فصلنامه فیزیولوژی ورزشی
پیاپی 53 (بهار 1401)

Increased strength after a period of resistance training or following relatively intense contractions (post-activation potentiation) and decreased strength after repetitive contractions (fatigue) or after static stretching movements (post-activation depression) are not only related to the muscle but also the nerve system. Over the past years, numerous methods such as surface electromyography (sEMG), evoked spinal reflex recording, and single motor unit recording has been used to prove the role of neurological factors in transient and sustainable changes in strength. Over the past 30 years, new methods such as TMS have been used to investigate neural mechanisms in response and adaptation to resistance exercise, and the importance of evoked and central nervous system activation in the occurrence of exercise fatigue and adaptation induced by resistance training has been demonstrated.

 In this study, the fundamentals and applications of TMS are briefly discussed.

The results showed that the level of excitability, especially in the motor cortex, increases following relatively intense contractions and after a period of resistance training but decreases after exhausting exercise and does not change after static stretching movements.

Although TMS is a valuable method for quantifying the contribution of neurological factors, it could not uncover whole mechanisms and adaptations that occur following the intervention, and a combination of methods in the field of neuroscience- should be used to provide more insight into cortical function and plasticity in response to acute and chronic exercise.

The purpose of the present study was to review the various methods, invasive and non-invasive, used to determine the anaerobic threshold (AT).  AT is the highest training intensity at which energy requirements of exercise are mainly provided by aerobic energy system, and the rate of lactate appearance in the blood is equal to the rate of its disappearance.  Since AT occurrence is associated with aerobic to anaerobic transition, it has a significant contribution to precise exercise prescription, determination of exercise intensity domains, and prediction of performance especially in endurance athletes. Direct measurement of blood lactate is the most accurate method to determine AT, but it has an invasive, expensive nature, and exposes the subject to the risk of blood sampling. As a result, other non-invasive methods that mainly use heart rate and workload relationship or changes in respiratory indexes such as oxygen and carbon dioxide equivalent, have been considered to determine AT. Meanwhile, the traditional method of AT determination usually uses two-phase models (one turn point). While recent researches prefer three-phase models (two turn points) which provide better estimation of training domains compared to those offered by two-phase models. Therefore, the present study intends to review the most common methods of AT determination and their pros and cons in the form of two- and three-phase models.

The aim of present study was to investigate the effect of 10-weeks of 4 energy restriction methods on histologic changes of adipose tissue and macrophage infiltration as well as glycemic indices in unsaturated-high-fat-fed obese male rats.

 Blood and tissue samples were collected from 72 wistar male rats (weight 195±5g, age 8 weeks) at 1st, 18th and 28th weeks after overnight fasting. After first sampling, remaining 64 rats were randomly divided into two groups of control (n=16) and high-fat-diet (UHFD)(n=48). UHFD group was randomly divided into food content change (SD), exercise training (EX), combination (CR+EX) and unsaturated-high-fat-diet (UHFD) subgroups after 18 weeks. Ex group ran for 10 weeks (5d/wks.) with intensity equivalent to 70-75% of Vo2max. CR was implemented reducing 25% of energy intake and SD group used a change from UHFD to a standard diet. Histologic changes of retroperitoneal and mesenteric regions as well as macrophage infiltration were assessed after tissue passage, H&E staining and high-resolution microscopic picturing.

The results of this study indicated that in comparison to UHFD, all experimental groups showed a significant difference in all glycemic indices and lipid profile variables (but HDL) as well as adipocyte size of studied adipocyte tissues (P > 0/05).

Therefore, it seems that regardless of the intervention type, energy intake manipulation methods possibly due to the reduction of adipocyte size had not change in macrophage infiltration to cause improvement in metabolic profiles.

The aim of this study was to construct physical fitness Norms for women aged 18-60 years of Isfahan and it was descriptive normative research.

 A number of 372 women, (Mean: 39.48 ±12.64 years; Height: 159.15±6.66 cm; Weight: 67.44±10.19kg; BMI: 26/71±4/27 kg/m2), were randomly selected as subjects. The measurement tools of this study were physical fitness standard tests including Flexibility sit & Reach, Rockport 1 mile walking/Running, curl up, hand grip and push up tests, that have been used for construction of norms. Descriptive statistics and computation of Z scores and point percentages were used to construct norms.

The analysis of research findings revealed that cardiovascular endurance means (38.34± 9.42ml.kg.min), body fat percent (30.30± 7.78), Handgrip (21.27±6.74kg), Endurance of shoulder girdle muscles (6.87±7.75 push-up), flexibility (30.45±7.66 cm) and endurance of abdominal muscles of subjects (13.74±13.48 curl-up) were respectively.

