The effects of different doses of caffeine on performance, rating of perceived exertion and pain perception in teenagers female karate athletes

The present study set to examine the effects of different doses of caffeine on performance, rating of perceived exertion (RPE), and pain perception in female teenager athletes of karate. Ten female karate athletes (16.8±1.23 years; height 1.59±0.28 m; body-mass 57.73±8.33 kg; BMI 22.71±3.05 kg/m2) participated in the study. A double-blind, randomized, and crossover counterbalanced design was used. In three sessions (with an interval of seven days'), ten female karate athletes ingested low dose (2 mg/kg), moderate dose (5 mg/kg) caffeine, and placebo. Sixty minutes after consumption, they performed the tests as below: one repetition maximum and 60% of one repetition maximum in the leg press, explosive power test, and anaerobic RAST test. After the tests, the participants' RPE (6-20 scale) and pain perception (0-10 scale) were recorded using various categorical scales. The results showed that caffeine ingestion at moderate dose significantly reduced RPE and pain perception values compared with the placebo during muscular endurance test (P=0.0001 and P=0.039, respectively). The findings suggest that caffeine dose of 5 mg/kg body mass appears to improve RPE and pain perception in female teenager athletes of karate. The dose of 2 mg/kg body mass does not confer any additional improvement in performance

The relationship between second-to-fourth digit ratio (2D:4D), muscle strenght and body composition to bone mineral density in young women

2D:4D ratio is determined by balance between androgens and estrogens. Low level estrogen reduces bone mineral density (BMD) and incurs negative changes to bone microarchitecture, increasing the risk of osteoporosis and, as a consequence, fracture risk in women. The purpose of this study was to investigate the relationship between 2D:4D, muscle strength and body composition to BMD in young women. One hundred twenty-seven young women (age range 24-36 years) voluntarily participated in this study. Lengths of the second (index) and fourth (ring) fingers, upper and lower body strength and body composition (body mass index, BMI; waist to hip ratio, WHR) and body fat percentage were estimated. Also, blood levels of calcium and 25-hydroxyvitamin D (25OHD) were evaluated and dual-energy X-ray absorptiometry device was used to measure BMD in the lumbar spine (LS) and femoral neck (FN). The results showed that digit ratios, upper body and lower body muscle strength, BMI and fat percentage had a positive relationship with LS and FN BMD (LS BMD: r=.47, r=.56, r=.46, r=.34, r=.28, p≤.001, respectively; FN BMD: r=.34, r=.49, r=.51, r=.45, r=.27, p≤.001, respectively). In addition, there was no significant relationship between WHR and BMD of LS and FN (p˃.05). Multiple linear regression analysis showed the upper body strength was a stronger determinant of LS BMD and the lower body strength was a stronger determinant of FN BMD. Based on the results, the researchers concluded that upper and lower body strength, 2D:4D ratios and BMI were important determinants of young women’s BMD. Also, it seemed that some of these factors may be able to help predicting the osteoporosis potential in young women

Adsorption of carbon dioxide using activated carbon impregnated with Cu promoted by zinc

In the present study, modified activated carbon (AC) was used in a fixed-bed column for CO2 adsorption of gaseous mixtures. The adsorbents were prepared by impregnation two metals Cu and Zn on the surface of the acid modified AC using a two-stage modification. At the first stage, the samples of AC were pretreated by oxidizing agent (nitric acid) to increase the amount of oxygen surface groups and at the second stage, the acid modified AC were impregnated by two metal salts Cu and Zn on the surface to produce a superior CO2 adsorbent. Metal-loaded acid modified AC was prepared by using different ratios of Cu/Zn ranging from 4 to 20%. The CO2 adsorbed have been measured over the temperature range of (30–50 °C), pressure (100–200 kPa) and CO2 concentrations from 5 to 50%. An increase of 49% CO2 adsorbed was resulted by using modified activated carbon. The breakthrough curves indicated that the breakthrough time increased with increasing the operating pressure, and decreased with increasing the temperature from 30 to 50 °C and CO2 concentration from 5 to 50%. The deactivation model was successfully applied to analyze the breakthrough curves under various operating conditions

Synthesis, characterization and performance evaluation of three-layered photoanodes by introducing a blend of WO3 and Fe2O3 for dye degradation

A three-layered photoanode has been synthesized by the introduction of an additional layer of mixed WO3 and Fe2O3. A total of nine differently-packaged films were prepared by sol-gel method. The fabricated photoanodes were then successfully characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). A comparative study was also done to differentiate the films fabricated with WO3, Fe2O3 and their mixture. Compact, columnar tree and shallow patterns were observed on the cross cleavage of the synthesized layers. These distinct patterns were associated with the growth of layers which consequently led to unique surface morphologies. An increase in photocurrent density was observed on the bicomponent film which has been linked to a high degree of surface roughness as well as improved internal porosity. Three-layered photoanodes, modified with an additional bicomponent layer of WO3:Fe2O3 established much higher photocurrent outputs compared to that of nanostructured WO3 or Fe2O3, regardless of the bicomponent layer arrangement. However, with the bicomponent layer on top and middle, the measured photocurrent soared more than three times as much compared to a slight increase observed when the bicomponent was placed on the bottom

