جستجوی مقالات مرتبط با کلیدواژه « حداکثر اکسیژن مصرفی » در نشریات گروه « تربیت بدنی »

Firefighting is a high-risk profession that requires high physical fitness, and it is important to have regular exercise to maintain optimal physical fitness and health. However, there is a little research on the best types and methods of training to improve the performance of firefighters and reduce the volume of self-contained breathing apparatus (SCBA) used in duty. Therefore, the purpose of this study was to investigate and compare the effect of 8 weeks of high-intensity interval and functional training on cardiorespiratory fitness (VO2max) and the used volume of SCBA in firefighters.

Thirty-nine firefighters working in the fire department of Tehran participated in the study and were randomly allocated in the three groups of control, HIIT and HIFT. Subjects in HIIT group performed 8 weeks of Tabata exercises with body weight, which were 4 exercises in the first two weeks and were increased to 6 and 8 exercises in the 6th and 8th weeks, respectively. In each session, they had 10 min general warm up, thereafter they performed 8 sets of each exercise, where sets included 20 s activity followed by 10 s rest and 2 min rest was allowed between exercises. Subjects in HIFT group had similar program to the HIIT group, with the exception that the exercises they performed were those exercises in the standard simulated test for firefighters which were performed based on the Tabata methods (20 s activity followed by 10 s rest). Two days before training and 48 hours after the last training session the VO2max test (Bruce’s protocol) and simulated firefighting test were carried out.

The statistical analysis of the data showed that HIFT and HIIT caused a significant increase in maximal oxygen uptake (VO2max) and performance, and a significant decrease in the volume of SCBA used in firefighters (p<0.05), though, these changes were not significantly different between HIIT and HIFT groups (p<0.05). VO2max increased by 6.35% and 4.26% in HIFT and HIIT groups, and performance increased by 5.21 and 4.74%, following HIFT and HIIT, respectively. In addition, VO2/HR increased by 11.64 and 6.52% in HIIT and HIIT groups, respectively, while, the volume of SCBA used decreased by 14.41% and 11.44%, respectively. However, the results of repeated measures of ANOVA showed no significant between-group differences for RER (P=0.269), HR (P=0.595), VE (P=0.392), VE/VO2 ratio (P0.778) =) and VE/VCO2 ratio (P=0.778).

According to the results of the present study it could be concluded that 8 weeks of HIFT and HIIT can improve cardiorespiratory fitness (VO2max), performance, and the volume of SCBA used in firefighters, and that performing these types of training based on the Tabata’s method is advised to firefighters.

Success in sports activities performance depends on many factors, including nutritional status of athletes therefor the aim of this study was to evaluate the effect of 4 weeks of glutamine supplementation on factors related to physical fitness in young wrestling.

In this experimental study, 16 teenage wrestlers (18.85±1.6 in age range) participated and were randomly divided into two control (n=8) and experimental (n=8) groups. Both groups participated in their normal exercises, then the experimental group received glutamine supplement and the control group received placebo (maltodextrin) during 4 weeks. Before and after the research protocol, indicators related to physical fitness (strength, maximum oxygen consumption and speed) were evaluated. In the following, the obtained information was evaluated using independent t-test and significance level of p≤0.05 and Spss statistical software.

The findings showed that the strength of the lower and upper body muscles (p=0.04), as well as the maximum aerobic power (p=0.001) of the wrestlers in the experimental group was significantly higher than the control group. However, there was no significant difference (p=0.4) in the speed of the two groups.

It seems that the consumption of glutamine amino acid supplement has an effect on the performance of physical activities and improves performance of strength and maximum oxygen consumption.

The information about the effect of ginseng supplementation on physiological responses in debilitating activities is unclear. The aim of this study was to investigate the effect of short-term ginseng consumption on maximal oxygen consumption, blood lactate and time to exhaustion in male athletes.

In this quasi-experimental study, which was performed as two blinds and crossovers, 10 male athletes (age: 18 ± 24 years) participated in a single group model with supplementation and placebo. Subjects took two 250 mg ginseng capsules and 6 mg of starch per kilogram of body weight daily as a placebo for one week and then participated in the Bruce Exhaustion Test. Information on maximal oxygen consumption, blood lactate and arrival time to exhaustion in the laboratory .Data were analyzed using paired t-test and covariance test at a significance level of 0.05.

The results showed that the maximum oxygen consumption (p = 0.01) and the time to reach exhaustion (p = 0.02) were significantly increased compared to the placebo group. There was significant decrease in blood lactate compared to the placebo group (p = 0.03).

