocontraction rate of medial gastrocnemius and anterior tibialis MUSCLES during the heel contact was higher (P=0.040) in individuals with mental retardation compared to the healthy group.Conclusion: It can be concluded that the mentally retarded individuals use different muscle activation patterns in comparison to healthy people. As a result, special attention should be given to the functioning of their LOWER EXTREMITY MUSCLES during the corrective power exercises.

Purpose: The proper neuromuscular recruitment patterns of hip and knee MUSCLES are essential for dynamic stabilization of the knee. According to the kinematic chain, weakness in the performance of one motor segment can affect other segments of motion. Thus, the aim of this study was to compare the isometric strength of selected MUSCLES of LOWER extremities in the hyper pronated foot with the same MUSCLES in healthy male athletes.Materials and methods: The present study is descriptive and correlational. Forty male athletes in two groups of hyper pronated foot and healthy male athletes (20 in each group) participated in this study. Pronated foot was examined by navicular drop and isometric strength of selected MUSCLES in LOWER extremities was examined by Manual Muscle Test system (MMT). Then, the ratio of isometric strength of each muscle to body weight was compared between two groups. Data were analyzed by SPSS software, version 20 and the independent t test was used to compare the variables between the two groups.Results: The results showed that isometric strength of MUSCLES, hip abductors (P = 0.002), external rotators of hip (P = 0.007), and quadriceps MUSCLES (P = 0.031) have decreased significantly in the the group of hyper pronated foot.Conclusion: The hyper pronated foot changes the muscle strength of LOWER EXTREMITY. These changes may be due to neuromuscular compensation because of the changes in the medial longitudinal arch. More research is needed to determine whether these changes in muscle strength are related to LOWER EXTREMITY injury.

Introduction: Several studies have shown the effects of muscular fatigue on proprioception and neuromuscular control. However all available researches have studied just the effect of local fatigue in ankle joint MUSCLES on postural control, and no study have found about the effect of fatigue in proximal MUSCLES of the LOWER EXTREMITY on postural control. Objective: To compare changes in postural control parameters after isokinetic fatigue of proximal and distal MUSCLES of LOWER EXTREMITY. Materials and Methods: Subjects were Twenty healthy men (age: 22.6±2.4 years, height: 173.7±3.6 cm, weight: 63.3±7.9kg). There were 4 test sessions, with a randomized order according to site and plane of fatigue. During each session one of these muscle groups were fatigued using a Biodex isokinetic dynamometer: ankle plantar / dorsi flexors, ankle evertor / inventors, hip flexor / extensors and hip abductor / adductors. The biodex stability system was used to perform dynamic balance test before and after muscle fatigue in each session. Overall, anterior / posterior, and medial / lateral stability indices were recorded. The higher the stability indices, the LOWER the balancing skill. Results: Analysis of pre-and post fatigue balance results of all sessions, demonstrated significant increase (P<0.05) in all stability indices. Repeated measures ANOVA performed on the rate of changes in stability indices during each session revealed that hip muscle fatigue caused much more increase in stability indices that hip muscle fatigue caused much more increase in stability indices than ankle muscle fatigue (P<0.05). Conclusion: Isokinetic fatigue of both ankle and hip MUSCLES significantly decreases postural control ability in healthy young men. In addition, our findings suggest that the hip joint musculature plays a more prominent role in postural control.

Background and Aims: The aim of the current study was to investigate the effect of hip abductor andexternal rotator MUSCLES strengthening exercises on pain, muscle strength, and LOWER EXTREMITY kinematicsin people with patellofemoral pain (PFP). Materials and Methods: A total of 35 patients with PFP were randomly assigned into exercise and control groups. The exercise group received abductor and external rotator strengthening exercises withthera-band 3 times per week for 12 weeks. The control groups did not receive any training intervention. Then, the two groups were compared to study the effect of independent variable on the experimentalgroup. Pain (VAS), hip muscle strength (handheld dynamometer), and LOWER EXTREMITY kinematics (videoanalysis) were assessed at baseline and post-intervention. Participants included patients with bilateral orunilateral patellofemoral pain; if pain was bilateral, exercises were performed bilaterally on both LOWERextremities but measurements were performed only on the LOWER EXTREMITY which was more painful; whenever the pain in both knees was equal, data were collected only from the superior LOWER EXTREMITY. Repeated measures ANOVA was applied using SPSS to assess the effects of the exercises on measuredvariables. Results: Pain decreased significantly in exercise group from baseline to post-intervention (P=0. 000). Hipabductor MUSCLES strength (women, P=0. 000 and men, P=0. 003) and external rotator MUSCLES strength (women, P=0. 024 and men, P=0. 000) increased significantly in exercise group after 12 weeks of strengthening program. There was a significant improvement in dynamic knee valgus during single-legged squat (women, P=0. 018 and men, P=0. 017) and contralateral pelvic drop during stair descendingjust in women (P=0. 04) in exercise group. There were no significant differences between men and women in the effect of exercises on the variables studied (P>0. 05). Conclusion: According to the results, hip strengthening can decrease pain, increase muscle strength, and change kinematics in the frontal plane movement patterns of the LOWER EXTREMITY, which can possibly be the mechanism of effect of this intervention on PFP symptoms. According to findings of the present study, it might be concluded that gender-specific rehabilitation program is not needed in patients with PFP.