نشریه ورزش و علوم زیست حرکتی
سال چهارم شماره 1 (پیاپی 7، بهار و تابستان 1391)

The anaerobic threshold was initially defined as a work intensity or level of oxygen consumption (VO2) preceding the onset of metabolic acidosis and the associated changes ingas exchange that take place.

The aim of this study was to investigate the effects of workload pattern in the exhausting protocols on anaerobic threshold in sedentary young girls.

Fifteen sedentary girls with the mean and standard deviation of age (20.42±1.12 years), height (161.64±5.8 cm), weight (54.92±5.48 kg) and VO2max(26.23±3.43 ml/kg/min) participated in our study. Anaerobic threshold computed by respiratory compensation point at two different exhausting protocols. The first protocol was initiated withthe %10 slope and 2.5 km/h speed. The slope and speed were increased by %2 and 1km/h every minute up to exhaustion, respectively; While during the second protocol, subjects warmedupfor 10 -15 minutes, testing protocol initiated with %75 of MHR of the subjects, and the treadmill speed increased by 2 km/h every minute up to exhaustion. The ventilatory threshold and gasexchange responses were collected by gas analyzer system. Data were analyzed by the two statistical models. Graphical Bland-Altman as well as the intraclass correlation coefficient(ICC) methods was used to assessment of the possible agreement. Paired samples T Test was used to comparing the predicted AT in the two protocol.

Although changes of the exhausting protocol types did not results in significant difference between two predicted AT by the means of the Paired Samples T Test, the Bland-Altman and the ICC methods revealed medium agreement between the two protocols (ICC=0.4399; ±1.96, 95% CI=-21.8 to +20.2).Discussion and

According to the doubtful agreement between two predicted AT in the two protocols, increasing of the exhaustive protocol duration affects the predicted AT which is not detectable by the means of the Paired Samples T Test. Therefore, application of the long durationprotocol not only is doubtful, but also, it is strongly recommended to use the optimal statistical methods.

There is an extensive research on the effect of endurance training on the male reproductive system. However, the effect of resistance training on the male reproductive system is not clear. Therefore, the aim of this study was to examine the effect of resistance training on male reproductive function. Twenty male rats were divided randomly into two groups as control group and resistance training group (n=10). The resistance training consisted of climbing (5sessions/week, 4 reps/3 sets) a ladder carrying a load suspended from the tail. The weights were increased gradually throughout the 8 weeks of training, with the average weight at the end oftraining equal to 200% body wt. After the 8 week training protocol, rats were anesthetized in separated group and sampling was done. Serum concentrations of luteinizing hormone,testosterone, follicle-stimulating hormone and prolactin were measured by radioimmunoassay method. The seminological profiles of all rats were assessed according to the Johnsen Scoremethods. Statistical analyses were performed using a Student’s independent t-test. After 8 weeks of training spermatogenesis quality significantly declined (P<0.05). In exercise group no significantly changes in sex hormones levels (testosterone, luteinizinghormone, follicle-stimulating hormone and prolactin) were observed (P>0.05).Discussion and These results suggested that progressive resistance training have negative regulatory effects on male reproductive system.

Myostatin, as a powerful inhibitor of skeletal muscle growth, and follistatin, as a potent inhibitor of myostatin, play an important role in regulation of body composition. The purpose of this study was to evaluate of myostatin and follistatin in wrestlers. 15 male wrestlers (22.5 ± 1.7 years, 77.1 ± 9.1 kg) decreased 4% of their body weight during 48 hours via traditional methods including severe diet and dehydration.Anthropometric and body composition variables were measured, and blood samples were obtained to assess any changes in myostatin and follistatin concentrations prior and after the protocol. Data were analyzed via paired t-student test by SPSS. Following weight loss, myostatin and follistatin concentrations were significantly increased and decreased, respectively (p < 0.01). Relative and absolute fat mass as well asabsolute fat free mass were also decreased (p < 0.01), while a significant increase appeared in relative fat free mass (p < 0.01).Discussion and Rapid weight reduction can beget a catabolic environment in fat free mass via an increase and a decrease in circulating myostatin and follistatin, respectively.