Short-term use of gensing supplementation may improve exercise performance and reduce fatigue. It is recommended that athletes take 500 mg of their sexing supplement daily to increase aerobic capacity.

Being overweight and obese during adolescence is associated with a wide range of complications and an increased risk of sudden occurrence of physical problems, mental disorders, and some cancers. Therefore, the purpose of this study was to investigate the effects of 10 weeks of spinning training on body composition, vo2max and ghrelin hormone levels in adolescents with overweight.

In this quasi-experimental study, with a design pre-test-post-test and a control group, 30 overweight teenagers with BMI=26.8 kg/m2 were selected purposefully and using a systematic random method were divided into 2 groups of 15 people (Exercise and Control). The spinning training protocol was implemented for 10 weeks, three times a week, and lasted about 50 minutes with an intensity of 65% of the maximum heart rate daily incrementally. Blood sampling and the measurement of height, weight, BMI, and Vo2max were done in two stages, pre-test, and post-test. In addition, in order to analyze the data, Covariance tests was used using SPSS26 software at a significant level (P=0.05).

The results of the study showed a significant decrease in weight (P=0.001), fat percentage (P=0.001) and BMI index (P=0.001) and a significant increase in Vo2max (P=0.001) and ghrelin hormone levels after 10 weeks of spinning training (P=0.001).

These findings indicate the beneficial effects of the effect of spinning exercise on body composition, VO2max and ghrelin hormone in overweight teenagers. Therefore, the use of spinning exercises is recommended as a suitable prevention and treatment method for overweight and obese teenagers.

Has proven to chronotype play a key role in the timing of peak athletic performance. Recent evidence suggests that accounting for these differences, known as the chronotype, leads to different daily physiological profiles. The aim of the current research was to investigate the effect of chronotype on the maximum oxygen consumption, melatonin and body temperature of the youth football players of Mes Kerman Club.

In this research, 30 male youth football players of Mes Kerman Club with an average age of 16.26 years were selected as samples. Based on the morning and evening questionnaire, the participants were divided into morning and evening types. In order to perform the incremental test on the treadmill, participants attended 3 sessions in the laboratory (at 7-9 and 6-8). Before the test, blood melatonin level and body temperature and during the test, the oxygen consumption of the participants were measured.

In the morning group, there was no significant difference between Vo2max and melatonin in the morning and evening (p>0.05), but in the evening compared to the morning, the body temperature showed a significant increase (p<0.005). In the evening group, there was no significant difference between morning and evening melatonin (p>0.05), but in the evening compared to the morning, body temperature (p<0.023) and Vo2max (p<0.001) showed a significant increase.

It seems that the chronotype affects the aerobic capacity of athletes. In people with evening-type chronotype, aerobic capacity is sometimes higher in evening physical activity hours compared to morning physical activity.

 Today, the consumption of caffeinated beverages such as coffee has increased among athletes. The aim of this study was to investigate and compare the effect of consuming two different doses of coffee on fluid balance, electrolytes and VO2max in active men.

In quasi-experimental studies, 54 trained men (Age: 20.89±1.31 y; Weight: 70.10±8.43 kg; Height: 174.7±5.65 cm; VO2max: 52.16±5.99 ml/kg/min) were randomly selected and  divided  into three equal groups (N=18). All subjects consumed equal amounts of 3 cups of coffee per day for 5 days (balancing stage), on the sixth and seventh day (test stage) subjects of three groups consumed 0, 3 and 8 cups of coffee per day (equivalent to 0, 258 and 688 mg caffeine per day, respectively). with no other dietary caffeine intake, for 7 days. Before and after the intervention, subjects 'body weight was measured, blood samples were taken to examine blood factors, and subjects' VO2max was assessed using the Fox protocol. The measuring of indices changes in subject's body fluids, electrolytes and VO2max in 3 levels of controlled coffee ingesting, were analyzed by multivariate test (MANOVA) and Tukey post hoc in (P≤0.05).

Percent plasma volume changes in ingestion level of 0 (cup / day) was increased significantly (P = 0.013), compared to ingestion level of 3 (cup / day). The mean body weight of subjects at the ingestion level of 0 (cup / day) showed a significant increase (P = 0.001), compared to the other two levels. Concentration of the serum sodium at the ingestion level of 3 (cup / day) showed a significant increase (P≤0.05), compared to the other two levels. There was no changes in the concentration of serum potassium between different levels of caffeine ingestion. Estimated VO2max in the two forms of absolute and relative at the ingestion level of 8 (cup / day), showed a significant decrease (P= 0.003) compared to the other two levels .

