فصلنامه علوم زیستی ورزشی
پیاپی 11 (زمستان 1390)

The aim of this study was to determine the effect of eight-week resistance training on muscular strength and balance in men with multiple sclerosis (MS). For this purpose, out of 40 MS patients in Iran MS Society, 18 patients (mean age 34.05±7.8 yrs; mean expanded disability status scale 2.94±1.54 score; mean weight 67.83±11.58 kg; and mean body mass index 22.40±3.81kg/m2) were randomly divided to two groups: experimental (n=8) and control (n=10). Control group continued consuming disease specific medication, while experimental group participated in eight-week resistance training, three sessions/week, 60-80 minutes with 50%-70% of 1RM. The data were analyzed with SPSS-13 software and t student method (α≤0.05). The result of t test showed that resistance training significantly increased leg extensor strength (p=0.001), knee extensors strength (p=0.001), chest press strength (p=0.001), seated rowing strength (p=0.001), and balance (p=0.023). The results of this study showed that resistance training appeared to be a well tolerated intervention to improve strength and balance and MS patients are capable of positive adaptations to resistance training associated with increasing muscular strength and balance. Finally, the result suggested that male patients with MS can use resistance training to improve their muscular strength and balance.

Visfatin is a newly discovered adipokine which increases along with obesity. It is not clear whether rhythmic aerobic endurance exercise training which induces changes in adipose tissue and blood lipid might decrease the plasma visfatin level. The aim of this study was to examine the effect of rhythmic aerobic endurance exercise training on rest visfatin levels some metabolic risk factors in obese women. 23 obese female university students (mean age 18 to 29 years, body mass index (BMI)≥30 kg/ m2 and waist circumference≥88 cm who did not participated in any regular training program) participated in this study and were randomly divided into experimental (n=13) and control (n=10) groups. The experimental group participated in a rhythmic aerobic exercise program (8 weeks, 3 sessions per week, one hour each session) with 55% HRmax in the first sessions, and gradually reaching 70% HRmax in the last session. Fasting visfatin and insulin were measured by an enzyme linked immunosorbent assay (ELISA). Cholesterol, triglyceride, lipoprotein with high and low density and glucose were measured by enzymatic system and insulin resistance was estimated using HOMA equation. In order to compare data within groups, dependent t test and to compare between groups, independent t test was used (α≤0. 05). The findings of this study showed that after 8 weeks of aerobic rhythmic exercise, serum level of plasma visfatin significantly decreased (p=0.002). The results showed that plasma triglyceride (p=0.04), plasma cholesterol (p=0.02) and plasma LDL (p=0.01) significantly decreased while plasma HDL significantly increased (p=0.005). Insulin, glucose and insulin resistance did not significantly change. Overall, it appears that rhythmic aerobic exercise training can decrease visfatin level in overweight women through reducing body fat percentage, waist and hip circumference, weight, LDL, triglyceride and cholesterol and increasing HDL.

The aim of the present study was to investigate the effect of an official basketball game and its result on serum testosterone and cortisol responses as well as a possible difference in these hormones between fixed and reserved players. For this purpose, two teams were purposefully selected from semi-final games of Tehran first clubs. The blood samples of 22 female players (mean age: 20 years, mean testosterone at rest: 0.507 ng/ml, mean cortisol at rest: 96.143 ng/ml) were gathered two hours before the game and 15 minutes after the game. The time each player actively participated in the game was recorded for each team separately and the collected data were analyzed by dependent and independent t tests. The results showed a significant increase in testosterone and cortisol of fixed players of both teams who actively played in 70% of the game (p<0.05). There was no relationship between the changes of testosterone and cortisol during the game and win and loss (p>0.05). In conclusion, it can be mentioned that an official basketball game with mental and physical challenges can dramatically increase testosterone hormones with strong anabolic effects as well as serum cortisol with catabolic effects in female players. Considering the physiological changes after basketball games can help to achieve suitable results and to improve player's health.

The aim of the study was to develop a non-exercise VO2max predictive model using a physical activity (PA) variable determined by pedometer-determined step counts (SC: steps/day) in active lifestyle men aged between 40 and 65. For this purpose, 69 subjects were used to develop and validate the new model. VO2max was measured using Rockport Fitness Walking Test. Anthropometric variables were measured. PA was measured by a pedometer (Hj-113 Omron, Japan) throughout the day for two consecutive weeks. The results showed a significant correlation between VO2max and independent (anthropometric and daily steps) variables (p>0.05). There was a significant relationship between SC and VO2max (partial correlation coefficient r=0.70, P<0.001). Multiple regression analysis showed that VO2max could be predicted with age, weight, WHR and daily SC (R=0.92, SEE=1.4 ml/kg/min, P<0.001). When the new prediction model was applied to estimate the participants’ VO2max, predicted VO2max and measured VO2max were significantly correlated (r=0.86, P<0.005). It seems that SC is a useful variable for non-exercise prediction of VO2max in middle-aged men. This model may increase the precision of regression models to predict VO2max in health-related studies.

