نشریه سوخت و ساز و فعالیت ورزشی
سال سوم شماره 1 (بهار و تابستان 1392)

Endothelial dysfunction is considered an important event in atherosclerosis improvement. On the other hand, diabetes is also associated with endothelial dysfunction. Among the endothelial dysfunction factors, vascular cell adhesion molecule can be mentioned. The purpose of this study was the effect of aerobic exercise on VCAM-1 and insulin resistance index in type 2 diabetes women. Sixteen women suffering type 2 diabetes (aged: 50.81±7.87, weight: 75.82±15.27 kg) were randomly divided in aerobic (n=11) and control (n=5) groups. The aerobic group exercised for 8 weeks in 45-60 min sessions 3 time a week with 60% HRR. Blood samples were obtained after 10-12 overnight fasting for measuring VCAM-1 serum and insulin levels at pre-and post-exercise training. Statistical analysis was done by independent t-tests and Pearson correlation coefficient. The results showed a significant difference between aerobic and control groups in VCAM-1 serum levels (P<0.05). Also there exists a relationship between VCAM-1 serum levels with insulin resistance following aerobic exercises (r=0.729). Eight weeks aerobic exercises can probably cause decreasing of vascular cell adhesion molecules and this decrease has a direct relation with insulin resistance. Decreasing of insulin resistance along with decreasing of adhesive molecules can probably decrease cardiovascular diseases in people with type 2 diabetes.

Apelin is an adipokine that is closely related with insulin resistance and type 2 diabetes. In this study, the effect of an aerobic exercise training program was investigated on plasma apelin levels in overweight healthy women. Eighteen healthy women were selected as subjects and were randomly divided into two exercise (n=9 aged 45±6.22 yrs, BMI 26.17±2.61 kg/m2) and control (n=9 aged 42.88±3.14 yrs, BMI 27.14±2.58 kg/m2) groups. Subjects in the exercise group performed 8 weeks running and walking exercise training 3 days a week at intensity corresponding to 60-70% HRmax. Before and after exercise training, body fat percentage, body mass index (BMI), waist to hip ratio (WHR) and plasma levels of apelin, insulin and glucose and HOMA-IR after a 12-hr fasting was measured. No significant changes were observed in apelin, insulin, glucose and plasma levels and also HOMA-IR in two groups comparing to pre-test and between groups. It seems that low to moderate intensity exercise training or decrease of fat mass cannot have significant effects on the amount of blood apelin and insulin resistance in overweight healthy women, though apelin levels may change with changes in insulin levels or insulin resistance index.

Diabetes mellitus is a metabolic syndrome which is determined by insulin deficiency-induced hyperglycemic or decrease of in body insulin sensitivity. Chronic inflammation conditions in diabetes are associated with Cyclooxigenase 2 enzyme (COX-2) expression. The major metabolites of this enzyme, which play an important role in cardiovascular homeostasis are Prostocyclin (PGI-2) and Tromboxane (TXA-2). However, Prostocyclin is a potent vasodilator and prevents platelet aggregation and Tromboxane causes vasoconstriction, proliferation of smooth muscles and aggregation and remodeling of platelets. The present study investigates the effect of 8 weeks of resistance training on the expression of COX-2 enzyme and its metabolites such as TXA-2 and PGI-2 in wistar diabetic male rats. For this purpose, in an experimental study 24 wistar rats were purchased from Pasteur Institute of Iran and divided into resistance training (n=12) and control (n=12) groups. The resistance training protocol included 8 weeks (3 sessions per weeks) of ten sets of ladder ascending with free weights were attached to the rats’ tails (70 to 75% of maximum capacity of carrying free weights by each rat).The animals were sacrificed 48 hours after the last session of training program and blood samples were taken. After the left ventricle was drained, stimulatory and inhibitory factors were measured and the data was analyzed by t-test via spss16 software. The results of independent t-test showed that there was a significant decrease in blood glucose (P<0.05); however, there was no significant difference in insulin levels among groups. In addition, t-test showed that resistance training did not induce any significant difference in TXA-2 and PGI-2 of training group in comparison with control group. In addition, COX-2 level in resistance training group (296.09±41.69) showed a significant increase compared with control group (252.8±26.8), (P<0.05). The results of the study show that 8 weeks of resistance training does not have any significant impact on stimulatory and inhibitory factors of coronary artery injuries. It appears that the mentioned protocol does not have a significant effect on cardiac microvascular injuries. Due to the lack of information in this area, further study is unavoidable.

