مجله بیومکانیک ورزشی
سال پنجم شماره 2 (تابستان 1398)

 The aim of this study is investigate the core muscles dysfunctions and their consequences in patients with chronic ankle instability.

 In this review study, search was conducted in three online databases of PubMed, Scopus, and Google scholar based on Patient, Intervention, Comparison, Outcome (PICO) strategy, and using keywords related to the role and function of core muscles, their electromyography, kinematic patterns of proximal segments, and postural stability in individuals with chronic ankle instability.

 Seven studies were finally selected for the review based on the inclusion and exclusion criteria. The results indicated that individuals with chronic ankle instability in comparison with healthy peers have different electromyography and kinematic patterns of proximal segments (trunk, abdomen and pelvis).

 Muscle activity and kinematic patterns of proximal segments in individuals with chronic ankle instability are different to those of healthy ones. These differences are compensatory strategies for postural stability. These strategies may not provide the body’s need to maintain and control the poster in new environments or during complex activities. Further studies are needed to investigate effects of the correction of core muscle function on the postural control in individuals with chronic ankle instability.

Carpal Tunnel Syndrome (CTS) is one of the most common compression neuropathy in the upper extremities. The aim of this study was to investigate the prevalence of CTS among male hairdressers in Bojnourd, Iran.

 This is a descriptive/analytical study with cross-sectional design conducted on 109 male hairdressers in bojnourd city. Among them, 38 had CTS symptoms such as finger numbness and underwent Phalen’s and Tinel’s tests, 22 of whom were positive. As a result, they were referred to a rehabilitation specialist for electrodiagnostic studies. Data analysis was carried out in SPSS v.22 software using descriptive statistics such as frequency and percentage and considering a significance level of 0.05.

 Twenty-two of 109 hairdressers had clinical and electrodiagnostic criteria for CTS (20.8%). Of these, 45.45% had mild (n=10), 31.81% moderate (n=7) and 22.72% severe CTS (n=5).

 Hairdressing is one of the potential jobs for CTS. Hairdressers’ work situations need to be improved. It is also necessary to improve the awareness of hairdressers about biomechanics and the correct ways of doing work.

 Stair ascent and descent is an essential movement task in daily life in which individuals are subjected to repetitive impact forces. The purpose of this study was to evaluate the intensity of Electromyographic (EMG) activity in lower extremity muscles of healthy young men during stair ascent and descent task wearing different type of shoes and carrying loads.

 Nine men with a mean age of 25.94±3.26 years, mean height of 174±7.4 cm, and mean weight of 70.95±8.25 kg were selected. Four stairs were fabricated and the electromyographic activity of their lower extremity muscles (two muscles in the posterior leg and three quadriceps muscles) in the right side of the body was measured using the 16-channel EMG system MA300 during the task. These tests were conducted in two conditions of with and without load carrying. The load was a cube-shaped box weighing 15% of the body weight. Three cases of footwear were set: barefoot, athletic shoes, and formal shoes. Repeated measure ANOVA was used for data analysis at the significant level of P<0.05.

The load factor had a significant effect on the intensity of muscle activity. The intensity of muscle activity during ascending stairs was higher than that during descending. In stair descent task, the EMG activity of the vastus medialis muscle was greater than that of the vastus lateralis and rectus femoris muscles, which causes the patella to be pulled inward more leading to patellofemoral articular cartilage wear in the long term.

 Stair ascent puts more pressure on the ankle and knee joints. When carrying the load up stairs, the use of proper shoes can greatly reduce the intensity of muscle activity and delay fatigue. It is, therefore, recommended that people with patellofemoral articular cartilage wear should not use the stairs, if possible.

 Numerous abdominal exercises with Swiss ball are used to improve core stability with strengthening and rehabilitation goals. It is claimed that the stability exercises have a greater impact on core muscle activation, but the validity of this claim is still in doubt. Moreover, there is no comprehensive study on the comparison of the core muscles activity in different core stability exercises. Therefore, the purpose of this study was to compare the Electromyography (EMG) activity of core muscles while performing side plank on stable and unstable (Swiss ball) surfaces.

 Fifteen male students of Allameh Tabataba’i University were selected for the study based on inclusion and exclusion criteria. The EMG activity of gluteus medius, rectus abdominis, external oblique, and internal oblique muscles in subjects was recorded while performing side plank exercise on a fixed surface and a Swiss ball (2 sets of 5 seconds with a 30-second rest interval).

There was a significant difference in the EMG activity of gluteus medius, external oblique and rectus abdominis muscles between two conditions of with and without Swiss ball (P<0.05), but no significant difference was observed in the EMG activity of internal oblique muscle (P>0.05).

 Side plank exercise on the unstable surfaces (Swiss balls) can cause changes in the EMG activity of gluteus medius, rectus abdominis and external oblique muscles compared to when the exercise is performed on stable surfaces, and highly involved the pelvic lumbar muscles effective in maintaining core stability. Therefore, the use of side plank exercise on unstable conditions in a progressive program with gradually increased intensity is recommended which can be effective in strengthening and applying effective muscle contractions useful for core stability.

Upper Crossed Syndrome (UCS) is a type of musculoskeletal system involvement that results in shortening of  anterior muscles and weakening of posterior muscles. The aim of this study was to examine the effect of selected corrective exercises with physioball on the postural status of female computer users with UCS.

This quasi-experimental study was conducted on 24 female students with UCS who were selected using a purposive sampling method. The subjects were randomly divided into two groups of exercise (n=12) and control (n=12). The exercise group performed exercises for 6 weeks. Photogrammetry method was used to measure the angle of the forward head and round shoulder. A flexible ruler was used to measure the angle of kyphosis, and tape measure was used to measure the chest expansion. These measurements were performed before and after intervention. The collected data were analyzed using paired t-test and ANOVA at the significance level of P<0.05.

There was a significant difference in mean values of kyphosis (P=0.001), round shoulder (P=0.001), forward head (P=0.002) and chest expansion (P=0.003) before and after exercise.

 Improvement in forward head, round shoulder and thoracic kyphosis angles and chest expansion showed the effectiveness of applied exercise program. Therefore, it is recommended to use this exercise program in computer users with UCS.

 For optimal performance of swimmers, it is necessary to determine a level for the functional interaction of upper and lower limbs. This level, created by more than 20 pairs of muscles, is the core of the body. The aim of this study was to investigate the effects of six weeks of core stability exercise on the stroke index and front crawl record of male swimmers.

 In this quasi-experimental study, 24 male swimmers were selected by a convenience sampling method and randomly assigned into control (n=12) and exercise (n=12) groups. The core stability training was performed for 6 weeks, 3 sessions per week, each for 45-50 minutes. Before and after training, the stroke index and 100-m front crawl records of subjects were evaluated. For the within-group and between-group comparisons, the student t-test and ANCOVA were used, respectively. The significance level was set at P<0.05.

 Six weeks of core stability exercise led to significant improvement in 100-m front crawl record in the exercise group. There was no significant difference in the mean scores of stroke index and 100-meter front crawl record between and within the two study groups.

 Core stability exercise is recommended for dryland training of swimmers.