نشریه سوخت و ساز و فعالیت ورزشی
سال دوم شماره 2 (پاییز و زمستان 1391)

The purpose of this study was to investigate the effect of 4 week resistance training on plasma omentin-1 levels in Streptozotocin induced diabetic rats. In this experimental study 24 male Wistar rats with mean weight of 288±22g (mean±SD) were randomly divided into 3 groups: non-diabetic control (n=8)، diabetic control (n=8)، and diabetic training (n=8). Diabetes was induced by a single intra-peritoneal injection of streptozotocin (STZ) at a dose of 55 mg/kg. The resistance training consisted of climbing a ladder carrying a load suspended from the tail (3 days/wk، for 4 wk). After 4-week body weight، plasma omentin-1، glucose، insulin، non-esterified fatty acids (NEFA) concentrations and lipid profiles were measured. After four weeks plasma omentin-1 levels in trained diabetic rats was higher when compared with diabetic control group، but it was not statistically significant. We did not find any significant difference in plasma glucose، insulin، NEFA and lipid profile levels between all groups. Body weights alteration in diabetic resistance trained rats were significantly lower compared with the diabetic control group. The results of this study indicated that plasma levels of glucose، insulin، lipid profile and omentin-1 remained unchanged in diabetic rats due to 4 weeks resistance training. Short duration of training program appears to be an effective factor in the absence of significant changes in plasma omentin-1 levels.

To examine whether time of day significantly affects salivary IgA, cortisol, α-amylase and total protein levels before and after sub-maximal swimming. Fourteen female swimmers (age 13±1.33 years, weight 48±4.75 kg, Vo2max 45.92±3.96 ml/kg/min) volunteered to participate in the study. In a fully randomized, cross over design, each subject performed 10×200 m front crawl at 80% of their seasonal best time, with one minute rest between each 200 m, at 08:00 and 18:00 hours on two days aware. Timed, unstimulated saliva samples were collected before and after exercise. Saliva samples were analyzed by two-factor analysis of variance (ANOVA) with repeated measures. Statistical significance was accepted at p<0.05. Significant time of day effects (am and pm respectively) were observed in s-IgA, S-IgA, cortisol, and saliva flow rate, αamylase and total protein before exercise (P<0.05). The exercise protocol did not significantly affect s-IgA but, in comparison with values before exercise, caused significant alterations in cortisol, S-IgA, saliva flow rate, αamylase and total protein (P<0.05). There was no significant interaction effect of time of day by exercise on any salivary variables measured except αamylase. These results suggest a significant circadian variation in the variables measured before exercise, with showing a significant effect on their acute responses to exercise except s-IgA and a significant interaction effect of time of day by exercise on salivary αamylase.

The aim of this study was to determine the effect of reduced muscle glycogen on maximal fat oxidation (MFO) and the exercise intensity at which maximal fat oxidation was occure (Fatmax) in untrained men. Eight healthy untrained males (age: 22.2±1; body mass index: 21.9±1.5 kg/m2; percent body fat (%): 15.1±1; VO2Peak: 2.82±0.41 L.min-1) participated in two studies carried out on separate days at least one week apart. Each subject in the fasting state (7:00 AM) performed graded exercise test with 3 min stages on a cycle ergometer to exhaustion, on two separate occasions randomly, in a normal glycogen state and under conditions of reduced muscle glycogen content. On one occasion, the day before the graded exercise test, subjects came to the laboratory at 18:00 pm to perform an exhaustive muscle glycogen lowering exercise. Indirect calorimetry was performed to determine oxygen consumption (VO2) and carbon dioxide production (VCO2) at during gradedexercise. Substrate oxidation, MFO and Fatmax was determined during graded exercise test, by use of the stoichiometric equations. The student’s t-test was used to analyze the variables. MFO in the lowering muscle glycogen (0.54±0.08 g.min-1) was significantly higher than in the normal muscle glycogen status (0.36±0.04 g. min-1) (P<0.01). In addition, Significantly difference in Fatmax occurred at an exercise intensity of around 46.12±3.13% and 65.01±3.42% VO2peak in the normal and reduces glycogen condition respectively (P<0.01). In conclusion, reduced muscle glycogen before exercise can be causes a displacement of MFO and Fatmax to higher level of exercise intensity. This means that the onset of decrease of fat oxidation occurs at a higher intensity and individuals start to rely on carbohydrate sources later.

