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1.
The objective of this study was to investigate the physiological indices of competitive routines in women''s artistic gymnastics by characterizing post-exercise heart rate (HR), oxygen uptake (VO2) and peak blood lactate concentration (Lmax) in a group of eight young elite-oriented female gymnasts. HR was continuously monitored with Polar RS400 monitors during the test event simulating a competition environment. Within 5 s of the end of each routine, the breath-by-breath gas analyser mask was placed on the face to record VO2. VO2max was calculated by the backward extrapolation method of the VO2 recovery curve. Lmax was obtained during recovery (min 1, 3, 5, 7 and 10) subsequent to each event. One week later, HR, VO2 and Lmax were measured during an incremental continuous treadmill test. The treadmill test was confirmed as the assessment with the highest physiological demand. The gymnasts reached their highest values of HR (183-199 beats · min-1), VO2/Bm (33-44 ml · kg-1 · min-1) and Lmax (7-9 mmol · l-1) in the floor and uneven bars exercises. The vault was the event with the lowest HR (154-166 beats · min-1) and Lmax (2.4-2.6 mmol · l-1), and the balance beam had the lowest VO2 (27-35 ml · kg-1 · min-1). The mean relative peak intensities attained in the different events, which ranged from 65 to 85% of the individual VO2max and HRmax recorded in the laboratory, suggest that cardiorespiratory and metabolic demands are higher than previously indicated. The high percentage of VO2 measured, particularly after the floor event, suggests that aerobic power training should not be neglected in women''s artistic gymnastics.  相似文献   

2.
《Chronobiology international》2013,30(8):1636-1646
Although the effects of aerobic exercise on resting heart rate, heart rate variability, and blood pressure have been investigated, there are scant data on the effects of aerobic exercise on the circadian rhythm of such cardiovascular parameters. In this study, we investigated the effects of aerobic exercise on the 24?h rhythm of heart rate and ambulatory blood pressure in the morning, when cardiovascular events are more common. Thirty-five healthy young subjects were randomized to control and aerobic exercise groups. Subjects in the latter group participated in their respective exercise program for two months, while those in the former group did not exercise. Twenty-four-hour electrocardiogram and ambulatory blood pressure monitoring data were obtained at baseline and at the end of the exercise intervention. The control group showed no changes, while the aerobic exercise group showed a significant decrease in heart rate (73.7?±?6.6?bpm to 69.5?±?5.1?bpm, p?<?0.005) and sympathetic activity such as LF/HF ratio (2.0?±?0.7 to 1.8?±?0.6, p?<?0.05) throughout the 24?h period, particularly in the daytime. The decrease in the heart rate was most prominent in the morning. However, heart rate and LF/HF ratio showed no statistical changes during the night. No significant changes were observed in blood pressure. These findings suggest aerobic exercise exerts beneficial effects on the circadian rhythm of heart rate, especially in the morning. (Author correspondence: hshio@kobe-u.ac.jp)  相似文献   

3.
Despite its growing popularity, few studies have investigated specific physiological demands for elite female futsal. The aim of this study was to determine aerobic fitness in elite female futsal players using laboratory and field testing. Fourteen female futsal players from the Venezuelan National team (age =21.2±4.0 years; body mass =58.6±5.6 kg; height =161±5.0 cm) performed a progressive maximal treadmill test under laboratory conditions. Players also performed a progressive intermittent futsal-specific field test for endurance, the Futsal Intermittent Endurance Test (FIET), until volitional fatigue. Outcome variables were exercise heart rate (HR), VO2, post-exercise blood lactate concentrations ([La]b) and running speeds (km · h-1). During the treadmill test, VO2max, maximal aerobic speed (MAS), HR and peak [La]b were 45.3±5.6 ml · kg-1 · min-1, 12.5±1.77 km · h-1, 197±8 beats · min-1 and 11.3±1.4 mmol · l-1, respectively. The FIET total distance, peak running velocity, peak HR and [La]b were 1125.0±121.0 m, 15.2±0.5 km · h-1, 199±8 beats · min-1 and 12.5±2.2 mmol · l-1, respectively. The FIET distance and peak speed were strongly associated (r= 0.85-87, p < 0.0001) with VO2max and MAS, respectively. Peak HR and [La]b were not significantly different between tests. Elite female futsal players possess moderate aerobic fitness. Furthermore, the FIET can be considered as a valid field test to determine aerobic fitness in elite level female futsal players.  相似文献   

