Research in Sport Medicine and Technology

Purpose:The aim of this study was to investigate the effect of muscle soreness due to the plyometric exercises on leg muscle EMG activity after concentric and eccentric contractions in untrained people. 20 students from untrained male students (at least 6 months out of practice), were randomly assigned to experimental (n=10) and control (n=10) groups. At  pre-test, surface electromyographic activity of gastrocnemius muscle were recorded using by the Biovision 18 channel device during the both concentric (squat / plantar flexion of the ankle) and eccentric (wirepuller / ankle dorsiflexion) contractions. Then, in order to build muscle soreness, experimental group exerted 10 minutes selected plyometric exercises, while the control group did not have any training. Finally, immediately after protocol training and also after 48 hours the same record was done. Data were analyzed by Dasylab and Matlab software, and the ANOVA Repeated Measure and Bonferroni post hoc also were used for statistical analysis at a significance level of P≤0/05. The results showed that fatigue resulting from plyometric exercises, could have significant reduction in activity of gastrocnemius muscle immediately and 48 hours after exercise during eccentric contraction (P=0/001), while it was not true for concentric. According to the results, the risk of eccentric contraction could be considered for untrained people during training.

Genu varus is one of the malalignment of the lower limbs, the failure to correct it leads to secondary abnormalities in adulthood. The purpose of this study was to investigate the effects of a corrective exercise program on ground reaction forces, loading rates, impulses and free moment during stance phase of walking. 17 children with genu varus were volunteered to participate in this study (Age:11.71±1.68 years, Height:1.40±0.09 meter, Weight:35.14±11.47 Kg, and BMI:17.49±3.61Kg/M²). Ground reaction forces were recorded with two Kisler force plates during pre and post-test. At the dominant limb, the amount of time to peak in the mediolateral ground reaction force component during heel contact decreased by of 61.90% (P=0.011). Also, the time to peak of the vertical ground reaction force component during mid-stance tend to increase significantly by 11.47% during the post-test compared to the pre-test (P=0.063). The values of peak ground reaction force components, loading rate, impulse and free moment did not show any significant differences between pre and post-test. The findings showed that the corrective exercise trainings used in the present study had the most effect on the time to peak components of the GRF, but there were no significant effects on the loading rate, impulses, and free moment components. The corrective exercises used in the present study have had the most effect on the time to peak of ground reaction forces and improve them. On the other hand, these exercises did not have any significant effect on the vertical loading rate, impact and free moment values.

The most commonly used empirical approach to address issues of attention constraint is evaluate the degree of interference in dual or multiple tasks. The purpose of this study was designing software to estimate the relative interference between multiple tasks and determine its validity in performance prediction of simultaneous multiple tasks. in order to assess the validity of software, 46 students with a driving certificate from East Tehran branch of Islamic Azad University were selected by available sampling method, the response time to the visual and auditory stimulus of participants during driving in different conditions was measured by using software and hardware installed on their cars, and then relative interference in the above mentioned conditions was estimated by using relative interference software. The result of pearson correlation analysis showed that there is a high, meaningful and direct correlation between the amount of estimated relative interference with the software and measured participants' response time in different driving conditions (r=0.95, p≤0.01). Therefore, the designed software can be used to predict the amount of interference between two or more simultaneous tasks.

Chronic low back pain is one of the most common musculoskeletal problems. This disease, in addition to causing pain and disability affects the gait parameters in patients. The purpose of this study was to investigate the effect of aquatic exercises therapy on the severity of pain, disability and Spatiotemporal parameters and kinetic of gait in women with chronic low back pain. Twenty-four women with chronic low back pain (with a mean age of 26.6 years) participated in this study. The exercise protocol was conducted in water for 8 weeks. The severity of pain and disability were measured by Quebec and Oswestry questionnaires respectively. gait parameters were evaluated using a foot pressure device. Aquatic exercises therapy significantly decreased pain and disability severity and significantly improved gait parameters in the experimental group (p≤0.05). Fore there more, the significant difference between the variables in the post-test was obtained between experimental and control groups (p≤0.05). No significant difference was observed between the pre-test and post-test comparisons in the control group (p≥0.05). Regarding the reduction of pain and disability and improvement of gait parameters after eight weeks’ intervention in experimental group, the use of this protocol is recommended to improve patients with chronic low back pain as a new method.
 