Consumption of coffee in different doses reduces body fluids, increases serum sodium concentration and possibly increases sodium excretion and decreases VO2max in active people. Accordingly, considering the importance of maintaining body fluids on the performance of athletes, it seems that coaches and sports professionals have the necessary care in the amount or time of consumption of this drink.

Smoking leads to disease, disability and premature death. This research aims to investigate the effect of six weeks of breathing exercise on carboxyhemoglobin (COHb), mean platelet volume (MPV), platelet count (PLT), lactate and oxygen saturation level (SpO2), and some hemodynamic indices such as heart rate, blood pressure and VO2max of smokers. In this quasi-experimental research, 20 male smokers were selected by targeted sampling and randomly divided into two exercise (n=10) and control (n=10) groups. Breathing exercise was done twice a day for six weeks, 5 sessions per week. For statistical analysis of data, ANCOVA test was used to examine the between groups differences (P<0.05). The results showed that 6 weeks of breathing exercise intervention significantly reduced COHb (P=0.001), MPV (P=0.001), PLT (P=0.001), systolic (P=0.008) and diastolic (P=0.03) blood pressure and heart rate (P=0.001) and a significant increase in SpO2 (P=0.001) in the training group compared to the control group. There was no significant difference in body mass index, maximum oxygen consumption and blood lactate level between the two groups (P<0.05). According to the results, performing breathing exercises by smokers can be useful in maintaining and improving their health and reducing the side effects caused by smoking.

Regarding the effects of high-intensity interval training and blood flow restriction on physiological indices, especially in athletes. The purpose of this study was to investigate the effect of four weeks of high-intensity interval training and blood flow restriction on cardiovascular fitness and inflammatory cytokines of interleukin-6 and interleukin-17 in active male students. 18 active Tehran students aged 20 to 30 years old were randomly divided into three groups: 1- training and blood flow restriction, 2- training and 3-blood flow restriction. The subjects performed four weeks and three sessions per week in high-intensity interval training and blood flow restriction groups. Blood samples were taken at the fasting time before and after the test. Repeated analysis of variances and t-test were used to analyze the data. Based on our results high-intensity interval training and blood flow restriction did not significantly change the Vo2max or vVo2max in the groups. According to the results of interleukin-6 and interleukin-17 levels were significantly different between groups. These indices were higher in HIIT group compared to two other groups (P

Considering the importance of the use of plant antioxidants in preventing inflammatory and muscular damage indices, the present study was performed to determine the effect of 8 weeks of pomegranate supplementation and aerobic training on inflammatory and muscular damage indices in overweight men.
Twenty overweight men were assigned into two equal supplement and placebo groups as randomized and double-blind study (225mg/day pomegranate or dextrose for 8 week). Meanwhile, both groups participated in running tests with 50 to 80% maximum oxygen consumption (VO2max) 8weeks, 3 sessions/ week. Then, blood samples were taken during three phases at baseline, immediately and 24 hours after different intensities of aerobic exercise (60% and 75% VO2max). The data was analyzed by SPSS software (V: 20) using repeated measure ANOVA and paired T tests at the significant level P≤0.05.
The result showed a significant increase in Tumor necrosis factor-alpha and C - reactive protein immediately after the exercise in both groups (P=0.001). However, these indices were decreased 24 hours after exercise in both groups, and this decrement was higher in the pomegranate group (P=0.001), (P=0.01). Although, no significant difference was found in Creatine kinase in any stage of the study in both groups (P=0.27), (P=0.20), but, a significant decrease was found in CRP levels in the supplement group as compared with placebo in 75% VO2max (P=0.03).
The results indicated that the combination of regular exercise and pomegranate supplementation had a significant effect on the control and decline of inflammatory markers particularly CRP in overweight males. However, more research is needed based on a few studies conducted in this area.

Various training methods have been suggested to increase aerobic endurance performance in soccer players. But, it's still not clear which training is better. Thus, the purpose of the present study was to investigate the effects of plyometric training (PT), high intensity interval aerobic training (HIIT) and concurrent training (CT) on specific aerobic endurance performance in men amateur soccer players.
Thirty-two third league soccer players (age = 25.4 ± 4.7 year, height = 177.6 ± 7.1 cm, body mass = 74.2 ± 11.1 kg) took part in this study. First, players were matched by positional role and aerobic power then randomly assigned to the HIIT (n = 11), PT (n = 11) and CT (n = 10). The HIIT consisted of interval training, four times 4 minutes at 90 to 95% of maximal heart rate, with a 3 minutes jogging in between. The PT included of 9 explosive jumping and throwing exercises in 3 sets with 10 repetitions which subjects have done with low to maximal intensity. The CT involved of both the PT and AT in one session that PT performed first. Training programs were carried out for 8 weeks and 3 sessions per week. Before and after training, Hoff-Helgerud football endurance test was performed to estimate specific aerobic endurance performance.
Specific aerobic endurance performance increased significantly after training (PT: from 1349 ± 18 to 1387 ± 36 m, HIIT: from 1359 ± 29 to 1412 ± 42, CT: from 1335 ± 23 to 1436 ± 33, P The CT improves specific aerobic endurance performance in men amateur soccer players to a greater extent than any of the PT and HIIT alone.