4.
在自然呼吸和窦性节律下,用浮置式玻璃微电极引导在体单个左心室肌纤维动作电位,作为兴奋的指标,以其 0相触发产生期前的试验刺激,测定有效不应期(ERP)。38只家兔的测定结果表明,在R-R间期为205—330ms的范围内,随着心率加快(R-R间期缩短),ERP减小,而 ERP/RR 间期增大,说明 ERP 与心率直接有关。并且,在较快的心率时,ERP 相对延长。通过相关与回归分析,制出了能够删除心率影响的校正公式。静脉注射酒石酸锑钾(50mg/kg)发现,在窦性和起搏节律下,酒石酸锑钾均能轻度延长 ERP(P<0.001)。窦性节律下的校正后值与起搏节律的测定结果完全一致。证明校正后值能够用来比较处理前后不同心率条件下,各种药物、离子及其它因素对ERP 的影响。 本文的校正公式虽然只适用于同种动物和方法,但此校正公式的制作原理也可以广泛应用到其它多种动物。  相似文献   

5.
6.
在比赛条件下观察了12名女子足球运动员的心率和血乳酸的变化。上、下半场比赛时,心率在170次/分以上者分别占总记录次数的20.8%和13.0%,心率小于150次/分者则分别为37.5%和48.2%。上、下半场赛后血乳酸分别为33.9±8.29mg%和21.64±6.96mg%(P相似文献   

7.
    

[Purpose]

The purpose of this study is to examine that not only the relationship of the resting metabolic rate (RMR) and cardiorespiratory fitness(VO2peak), but also the comparison between measured and predicted results of RMR in obese men.

[Methods]

60 obese men (body fat>32%) were recruited for this study. They did not participate in regular exercising programs at least 6 months. The RMR was measured with indirect calorimetry and predicted RMR using Herris-Benedicte equation. The cardiorespiratory fitness was determined by directly measuring the oxygen consumption (VO2peak) during the exercise on the treadmill.

[Results]

The significance for the difference between the measured results and predicted result of RMR were tested by paired t-test. Correlation of measured date was obtained by Pearson correlation coefficient. The value of predicted RMR and measured RMR were significantly different in these obese subjects. (p < 0.001). The difference between RMR cardiorespiratory fitness and cardiorespiratory fitness showed significant correlation (r=0.67, p < 0.05).

[Conclusion]

The current formulas of predicted RMR have limited the evaluation of measured RMR for Korean obese men. Therefore, this study suggests that new formula should be designed for Korean in order to obtain more accurate results in obese.  相似文献   

8.
Bioavailability of engineered metal nanoparticles affects uptake in plants, impacts on ecosystems, and phytoremediation. We studied uptake and translocation of Ti in plants when the main source of this metal was TiO2 nanoparticles. Two crops (Phaseolus vulgaris (bean) and Triticum aestivum (wheat)), a wetland species (Rumex crispus, curly dock), and the floating aquatic plant (Elodea canadensis, Canadian waterweed), were grown in nutrient solutions with TiO2 nanoparticles (0, 6, 18 mmol Ti L?1 for P. vulgaris, T. aestivum, and R. crispus; and 0 and 12 mmol Ti L?1 for E. canadensis). Also examined in E. canadensis was the influence of TiO2 nanoparticles upon the uptake of Fe, Mn, and Mg, and the influence of P on Ti uptake. For the rooted plants, exposure to TiO2 nanoparticles did not affect biomass production, but significantly increased root Ti sorption and uptake. R. crispus showed translocation of Ti into the shoots. E. canadensis also showed significant uptake of Ti, P in the nutrient solution significantly decreased Ti uptake, and the uptake patterns of Mn and Mg were altered. Ti from nano-Ti was bioavailable to plants, thus showing the potential for cycling in ecosystems and for phytoremediation, particularly where water is the main carrier.  相似文献   