Fat oxidation during exercise can be influenced by exercise intensity and duration, training status, diet and physical activity level. However, few studies have investigated the effect of time of day on the rate of fat oxidation during exercise. Thus the present study was designed to investigate the effect of time of day on indexes of fat oxidation in active young women. For this purpose, 14 healthy women (mean±SD age, BF%, weight, BMI and Vo2max: 21.6±1.6 years, 18.3± 4.6 %, 51.2± 3.3 kg, 22±1.7 kg/m2, 40.8±4.2 ml/kg.min) voluntarily participated in this study. The exercise test was performed in two separate sessions in the morning (7:00) and evening (19:00). There was a 7-day interval between the two tests. The protocol was an incremental exercise to exhaustion on a treadmill. The volunteers started exercising at a speed of 58.3 m/min and at a gradient of 1%. Then, the speed increased to 16.7 m/min every three minutes until 125 m/min. At this point, the gradient increased by 2% per three minutes until RER=1 was achieved. VO2 and VCO2 were measured throughout the exercise by an automated gas analysis system. The data were analyzed using independent t test (α=0.05). The findings of the present study showed that no significant difference in maximal fat oxidation between morning and evening exercises (morning: 0.39±0.13 vs. evening: 0.44±0.11, P>0.05). There was no significant difference in FAT Max between morning and evening (P>0.05). However, the mean intensity of maximal fat oxidation was higher in the evening. Finally, it can be concluded that probably time of day (morning and evening) does not have an effect on substrate oxidation during intensive exercise.

Obesity is accompanied with renal dysfunction, so renal impairment is more prevalent in obese people. Renal function can be assessed via markers such as cystatin C (Cys C), creatinine (Crn) and glomerular filtration rate (GFR). As the effect of exercise training on renal function has been less investigated, this study aimed to study the effect of eight weeks of aerobic training and 10 days of detraining on renal function markers in obese girls. For this purpose, 24 obese girls (age: 21±2 yrs, BMI≥32) were divided into two groups: aerobic training (n=12) and control group (n=12). Aerobic training group trained for 8 weeks, 4 sessions/week, 60 min./each session, intensity %65-75 HRmax. Then, 10 days of detraining followed. Cys C, Crn and GFR were measured. ANOVA with repeated measures was used for statistical analysis. The results showed that Cys C decreased insignificantly in the training group (p=0.739). Crn and GFR increased insignificantly (p=0.864 and p=0.759 respectively). Detraining had no significant effect on any variables (p>0.05). The results showed that eight weeks of aerobic training had no significant effect on renal function markers in obese girls. It seems that in order to improve the effect of the training, it is necessary to perform training programs with higher volume and proper diet

The aim of this study was to investigate the effect of protein whey isolate supplementation on antioxidant status during a resistance training program in overweight young men. 30 individuals (body mass index between 25-30 kg.m2) participated in this study and were randomly divided into three groups (each 10 subjects): experimental group 1 (supplement + six weeks of resistance training) (W), experimental group 2 (placebo + six weeks of resistance training) (P), Control (C). Total antioxidant capacity (TAC) in the whey supplement group significantly increased in posttest compared with pretest (p<0.05). Glutathione (GSH) and vitamin C levels showed a significant increase in both whey supplement and placebo groups in posttest (p<0.05). It can be concluded that although exercise alone could improve the antioxidant system in the overweight subjects, the combination of resistance training and whey protein consumption had more effects.

The present study aimed to compare substrate oxidation and total energy expenditure during running with low and moderate intensity until exhaustion and one hour after exercise in obese male students. For this purpose, in a crossover study design, 11 male university students (mean age 20.45±1.69 years, BMI 31.26±1.3 kg/m2, body fat percentage 28.47±3.53 %) participated in this study. Two exercise protocols, running with low intensity (45% VO2max equivalent to 66% of maximum heart rate) and moderate intensity (60% VO2max equivalent to 76% of maximum heart rate) were performed on a treadmill with an 11-day interval. Subject's respiratory gases were collected and analyzed 30 minutes before the exercise while subjects were in prostrate position and also during the low and moderate exercises till they reached the exhaustion level, and also one hour after exercise as EPOC. The amount of fat oxidation, carbohydrate and energy expenditure was measured by indirect calorimeter. The results showed that during the exercise, fat oxidation during moderate intensity exercise was significantly higher than low intensity exercise. However, in the total exercise there was no significant difference between the two intensities. There was no significant difference in carbohydrate oxidation during the exercise and in the total exercise between the two intensities. Also, in the total exercise, energy expenditure during low intensity exercise was significantly higher than moderate exercise. Accordingly, low intensity activities until exhaustion was preferred to lose weight in comparison with moderate activities until exhaustion. However, if we do not consider the time of the exercise, because the maximum of fat oxidation occurs during intensity close to moderate intensity, the exercise training with moderate intensity is more suitable for maximum of fat oxidation and weight loss.