Range of motion and angular velocity analysis during landing from different heights, of the lower limb joints in patients with reconstructed anterior cruciate ligaments

 Aims and background: Anterior cruciate ligament injury is the most common ligament injury of the lower limb that necessitates reconstruction as a proper treatment approach. It is now up to the researchers to ask, are the altered kinematic patterns in the lower limbs corrected by this reconstruction? The present study aims to analyze the range of motion and angular velocity of the lower limb joints in patients with reconstructed Anterior cruciate ligaments during landing. Materials and Methods: 20 male subjects who participated voluntarily were divided into 2 groups. One group consisted of healthy subjects (control) the other of patients with reconstructed Anterior cruciate ligament (experimental). They were evaluated in 3 assignments: landing from a box, a vertical jump-landing, and a jump from an obstacle-landing. 3-Dimensional kinematics of the range of motion and angular velocity of the lower limb joints were recorded using 4 cameras and processed by visual 3D software. Findings: In the sagittal plane, the experimental group’s knee and hip joints range of motion was less than the control group (p=0.00) The ankle joint  was more (p≤0.05) than the control group. In per 3 planes, the experimental group’s ankle and knee joints angular velocity was lower than the control group. The hip joint was higher than the control group (p≤0.05). In most cases, both variables showed the smallest value in the landing from the box task and the highest value in the jump from obstacle-landing task (p≤0.05). conclusion: During complex tasks such as landing, patients exhibit altered kinematic patterns that are followed by compensatory mechanisms in adjacent joints. These altered patterns will persist for at least 2 years after the Anterior cruciate ligament is reconstructed. These patients, in the absence of care, are at risk for Anterior cruciate ligament re-injury and prone to develop knee osteoarthritis in future

Kinematic and Spatio-Temporal Characteristics of Gait in Blind Individuals

Introduction: Visual inputs in the neuromuscular response process of the central nerve system have an important role in various motor tasks. The identification of the influence of lack of visual input on gait in blind people may be useful in rehabilitation planning and correction of gait pattern. The aims of this study were to compare spatio-temporal variables and the symmetry index of gait among blind and healthy individuals, and investigate the effects of closing the eyes on kinematics of gait in healthy subjects.  Materials and Methods: In the present study, 10 blind and 10 healthy subjects with similar age, height, and mass participated. Spatio-temporal variables of gait were measured in blind subjects without a cane and in normal subjects with and without vision. The differences between the two groups and the two walking conditions were determined through repeated measure and significance level of P < 0.05. Results: Stride length, step length, and gait velocity were lower in blind individuals than healthy individuals with vision (P < 0.05). Stride length, step length, and stride time in healthy individuals without vision were greater than in blind individuals. In healthy individuals without vision, stride and step time, fluctuation time, and single support time were increased while cadence was decreased. Moreover, the asymmetry index in the healthy group without vision in terms of variables of single support time, fluctuation time, and toe raised off the ground time had greater symmetry than the blind subjects.  Conclusion: Blindness is accompanied with reduced walking speed and step and stride length. Lack of vision in healthy subjects, caused increased stride time, single support time, and fluctuation time and decreased cadence. Stride length, step length, and stride time in healthy subjects without vision were greater than in blind individuals. It seems that the role of proprioceptive receptors is more pronounced in blind individuals than normal individuals

The Effect of Foot Position on the Muscles Activity of the Shoulder and Trunk Muscles in Load Lifting

Objective: This study aimed to investigate the effects of leg positioning on the activity of shoulders and body while lifting weights. Methods: Employing an electromyography set (BTS free EMG 300) and surface electrodes, the activity of such muscles as biceps, triceps, anterior, medial and posterior deltoid, trapezius and erector spinae, while lifting a weight weighing %15 of body mass, in three leg positions (straight, bending and a leg on a step), were measured. Each muscle`s RMS data, during performing the skills, were divided by the amount of maxinmum voluntary isometric contraction (MVIC) then multiplied by 100. Repeated Measurewas used to analysis the data at the significance level of (p<0.05) in SPSS 16. Results: The results showed no significant difference among the activity of such muscles as biceps, triceps, anterior, medial and posterior deltoid, trapezius and erector spinae in three different positions. However, there existed a significant different between the different pectoral gridle and erector spinae muscles in terms of their intensity of activity (p=0.01). The maximum of intensity of activity was respectively assigned to erector spinae, anterior deltoid, medial deltoid, trapezius, posterior deltoid, bicepts and tricepts. Moreover, the comparison of the activity of the muscle L3 in the three different leg positions in lifting a weight did not show a significant difference (p=0.05). Conclusion: The way of lifting the object does not lead to a significant difference in the intensity of the activity of different muscles