9.
The association between impairment in mitochondrial muscle fat oxidative capacity (OXFA) and occurrence of insulin resistance was examined in 14 healthy trained men (age, 24 ± 4 yr) submitted to 4 weeks of training cessation. Training stop induced a significant decrease in mRNA levels of proteins involved in muscle fat metabolism, particularly PPARα (−58%, P < 0.01) and PGC-1α (−30%, P < 0.05), a 21% reduction in OXFA (P < 0.01), and reduced fat oxidation during moderately intense exercise (P < 0.05). In contrast, there was no significant alteration in insulin sensitivity. In conclusion, decline in OXFA is a rapid metabolic event following training cessation. It is involved in the regulation of whole body fat balance but not in the deterioration of insulin sensitivity.  相似文献   

10.
11.
Saiki C  Miura A  Furuya H  Matsumoto S 《Life sciences》2007,80(13):1206-1212
This study was designed to examine how systemic administration of an N-methyl-d-aspartate (NMDA) receptor antagonist, MK-801, altered respiratory timing in unanesthetized rats under normoxia and hypoxia. To detect fine changes in inspiratory time (TI) and expiratory time (TE), and cycle duration (TTOT), we prepared a diaphragmatic electromyogram (EMGdia). Diaphragm electrodes and arterial and venous catheters were inserted into Wistar rats (n = 8) under pentobarbital anesthesia. The next day, EMGdia was recorded before and after intravenous administration of MK-801 (3 mg/kg) under normoxia and hypoxia (12% O2) without anesthesia, and the respiratory timing (TI, TE, TTOT), respiratory frequency (fR), and amplitude of the integrated EMGdia were measured. Arterial blood gases (ABGs), mean arterial pressure (MAP), and heart rate (fH) were also measured with the EMGdia. Under normoxia, MK-801 increased fR owing to a significant decrease in TE, and elevated both MAP and fH. Under hypoxia, MK-801 suppressed an increase in fR owing to a significant increase in TI, and did not accelerate fH. In both gaseous conditions, on ABGs, MK-801 did not alter partial pressure of O2 (PaO2) or CO2 (PaCO2), and slightly decreased pH (but not less than 7.4). MK-801 significantly decreased hypoxic response (%change from normoxia) in fR, and increased that in EMGdia amplitude, and did not alter a total ventilatory index (fRxEMGdia amplitude). The results suggest that an NMDA receptor-mediated mechanism partially determines fR through significant alterations in respiratory timing, particularly in which the hypoxic ventilatory response was obtained in unanesthetized rats.  相似文献   

12.
As a consequence of the increasing importance of vegetables in the human diet, there is an interest in enhancing both the productivity and quality of vegetables. A number of factors, including plant genotype and environmental growing conditions, can impact the production and quality of vegetables. The objective of this study was to determine whether elevated CO2, salinity, or high light treatments assayed individually, or salinity or high light in combination with elevated CO2, increased biomass production and antioxidant capacity in two lettuce cultivars. Elevated CO2 and its combination with salinity or high light increased biomass production in both cultivars, while high light treatment alone increased production in green-leaf lettuce but not in red-leaf lettuce. On the other hand, elevated CO2 and its combination with salinity or high light increased the antioxidant capacity of both cultivars, while high light treatment alone increased the antioxidant capacity of red-leaf lettuce, but not of green-leaf lettuce.  相似文献   

13.
Environmental constraints disturb plant metabolism and are often associated with photosynthetic impairments and yield reductions. Among them, low positive temperatures are of up most importance in tropical plant species, namely in Coffea spp. in which some acclimation ability has been reported. To further explain cold tolerance, the impacts on photosynthetic functioning and the expression of photosynthetic-related genes were analyzed. The experiments were carried out along a period of slow cold imposition (to allow acclimation), after chilling (4 °C) exposure and in the following rewarming period, using 1.5-year-old coffee seedlings of 5 genotypes with different cold sensitivity: Coffea canephora cv. Apoatã, Coffea arabica cv. Catuaí, Coffea dewevrei and 2 hybrids, Icatu (C. arabica × C. canephora) and Piatã (C. dewevrei × C. arabica). All genotypes suffered a significant leaf area loss only after chilling exposure, with Icatu showing the lowest impact, a first indication of a higher cold tolerance, contrasting with Apoatã and C. dewevrei. During cold exposure, net photosynthesis and Chl a fluorescence parameters were strongly affected in all genotypes, but stomatal limitations were not detected. However, the extent of mesophyll limitation, reflecting regulatory mechanisms and/or damage, was genotype dependent. Overnight retention of zeaxanthin was common to Coffea genotypes, but the accumulation of photoprotective pigments was highest in Icatu. That down-regulated photochemical events but efficiently protected the photosynthetic structures, as shown, e.g., by the lowest impacts on Amax and PSI activity and the strongest reinforcement of PSII activity, the latter possibly reflecting the presence of a photoprotective cycle around PSII in Icatu (and Catuaí). Concomitant to these protection mechanisms, Icatu was the sole genotype to present simultaneous upregulation of caCP22, caPI and caCytf, related to, respectively, PSII, PSI and to the complex Cytb6/f, which could promote better repair ability, contributing to the maintenance of efficient thylakoid functioning. We conclude that Icatu showed the best acclimation ability among the studied genotypes, mostly due to a better upregulation of photoprotection and repair mechanisms. We confirmed the presence of important variability in Coffea spp. that could be exploited in breeding programs, which should be assisted by useful markers of cold tolerance, namely the upregulation of antioxidative molecules, the expression of selected genes and PSI sensitivity.  相似文献   