The present study investigates the effects of one month of fasting Ramadan on some blood variables including fasting blood glucose, TC, TG, HDL, LDL, VLDL, urea, creatinine, SGOT, SGPT, ALP, hs-CRP, body weight, fat weight, and lean body mass. 14 healthy male soccer players (who continued their regular exercise program through Ramadan) participated in this study. The subjects were randomly divided into fasting (age: 22.61±3.83 years, height: 174.12±6.33 cm, weight: 69.6±15.052 kg) and control groups (age: 24.7±3.54 years, height: 172.98±5.44 cm, weight: 67.74±10.15 kg). Blood samples were taken on two occasions; the first at 10 am, one day before Ramadan and the second at 5 pm of the 29th (both following 12 hours of fasting). The data was analyzed by a paried t-test (at 0.05 statistical significance level) after the normal data distribution order was verified using the k-s test. One month of fasting had no significant on any of the variables, in any group. It can be concluded that fasting probably because of the previous adaptations, could have no hazardous consequences on athlete health if there is no detectable fluctuations in daily caloric intake and physical activity level.

The purpose of the study was to compare the effect of eight weeks of continuous and intermittent aerobic training on Visfatin and insulin resistance plasma levels in 17-25 years obese males. Fifty participants (age: 22.05±3.9 years; weight: 89.85±12.8 kg; height: 176.7±10.09 cm) were randomly divided into continuous and intermittent aerobic groups. The continuous aerobic group performed the training protocol with 60 to 80 percent of Vo2max and the intermittent aerobic group with 55 to 85 percent of Vo2max for 60 minutes in session, 5 days per week. Fasting plasma Visfatin and insulin levels were measured by ELISA and fasting plasma glucose was measured by a enzymatic method. Insulin resistance was determined by HOMA-IR formula. The significance of the effects of training were assessed by the dependent t-test and post-test significance between groups was assessed using the independent t-test (P≤0.05). Findings have shown that the eight weeks of continuous aerobic training significantly decreased visfatin plasma levels and insulin resistance resting levels (P≤0.05), and the eight weeks of intermittent aerobic training were significantly decreased in visfatin plasma levels (P≤0.05) and insulin resistance resting levels (P≤0.05), but there was no significant decrease between post-tests in visfatin plasma levels and insulin resistance resting levels. The eight-week continuous and intermittent aerobic training programs may effect to reduce visfatin plasma level and insulin resistance resting that related to decrease of body mass index.

The effect of creatine (Cr) supplementation on exercise induced-lactate is still debatable. Thus, the aim of this study was to examine the effect of creatine supplementation on blood lactate levels after an exhaustive aerobic exercise. Twenty healthy young men (age: 22.4±0.8 years; weight: 71.8±8.5 kg; body mass index (BMI): 23.5±2.5 kg/m2; maximum oxygen uptake: 37.7±7.2 ml.kg-1.min-1; mean±SD) were randomly assigned to either a creatine (20 g Cr for 7 days) or a placebo group (same dosage of a glucose polymer) using a double-blind research design. After a week of supplementation, the subjects underwent an exhaustive aerobic exercise. Blood samples were taken before the exercise and immediately, 10 and 20 minute after the exercise. The results showed that body weight, BMI, lean body mass and creatine levels were increased significantly after supplementation in the creatine group (P<0.05). Blood lactate levels increased significantly after the exercise in both groups (P<0.05). Blood lactate levels decreased 10 minutes after the exercise in both groups (P<0.05) and the decrease in the creatine group was greater than in the placebo group (P<0.05). The decrease of blood lactate levels continued to 20 minutes after the exercise (P<0.05) and the decrease in the creatine group was greater than in the placebo group (P<0.05). Creatine supplementation may be effective for faster lactate removal after the exercise. However, additional research is needed.

Various studies have demonstrated that different rest intervals has a significant effect on hormonal, metabolic, and cardiovascular responses. This factor can lead to different muscle damage responses and manipulate training goals. The purpose of this study was to compare the effect of 1 and 3 minute rest intervals between sets and exercises on muscle damage and sustainability of repetition in consecutive exercises. 12 untrained subjects (aged 23.17±2.06 years, height 175±3.55 cm, weight 67.33±8.26 kg, fat 16.67±1.82 percent) volunteered to participate in this study in two resistance exercise sessions with a 2-week recovery between sessions. Exercises order in each session consisted of front leg extension, biceps curl, leg curl, triceps extension, leg press and bench press with 80% of one repetition maximum (1RM) until fatigue. Subjects randomized for 1 and 3 min rest intervals in each session. The levels of CK and AST were analyzed before, 24 and 48 hours after resistance exercises. Also muscle soreness was evaluated by the Shailaja scale (PAS) at before, immediately, 24 and 48 hours after resistance exercises. Variance analysis with repeated measurment, pair sample t-test and Bonferroni post-hoc were used for statistical analysis of data. CK and AST concentration increased significantly after 24 and 48 hours and muscle soreness also elevated immediately, 24 and 48 hours after resistance exercises (P≤0.05), but no significant difference in muscle soreness and enzymes concentration was found between groups at different time points. The results demonstrated that 3 min rest intervals lead to increased repetitions (P≤0.05). Differences of load volume and sustainability of repetitions at different time points of rest intervals are independent of muscle damage responses and muscle soreness. Also, 3 min rest intervals led to repetition sustainability and appropriate recovery.