Showing 251 results for Type of Study: Research
M.h Noori, H Sadeghi,
Volume 18, Issue 19 (7-2020)
Abstract
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.
N Shaterkazemi, Sh Zandi, E Shirzad,
Volume 18, Issue 19 (7-2020)
Abstract
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.
S.f Qeysari, Sh Tahmasebi Broujeni, M Shahbazi,
Volume 18, Issue 19 (7-2020)
Abstract
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.
R Shiri, H Nikbakht, M Gholami, Kh Ebrahim,
Volume 18, Issue 19 (7-2020)
Abstract
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.
P Zalbeik, A Letafatkar, Sh Rezvan Nobahar,
Volume 18, Issue 19 (7-2020)
Abstract
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.
M Termeh, A Ghanbarzadeh, M.h Honarvar, K Heidari Shirazi,
Volume 18, Issue 19 (7-2020)
Abstract
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.
Abdolreza Kazemi, Fatemeh Khajepor, Alireza Sharifabadi, Mahdi Madahi,
Volume 18, Issue 20 (11-2020)
Abstract
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.
Ali Molaei , Sedigheh Hosseinpour Delavar, Ghahramani Mehran, Reza Jabbari, Mohammad Jalilvand,
Volume 18, Issue 20 (11-2020)
Abstract
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)
Ebrahim Banitalebi, Mohammad Faramarzi, Farideh Savari Niko, Neda Soltani, Majid Mardaniyan Ghahfarrokhi,
Volume 18, Issue 20 (11-2020)
Abstract
Osteosarcopenic obesity is the result of processes that lead to muscle and bone breakdown and increased fat tissue. The purpose of this study was to investigate the effect of 12 weeks elastic band resistance training on functional indicators and Osteosarcopenic obesity index in women with Osteosarcopenic obesity. In this single blind randomized clinical trial, 49 elderly women with age 64.13 ± 3.6yrs, fat percentage 45.4 ± 6.56 %, T score of the minerals of the were -1.86 ± 1.42 were divided into two groups: control (n=22) and training (n = 27). The training group performed elastic band resistance training for 12 weeks. significant increases in short-term physical function (SBBP) (P = 0.024) and Z score of Osteosarcopenic obesity (P = 0.041), in the training group compared to the control group, and non-significant difference in muscle quality (MQ) (P = 0.200), fracture risk (FRAX) (P = 0.259), between exercise and control group. 12 weeks of elastic band resistance training seems to improve in short physical performance battery and Z score of Osteosarcopenic obesity in elderly women with Osteosarcopenic obesity, but, probably a longer period of training is needed to further influence the other osteosarcopenic obesity index.
Soroush Shah Hosseini, Amir Hossein Barati, Mohammad Hossein Nasermeli, Mohsen Moradi,
Volume 18, Issue 20 (11-2020)
Abstract
Given that more than 50 percent of patellofemoral pain syndrome include of overuse injuries, the aim of this study was to compare the vastus medialis muscle activity in individuals with patellofemoral pain syndrome after a period of strength and flexibility training with and without the electrophysiological feedback. A total of 30 subjects (15 men and 15 women) participated in this study. Subjects were divided into three group's control, therapeutic and therapeutic with electrophysiological feedback. One-way ANOVA was used to compare the activity of vastus medialis muscle in between groups. The results of this study showed that there was a significant difference between the groups in the activity of the vastus medialis muscle activity (P <0.05). The results of Tukey's post hoc test for intra-group comparisons showed that there was a significant difference between the control group with the therapeutic group (P = 0.024), the control group with the therapeutic group and the electrophysiological feedback (P=0.028) and the therapeutic group with the therapeutic group and the electrophysiological feedback (P<0.001). Conclusion: Regarding the results of this study, therapeutic exercises with electrophysiological feedback have a greater effect on the activity of vastus medialis than the therapeutic group in patients with patellofemoral pain syndrome.