Linear and Non-Linear Changes of Center of Pressure due to Vestibular System Disorders: Comparison of Balance and Gait in Hearing and Sensorineural Deaf Children

Background and Objectives: Balance weakness and changes in the walking pattern of deaf children due to vestibular disorders have been clarified by past studies. This study aimed to investigate static balance and walking in sensorineural deaf children with two methods of linear and non-linear assessment of posture control. Materials and Methods: This descriptive study was conducted on 20 hearing and healthy boys (10.80±1.46 years old) and 20 boys with deafness greater than 75 dB (11.30±1.89 years old). Static balance was evaluated during tandem stance and with feet together on an unstable surface using a force plate. Kinetic and kinematic variables of gait were also investigated. The independent and dependent t-tests were used to assess the inter-group and between-group differences in SPSS21 software with p < 0.05. Results: The results of static balance showed a significant difference between groups in linear variables. The amount of sway, path, area, and speed of the center of pressure movement in the deaf was significantly higher than that in the control group (P<0.05). However, entropy (non-linear evaluation) was only significant in the medial-lateral direction of tandem test (P<0.05). Lower gait speed and an increase in the medial-lateral component of the ground reaction force were observed in the deaf (P<0.05). Conclusion: According to the results, the evaluated linear variables were more sensitive to deafness and vestibular system disorder than the nonlinear variable. Entropy is a sign of variability and irregularity in a person's performance; therefore, deaf people may be more likely to be vulnerable in the medial-lateral direction due to more irregularity in this direction

The Effects of Shoulder- Girdle Muscles Fatigue on Ground Reaction Force, Elbow and Shoulder Joint Angle, and Accuracy of the Athletic Performance in Handball Penalty Throws

Objective: Fatigue is an integral part of sports that can affect athletic performance. The aim of this study was to determine the effect of shoulder girdle muscle fatigue on ground reaction force, Elbow and shoulder angle, and accuracy in handball penalty throws. Methods: 10 healthy male handball player with no history of injury in the shoulder (mean age 9/18 years, weight 79/72 kg, height 179 cm, 6/5 year membership in the team) voluntarily participated in this study. The subjects with full respect for the laws took a total of 16 penalty shots before and 16shots after reaching fatigue. Ground reaction force, angle of elbow and shoulder, and accuracy of launch of the two phaseس (phase of preparation for throwing and phase of the release of the ball) were recorded before and after fatigue. Results: Results showed significant differences in ground reaction force and accuracy of the throws before and after fatigue (p0.05). Discussion: As the subjects were professional, muscle fatigue did not have a significant effect on postural control, angles and angular velocity; but did affect the reaction force and accuracy of the throws before and after fatigue, which could ultimately affect the performance of athletes and competition results

The Effects of External Focus of Attention on Shoulder Muscle Activities during Forehand Drive in Table Tennis

Objective: The aim of this study was to evaluate the impact of the external focus of attention on the rotator cuff muscle activity for the timely hit forehand drive by table tennis players. Methods: Twelve professional table tennis players with mean age of 26.5 years voluntarily participated in this study. The electrical activities of the muscles of the shoulder girdle using M.A 300 machine and bipolar electrodes surface under two conditions .First with external focus of attention and then without such attention were recorded, first without any guidance blows forehand drive was carried out by subjects (without focus). Then such subject was asked to focus their attention on the area marked for the ball landing (external focus of attention). &nbsp;&nbsp;&nbsp;&nbsp; Muscle activities in both preparation and tapping phases were analyzed the three &ndash;dimensional (200 Hz, Vicon, with four camera series T) motion analysis system was used to obtain the data. Data was analyzed by running reported measures ANOVA at a significance level of p<05. Results: In without external attention situation, muscle activity did not change significantly compared with the external focus of attention situation (p>0.05) but the different between the intensity of muscle activity was meaningful. This suggests that there is a mutual influence between the two attention factors and muscles (p=0.03), that is, orientation can have a significant effect on the severity of muscle contraction. Intensities of muscle contraction in the preparation and tapping were different (p<0.05). Conclusion: On the forehand drive technique, the anterior deltoid muscle has the most activity. The type of focus and attention had a significant impact on the change of activity of muscles relative to each other, and the greatest impact is on the reduction of activity of the infraspinatus muscle. This type of focus delays fatigue and results in an increase in the efficiency of neuromuscular in the activities of skills

Assessing the Effects of Fatigue on Ground Reaction Force Variations during Landing after a Spike in Professional Volleyball Players

