نشریه مطالعات کاربردی علوم زیستی در ورزش
پیاپی 26 (تابستان 1402)

Accurate and fast estimation of maximal oxygen uptake (VO2max) as an indicator of cardio-respiratory fitness (CRF) by regression equations without exercise tests in large populations is of great importance in the field of health and sport sciences. Therefore, the aim of this study was to evaluate the cross-validation of the non-native non-exercise (N-EX) regression equations in estimating VO2max of healthy and adolescent boys using the standard method of respiratory gas analysis.

This research was a cross-sectional study in which 349 healthy boys children and adolescents (age: 12.49±2.72 year, BMI: 20.13±4.70 kg/m2 and VO2max: 41.50±6.47 ml/kg/min) were participated. VO2max was measured on a treadmill by the respiratory gas analysis in modified Bruce exercise test (criterion method) and then estimated by three non-native N-EX regression equations. To evaluate the cross-validation the validity of the N-EX regression equations, Pearson correlation, paired sample t-test and Bland-Altman agreement were used for extraction of results.

A significant correlation was observed between VO2max measured by criterion method and N-EX equations (R=0.63 - 0.73, p<0.01). However, a significant difference (p<0.01) was observed between VO2max of criterion method and predicted VO2max by N-EX regression equations (mean difference=6.4–11.69 ml/ kg/min). Also, the Bland-Altman plot showed low agreement between measured and predicted VO2max.

The nonnative N-EX regression equations studied in the present research do not have the necessary accuracy to estimate the VO2max of in healthy children and adolescent boys. Therefore, it seems necessary to verify foreign N-EX VO2max regression equations before use in the Iranian population.

Limited studies have investigated the effect of electrical muscle stimulation (EMS) on muscle growth factors in athletes after the anterior cruciate ligament (ACL) rehabilitation. The aim of the present study was to compare the effect of resistance training and resistance training combined with EMS on serum levels of peroxisome proliferator activated receptor-gamma co-activator 1-alpha (PGC-1α), insulin-like growth factor-1 (IGF-1) and myostatin in male athletes after ACL surgery.

Twenty volunteers with 26.01±1.12 year’s old, 177.10±9.59 cm height and 71.16±6.65 kg weight were randomly divided into two groups including resistance training combined with EMS and resistance training. The subjects in both groups performed three sets of resistance training movements with an intensity of 30-70% of 10 maximum repetitions for 12 weeks. The subjects in the resistance training combined with EMS group performed exercise training with electrical stimulation with a frequency of  35-70 Hz. Blood samples were taken from all subjects before and 48 hours after the last training session. ELISA method was used to measure serum PGC-1α, IGF-1 and myostatin levels. The comparison between groups was done using analysis of covariance test at a significance level of p<0.05.

The results showed that 12 weeks of resistance training combined with EMS compare to resistance intervention caused a significant increase in serum IGF-1 concentration and a significant decrease in serum myostatin levels, without significant change in serum PGC-1α of the participants.

Overall, resistance training combined with EMS compared to traditional resistance training may lead to changes in serum levels of myostatin and IGF-1, which in turn increases the volume and strength of quadriceps and hamstring athletes after ACL surgery and can be used in ACL rehabilitation period.

Increased oxidative stress due to exercise as well as the body’s ability to deal with its complications cause different levels of health and disease in people. Therefore, this study aimed to evaluate the effect of two weeks of curcumin supplementation on serum level of malondialdehyde (MDA) and superoxide dismutase (SOD) indices after a session of intense intermittent training in overweight and obese girls.

Twenty two overweight and obese girls (mean age: 21±1.79 years; weight: 68.80±7.81 kg; body mass index: 31.18±1.96 kg/m2) as purposefully selected and randomly divided into two homogeneous groups (experimental and placebo) according to age and body mass index. The experimental group was underwent intense acute intermittent activity (shuttle run activity protocol; 85 to 95% heart rate percent) and curcumin supplement (80 mg/day post-lunch). The results were extracted using repeated measures ANOVA, one-way ANOVA, and LSD post hoc tests at the level of p<0.05.

Intense intermittent activity caused a significant increase in MDA (p=0.001) and a significant decrease in SOD (p=0.001) while two weeks of curcumin supplementation caused a significant decrease in MDA (p=0.009) and a significant increase in SOD (p=0.01). On the other hand, two weeks of curcumin supplementation before intense intermittent activity did not significantly change MDA (p=0.06) and SOD (p=0.21).

Two weeks of curcumin supplementation could inhibits lipid peroxidation.

Exercise and training can maintain the health and plasticity of the nervous system. Tropomodulin-2 (Tmod2) plays an important roles in the central nervous system and it correlated with various functions such as the formation of new synapses and increased neuritis extension. The aim of this study was to evaluate the effect of low-intensity endurance training on Tmod2 protein levels and Malondialdehyde (MDA) in the hippocampal tissue of male Wistar rats.