Mahdi Safari Bak, Reza Baharifard, Amin Gandomkar,
Volume 18, Issue 20 (11-2020)
Abstract
The chronic ankle sprain is the most common injury among athletes, and using the tape is one way to prevent it. The aim of the present study was to determine the effect of the Kinsio-tape on the compressive and shear mechanical forces of the ankle joint during single-leg jump landing. 12 subjects were selected based on inclusion criteria. Subjects were asked to perform landing after jump in the conditions of with Kinsio-tape and barefoot, with the injured leg. The peak and mean compressive and shear forces of ankle joint were calculated in MATLAB software. Paired t-test was used to test the hypotheses (P≤0.05). There is no significant difference in all variables between two condition of landing with barefoot (mean of shear force= 0/05 ± 0/01, peak of shear force= 0/85 ± 0/06, mean of compressive force= 0/39 ± 0/02, peak of compressive force= 4/41 ± 0/22) and with Kinsio tape (mean of shear force= 0/05 ± 0/01, peak of shear force= 0/82 ± 0/06, mean of compressive force= 0/38 ± 0/03, peak of compressive force= 4/43 ± 0/28) (P>0.05). Since the use of the Kinsio-tape did not make a significant difference in the variables, it cannot be suggested as a safe prescription to protect ankle joint from compressive and shear mechanical forces in volleyball players.
Amir Milan Amini, Mohamad Fashi, Rana Fayaz Milani,
Volume 18, Issue 20 (11-2020)
Abstract
This study aimed to assess the effects of acute calcium lactate supplementation intake on the performance and buffering capacity of elite amateur boxing athletes. 8 elite amateur boxers (180±4.33 cm, 24.12±3.68 years, Weight categories: -75, -64, -69, +81) were assigned to acutely receive calcium lactate (0.5 g, 80 mg calcium lactate/kg body weight) and placebo in a double-blind crossover design 90 minutes before the box competition. 90 minutes before, before competition and immediately after, blood samples were taken and lactate, PH, HCO3-, and PCO2 and also, average heart rate, and number of effective hand kick were evaluated. lactate and HCO3- significantly increased and decreased at three evaluation times in calcium lactate supplementation and placebo groups respectively (P<0.05). There was no significant difference between calcium lactate supplementation and placebo groups in lactate, pH, HCO3-, PCO2, heart rate and performance at three evaluation times (P>0.05) .Calcium lactate supplementation improves performance without significant changes in the buffering system. In other words, more effort with a similar acidity to placebo could indicate the effect of calcium lactate supplementation on the performance of amateur boxing athletes.
Mr Amir Reza Sedighi, Dr Mehrdad Anbarian,
Volume 18, Issue 20 (11-2020)
Abstract
The purpose of this study was to determine the immediate effect of three types of shoe insoles, on electromyography activity of selected lower extremity muscles during running on treadmill. The electromyography activity of the rectus femoris, vastus lateralis, vastus medialis, biceps femoris, tibialis anterior and gastrocnemius lateralis muscles of 14 male athletes were recorded in non-insole, wearing soft, semi-rigid and rigid insoles conditions during running on treadmill. Electromyography activity of the rectus femoris muscle in the loading phase was lower in soft insole condition than other conditions. In the pre-swing/early swing phase, there was difference of the rectus femoris muscle activity in the soft/non-insole and soft/semi-rigid conditions. In this phase, the biceps femoris muscle had different activity in the semi-stiff/non-insole and semi-rigid/rigid conditions. In the mid-swing phase, there was a difference in the activity of the rectus femoris and the tibialis anterior muscles in the non-insole/semi-rigid condition, and the gastrocnemius lateralis muscle in the non-insole condition with other conditions. There was difference also for biceps femoris muscle activity in the semi-rigid/non-insole condition in the pre-activation phase. The vastus lateralis and gastrocnemius lateralis muscles activity in the soft insole condition was lower than that of the semi-rigid condition. It seems that the intensity and contraction pattern of the muscles change while using different shoe insoles with different variety of stiffness during running. It could be useful in choosing a shoe insole with a suitable stiffness material level for clinical and training purposes.