Concurrent increase in strength and endurance is one of the main factors of reaching the peak performance in paddlers. The aim of this study was to compare the effect of 8 weeks of resistance-paddling training and paddling training on some physiological characteristics and performance of paddlers. 16 female dragon boat paddlers were selected purposively and divided to resistance-paddling training group (n=9) and paddling training group (n=7). Resistance-paddling group participated in padding training along with resistance training for 8 weeks, 3 sessions per week, each session 90-120 min. The paddling group performed paddling training at the same time. Upper body anaerobic power, VO2max, hand grip strength, 1-RM of bench press and paddling and 500-meter paddling performance were measured before and after 8 weeks of training. ANCOVA was used to compare changes between the two groups and the significance level was 0.05. The results showed a significant increase in upper body anaerobic power and VO2max (40% and 23% respectively) in resistance-paddling training group which was significant compared with the control group (P=0.001). Hand grip strength did not change significantly in resistance-paddling group compared with the control group (P=0.1). 1-RM of bench press and paddling increased (36% and 16% respectively) in resistance-paddling group. The time of 500-m paddling performance significantly improved in resistance-paddling group (17.5%) compared with the paddling group (P=0.02). It seems that resistance-paddling training can improve performance through increased aerobic power, anaerobic power and paddler's strength.

  The purpose of this study was to develop and investigate the accuracy of regression equation to predict VO2max and estimate cardiorespiratory fitness (CRF) based on non-exercise (N-EX) data in adult women. Research In order to achieve the purpose of research, 30 female students studying at Kharazmi University, Tehran; Iran, with the average age 24.96±2.41 yr., weight 57.07±7.08 kg, and height 162.55±5.15 cm were selected as the research sample. At first, the subjects filled in the consent for participation in research form and revised physical activity readiness questionnaire (rPar-Q). The N-EX data were collected just before the maximal graded exercise test (GXT)included the participant’s age, body mass index (BMI), perceived functional ability (PFA) to walk, jog, or run given distances, and current physical activity (PA-R) level. Then, all participants (N = 30), aged 18-30 years old, successfully completed a Bruce maximal GXT on treadmill using gas analyzer to assess VO2max.The data were analyzed by multiple linear regression, ANOVA R.M, Pearson correlation, cross validation using predicted residual sum of squares (PRESS), and LSD post hoc test statistical methods. The data analysis revealed a high correlation, minimal shrinkage and difference; thus, Jackson, George and Bradshaw regression models yield relatively accurate results and are a convenient
way to predict VO2maxand estimate CRF in adult women (18-30 yr.).In order to predict VO2max and estimate CRF in adult women, the three new regression equations (Ghafari-Jackson, Ghafari-George, and Ghafari-Bradshaw models) should yield acceptable accuracy when applied to an independent sample of adult women (aged 18-30 yr.) with a similar cardiorespiratory fitness level. It should be mentioned that non-exercise regression equations are not as accurate as gas analyzer criterion test and cannot be used instead of this criterion test. But they would predict VO2max and estimate CRF in adult women accurately if they were used correctly and can be used instead of Bruce treadmill equation criterion test. The new established regression equations or the old developed ones are safe and quite accurate, easy, fast, and inexpensive for large groups, elders, and persons with cardio-vascular diseases.