For this experimental research, 20 rats were randomly divided into two groups including training (n=10) and control (n=10), that for the training group, the endurance training program was run for six weeks at 20-40 percent of maximum running speed. Forty eight hours after the last training session, the rats were dissected and hippocampal tissue was extracted. Immunohistochemistry and Elisa methods were used for measuring the expression of Tmod2 protein and MDA respectively. Independent t-test was used to compare the groups at the significant level of p<0/05.

Based on the results, low-intensity endurance training significantly increased the expression of Tmod2 protein (p=0.01) but the MDA concentration (p=0.001) reduced during training as compared to the control group.

Endurance training showed a beneficial effect on Tmod2 and also the nervous system; however, reducing the concentration of MDA can be considered as a decreasing of the oxidative stress; a change that shows the protective effects of this training method against oxidative stress.

Considering the role of zinc in activating antioxidant enzymes, the aim of the present study was to investigate the effect of eight weeks of endurance training and zinc supplementation on glutathione peroxidase activity and total antioxidant capacity in the skeletal muscle of male Wistar rats.

Thirty two mature male Wistar rats, were randomly divided into four groups (each group was included eight rats) as control, endurance training, zinc supplementation and endurance training+supplement. The training protocol consisted of running on a treadmill for eight weeks (five days/week) with ad libitum access to water and food. In the zinc supplemented and endurance training+zinc groups, 227 mg of zinc sulfate were used per 100 ml of consumed water for eight weeks period. Then, 48 hours after the last exercise session and after eight hours of fasting, tissue samples of gastrocnemius muscle were collected and enzyme activity of glutathione peroxidase (GPX) and total antioxidant capacity (TAC) in gastrocnemius muscle was measured by spectrophotometric method. Data were analyzed using one-way analysis of variance and Tukey’s post hoc tests at the significant level p≤0.05.

The results showed that after eight weeks of endurance training along with zinc supplementation there was a significant increase in GPX of gastrocnemius muscle compared to the endurance training group (p=0.001). In addition, eight weeks of endurance training showed a significant decrease in GPX of gastrocnemius muscle compared to the control group (p=0.03). Moreover, endurance training along with zinc supplementation also showed a significant increase in TAC of gastrocnemius muscle as compared to supplement (p=0.008) and training (p=0.001) groups.

Considering the effect of zinc supplementation along with endurance training on increasing of GPX and TAC, zinc supplementation will probably prevent the reduction of antioxidant enzymes and complications caused by strenuous endurance training.

Evidence has shown that C-reactive protein (CRP) is not only an inflammatory biomarker but also an important risk factor associated with aging-related diseases including cardiovascular, metabolic, and kidney disorders. Therefore, the aim of this study was to investigate the comparison of serum high-sensitivity CRP (hs-CRP) and lipid profile levels in active and sedentary elderly people during the first peak of Covid-19 pandemic.

Seventy seven elderly men and women (mean age 61.43±6.07 years) based on body mass index (BMI) were divided into three groups including the healthy (BMI as 18.5-24.9 kg/m2), overweight (BMI as 25-29.9 kg/m2), and obese (BMI as more than 30 kg/m2) groups. Serum lipid profile and hs-CRP, and waist-hip ratio (WHR) were measured in the study groups. Data analysis was performed using one-way analysis of variance (ANOVA), chi-square (χ2) and regression coefficient at the significant level of p≤0.05.

The average levels of hs-CRP in obese older were significantly higher than normal weight (p=0.01). Also, serum hs-CRP and low density lipoprotein cholesterol (LDL-C) were significantly higher in elderly people with low physical activity level than same people with moderate physical activity level (p=0.0001 and p=0.006; respectively). A negative and significant correlation was also observed between the level of physical activity with WHR (p=0.01) and BMI (p=0.006).

Obese older adults who are inactive and with least physical activity in the condition of Covid-19 pandemic due to high hs-CRP and LDL-C, are more at risk of inflammation and weakened immune system.

Intercellular adhesion molecule-1 (ICAM-1) and lipid profiles are the main factors in the occurrence of atherosclerosis and inflammatory diseases. Therefore, the purpose of current study was to investigate the effects of eight weeks of combined trainings (Resistance - Aerobic) along with vitamin E supplementation on the serum levels of ICAM-1 and lipid profiles in sedentary and overweight men.

For this purpose, 32 healthy sedentary overweight men (body mass index, 26.69 ± 0.91 kg/m2) participated in this semi experimental study and were randomly divided into four equal groups (n=8) of control, supplementation, exercise + placebo, and exercise + supplementation. Participants used 400 IU of vitamin E per day for eight weeks. Concurrent exercise (Resistance - Aerobic) was performed for eight weeks, three sessions per week. Fasting blood samples were taken pre and post of study protocol. Analysis of covariance test was used to evaluate the data at a significance level of p<0.05.

No significant intra-group changes were observed in the serum level of ICAM-1, low density lipoprotein cholestrol and triglyceride (p>0.05). Despite this, high density lipoprotein cholestrol increased significantly in the training–supplementation group (p<0.05). There was no significant inter-group difference in ICAM-1 serum levels  and lipid profile after interventions (p>0.05).

The results of current study suggested that concurrent exercise training along with vitamin E supplementation had no effect on serum ICAM-1, but it improved aerobic power in sedentary overweight men.