Compared to available norms in this area and other countries, findings of results revealed that in cardiovascular endurance, endurance of abdominal muscles and handgrip strength, subjects were in weak conditions, also in endurance of shoulder girdle & body fat percent, subjects’ conditions were moderate, but in flexibility of body, they have nearly optimal conditions.  Generally, physical fitness status and regular physical activity of subjects were not optimal.

Human athletic performance is an enormously complex multifactorial phenomenon, and is affected by numerous intrinsic (genetics) and extrinsic factors (e.g., training, nutrition). Total genotype score is a new model that was developed as a favorable polygenic profile in the elite athlete group, so the aim of this survey was the comparison of total genotype score of power/ strength responsible ACE, HIF1α and IGF1 polymorphisms of elite, amateur karate-kas vs. non-athletes.

 This survey was done on 252 healthy Isfahanian subjects aged 27.2 ± 7.4 years including 124 males and 128 females sub-divided into elite (N= 80); amateur (N= 86) vs. non-athlete (N= 86 people with the same anthropometric characteristic by elite and amateur corps) groups. The amount of 5cc blood from brachiocephalic vein was taken in tubes including EDTA, then DNA was extracted using a modified salting-out method; polymorphisms were determined by PCR; and the restriction fragment lengths of the products were analyzed by electrophoretic separation, so TGS was calculated finally. Non–parametric Chi-Square and one-way ANOVA by using the SPSS software were used to assess the statistical differences. The level of significance was considered at P <0.05.

Genotyping analyses indicated that in elite karate-ka, an increase in DD frequency was observed (63.0%) compared to non-athlete (41.0%) and amateur Karate-ka groups, significantly (14.7%) (χ2=14.430; P=0.011); but genotype distribution of HIF1α (χ2=2.746, P=0.60) and IGF1 (χ2=1.549, P=0.81) weren’t significantly different.  In addition, the mean of TGS of elite karate-kas (69.85) was higher than amateur Karate-kas (64.40) and non-athlete (63.37), but it wasn’t significant (F=1.66, P=0.08). 

Results have proved that the ACE is a sensitive polymorphism tool to differentiate elite from amateur karate-kas. Additionally, the use of TGS hadn’t been revealed in survey because karate has the multifactorial demands to for success likely; so, the genetic talent needs to be checked by a variety of polymorphisms in different geographical zones, too.

The aim of this study was to investigate the effect of eight weeks of aerobic training and pumpkin seed supplementation on pulmonary oxidative stress indices of H2O2 poisoned rats. 

 42 male Wistar rats were randomly divided into 7 groups: control, poisoned, poisoning+ 1 g pumpkin, poisoning+ 2 g pumpkin, poisoning+ aerobic exercise, poisoning+ 1 g pumpkin+ exercise, poisoning+ 2 g pumpkin+ exercise. Induction of oxidative stress by intraperitoneal injection of 0.1 mg/ kg of hydrogen peroxide for 3 days per week, receiving pumpkin seeds at 1 and 2 g per kg of body weight and exercise program including increasing running on a treadmill for 8 weeks (3 days Per week with a minimum speed of 8 meters per minute and a slope of 10 degrees). Specialized kits were used to measure cytochrome c, ATP, MDA and PAB indices and the data were analyzed by two-way analysis of variance at a significance level of 0.05.

The results showed that H2O2 poisoning caused a significant decrease in ATP and significant increase in pulmonary cytochrome C, MDA and PAB (P <0.05). Pumpkin seed doses had no significant effect on MDA, cytochrome c and ATP concentrations (P> 0.05). On the other hand, receiving 2 g of pumpkin seeds caused a significant decrease in PAB concentration (P <0.05). Eight weeks of aerobic exercise had no significant effect on pulmonary MDA concentration (P> 0.05), but significantly increased ATP concentration and decreased cytochrome c and PAB concentrations (P <0.05). Interaction of aerobic exercise with pumpkin seed doses increased ATP and decreased concentrations of MDA, cytochrome c and PAB (P <0.05).

The single effects of pumpkin seeds seem to be dependent on tissue and dosage. Eight weeks of aerobic exercise is also a good antioxidant solution in hydrogen peroxide poisoning, depending on the factors. The combination of aerobic exercise and high doses of pumpkin seed supplement has additional effects on oxidative indices of lung tissue in rats poisoned with Hydrogen Peroxide.