Diabetes is a common metabolic disease. In diabetic patients glucose uptake is reduced and FGF-21 plays an important role in glucose uptake, alsoTNF-α is an inflammatory factor that increases in diabetes. The purpose of this study was to investigate the effect of 6 weeks of HIIT training on the gene expression FGF-21 in the liver and the serum TNF-α level of male diabetic rats. For this purpose, 48 Wistar rats were randomly divided into four groups Control, diabetes, high intensity interval training, and diabetes and high intensity interval training. For the induction of diabetes, peritoneal injection (Streptozotocin 50 mg/kg) was used. Training protocol including 10 set of 1-minute running (between each set of 2 minutes of rest) 3 sessions per week and was completed within 6 weeks. Finally, after the extraction of liver samples, the expression of the FGF-21 gene was measured by Real Time PCR and serum TNF-α level with ELISA kit.There was no significant change in expression of FGF-21 in any group, but the reduction of serum levels of inflammatory factors, such as TNF-α protein at the level of significance (p=0.05), and maintaining and improving the time to exhaustion, was shown by high intensity interval training (0.000).Likely the inflammatory factors of diabetes such as TNF-α have a deleterious effect on the expression and binding of FGF-21 (β-Klotho) cofactors And causes resistance to FGF-21 into various tissues of the body, such as the liver. Exercise can reduce inflammation caused by diabetes.
 

The purpos of this study was to determine the effect of  twelve session of high intensity cycle training with blood flow restriction on aerobic and anaerobic performance of active student men. To this purpose, 24 valentear active students men from physical eduction faculty of kharazmi university aged 19-23 years old, students (mean ± SD weight: 67.89±6 kg, height: 173.92±5.41cm, and  BMI: 22.7±6.84kg/m2) divided into three groups of blood flow restriction (BFR) (n=8), none blood flow restriction(NBFR) (n=8) and control group (n=8). The exercise consisted of cycling at 80% Wmax for ten 1-min bouts, with a 2-min rest between bouts with 50% Wmax (total time, 30 min). Before and after implementation of the training protocol, Astrand Test to check the aerobic  performance and Wingate test to check anaerobic performance was conducted. To data analysis, the independent t-test, analysis of variance test and post hoc test (LSD) was used. Results indicated that two weeks of high intensity cycling with and without blood flow restriction does have a significant impact on VO2max(p=0.000) and Wmax(p=0.000) and time to exhaustion (p=0.001). The results indicate a further increase in aerobic performance components, in exercise with blood flow restriction training group compared to the unrestricted blood flow training group. The results olso indicated that tow weeks of cycle training with occlusion does not have a significant impact on peak anaerobic power(p=0.064), average anaerobic power(p=0.058) and minimum anaerobic power(p=0.826). In general, the results showed a partial restriction of blood during cycling interval training have affect on aerobic adaptations, but  does not affect on anaerobic adaptations.

The aim of this study was to investigate changes in immunoreactivity of Ras and Raf-1 in lung epithelial cells of rats exposed to carcinogen NNK after swimming training. 50 Wistar rats were randomly divided into five groups: control, training, training + NNK, NNK and sham. NNK-induced groups received NNK Subcutaneously once a week at a dose of 12/5 mg per kg body weight for 12 weeks. The exercise training consisted of submaximal swimming training for 12 weeks. The percentage of reaction of Ras and Raf-1 in lung epithelial cells were measured by HIC. It was observed no significant change in the Ras and Raf-1 immunoreactivity of lung epithelial cells in training group compared to control. A significant incretion of the Ras and Raf-1 immunoreactivity was found in NNK group compared to control group (p=0.001). Furthermore, a significant reduction of the Ras and Raf-1 immunoreactivity was observed in exercise + NNK group when compared to NNK group (p=0.001). Generally it could be confirmed that regular submaximal aerobic training plays an important role in inhibition of the effects of lung carcinoma induced by NNK via reduction of Ras and Raf-1 activity.
 

