مجله بیومکانیک ورزشی
سال هشتم شماره 3 (پاییز 1401)

The purpose of the current research is to examine the effect of functional fatigue protocol on the outcomes of functional movement screening test in professional female volleyball players.

In this research, the population included 40 professional active female volleyball players of premier league who had at least three years of experience in playing volleyball aging from 16 to 20 years, who were chosen as convenience sampling and were included in one group. All 40 test subjects took 12 test items in form of pre-test in which all the subjects' movements were observed and scored by the researcher. Immediately after the test, the subjects performed the functional fatigue protocol defined by Sasco and Vickins. After performing the fatigue protocol, the functional screening test for volleyball was taken again.

The obtained results from the research shows that performing the fatigue protocol has a meaningful effect on total grades obtained on functional movement screening tests for volleyball players (P≤0.05).

The findings of this study show that in order to identify changes in the movement pattern, it is necessary to examine the screening of volleyball athletes in the state of fatigue. Identifying changes in the quality of movement in volleyball athletes in a fatigued state shows that screening of the athletes should also be done when they are in a fatigue state, so that it may be possible to identify movement patterns that may lead to injury.

Attention Exercise is done for various purposes among athletes and the general public. One of the main problems in sports venues, especially with the spread of the corona virus, which has led to a threat to the health of the athlete community, is the presence of dangerous and pathogenic microorganisms such as germs, viruses, bacteria, etc. Therefore, the aim of the present study is to design and manufacture new antimicrobial shoes using nano-silver in order to prevent the spread of germs and viruses in the community of athletes.

The present study is an applied research carried out for designing and manufacturing new antimicrobial shoes using nano-silver in order to prevent the spread of germs and viruses in the athlete community.

The results showed that the resistance of nanosilver solution at concentrations of 75, 50, 25 ppm against E. coli continues with a decrease of 70, 90 and 97.88%, respectively. The results also indicated that in concentrations of 50 and 75 the reduction in S. aureus bacteria is 70% and 90%, respectively. Moreover, the research findings demonstrated that from 100 ppm onwards, the reduction of S. aureus bacteria appears up to 99.99%.

The use of nano-silver in the design and manufacture of sports shoes to prevent and control many microbes and viruses can be useful.

Obesity and overweight have changed to very important factors in people movements in the modern world. Therefore, the present study was carried out to examine the effects of overweight on gait kinematic factors in children, young adults, middle-aged, and older adults.

The present study was a causal-comparative study in which 40 participants aged 9-85 were selected based on purposive sampling and were divided into eight groups (four normal groups and four overweight groups) based on body mass index (BMI). All the participants were healthy and had no physical abnormalities. The participants gait was normal.  The 3D motion analysis system was used for measuring gait parameters such as walking speed, stride length, stride width, single support phase duration, double support and swing phase duration. Two-way ANOVA was run for the purpose of data analysis.  SPSS 19 was used for statistical analyses at a significance level of p<0.05.

Result showed that there was not significant differences between parameters of gait such as walking speed [age effect (0/364) and body position (0/478)], double support-phase duration [age effect (0/304) and body position (0/092)] and stance-phases duration [age effect (0/094) and body position (0/271)], while significant differences were observed in stride length [age effect (00001) and body position (0/038)], stride width [age effect (0/01) and body position (0/017)] and swing phase [age effect (0/0001) and body position (0/731)], between normal and overweight groups in different ages. The result of present study show that overweightness can affect some of the spatiotemporal parameters in people’s gait which can cause changes in the obese people’s gait pattern.

It seems that age and body status through height, weight and balance can affect some spatiotemporal parameters of gait.

Running is known as one of the most popular sports for which there is no time and space limit. Recently, due to lifestyle changes, the use of treadmills for walking and running has increased. However, the biomechanical differences in coordination between running on a treadmill at different speeds have not been sufficiently addressed. The aim of this study was to investigate the effect of increasing running speed on three-dimensional changes of lower extremity joint angles in the open motor chain and swing phase.

28 elite runners participated in this study. Subjects ran on an equipped treadmill while kinematic running data was recorded for 30 seconds through a three-dimensional 12-camera motion recording system at speeds of 2.5, 3.5 and 4.5 m / s. Data were normalized based on the subjects' body mass as well as 101 time points in the running cycle. The normality and homogeneity of variance of the dependent variable were tested using Bartlett and Leven’s tests. Repeated measurement test was performed to measure the angles of the pelvis, knee and ankle between the dominant and non-dominant lower limb joints in the running swing phase.

In the range of motion of hip, knee and ankle joint, there were significant differences among all the three speed rates of 2.5, 3.5 and 4.5 on all planes.

Changes in the angle and range of motion of the hip, knee and ankle joints are significantly greater in the swing phase as the running speed increases. Due to the fact that in high-speed running, the stability of the body decreases, the central nervous system commands to increase the range of motion of the angle of the mentioned joints to regulate the structure of the body and reduce the instability in response to the applied disorders. The results also show that the ankle joint, as the closest joint in contact with the ground, helps to run faster and more efficiently by increasing changes in the angle and range of motion of the ankle joint during running, and by reducing the time of foot contact with the ground at each step. It can be concluded that this point is effective in increasing speed.

The Objective Ankle sprains are among the most common injuries in athletes. One of the limitations of people with chronic ankle instability is the lack of postural control. Balance and coordination training are among the most common interventions for people with chronic ankle instability. Therefore, the aim of this study was to investigate the effect of balance training on postural control in athletes with chronic ankle instability.

Randomized clinical trials (RCTs) that examined the effects of balance training on postural control in athletes with chronic ankle instability were searched through the Scopus, PubMed, Cochrane and PEDro databases using keywords and concepts of postural control, balance training, and ankle instability from inception until April 2022. The quality of studies was assessed using the PEDro scale.

Eight RCTs were included in this study, based on inclusion and exclusion criteria. Balance exercises reduced postural sway, decreased the distribution of center of mass, improved the overall body balance index and anterior-posterior balance index in the Biodex balance system, increased the duration of balance maintenance, and reduced the number of errors in the foot lift test when checking static postural control, and improved the reaching distance in the star balance test when checking dynamic postural control.

Four to six weeks of balance training can improve postural control in both static and dynamic situations in athletes with chronic ankle instability.

The purpose of the present study was to investigate the center of pressure (CoP) movements during the jump-landing while defending on the net in professional volleyball players and compare it with beginner volleyball players.

In this research, 10 professional volleyball players and 10 beginner volleyball players voluntarily participated in this study. The CoP movements in anterior-posterior (AP) and medial-lateral (ML) directions in 5 forms of volleyball net defense skills including static jump, right and left side step, right and left long cross step by using Vicon three-dimensional motion analysis machine and two Kistler force plates were measured.

In the jumping-phase of static jump, left side step jump and left long cross step jump, there was a significant difference in CoP movements and in the AP direction (p < 0.05), but in right side step jump, there was a significant intergroup difference in CoP movements in the direction of AP and ML (p < 0.05). In the landing phase, there was a significant difference between the two groups in the AP direction in the right side step jump and left long cross step jump (p < 0.05).

Beginners are exposed to more musculoskeletal injuries due to greater CoP movement in both AP and ML directions. Failure to control the CoP movement may lead to a fall during landing.