Karar Khajeh Nemat, Heydar Sadeghi, Ismaeil Ebrahimi Takamjani, Raghad Memar,
Volume 18, Issue 20 (11-2020)
Abstract
Proprioception is essential for joint function and through which individual can detect body parts movement in space. Aim of present study is to investigate effect of balance training on unstable platform with tilting, translation and combined motion on knee joint position sense in active young males. 39 healthy active male divided in to three training and control (n=9) groups. Training on unstable platform with tilting motion group (n=10), Training on unstable platform with translating motion group (n=10) and combined training group (n=10) performed exercises program for 8 weeks, three times a week. Errors in repositioning of knee joint in 30, 45 and 60⁰ angles (active and passive) was measured by Biodex system 3, before and after training period. Data was analysed by using one-way ANOVA test (P≤0/05). Although after 8 weeks, active and passive errors in repositioning of knee joint in mentioned angles decreased in training groups but this difference was not significant (P≤0/05). Balance training on unstable platform alone cannot have a big effect on knee joint position sense in active young male.
Mr Hamid Mahmodi, Dr Hamid Rajabi, Mr Mohsen Bapiran, Dr Pezhman Motamedi,
Volume 19, Issue 21 (9-2021)
Abstract
The purpose of this study was to compare the effect of plyometric training pre and post maturation period with soccer training on electromyographical index and soccer players performance. 30 students of soccer player's pre maturation period (weight 32.38±6.59 kg, age 10.35±0.59 years, and height 141±0.06cm) and post maturation period (weight 43.79±10.96 kg, age 15.43±0.72 years, and height 156.84±0.09 cm) were selected. Subjects in the experimental group were 15 students before and after maturity period. To evaluate the age of the indices such as height, age, dental and bone age (radiographic method) was used. Then, for homogeneous groups of index of biological age radiography was used by radiologists. Before and after 4 weeks of training,, functional tests of two 20 meter speed, agility, vertical jump and also Amplitude for vastus lateralis muscle Were taken. The result by using Paired t-test showed that in pre maturation group in the vertical jump, agility and 20 meters there was a significant difference (P=0.002,P=0.006,P=0.001) and the other variables there was no significant difference. In variations between the groups, independent t-test showed that only significant differences was found in the test 20 meter speed (P = 0.007) and in the other variables not significantly different. The results showed that plyometric training in the Pre maturation group compared to post maturation group were more effect and these results can help in the design training for premature age groups
Mr Iman Rouzbeh, Dr Amirhossein Barati, Dr Hooman Minoonejad,
Volume 19, Issue 21 (9-2021)
Abstract
As Squat is a popular exercise for support of lower extremity muscles in order to injury prevention this study has been hold to comprise the electromyography of vastus medialis and vastus lateralis muscles in three Squat techniques of man soccer players. 15 soccer players, aged 18-25 years old, who had regular exercise more than two years did open, closed and lung Squats exercise while electromyography of vastus medialis and vastus lateralis muscles were recorded. Data analyzed by using dependent and independent T test and repeated measure ANOVA. There was not significant difference of vastus medialis and vastus lateralis muscles’ electromyography during getting up, going down phases and also for different squat techniques. The vastus lateralis muscle show more activity in all conditions. Though, it is recommended that vastus medialis has bold role for controlling of squat exercise, reduction of Q angle and participants’ knee varus in this study can be the reason of antithesis.
, , Elham Shirzad,
Volume 19, Issue 21 (9-2021)
Abstract
Despite the importance of talent for sports, but it has yet received little attention. The purpose of this study was to present a pattern design for talent identification in karate based on artificial intelligence algorithms. Subjects divided to adolescent elite karate athletes (n = 19) and non-karate athletes adolescent (n=20) by convenience sampling. Besed on previous literature, we selected and measured biomechanical and anthropometric variables. The normal distribution of all data was analyzed using Shapiro-Wilk test. Principal component Analysis (PCA) was performed to reduce the number of variables and identify the most important anthropometric and biomechanical variables. Then, for modeling, the neural network algorithm was used with three input layer (10 neurons), middle (7 neurons) and output (2 neurons). The results showed the most important anthropometric variables of adolescent elite karate athletes were thoracic subcutaneous fat, height, jump, static balance, grip strength, chest circumference, ankle circumference, abdominal subcutaneous fat and apparent length leg respectively. Also, percentage of correct classification and sensitive of data was high and 87% and 85% respectively. According to the results of this study, this method can be used for talent karate athletes along with other methods.