Pronation distortion syndrome is one of the most common abnormalities in the body that causes distortions in the structures of the skeletal structures of the lower extremities and increases postural sways. The purpose of this study was to determine the effect of 12-week corrective exercises on postural sways in male students with pronation distortion syndrome. In this semi experimental research, 30 volunteers had pronation distortion syndrome, were selected and then randomly and equal divided into two groups of control and experimental (n=15). The experimental group performed corrective exercise consisting of inhibitory, stretching, strengthening, and integrated exercises for three months, but the control group carried out their routine exercise. The postural sways conterol were evaluated before and after of the three month of performing corrective exercises. Independent and dependent t-test were used to analyze the results (P≤0/05). The showed significant improvement in postural sways control and ground reaction force (P≤0/001), effect size 0.8 and 95% confidence interval after three months of corrective exercise, but in control group there was no significant difference (P≥0/05). In addition, after intervention, the experimental group were significantly lower in postural sways conterol and ground reaction force than the conterol group (P≤0/001), but this difference was not  significant in the pre-test (P≥0/05). It seems that systematic corrective exercise led to improve the activity of the muscles responsible for body sways conterol, which also reduces postural sways and ground reaction force in people with pronation distortion syndrome, so it is recommended that researchers, trainers, and specialists consider systematic corrective exercise in order to improve posture sways conterol and ground reaction force in people with pronation distortion syndrome.

Using appropriate devices and scientific methods by coaches and trainers can accelerate the process of sport talent identification and development, and could also provide condition in which capable athletes to be directed in to suitable sport according to their abilities and skills. Former researches in scope of sport talent identification usually have been done in order to determine or normalize effective parameters. The purpose of this study was to design volleyball talent identification algorithm based on fuzzy logic which ranks the volleyball athletes. Due to expert opinion, essential parameters of volleyball talent identification which also used in this software are; Height (Anthropometry), Velocity (Ability of motion), Vertical jump with run-up (technical skill) and Pair jump (functional skill). Norms of young elite volleyball players are also used as index. Then with considering parameters and index, a fuzzy algorithm is designed which classifies volleyball players in Unmatched, Semi-matched, Matched, Brilliant and Rare class. These results can help trainers and coaches in order to select talented and capable volleyball players.

Regarding the effects of the kinematics of the movement on athletic performance and the Importance of promoting athlete’s performance on the sport fields, there is limited knowledge about the mechanism of the effect of different variables of volleyball spike. Therefore, the aim of this study was the prediction of jump performance in elite female volleyball players with selected kinematic variables.  Thirty elite female volleyball players with mean age of 21.44±3.42 have volunteered for this study. Lower limbs kinematics have been recorded using 16 reflexive markers with Vicon motion analysis system during volleyball spike jump performance. Jump height and time of concentric phase of jump have been predicted by center of mas velocity during step, final step length and ranges of the motion of hip, knee and ankle with stepwise regression (α≤0.05). The results showed that knee range of motion center of mass velocity and step length could be the predictors for time of jump and center of mass velocity and hip range of motion could be the predictors for the jump height as well. Considering these results and the goal and situation of the volleyball match, the players should focus on different phases and affecting variables of the spike jump.
 

Various studies have shown that the external focus of attention is better than the internal focus of attention. But, so far no study has been investigated the level of electrical activity of the rectus abdominus muscle as a trunk stabilizer muscle. Therefore, the purpose of this study was to investigate the effect of focus of attention on electromyography activity of the rectus abdominus muscle during Different phases of vertical jump.Twelve male elite volleyball players from university of Tehran Participated in this research voluntary. They performed a vertical jump on the force plate in both internal and external focus of attention condition. Rectus abdominus Surface electromyography (SEMG) signals recorded by electromyography apparatus during vertical jump and The electrical activity of this muscle was calculated in the different phases of vertical jump motion.  Paired t-test results showed that height of jump under the external focus was higher than the internal focus. In addition, this  results showed that internal focus caused significant increasing in Rectus abdominus EMG in comparison to external focus during concentric phase. But, there was no significant difference in the eccentric phase between the external and internal focus of attention conditions. These results suggest that the external focus of attention effectively increases the efficiency of vertical jump. Therefor; we recommend using the external focus of attention instructions when executing vertical jump movement.


 

Time under Tension of muscle is one of the variables of strength training that contributes to its adaptation. The present study was conducted the effects of six weeks of resistance training with the varying Time under Tension of muscle on VEGF and endosotene serum levels  in healthy young women. This study was conducted on 20 female students (22.65±2.03years) Subjects were randomly and equally assigned to two groups with a Time under Tension of 1s- 1s(Normal Speed Contraction) and 3s- 3s (slow Speed Contraction). The exercise load was the same in both groups and resistance training was done in a circular manner for six weeks, three days a week in eight stations. Blood samples were taken from the subjects to study  research variables before the training period and 48h after the last session of the training. Data were analyzed by covariance analysis at a significant level of P≤0.05. There was no significant difference between the serum levels of VEGF and endostein in both groups (P≥0.05). In the strength test, the  SSC group experienced increase power further. However, there was no difference between the two groups in indicators related to angiogenesis for six weeks and  most probably, for this indicator needed more training time, but  practice with more Time under Tension (3s- 3s) can lead to increase power further.
 