Abstract The purpose of this study was to investigate the relationship between resting visfatin levels and visfatin changes during endurance exercise with aerobic fitness and body composition. For this purpose, forty six subjects (Mean±SD; age, 42.8±16.0 y; height, 171.7±5.4 cm; weight, 73.6±9.7 kg) participated in this study. In one session after determining body composition characteristics including weight, WHR and BMI, maximal oxygen consumption (Vo2max) was determined after 5 minutes warm-up by using a progressive exercise test on a cycle ergometer. After one week all subjects performed an acute endurance exercise at 60% of Vo2max for 30 minutes on a bicycle. Two blood samples were taken before and immediately after exercise and were analyzed for visfatin and glucose concentrations. To determine the correlations among the variables Pearson’s correlation was used. Results showed no significant correlations between serum visfatin with aerobic fitness (r=0.17, P>0.05) and body composition parameters (P>0.05). However, changes in visfatin during endurance exercise were positively and significantly correlated with aerobic fitness (r=0.349, P=0.018) and glucose (r=0.363, P=0.013). In addition, data analysis revealed that aerobic fitness is negatively and significantly correlated with resting glucose and glucose changes during exercise (P<0.05). Based on the results of the present study it could be concluded that aerobic fitness has no relationship with resting serum visfatin, though the higher aerobic fitness might result in more changes in visfatin responses to exercise, which might be an indicator of visfatin rules in improving the aerobic performance through NAD+ and increases in insulin during and immediately after exercise. Key words: Endurance exercise, Vo2max, NAMPT, BMI, WHR

The aim of this study was to evaluate the effects of four weeks of CoQ10 supplement consumption on VO2max, peak anaerobic power and specific endurance in indoor soccer players. 14 indoor soccer players (age 21.42±1.69 yr, peak anaerobic power 437.94±54.63 watt, VO2max 48.84±3.87 ml/kg/min) who were experienced in national college championships were randomly divided into two groups where supplement group (N=8) consumed CoQ10 supplement (300 gr/day) and placebo group (n=6) consumed placebo. Both groups trained for four 90-min. sessions per week. Supplement and control groups consumed 300 mg of CoQ10 and placebo respectively daily. Bruce test was performed on a treadmill to measure VO2max and time to exhaustion, Rast test and Hoff test were used to measure peak anaerobic power and specific endurance. The values were obtained before and after the intervention period and compared using student paired and unpaired t tests. Findings showed that after supplement consumption, posttest VO2max did not change in supplement group (from 48.65 ml/kg/min to 51.58 ml/kg/min). Time to exhaustion (from 811.87 seconds to 816.66 seconds) and specific endurance (from 1291.25m to 1381.25m) did not significantly change. It can be concluded that four weeks of CoQ10 supplement consumption could not increase VO2max, time to exhaustion, anaerobic power and specific endurance of indoor soccer players. So the consumers should take this supplement longer so that they can benefit from its positive effects.

The Yo-Yo Intermittent Recovery Test 2 (YIRT2) that designed mainly to estimate VO2max in soccer players, it used to assess athletes abilities to repeatedly perform highintensity exercise. The purpose of the present study was to determine the validity and reliability of the Yo-Yo Intermittent Recovery Test 2 (YIRT2) to estimate maximal oxygen uptake (VO2max) in elite female futsal players. Subjects were Iranian elite female futsal players (n = 33: mean age 22.46±3.04 yrs, height 164.1±4.85 cm, and body mass 56.6±7.31 kg). All subjects performed a graded exercise test on motorized treadmill to examine VO2max by breath to breath gas analyzer apparatus (K4B2, COSMED, Italy) and the YIRT2 to estimate VO2max. The significant correlation found between VO2max measured by gas analyzer and estimated by YIRT2 (r=0.88, r2=0.77, P=0.001), indicating that the YIRT2 is valid test toestimate VO2max.Test-retest results showed that the YIRT2 is the reliable test to estimate VO2max (r=0.98, r2=0.96, P=0.001).Discussion and It is concluded that YIRT2 were a valid and reliable test to estimate VO2max in elite female futsal players. The YIRT2 appears to measure aerobic fitness but may also be used as a field test of the ability to repeat high-intensity efforts.

Music is one of the important and affecting factors on sports performance. Most research investigated the effects of music on the indexes decisive in the exercise. However, the present study was to investigate the effect of music on the maximum and sub maximum performance non-athletic men. In test project with a group of 12 men non-athletes with a frequently participated in this study. During those four weeks, with take a week off from the first to fourth weeks, respectively in different circumstances without music, with stimulating music, light music and arbitrary music, Bruce protocol was performed to the extent of fatigue. We use the ANOVA with repeated measures to analysis the difference of the averages of the various stages. The significance level was (p≤0/05). The results showed playing variety of music during the peak of the Bruce protocol on time to exhaustion, the maximal oxygen uptake and the perceived exertion rate no significant effect. Also, we didn’t observed significant difference on measured indexes in the three type of music. In sub maximal performance in second stage Bruce test, was observed a significant difference in the perceived exertion rate when playing stimulatory and arbitrary music. According to the findings obtained from this study and comparison it with previous research it can be concluded that despite useful effects of music on sub maximal performance, in the maximum activity, the type music no significant effect on the training indexes.