جستجوی مقالات مرتبط با کلیدواژه "peak torque" در نشریات گروه "پزشکی"

Since the optimization of different forms of exercise and training in exercise and treatment, especially the use of open and close chains, has been discussed in the past studies, the present study was conducted to compare the selected kinetic variables (peak torque, time to torque, average power, and total work) agonist and antagonist muscles of the knee extensor in active women at two open and closed kinetic chain ways at 60 and 180 °sec, respectively.

Participants of the current semi-experimental comparative study included groups of active women. The isokinetic device was used with two special attachments for the open and closed knee movements, while for each type of the test, the device was adapted to the type of test and type of speed and physical physics. The method of testing were first explained to the participants. The information and type of test related to each participant was recorded and stored on the device. For data analysis, mean, standard deviation, and independent T test were used to compare variables as well as the two types of kinetic chain at two speeds with the significance rate set at 0.05.

The results revealed a difference between two open and closed kinetic chain ways with isokinetic device at two speeds of 60 and 180 degrees per second in active group. According to the findings of peak torque, the average power and total work variables in the open kinetic chain in the active group at 60 and 180 degrees per second at two speeds were more in active group and the time of peak torque in closed chain was more than that of open kinetic chain at both speeds.

According to the findings of the study, due to the differences in the results of flexion and extension testing of knee in the open and closed kinetic chains at two speeds of 60 and 180 degrees/s, the results indicated more control and accuracy of the isokinetic test in closed chain in comparison with the open chain at both speeds in the active group. Meanwhile, the results indicated that the time to peak torque of the closed kinetic chain test can be possibly a preference for using this method for post-traumatic rehabilitation; therefore, it is recommended to educators and therapists. Also, due to the higher kinetic values in other variables except for time at both speeds in open kinetic chain, to improve muscle strength and function, performing an open kinetic chain is suitable and useful.

The correct execution of sports movements depends on the method of warming up and the type of stretching. That is why it is very important to warm up properly to prevent any damage to the body and improve performance, appropriate to the type of exercise. In addition, the main reason for warming is the increase in core body temperature, which in turn leads to more blood flow to the active muscles and increases the rate of transmission of nerve impulses and chemical reactions. Although there are different debates about which stretch should be used with what intensity and volume before exercise, but usually static stretch before training and sports competition in warming up section is used. PNF stretching  is thought to be superior to other stretch methods in developing range of motion due to the activation of the golgy tendon organ by the Autogenic Inhibition method and the facilitation of muscle inhibitory receptors, but the effects of PNF stretch on the performance is very controversial. Therefore, The current study aimed to determine the effects of static and PNF stretching on maximum torque and agility of male futsal players.

Having at least 2 years of training experiences, twelve trained male Futsal players with a mean age (22.33±0.88 years), height (175.75±6.21 cm), weight (68.75±3.64 kg), BMI (22.57±1.23 kg/m2) and body fat (15.65±3.58 %) were randomly selected. They were divided into four training protocols, including static stretches (3×5 s and 3×15 s), PNF stretch (30s×6s×15 s) and control condition. The SECA1 height measurement device with a measurement accuracy of one millimeter (made in Germany) was used to measure height. The Buerer digital weight measurement device with an accuracy of 0.1 kg (made in Germany) was also used to measure the body weight of the subjects. In addition, the yo-yo recovery test was used to determine the subjectschr('39') aerobic capacity (VO2max), and the Zeus 9.9 body analyzer was used to measure body composition and fat percentage. Isokenitic dynamometer Gymnex model ISO-1 with the speed of 60 degrees per second and Balsom agility test were applied to measure maximum force torque and agility respectively. Furthermore, two-way ANOVA with repeated measures was used to compare the mean difference. Bonferroni  post hoc test was applied when the differences were significant and interval confidence of p < 0.05 considered at all stages of the test.

The results of data analysis with repeated measures test in comparison between the type of stretches with the control condition in the variable of maximum torque at a speed of 60 degrees per second showed that the effect of the type of stretch(group) was significant (p=0.024, F=2.061). These results show that only the PNF stretch protocol was different from the control condition (p<0.05) and the static stretch protocols 3 × 5 s (p= 0.17) and 3 × 15 s (p=0.34) were not significantly different from the control condition. In addition, the results of the present study showed that the interaction between the type of stretch(group) and time was significant (p=0.009; F=4.59). On the other hand, The results of data analysis with repeated measures test in comparison between the type of stretches with the control condition in the variable of agility showed that the effect of the type of stretch (group) was significant (p=0.039, F=5.23).The results showed that only the PNF stretch protocol was different from the control condition (p<0.05) and the static stretch protocols 3 × 5 s (p=0.35) and 3 × 15 s (p=0.57) were not significantly different from the control ondition. In addition, the results of the present study showed that the interaction between the type of stretch(group) and time was significant (p=0.044; F=4.45).

Overall, the results show that the implementation of static stretching protocols and PNF above 90 seconds has a destructive effect on the performance of torque and agility of futsal players. Among the most important mechanisms affecting performance can be the destruction of muscle tendon features, involved neural mechanisms (decrease in firing frequency, increase in nervous fatigue and decrease in concentration), mechanical properties and muscle elasticity, duration, intensity and type of stretch, gender and level of fitness of the athlete employed were mentioned. Therefore, to reduce the destructive effects of this type of stretching and on the other hand increase the efficiency of muscles to improve performance in the warm-up phase, it is recommended to futsal players, If using static  and PNF stretches, do not use times longer than 90 seconds..

Recent conservative management of sub-acromial shoulder impingement (SSI) includes general strengthening exercises, especially for internal (IR) and external (ER) shoulder rotators. Despite various studies, so far, there is no directly investigated for indicating the difference in muscle strength between patients with SSI and normal subjects. This study was done to compare the shoulder joint muscles’ strength in male students with and without SSI. This case-control study was conducted on Twenty-four students with SSI as case group and 24 normal students as controls.The subjects in both groups matched for hand dominance and physical activity level, completed isokinetic shoulder IR and ER testing. In the case group, 18 patients had the symptoms in their dominant and 6 patients in their non-dominant side. Both sides IR and ER of shoulder were measured separately using continuous reciprocal concentric and eccentric contraction cycles at speed of 60 and 120 degrees per second, respectively. Values of peak torque were compared between the case and control groups. There was a significant difference between the two groups only when the symptomatic SSI shoulder was the dominant shoulder. Eccentric and concentric ER peak torque at 120 degree per second (22.20±7.01, 11.36±3.36), eccentric ER peak torque at 60 degree per second (20.53±6.15) and eccentric IR peak torque at 60 degree per second and 120 degree per second were significantly lower in the symptomatic dominant shoulder case group in compared to the dominant shoulder control group (P<0.05). Changes in eccentric and concentric peak torque in SSI group may be related to limb dominance, which may have implications for strengthening regimes. Therefore, clinicians and therapeutic exercise expertise may benefit from eccentric isokinetic exercises for shoulder IR and ER rotators in order to design a treatment plan for patients with SSI.