The multiple roles of dietary protein and key amino acids such as leucine and glutamine create a variety of potential applications for athletes. Therefore, the purpose of the present study was to examine the effect of glutamine supplementation on delayed onset muscle soreness and electromyographic activity (Mean power frequency, Median frequency) after eccentriccontraction in untrained men. Seventeen healthy men (age: 22.35 ±2.27 yr; body mass: 69.91 ±9.78 kg; height: 177.08 ±4.32 cm) were matched and randomized; double-blind study with subjects assigned to either a glutamine supplementation (n=9) or placebo (n=8) group (0.1gr.Kg-1). The subjects in two groups were asked to take three times in week for 4 weeks. Each subject was screened for dietary habits before inclusion into the study. Participants performed 6 sets to exhaustion eccentric leg extensions at 75% of 1RM and rest intervals were 3 minute among sets. Creatine kinase and EMG activity measurements were taken before exercise protocol and 24 and 48 hours afterwards. There was no statistically significant difference between groups in creatine kinase, EMG activity, knee range of motion, perceived muscle soreness and maximal voluntary contraction (P>0.05). The results indicate that glutamine supplementation has no significant effect on muscle injury markers in between groups.

To day, the use of recovery as a active, passive, massage, stretching, electrical stuimualtion and combination of them have been attention, but, the results of studied on their effectiveness is conflicting

The purpose of this research was to study effect of four types of recovery, namely: active recovery, passive recovery, active combined massage, and massage after intense activity on anaerobic function, blood lactate, rating of perceived fatigue, rating of perceived vigor and finally on the rating of perceived exertion on the physical education students.

12 male students of Kharazmi University Voluntary participated as the subjects of this study. Firstly, these subjects performed standard warm up for 5 minutes on the cycle ergometer, and then immediate completed six stage high intensity bouts of exercise on a cycle ergometer. After five minutes active recovery, subjects practiced different recoveries for 20 minutes with cross design way. Blood lactate was measured 0, 5 and 25 minutes after intense activity. At the end of recovery, the Wingate test performed in 30 seconds.

one way analysis of variance with repeated measuring and the LSD test demonstrated that the efficiency rating of combined recovery on blood lactate cleaning, combined and passive recovery on peak power improvement, combined recovery on average power improvement, combined and active recovery on minimum power improvement, combined, active and massage recovery on fatigue index improvement, combined and massage recovery on the Rating of perceived exertion and rating of perceived vigor improvement is higher than other types of recovery (p <0.05).Discussion and

based on research results it seems that the combined recovery has the highest effect on cleaning the blood lactate, improving anaerobic function, rating of perceived fatigue and perceived vigor than other types of recovery.

Background and

Creatine supplementation in young athletes has been widespread. The aim of this study, then, was to determine the effect of creatine supplementation on some performance indexes on young soccer players.

Seventeen young soccer players (age: 17.18 ± 1.37 y, height: 169.6 ± 6.17 cm and weight: 61.67 ± 1.37 kg) participated in this study. Subjects were assigned to either a creatine (5 g of Cr, 4 times per day for 7 days) or a placebo group (same dosage of a glucose polymer) using a double-blind research design. Before and after supplementation, anaerobicpower of legs, muscle strength, agility and dribbling were measured with valid tests. The independent and dependent t tests were used for data analysis.

Results showed that the weight and lean body mass increased significantly in the creatine group (P<0.01), in the placebo group was not significant. On the other hand, resultsshowed that the time of agility (P<0.001) and dribbling (P<0.04) test improved significantly in the creatine group (P<0.05). Anaerobic power of leg (P<0.002) and muscle strength (P<0.001)were increased significantly in creatine group, but mean different between two groups were not significant.

In conclusion, creatine supplementation improves on some performance indexes on young soccer players.

Diabetes is a metabolic disorder that caused followed the decline in insulin secretion or insulin resistance. Visfatin is a recently discovered protein that is expressed andsecreted in visceral fat tissue that will improve insulin sensitivity. The purpose of this study was to explore of one session of aerobic exercise on visceral adipose tissue visfatin gene expression in rats with diabetes type 2. diabetes in this experimental study was induced by streptozotocin (50 mg/kg) injection in single dose in mice. 20 male wistar rats with average weight of 165 ±5 g were randomly divided into a control group and three exercise groups. The training groups run a session with a speed of 20 meters per minute for 45 minutes on the treadmill. Rats were anesthetized in separated group, immediately, 4h after exercise and 24h afterexercise and sampling were done. Finally, to determine the relative levels of gene expression, semi-quantitative RT-PCR was performed. The results showed significantly increased expression of visfatin in 4 h and 24 h after exercise compared with the control group (P<0.05).Discussion and In summary, exercise can improve the visceral fat tissue levels of visfatin mRNA expression. Increasing the visceral fat tissue visfatin mRNA suggested thatvisfatin in visceral fat tissue could possibly act as Paracrine and also may be play important rol in glucose and lipid metabolism.

