مجله بیومکانیک ورزشی
سال دوم شماره 3 (پاییز 1395)

The effects of scoliotic deformity on the biomechanics of gait are not clear. The aim of this study was to compare the spatiotemporal variables during gait in adolescent idiopathic scoliosis and healthy individuals.
Eighteen healthy adolescent girls and 19 adolescent patients with idiopathic scoliosis that were matched for age, height, mass and BMI participated in this study. Using a Vicon motion analysis system (100 Hz), subjects’ gait were recorded and spatiotemporal variables including velocity, cadence, stride and step length, initial heel contact and toe off instants (% of gait cycle), duration of single and double supports, duration of the steps and strides of the right and left feet as well as the asymmetry indices (AI) for all variables were evaluated. ANOVA was run at a significance level of p It was found that the cadence, velocity, stride and step length, stride and step time, duration of double support and single support, and heel contact and toe off instants were similar in both groups (p>0.05). Also, there were not any between group differences in asymmetry indices for all variables (p>0.05).
spatiotemporal variables in right thoracic scoliotic patients were similar to healthy individuals; there for, it could be suggested that scoliosis does not affect the spatiotemporal variables. Other biomechanical parameters should be examined for etiology of scoliosis.

The purpose of this study was modeling some selected method of load carriage during sitting and arising, in order to introduce the best method to reduce energy consumption and risk of injury among troops.
In this research, ten subjects participate to determine the anatomical constraints, record the kinematic of motions and extract some parameters for modeling. Subsequently, the center of gravity position of four equipment for load carriage, including: Backpack, Double pack, Trunk vest and Double satchel, were determined and four different dynamic models of body and the load entered, were developed based on inverse dynamics equations by Lagrangian method. To calculate joint torque and mechanical energy, two dimensional models with four segments were run with kinematics information.
According to investigation results, mechanical energy consumption in Backpack method and hip torque in Double satchel method were lowest.
A more practical choice for military operations is to carry a load as close as possible to the center of mass of the body. In a nutshell, between all methods, carrying operation by Backpack method, according to its capabilities, is the best choice for carrying heavy and bulky equipment.

this study aims to determine the effects of ankle, knee, and hip ISO kinetic fatigue on shock absorption and rate of loading during paired-leg landing.
Fifteen female students with an average age of 19.67± 0.62 years, weight of 54.60 ± 9.44 kg, and height of 163.30 ± 5.54 cm were selected randomly as subjects in this study. First, the participants were tested by jumping from a box with the height of 30cm, to land on a force plate and information relevant to this test was recorded. Then, the Isokinetic fatigue protocol of the ankles, knees, and hips muscles’ was implemented for everyone by an Isokinetic System, and related information was recorded. The second test of paired- leg landing with fatigue muscles, was carried out on a force plate immediately. For statistical analysis, SPSS18 software, Dependent T-test, and Analysis of Variance with Repeated Measurement at the significance level of P Dependent T- test results showed no significant difference in comparing the rate of load throughout landing before and after fatigue in the joints of the lower extremities. Also, the analysis of variance with repeated measurements, showed no significant difference between the rate of load before and after ankle, knee and hip fatigue.
Findings of this study indicate that the fatigue protocol using Isokinetic devices with uniform speed, increases muscle strength due to generating stress at all the joints, thereby, compensating the active and passive joints for shock absorption, and load distribution on the lower extremities.

Shoulder muscle injuries are very prevalence. So determining of injuries mechanism could be a suitable way for identifying rehabilitation methods. The purpose of this study was to compare the electromygraphical activity of shoulder girdle muscles in lowback pain patients and healthy subjects during arm flexion with and without load.
Tensubjects with chronic low back pain and ten age-matched control healthy subjects participated in this study. All participants were asked to perform arm flexion activities with and without load (with both dominant and nondominant sides) in a standing position. The outcome measures included electromygraphical activity of anterior and medial deltoid, infra and supra spinatus muscles for both groups. MANOVA and repeated measure statistical tests were used for between and within group comparisons. Alpha level was set at p˂0.05.
The intensity of muscle activity in anterior and medial deltoid, infra spinatus and supra spinatus muscles of dominant upper limb in healthy group were 26.3±2.67, 17.01±2.02, 11.1±1.67, 12.40±2.34 percent of maximum voluntary isometric cotraction, respectively. These values for patients group were 27.90±3.78, 14.73±3.14, 16.48±2.37, and 18.19±3.31, respectively. There were not any significant diffrences between groups (p˃0.05). Load effect in dominant upper limb for the groups accounted for 132% and 136% increase in the total muscular activity.
Shoulder girdle muscle activity is similar in low back pain patients compred with the healthy subjects during arm flexion. It seems that low back pain didnt have any affect on shoulder muscular activiry; however, further studies are warranted.