Journal of Sport Biosciences
Year:2011 | Volume:- | Issue:9|Papers Count:11

This study aimed to assess the effects of four weeks of detraining after eight weeks of intense sprint training on risk factors of atherogenic inflammatory damages. For this purpose, 42 male rats were divided randomly into two groups: sprint training group (experimental) (n=24 and weight 210±7) and control group (n=18 and weight 211±3). The training program was performed for 12 weeks, three sessions per week with definite duration and speed (between %80-%100 and above 100% VO2max). After 24 sessions, six trained rats experienced the detraining, so the effects of detraining could be studied. The blood samples were gathered after 14 hours of fasting in different phases of training. Data were analyzed by Kolmogorov-Smirnov, one-way ANOVA with repeated measures, LSD post hoc and independent t tests. The results indicated that after 36 sessions of training, sICAM-1 (P=0.004), IL-1 b(P=0.023) and TNF-a (P=0.040) increased significantly. Also, following four weeks of detraining after eight weeks of intense sprint training, inflammatory biomarkers of sICAM-1 (P=0.152), IL- IL-1b (P=0.063) & TNF-a (P=0.099) insignificantly decreased, but they were significant compared with the training group sICAM-1 (P=0.024), IL-1b (P=0.037) and TNF-a (P=0.018). In general, it can be concluded that four weeks of detraining after an intense sprint training lead to a decline in risk factors of atherogenic inflammatory damages.

The purpose of the present study was to investigate whether duration of static stretching could affect the maximal voluntary contraction (MVC) and flexibility of hamstring muscles.10 male physical education students randomly performed three warm-up protocols on different days. The protocols included: a) five minutes of treadmill run and 45 seconds (3×15 seconds) of static stretching of hamstring muscles, b) five minutes of treadmill run and 90 seconds (3×30 seconds) of stretching, c) five minutes of treadmill run (control condition). In each session, before and after each protocol, hamstring flexibility was measured by a sit and reach test and then MVC of hamstring muscles was measured. The results showed that hamstring flexibility significantly increased after 3×15 and 3×30 seconds of static stretching (p<0.05); however, there was no significant difference between the two stretching protocols (p>0.05). The MVC significantly decreased after 3×30 seconds of static stretching compared to the control and 3×15 seconds of protocols (p<0.05). However, there was no significant difference between control and 3×15 seconds of static stretching conditions (p>0.05). Therefore, it was concluded that the short duration (3×15 seconds) of static stretching did not have a negative effect on the production of muscle force.

The purpose of this research was to compare the effect of an exhaustive exercise session on the concentration of serum testosterone and cortisol and cortisol/testosterone ratio in the morning and the evening in female volleyball players. For this purpose, 12 female volleyball players (mean age 23.26 years, mean weight 58.8 kg, mean height 166.49 cm and at least four years of activity) participated voluntarily in this research. Bruce Test was performed on a treadmill in the morning and evening. The blood samples were collected before and after of Bruce test. The levels of these hormones were measured by Eliza method. SPSS 16 software was used to statistically analyze the data; descriptive statistics were used to describe the data and to investigate the characteristics of the groups and t test was used to compare the groups. The results showed no significant difference in testosterone and testosterone/cortisol ratio between the morning and evening; but an exhaustive exercise session significantly decreased cortisol in the morning and evening. It can be concluded that an exhaustive exercise session cannot affect testosterone and testosterone/cortisol ratio while it may significantly reduce cortisol.

Treatments for breast cancer such as chemotherapy or hormone therapy can increase osteoporosis. It seems that exercise training can improve bone mineral density. Therefore, the aim of this study was to investigate the effect of combined exercise training on bone mineral density (BMD) in postmenopausal women with breast cancer.29 postmenopausal women with breast cancer (58.27±6.31 years) who received surgery, chemotherapy and radiation-therapy and were under hormone therapy at the moment were divided into two groups: experimental and control. Experimental group performed 15 weeks of combined exercise training including walking (2 sessions per week) and resistance training (2 sessions per week on days different from walking days). Control group did not participate in any exercise training. Body weight, body mass index (BMI), Vo2peak and lumbar spines and femur bone density were measured in two groups before and after 15 weeks. Data were analyzed by ANCOVA. Results indicated that after 15 weeks, there was a significant difference in weight, BMI and Vo2peak between experimental and control groups (p<0.05). Body weight and BMI decreased and Vo2peak increased in the experimental group after 15 weeks while there was no significant difference between the two groups in BMD of total lumbar spines (F=2.98, P=0.096) and femur (F=0.95, P=0.147). It can be concluded that 15 weeks of combined exercise training had no positive effect on BMD in postmenopausal women with breast cancer.