The aim of this study was to determine the effect of exercise training in water on serum adiponectin and insulin resistance in obese children and adolescents. For this purpose 60 obese subjects (children 10-12 years and adolescents 14-16 years) were randomly assigned into one of four groups: exercise training in water for both children and adolescents, and control groups (children and adolescents). Experimental groups underwent exercise training for 8 weeks; 3 sessions per week and 60 minutes per session, with an intensity of 60-85% of maximum heart rate. Blood samples, anthropometric and body composition measures were taken before and after training program. Data analysis using ANOVA showed that exercise training in water caused a significant decrease in body fat percent, and increase in VO2max in the children and adolescents. Exercise training in water had no effect on serum adiponectin and insulin resistance. In summary, since 8 weeks exercise training in water did not cause weight loss, it probably had no effect on adiponectin and insulin resistance.

Brain derived neurotrophic factor (BDNF) is an important factor affecting cognitive function which has recently interested a bulk trend of effort in the health context. In spite of a good body of evidence reported concern to positive association between aerobic fitness, cognitive function and serum BDNF, there is no enough information about the effect of aerobic training and also detraining period on memory function and circulatory BDNF in middle aged individuals. Twenty one middle aged males (age: 58.08±5.99, weight: 75.79±12.13 kg, BMI: 25.78±2.76 kg.m-2) randomized in two groups including aerobic exercise (Ex, n=11) and control (Con, N=10). Ex subjects participated in six weeks of endurance exercise sessions, 3 sessions/week by the intensity of 60-70% of HRR for 25 to 40 min in each min. Midterm and Short term memory tests were conducted and also blood samples were taken in three occasions including pretest, after six weeks of training and after the following six weeks of detraining period. Data were analyzed using independent t test, ANOVA and ANCOVA repeated measures. Six weeks of aerobic training in Ex group significantly increased basal serum BDNF level, and also short term and midterm memory function (P<0.05) which all were restored following to six weeks of detraining. Regular exercise training is capable to augment basal serum BDNF and though to improve memory function in healthy subjects, however, theses adaptations were washed up throughout detraining. From clinical point of view, these findings confirm the importance of aerobic fitness to improve and maintaine memory function and future dementia to be prevented.

The purpose of this study was to examine the effect of short term Beta-hydroxyl beta-methylbutyrate (HMB) supplementation on plasma creatine phosphokinase (CPK) level after resistance training program, in untrained women. Sixteen untrained women, aged 24.3±1 years, height 163±2.35 cm and weight 61.5±2.25 kg were selected and randomly divided into two HMB supplementation (n=8) and placebo (n=8) groups. All subjects trained 3 times per week for 2 weeks. HMB group and placebo group received 3 gr/day of HMB and placebo, respectively.The muscle injury marker (CPK) and upper and lower body 1-RM were measured in pre and three post tests. To investigate the differences between pre and post-test results in each group Bonferroni test was used and the difference between two groups was determined by independent student t-test. The result showed that the mean of plasma CPK level was significantly (P<0.05) decreased in HMB supplementation group. This decrease, however, was not found in placebo group. Also upper and lower body 1-RM in HMB and placebo groups were increased, but these increases were not statistically significant. Supplementation of 3 gr HMB result in a decrease creatine phosphokinase response after resistance training. This finding support the hypothesis that HMB supplementation prevents exercise induced muscle damage, specially in beginner female following resistance training.

The aim of present study was to examine the influence of acute resistance exercise orders on response serum leptin and testosterone in overweight young men. Fourteen young men (mean age: 21.36±1.25 years and BMI: 27.95±1.88 kg/m2) were selected randomly and completed two sessions of resistance exercise.The Exercise protocol consisted of two different protocols [protocol A: from large to small muscles (Leg press, bench press, Lat Pull-down, overhead press, biceps curl, triceps extension) and Protocol B: from small to large muscles (Reverse Sequence of protocol B)] and with %85 of one repetition maximum (1RM) were done. For this purpose in first session randomly, half of the subjects performed protocol A and the other subjects completed the protocol B. One and two minutes rest intervals were set between sets and exercises movement, respectively. One week after, in the second session, subject’s protocols were contrary. Blood samples were collected before the exercise, immediately and 30 minutes after each exercise protocol. Hormone measurements were performed using radio immune-assay (RIA). By using ANOVA with repeated measure (within and between subject effects) the results indicated that serum leptin concentrations in both protocols, was decreased significantly immediately and 30 minutes after exercise (P≤0.05). So, the testosterone concentration decreased significantly immediately (protocol B) and 30 minutes after exercise (in both protocol) (P≤0.05). While, there was no differences between sessions for leptin and testosterone. Moreover, there was correlation between leptin and testosterone in order B and not in order A (P≤0.05). Overall findings showed that the large or small muscles order used at the beginning of the exercise do not affect on the secretion hormone leptin and testosterone. Although, more research is needed to prove the link between these two hormones.