The characterization of oxaliplatin-induced peripheral neuropathy using electromyography in gastrointestinal cancer patients

Oxaliplatin-induced peripheral neuropathy (OIPN) is a common dose-dependent chemotherapy complication in gastrointestinal cancer (GIC). This side effect may restrict therapeutic dose elevation of oxaliplatin. Here, OIPN frequency and determinants of neuropathy appearance in oxaliplatin-treated GIC patients. A total of 102 GIC patients who underwent chemotherapy with fluorouracil, folinic acid and oxaliplatin (FOLFOX4) regimen participated in this longitudinal study. Electromyography (EMG) was accomplished for ulnar, radial, sural, peroneal nerves and superficial peroneal nerve (SPN) before, 3, and 6 months after treatment. National Cancer Institute-Common Toxicity Criteria V.3 and clinical version of the Total Neuropathy Score were used for the neuropathy diagnosis at six months after treatment onset. Of all entered patients, twelve people discontinued this study, and five patients passed away. About 85 patients remained three and six months after chemotherapy onset. Approximately 95% of patients three months after chemotherapy demonstrated OIPN manifestations. Finally, data for 81 patients having neuropathy were analyzed. Mean age of patient 64.0±10.9 years. There were about 3.7%, 30.9%, 63% grade III, II, I of neuropathy, respectively. Interestingly, a significant decrease in action potential (AP) amplitude of SPN, sural and radial nerves but not ulnar and peroneal was observed after treatment onset. However, only the ulnar nerve indicated a substantial deceleration of nerve conduction. Age, sex, weight, past medical diseases, smoking and acute neuropathy were not significantly associated with OIPN. The occurrence of OIPN is detectable by electrophysiological changes of SPN, radial, and sural nerves at three and six months after starting chemotherapy with the FOLFOX4 regimen

Effect of intermediate layer in photocurrent improvement of three-layer photoanodes using WO3 and Fe2O3

Sol–gel method was applied to synthesize WO3/Fe2O3 three-layer films in order to improve the generated photocurrent under UV–vis light irradiation. The films were deposited on FTO glass substrates through doctor bladding method. The samples were then calcined at 500 °C. The photocurrents of the synthesized photoanodes were evaluated by measuring the electric current and voltage under UV–vis light at room temperature. Scanning electron microscopy (SEM) revealed unique surface morphologies owing to the presence of the intermediate layers. At an applied potential of 1300 mV, the WO3\Fe2O3\WO3 and Fe2O3\WO3\Fe2O3 photoanodes exhibited photocurrent densities up to 0.1 mA/cm2 and 0.6 mA/cm2, respectively. It was found that porous films with easy accessibility to the inner surface reveal high photocurrents. The intermediate layer of WO3 demonstrated higher values of photocurrent due to roughness enhancement on the upper surface with columnar tree-growth particles. However, a compact state was observed on the cross section of Fe2O3 growth. A comparison was also drawn between the two and three-layer photoanodes using Fe2O3 andWO3. The films were characterized by XRD, SEM/EDX, and UV–vis irradiation to determine the photocurrent densities

The effects of different doses of caffeine on performance, rating of perceived exertion and pain perception in teenagers female karate athletes

ABSTRACT The present study set to examine the effects of different doses of caffeine on performance, rating of perceived exertion (RPE), and pain perception in female teenager athletes of karate. Ten female karate athletes (16.8±1.23 years; height 1.59±0.28 m; body-mass 57.73±8.33 kg; BMI 22.71±3.05 kg/m2) participated in the study. A double-blind, randomized, and crossover counterbalanced design was used. In three sessions (with an interval of seven days'), ten female karate athletes ingested low dose (2 mg/kg), moderate dose (5 mg/kg) caffeine, and placebo. Sixty minutes after consumption, they performed the tests as below: one repetition maximum and 60% of one repetition maximum in the leg press, explosive power test, and anaerobic RAST test. After the tests, the participants' RPE (6-20 scale) and pain perception (0-10 scale) were recorded using various categorical scales. The results showed that caffeine ingestion at moderate dose significantly reduced RPE and pain perception values compared with the placebo during muscular endurance test (P=0.0001 and P=0.039, respectively). The findings suggest that caffeine dose of 5 mg/kg body mass appears to improve RPE and pain perception in female teenager athletes of karate. The dose of 2 mg/kg body mass does not confer any additional improvement in performance