Objective This study examines the impact of fatigue on kinetic variables during landing after performing a spike in professional volleyball players. Fatigue can significantly affect athletic performance and increase the risk of lower limb injuries, particularly in movements that require precise landings. Methods In this study, 28 professional volleyball players performed a spike over the net and landed on a force plate before and after inducing fatigue. Kinetic variables, including ground reaction forces and loading rates, were evaluated at both stages. A paired t-test was used to examine the effect of fatigue on these variables during the landing task after the spike. All statistical analyses were conducted using SPSS software with a significance level set at P<0.05. Results The results showed that fatigue caused a significant reduction in the vertical ground reaction force at initial contact, the maximum posterior force, and the medio-lateral force at initial contact in the dominant leg. Fatigue did not have a significant effect on the other variables. Conclusion The results indicated that the ground reaction force in the dominant leg after inducing fatigue was significantly different from before. Given the asymmetry in ground reaction forces between the dominant and non-dominant legs, it is crucial to address this in training programs

Investigating the Present Procedure in Return to Play After Injury in Athletes of Football Primary League in Iran

Abstract: For many injured athletes, a safe and successful return to play following injury is the ultimate aim of injury recovery. The aim of this study is to investigate the present procedure in return to play after injury in athletes of football primary league in Iran. The participants in the present study were trainers‚ coaches‚ physicians and physiotherapists of football primary leagues in 2010-2011. 53 persons (73%) responded to the sent questionnaire. To achieve the aim of the research, questionnaire was used based on: The decision about the time a person can return to the competition. The results of this study show that only 37% of teams surveyed, routinely used fitness testing and full recovery was not always deemed necessary before a player returned to training and competition, and set procedures were not always communicated or followed. Despite the high profile given to &apos;fitness testing&apos;, this study show that this element did not rank highly as return to play criteria. Thus, it is necessary to exist the procedure in return to play after injury, and use the professional personnel in this field

Measuring the Effect of Vision on the Synergy of Lower Extremity Muscles during Walking using Nonnegative Matrix Factorization (NNMF) Algorithm Method

Introduction. Lack of visual information in blind people during walking can affect the choice of muscle synergy from among the many incoming messages that reach the central nervous system (CNS). This study aimed to determine the effect of vision on the synergy of lower limb muscles during walking using the nonnegative matrix factorization algorithm (NNMF). Methods. Ten blind people and 10 people with normal vision participated in this study. Activities of involved muscles were recorded during walking. Muscle synergy matrix and synergy activation coefficient were calculated using the NNMF algorithm, while the variance accounted for criterion was used to determine the number of synergies required during walking. In order to assess the similarity of muscle synergy pattern and the relative weight of each muscle in each synergy in each group, Pearson correlation and independent samples t-test at a significance level of α ≤ 0.05 were used. Results. Four muscle synergies were extracted from EMG data during walking. The first (r = 0.431) and the second (r = 0.457) synergy patterns showed a moderate correlation between the two groups. However, the third (r = 0.302) and the fourth (r = 0.329) synergy patterns showed a weak correlation between the two groups. In the blind group, the relative weight of the muscles in the first synergy was significant for the external extensor muscle (P=0.023), and in the second synergy for the biceps femoris. Also, in the third synergy, the relative weight was found to be significant in none of the muscles. In the fourth synergy, however, the relative weight of external extensor muscle in the blind group showed a significant decrease, as compared to the group with normal vision. Conclusions. These changes can be the strategy of the CNS to preserve the optimal functioning in the motor system of blind people

Development of Static Postural Control: Regulating the Center of Pressure Trajectory

Introduction: Studying the developmental process, it may be possible to examine the role of sensory and cognitive systems involved in postural control. The aim of this study was to evaluate static postural control in both linear and nonlinear methods in children aged 7 to 12 years and compare them with young-adult. Materials and Methods: The center of pressure (COP) in eight postural task was assessed in 420 girls and boys 7 to 12 years old and 20 young adults. The linear method included sway, deviation, the amplitude of CoP and velocity. To characterize the nonlinear evaluation, sample entropy (SampEn) was measured. Results: The results showed that 7 and 8-year-old have the most sway, amplitude, speed of CoP and deviations than others (p&lt; 0.05) and adults had the lowest amount. But the SampEn, decreases significantly with age (p&lt; 0.01). The base of support was greater effect on linear and nonlinear than that other conditions, especially in children (p&lt; 0.001). The closed-eyes condition, were not aligned in linear and non-linear evaluation (p&lt; 0.001). Conclusion: The differences between age groups were significant in the challenging situation than that stable condition, due to changes in postural control strategies. Task demands did not have a significant effect on balance variability in adults, but it did affect children and linear variables.&nbsp;&nbsp