14.
The objective of this study was to determine the response of nitrogen metabolism to drought and recovery upon rewatering in barley (Hordeum vulgare L.) plants under ambient (350 μmol mol−1) and elevated (700 μmol mol−1) CO2 conditions. Barley plants of the cv. Iranis were subjected to drought stress for 9, 13, or 16 days. The effects of drought under each CO2 condition were analysed at the end of each drought period, and recovery was analysed 3 days after rewatering 13-day droughted plants. Soil and plant water status, protein content, maximum (NRmax) and actual (NRact) nitrate reductase, glutamine synthetase (GS), and aminant (NADH-GDH) and deaminant (NAD-GDH) glutamate dehydrogenase activities were analysed. Elevated CO2 concentration led to reduced water consumption, delayed onset of drought stress, and improved plant water status. Moreover, in irrigated plants, elevated CO2 produced marked changes in plant nitrogen metabolism. Nitrate reduction and ammonia assimilation were higher at elevated than at ambient CO2, which in turn yielded higher protein content. Droughted plants showed changes in water status and in foliar nitrogen metabolism. Leaf water potential (Ψw) and nitrogen assimilation rates decreased after the onset of water deprivation. NRact and NRmax activity declined rapidly in response to drought. Similarly, drought decreased GS whereas NAD-GDH rose. Moreover, protein content fell dramatically in parallel with decreased leaf Ψw. In contrast, elevated CO2 reduced the water stress effect on both nitrate reduction and ammonia assimilation coincident with a less-steep decrease in Ψw. On the other hand, Ψw practically reached control levels after 3 days of rewatering. In parallel with the recovery of plant water status, nitrogen metabolism was also restored. Thus, both NRact and NRmax activities were restored to about 75-90% of control levels when water supply was restored; the GS activity reached 80-90% of control values; and GDH activities and protein content were similar to those of control plants. The recovery was always faster and slightly higher in plants grown under elevated CO2 conditions compared to those grown in ambient CO2, but midday Ψw dropped to similar values under both CO2 conditions. The results suggest that elevated CO2 improves nitrogen metabolism in droughted plants by maintaining better water status and enhanced photosynthesis performance, allowing superior nitrate reduction and ammonia assimilation. Ultimately, elevated CO2 mitigates many of the effects of drought on nitrogen metabolism and allows more rapid recovery following water stress.  相似文献   

15.
Short-lived neutrophils play a predominant role in innate immunity, the effects of exercise training on neutrophil survival is unclear. In this study, we investigated the underlying mechanisms of training effects on human neutrophil apoptosis. Healthy male subjects were trained on a cycling ergometer for 8 weeks and followed by 4 weeks of detraining. Blood neutrophils were collected before exercise, after training, and after detraining. Comparing with pre-exercise specimens, neutrophils collected after training showed reduced apoptosis rate, which partially returned after detraining. Various intracellular proteins, including iNOS, Mcl-1, A1, Grp78, and IL-8, were upregulated by training, and they remained high after detraining. Upregulated iNOS was closely correlated with these anti-apoptotic molecules in neutrophils. Furthermore, the possible mechanism by which iNOS suppressed apoptosis was explored. Neutrophil apoptosis was accelerated by blocking and retarded by stimulating the endogenous iNOS activity. As an anti-apoptosis mediator of NO signaling, the Mcl-1 level dropped by depletion of the major NO downstream molecule cGMP and such loss of Mcl-1 was avoidable when supplying exogenous NO. Upon activation of NO-cGMP signaling, neutrophils held increased Mcl-1 expression and delayed apoptosis. Collectively, our results suggested that exercise training may retard neutrophil apoptosis by upregulating the iNOS-NO-cGMP-Mcl-1 pathway.  相似文献   