The physiological responses and adaptations that swimming exercise evokes are complex and are different from those of land based aerobic activities. The aim of this study was to investigate hemodynamic responses after interval running and swimming exercise in trained young men. sixteen trained runner (n=8) and trained swimmer (n=8) normotensive men (age:22.5±1.4, height:176±4.75cm, BMI:22.2±0.8 kg/m2, body fat:13.1±1.2percent, VO2max:54.1±3.2 ml.kg.min) participated in an interval exercise sessions at 65-75% of Heart rate reserve for 40 minutes, and a control sessions, randomly. Heart rate, blood pressure and rate pressure product were measured before, after the exercise and control sessions. Maximum reduction was found in systolic blood pressure at 30 min in the runner group and for swimmers group was at 15 min in comparison with before exercise state (p<0.05).Systolic blood pressure decreased in the swimmer was significantly greater than runners at 15 min after exercise (p<0.05), but no difference was found for diastolic blood pressure between two groups. Heart rate was different between two groups at 15, 30 and 45 min after exercise (p<0.05); and rate pressure product was different between two groups at 15, 30 and 45 min after exercise (p<0.05).Discussion and The results showed that the type of activity (running and swimming) hasdifferenteffect on the magnitude and durationof blood pressuredecreased afterexercise. The duration of hypotension after the running was longer than swimming, although the magnitude of hypotension was different between two groups only at 15 min after exercise.

The Yo-Yo Intermittent Recovery Test 2 (YIRT2) that designed mainly to estimate VO2max in soccer players, it used to assess athletes abilities to repeatedly perform highintensity exercise. The purpose of the present study was to determine the validity and reliability of the Yo-Yo Intermittent Recovery Test 2 (YIRT2) to estimate maximal oxygen uptake (VO2max) in elite female futsal players. Subjects were Iranian elite female futsal players (n = 33: mean age 22.46±3.04 yrs, height 164.1±4.85 cm, and body mass 56.6±7.31 kg). All subjects performed a graded exercise test on motorized treadmill to examine VO2max by breath to breath gas analyzer apparatus (K4B2, COSMED, Italy) and the YIRT2 to estimate VO2max. The significant correlation found between VO2max measured by gas analyzer and estimated by YIRT2 (r=0.88, r2=0.77, P=0.001), indicating that the YIRT2 is valid test toestimate VO2max.Test-retest results showed that the YIRT2 is the reliable test to estimate VO2max (r=0.98, r2=0.96, P=0.001).Discussion and It is concluded that YIRT2 were a valid and reliable test to estimate VO2max in elite female futsal players. The YIRT2 appears to measure aerobic fitness but may also be used as a field test of the ability to repeat high-intensity efforts.

Optimal performance of paddlers depends on the combination of anthropometrical, physiological, biomechanical and psychological factors.

The aim of this study was to investigate the relationship between physiological characteristics and performance of the Iranian Female National Kayak Paddlers’ Team.

In this study, all members of the Iranian women's national kayak team (aged 16.8 ± 2.4 yr., height 171.6 ± 3.5 cm, body mass 62.73 ± 5.51 kg, fat mass 17.05 ± 3.76 % and body mass index 21.34 ± 09 kg/m2) were examined and recruited as subjects. Physiological characteristics included maximal aerobic power, lactate threshold, maximal heart rate, anaerobic peak power, anaerobic mean power, fatigue index and performance index was 500m paddler in flat water. The normality of distribution of the variables was analyzed by Kolmogorov-Smirnov test. To determine the relationship between physiological characteristics and exercise performance was used Pearson’s Correlation of Coefficient Test.

The results showed that between 500m performance of Iranian Female National Kayak Paddlers’ Team and absolute anaerobic peak power (r= -0.72; P= 0.02), absolute anaerobicmean power (r= -0.72; P= 0.02), and relative anaerobic mean power (r= -0.66; P= 0.04) there was statistical significant relation.

Therefore, according to the results of this study we can suggested that kayak paddlers not only need a high body dimensions but the anaerobic system contribution is also veryimportant for successful exercise performance.