Feedback instruction is a proven modality for the alteration of motion patterns. There are no existing data on the contribution of strength training, when combined with feedback instruction, to the altering of lower extremity biomechanics. Thus the purpose of the current study was comparison of strength training  program with external and internal focus of attention strategies on kinetic and functional factors in athletes with plyometric pattern. 36 athlete females (handball, Basketball and vollyball) voluntarily with avarage age 22.3±2.27 years were randomly assigned to strength training with external focus, strength training with internal focus and strength training groups. Participants completed these training for 8 weeks. Kinetic factors were measured using force plate during landing, as well as functional movement and movement pattern respectively were measured by single leg triple hop test (SLTH) and landing error scoring system. One-way analysis of variance (ANOVA) showed that the effect of strength training with external focus group training significantly was better than two others groups in Peak vertical ground reaction  (p=0.039), posterior ground reaction force (p=0.046), mediolateral time to stability (p=0.032), single leg triple hop test (p=0.041) and landing error scoring system  scores (p=0.030). But there was no significant between-group difference in anteroposterior time to stability (p=0.312). Subjects in strength training with external focus group showed significantly within-group changes in all variables except anteroposterior time to stability from posttest to pretest. Programs that include both strength training and movement education through external focus of attention may be necessary in order to prevent ACL injuries and increase athletic performance.

 

In a walking cycle design, maximizing the upright balance should be considered in addition to the kinematic constraints, energy consumption rate must be considered. The purpose of this study is to find the optimal step length obtained for each person according to the physical features. In this research, in order to minimize energy consumption rate by considering maximum balance two cost function were defined. the fall cost function was designed based on the concept of MOS and balance index. To investigate the upright balance and to reconstruct the movement pattern, Data from normal walking gait of healthy subjects was taken and seven links model was defined. In this study, the optimal step length was obtained for the person with height, weight and gait cycle characteristics. it is shown that for a person of 92kg mass and 1.87 meters height, the best step length in walking would be 0.54 meters. In this study, the kinematic and kinetic characteristics of human motion were identified by the analysis of gait patterns on a treadmill. Through the calculation of the balance index, individuals are helped to find the optimal step length for which the maximum balance is achieved. The results of the study can provide the optimal step length to correct the gait pattern.
 

Due to the positive affect of the training on the improvement of MS, "the effect of the comprehensive training on neurotrophin- 4/5 and other variables in women with MS" was investigated. Experimental groups (A, B, and C) performed their intervention. Based on the level of disability, different training was used. Control groups (A, B, and C) received only stretch training. At first, all pre-tests were performed and then the experimental groups performed their exercises during 12 weeks. At the end, depended variables were measured and ANCOVA was used. According to the results, showed that rehabilitation protocol has no effect on the levels of neurotrophin 4/5 in MS patients at levels A and C (P=0.504 and P=0.083) but significant increase observed in B level (P=0.010). The results also showed that at level A: BMI, fat percentage, speed and VO2max, and at level B: weight, BMI, fat percentage, endurance, dynamic balance, waist circumference, hip circumference, WHR and VO2max had a significant improvement. On the other hand, at level C, only BMI, fat percentage and VO2max were significantly improved. These results show that rehabilitation exercises have a positive effect on these variables and can increase the quality of life in these patients.

The present study was aimed to determine the effect of cold-water immersion and (TDCS) during the recovery period on blood lactate changes in and subsequent performance of professional male swimmers. For this purpose, 20 male participated in this study in two days with an interval of 48 hours. The two-hundred meter breaststroke was performed every day and then the subjects participated in one of the protocols, an anodic stimulation (with intensity of 2 mA)or the artificially exposed to anodic stimulation on the first day, and on the second day they were experienced the cold water immersion (12° C).The subjects' blood lactate was measured. Finally, in order to measure the effect of the investigated methods on their performance, the 200-meter swim was repeated. To analyze the data dependent t-test and analysis of covariance, LSD follow-up, analysis of variance with repeated measures, were used. The results of this study indicated that swimming performance significantly improved only in the TDCS group, with a reduction in the record time (P = 0.001). Blood lactate showed a greater decrease in the cold water immersion group (P = 0.001)