16.
Nitrate assimilation diminishes under water stress. This can augment the photorespiratory rate as a protection mechanism, increasing the ammonium concentration, which must be rapidly assimilated. We therefore examined the effect of moderate water stress in photorespiration and N assimilation, as possible tolerance mechanisms in cherry tomato. Five cherry tomato cultivars with different degrees of water stress tolerance were submitted to two water treatments: well-watered (100% FC) and water stress (50% FC). In the susceptible cultivars, nitrate assimilation declined but without stimulating photorespiration. Zarina, a stress-tolerant cultivar, showed increased activity of the main enzymes involved in photorespiration, together with greater assimilation of nitrates and of the resulting ammonium. This translates as higher concentrations of N as well as amino acids and proteins. We characterize these mechanisms in the cv. Zarina (tolerant) as essential to water stress tolerance, acting on N metabolism as well as helping to maintain or augment biomass.  相似文献   

17.
Antioxidants are compounds that can delay or inhibit lipid oxidation. The peroxidation of linoleic acid (LA) in the absence and presence of Cu(II) ion–ascorbate combinations was investigated in aerated and incubated emulsions at 37 °C and pH 7. LA peroxidation induced by copper(II)–ascorbic acid system followed first order kinetics with respect to hydroperoxides concentration. The extent of copper-initiated peroxide production in a LA system assayed by ferric thiocyanate method was used to determine possible antioxidant and prooxidant activities of the added flavonoids. The effects of three different flavonoids of similar structure, i.e. quercetin (QR), morin (MR) and catechin (CT), as potential antioxidant protectors were studied in the selected peroxidation system. The inhibitive order of flavonoids in the protection of LA peroxidation was: morin > catechin ≥ quercetin, i.e. agreeing with that of formal reduction potentials versus NHE at pH 7, i.e. 0.60, 0.57 and 0.33 V for MR, CT, and QR, respectively. Morin showed antioxidant effect at all concentrations whereas catechin and quercetin showed both antioxidant and prooxidant effects depending on their concentrations. The structural requirements for antioxidant activity in flavonoids interestingly coincide with those for Cu(II)-induced prooxidant activity, because as the reducing power of a flavonoid increases, Cu(II)–Cu(I) reduction is facilitated that may end up with the production of reactive species. The findings of this study were evaluated in the light of structure–activity relationships of flavonoids, and the results are believed to be useful to better understand the actual conditions where flavonoids may act as prooxidants in the preservation of heterogeneous food samples containing traces of transition metal ions.  相似文献   

18.
19.
The cariogenic bacterium Streptococcus mutans is an important dental pathogen that forms biofilms on tooth surfaces, which provide a protective niche for the bacterium where it secretes organic acids leading to the demineralization of tooth enamel. Lipids, especially glycolipids are likely to be key components of these biofilm matrices. The UA159 strain of S. mutans was among the earliest microorganisms to have its genome sequenced. While the lipids of other S. mutans strains have been identified and characterized, lipid analyses of UA159 have been limited to a few studies on its fatty acids. Here we report the structures of the four major glycolipids from stationary-phase S. mutans UA159 cells grown in standing cultures. These were shown to be monoglucosyldiacylglycerol (MGDAG), diglucosyldiacylglycerol (DGDAG), diglucosylmonoacylglycerol (DGMAG) and, glycerophosphoryldiglucosyldiacylglycerol (GPDGDAG). The structures were determined by high performance thin-layer chromatography, mass spectrometry and nuclear magnetic resonance spectroscopy. The glycolipids were identified by accurate, high resolution, and tandem mass spectrometry. The identities of the sugar units in the glycolipids were determined by a novel and highly efficient NMR method. All sugars were shown to have α-glycosidic linkages and DGMAG was shown to be acylated in the sn-1 position by NMR. This is the first observation of unsubstituted DGMAG in any organism and the first mass spectrometry data for GPDGDAG.  相似文献   

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