The aim of this study was to compare the effect of a session of aerobic and anaerobic exercise on changes of IgA/Salivary total protein ratio in non-athlete girls.36 non-athlete girls were randomly divided into three groups: anaerobic (n=12) with mean age of 23±1.91 years, aerobic (n=12) with mean age of 21±1.45 years and the control group (n=12) with mean age 23.25±2.09 years. Salivary samples were collected before and immediately after the test. In this study, RAST test was used for anaerobic exercise and Shuttle Run for aerobic exercise. Control group did not exercise during the study. Data were analyzed by one-way analysis of variance, t test and SPSS 16 software. The results showed no significant difference in changes of IgA/salivary total protein ratio among the groups. Correlated t test results showed no significant changes of IgA/salivary total protein ratio with each group. Also, no destructive effect of exercise on mucosal immunity was observed.

The purpose of the present research was to determine the effects of intermittent and continuous training programs on some selected cardiovascular risk factors in young obese females. For this purpose, 36 obese sedentary subjects with BMI>30 were randomly assigned to three groups of intermittent exercise (mean±SD of height, weight, and age: 163.2±5.8cm, 86.8±11.8kg, 20.7±1.3yr), continuous exercise (160.2±6.4cm, 83.8±9.5kg, 22.1±2.2yr) and control (166.2±7.1cm, 86.6±10.5kg, 22±2.4yr). The intermittent group participated in eight weeks (three sessions per week) of 800 meters (4×200m) exercise with 80%-90% of reserved heart rate and 1/3 rest interval whereas the continuous group ran this distance with 60%-70% of reserved heart rate with no rest interval. A distance of 400 meters (2×200 meters) was added to the primary distance every week in the intermittent group and 400 meters in the continuous group. Before and after the protocol, HDL, LDL, CHOL and VLDL were measured by Alpha-X auto analyzer apparatus. Also, weight and height of the subjects were measured at the beginning and the end of the protocol. The control group only participated in pretest and posttest. To analyze the data, one-way analysis of variance, paired t-test and LSD post hoc test were used. The results showed that TC significantly decreased in the intermittent group whereas HDL significantly increased. HDL significantly increased (p=0.03) while LDL (P=0.004), TC (p=0.05), VLDL (p=0.05) and the weight of the participants (p=0.005) decreased significantly in the continuous group (P>0.05). The results also showed a significant change in weight (p=0.005), TC (p=0.001), HDL (p=0.009) and VLDL (p=0.004) in the posttest for all three groups (P>0.05). These significant differences existed between control group with intermittent and continuous groups while there was no significant difference between intermittence and continuous groups. There was no significant change in TC and LDL in the posttest of all groups. It was concluded that both types of exercise positively changed cardiovascular risk factors in obese female subjects.

The purpose of the present research was to examine the effect of one bout of exhaustive aerobic exercise with two different intensities on levels of serum MDA in male smokers. For this purpose, 12 male smokers (age: 22.08±1.31 years, percent of body fat: 17.26±4.92% and body mass index: 23.21±2.96 kg/m2) were voluntarily selected and randomly participated in a crossover design in three situations of control, exhaustive aerobic exercise at 70%-75% intensity of maximal heart rate and exhaustive aerobic exercise at 90%-95% intensity of maximal heart rate. Blood samples were collected before and immediately after the exercise. Malondialdehyde level was determined with method of ELISA. The data were analyzed using one-way ANOVA and dependent t tests. The results indicated that MDA in two experimental groups was significantly higher than the control group. Also, the comparison of the two experimental groups showed that aerobic exercise at 90%-95% intensity of maximal heart rate increased serum MDA more than aerobic exercise at 70%-75% intensity. It is suggested that smokers perform the physical activities with moderate intensity (70%-75% intensity of maximal heart rate) because oxidative stress is produced in these activities less than activities with higher intensity.

Ghrelin is an orexigenic peptide secreted by the stomach. The aim of this study was to investigate the effect of three weeks of endurance training on plasma and fundus ghrelin as well as growth hormone (GH), cortisol hormone and weight in male wistar rats.20 male wistar rats (14 –16 weeks old) were randomly assigned to control (n=10) and training (n=10) groups. The rats in the training group exercised on a motor-driven treadmill at 25 m/min. (0% grade) for 60 min./day, 5 days/week for three weeks. The animals were sacrificed 48 hours after the last session of training program and their tissues were analyzed. Independent t test was used to analyze the data. The results showed that in trained rats, stomach and plasma ghrelin concentrations and weight were significantly lower and cortisol was higher than the control group (p<0.05). It can be concluded that hormonal changes during exercise training may be effective in ghrelin adaptation.