The relationship between digit ratio (2D:4D) and phy sical fitness in boys 7 to 13 years

The relative lengths of the index finger to the ring finger (2D:4D) is sexually dimorphic. It is believed that the 2D:4D negatively correlates with prenatal testosterone and positively with prenatal estrogen. Low 2D:4D is related to masculine traits such as aggression, physical fitness and performance in different sports. The aim of this study is to investigate the relation ship between the 2D:4D and physical fitness among 7 to 13 year - old boys. 316 boys were selected, all participants were in pre - pubertal stage. After completing the consent by their parents; height, weight, lengths of the index and ring fingers and physical fitness such as: strength, muscle endurance, power, speed, agility, flexibility and aerobic fitness were measured. The partial correlation coefficients was used to determine association between variables. Data analysis was done by SPSS software, version 20 , and the level of significance was considered as P≤0.05. The results showed that the digit (2D:4D) ratio has no significant correlation with handgrip strength and aerobic fitness (P ˃ 0.05). Also, according to the results, no correlation has been observed between the 2D:4D and muscle endurance, power, speed, agility and flexibility (P ˃ 0.05). It seems that 2D:4D is associated with level of testosterone and prenatal estrogen; this index has no significant correlation with physical fitness in children and ca nnot be used to identify and discover talented individuals for various sporting fields. However, more researches are still needed in this area

Creatine Supplementation, Physical Exercise and Oxidative Stress Markers: A Review of the Mechanisms and Effectiveness

Oxidative stress is the result of an imbalance between the generation of reactive oxygen species (ROS) and their elimination by antioxidant mechanisms. ROS degrade biogenic substances such as deoxyribonucleic acid, lipids, and proteins, which in turn may lead to oxidative tissue damage. One of the physiological conditions currently associated with enhanced oxidative stress is exercise. Although a period of intense training may cause oxidative damage to muscle fibers, regular exercise helps increase the cells’ ability to reduce the ROS over-accumulation. Regular moderate-intensity exercise has been shown to increase antioxidant defense. Endogenous antioxidants cannot completely prevent oxidative damage under the physiological and pathological conditions (intense exercise and exercise at altitude). These conditions may disturb the endogenous antioxidant balance and increase oxidative stress. In this case, the use of antioxidant supplements such as creatine can have positive effects on the antioxidant system. Creatine is made up of two essential amino acids, arginine and methionine, and one non-essential amino acid, glycine. The exact action mechanism of creatine as an antioxidant is not known. However, it has been shown to increase the activity of antioxidant enzymes and the capability to eliminate ROS and reactive nitrogen species (RNS). It seems that the antioxidant effects of creatine may be due to various mechanisms such as its indirect (i.e., increased or normalized cell energy status) and direct (i.e., maintaining mitochondrial integrity) mechanisms. Creatine supplement consumption may have a synergistic effect with training, but the intensity and duration of training can play an important role in the antioxidant activity. In this study, the researchers attempted to review the literature on the effects of creatine supplementation and physical exercise on oxidative stress

Creatine Supplementation, Physical Exercise and Oxidative Stress Markers: A Review of the Mechanisms and Effectiveness

Oxidative stress is the result of an imbalance between the generation of reactive oxygen species (ROS) and their elimination by antioxidant mechanisms. ROS degrade biogenic substances such as deoxyribonucleic acid, lipids, and proteins, which in turn may lead to oxidative tissue damage. One of the physiological conditions currently associated with enhanced oxidative stress is exercise. Although a period of intense training may cause oxidative damage to muscle fibers, regular exercise helps increase the cells’ ability to reduce the ROS over-accumulation. Regular moderate-intensity exercise has been shown to increase antioxidant defense. Endogenous antioxidants cannot completely prevent oxidative damage under the physiological and pathological conditions (intense exercise and exercise at altitude). These conditions may disturb the endogenous antioxidant balance and increase oxidative stress. In this case, the use of antioxidant supplements such as creatine can have positive effects on the antioxidant system. Creatine is made up of two essential amino acids, arginine and methionine, and one non-essential amino acid, glycine. The exact action mechanism of creatine as an antioxidant is not known. However, it has been shown to increase the activity of antioxidant enzymes and the capability to eliminate ROS and reactive nitrogen species (RNS). It seems that the antioxidant effects of creatine may be due to various mechanisms such as its indirect (i.e., increased or normalized cell energy status) and direct (i.e., maintaining mitochondrial integrity) mechanisms. Creatine supplement consumption may have a synergistic effect with training, but the intensity and duration of training can play an important role in the antioxidant activity. In this study, the researchers attempted to review the literature on the effects of creatine supplementation and physical exercise on oxidative stress