Azadeh Doroodgar, Khalil Khayambashi, Shahram Lenjannejadian, Ghasem Yadegarfar,
Volume 19, Issue 21 (9-2021)
Abstract
Hamstrings (Hams) to Quadriceps (Quadr) strength ratio is known as a risk factor for Anterior Cruciate Ligament (ACL) injury and affects by knee and hip flexion angles. Gluteus Maximus (Gmax) muscle acts as a synergist for Hams in hip extension in a closed kinetic chain. The aim of this study was to investigate the effect of Gmax strengthening exercises on the kinetic and kinematic risk factors of ACL injury when single-leg landing from a jump. 25 volunteer women aged 18-30 years were assigned into control (n =13) and experimental (n =12) groups. Maximum isometric strength of Gmax, hip and knee joint angles and ground reaction force (GRF) was measured at landing, by dynamometer, 2D imaging and foot scan respectively,. After 8 weeks of 3 sessions of Gmax resistance training, Following the significant within-subject difference for GRF (F=5.245, P=0.032) by using Two-way mixed model ANOVA, Pre and post-test Differences were significant with 16.63% decrease (P= 0.038, t=2.354). Differences between pre and post-test peak force, time to peak, mean joint angles, impact and load rate were not significant (α = 0.05). According to a 4.55% and 3.47% increase in Gmax strength and time to peak force, and considering the fact that at the beginning of landing, the mechanical advantage of Hams is lower than that of Gmax, the risk of ACL injury could be reduced by reducing GRF following an increase in the Gmax strength.
Dr Shirin Yazdani, Prof Nader Farahpour,
Volume 19, Issue 21 (9-2021)
Abstract
Background and Objective: although it is documented that the spine and hip alignments alter in scoliosis subjects, but the effect of these changes on the lower extremities’ biomechanics have not been well understood yet. So, the aim of this study was to compare hip, knee and ankle joint’s power generation and absorption during gait in patients with adolescent idiopathic scoliosis (AIS) and healthy controls. Methods: Using motion analysis system with 4 Vicon-460 cameras and two Kistler force plates, the kinematics and kinetics of gait was assessed in twenty girls with AIS and 20 matched healthy controls, then the power of the right and left hip, knee and ankle joints in sagittal plane was calculated. Data was analyzed using ANOVA statistical method with significance level of α<0.05. Results: Results showed that in scoliosis group, the peak power absorption of the right knee was significantly 12.5% smaller than that in control group (p=0.01). But, peak power generation and absorption of the hip and ankle joints in both right and left limbs were not statistically differed between the two groups (p>0.05). Conclusion: scoliosis is associated with the smaller power absorption of the knee joint at convex side. This might be linked with unilateral alterations of the joints' moment, joint forces, and the related muscle activity which might impose asymmetrical force to the hip and cause curve progression.
Dr. Leila Ghazaleh, Mis Fahimeh Bakhshizadeh, Dr. Rana Fayazmilani,
Volume 19, Issue 21 (9-2021)
Abstract
It is necessary to examine the changes of muscle co-contraction in different percent of fatigue-induced force reduction. The present study aims to investigate the effect of fatigue-induced force reduction of knee extension on muscle co-contraction. Ten healthy and active women aged 26.10±2.99 years performed fatigue protocol including 5 seconds of maximal voluntary isometric contraction (MVIC) of the knee extension and a 5-second rest. Muscle co-contraction was calculated for each subject in the repetitions in which the MVIC force was reduced by 10, 20, 30, 40 and 50% as compared to the pre-fatigue MVIC force. Knee extension force and muscle activity measured by Isokinetic and electromyography apparatus, respectively. The difference between co-contraction of vastus lateralis and medialis in different percentages of force reduction was not statistically significant. The co-contraction of rectus femoris and biceps femoris increased by 40 and 50% of force reduction compared to pre-fatigue co-contraction (P<0.01). Co-contraction of biceps femoris and vastus lateralis increased by 20, 30, and 40%, as well as co-contraction of biceps femoris and vastus medialis increased 40% of the force reduction, compared to pre-fatigue co-contraction (P <0.05). The results, overall, showed that the change of co-contraction during fatigue is influenced by the selected muscle and the rate of force reduction. This finding can help researchers decide how neuromuscular fatigue effects on muscle co-contraction
