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1.
A positive relationship between running economy and maximal oxygen uptake (V̇O2max) has been postulated in trained athletes, but previous evidence is equivocal and could have been confounded by statistical artefacts. Whether this relationship is preserved in response to running training (changes in running economy and V̇O2max) has yet to be explored. This study examined the relationships of (i) running economy and V̇O2max between runners, and (ii) the changes in running economy and V̇O2max that occur within runners in response to habitual training. 168 trained distance runners (males, n = 98, V̇O2max 73.0 ± 6.3 mL∙kg-1∙min-1; females, n = 70, V̇O2max 65.2 ± 5.9 mL kg-1∙min-1) performed a discontinuous submaximal running test to determine running economy (kcal∙km-1). A continuous incremental treadmill running test to volitional exhaustion was used to determine V̇O2max 54 participants (males, n = 27; females, n = 27) also completed at least one follow up assessment. Partial correlation analysis revealed small positive relationships between running economy and V̇O2max (males r = 0.26, females r = 0.25; P<0.006), in addition to moderate positive relationships between the changes in running economy and V̇O2max in response to habitual training (r = 0.35; P<0.001). In conclusion, the current investigation demonstrates that only a small to moderate relationship exists between running economy and V̇O2max in highly trained distance runners. With >85% of the variance in these parameters unexplained by this relationship, these findings reaffirm that running economy and V̇O2max are primarily determined independently.  相似文献   

2.
Ecto-5′-nucleotidase or CD73 is the main source of extracellular adenosine involved in the activation of adenosine A2A receptors, responsible for the ergogenic effects of caffeine. We now investigated the role of CD73 in exercise by comparing female wild-type (WT) and CD73 knockout (KO) mice in a treadmill-graded test to evaluate running power, oxygen uptake (V̇O2), and respiratory exchange ratio (RER) — the gold standards characterizing physical performance. Spontaneous locomotion in the open field and submaximal running power and V̇O2 in the treadmill were similar between CD73-KO and WT mice; V̇O2max also demonstrated equivalent aerobic power, but CD73-KO mice displayed a 43.7 ± 4.2% larger critical power (large effect size, P < 0.05) and 3.8 ± 0.4% increase of maximum RER (small effect size, P < 0.05). Thus, KO of CD73 was ergogenic; i.e., it increased physical performance.  相似文献   

3.
This study compared resting and exercise heat/hypoxic stress-induced levels of plasma extracellular heat shock protein 70 (eHSP70) in humans using two commercially available enzyme-linked immunosorbent assay (ELIS)A kits. EDTA plasma samples were collected from 21 males during two separate investigations. Participants in part A completed a 60-min treadmill run in the heat (HOT70; 33.0 ± 0.1 °C, 28.7 ± 0.8 %, n = 6) at 70 % V̇O2max. Participants in part B completed 60 min of cycling exercise at 50 % V̇O2max in either hot (HOT50; 40.5 °C, 25.4 relative humidity (RH)%, n = 7) or hypoxic (HYP50; fraction of inspired oxygen (FIO2) = 0.14, 21 °C, 35 % RH, n = 8) conditions. Samples were collected prior to and immediately upon termination of exercise and analysed for eHSP70 using EKS-715 high-sensitivity HSP70 ELISA and new ENZ-KIT-101 Amp’d™ HSP70 high-sensitivity ELISA. ENZ-KIT was superior in detecting resting eHSP70 (1.54 ± 3.27 ng·mL−1; range 0.08 to 14.01 ng·mL−1), with concentrations obtained from 100 % of samples compared to 19 % with EKS-715 assay. The ENZ-KIT requires optimisation prior to running samples in order to ensure participants fall within the standard curve, a step not required with EKS-715. Using ENZ-KIT, a 1:4 dilution allowed for quantification of resting HSP70 in 26/32 samples, with a 1:8 (n = 3) and 1:16 (n = 3) dilution required to determine the remaining samples. After exercise, eHSP70 was detected in 6/21 and 21/21 samples using EKS-715 and ENZ-KIT, respectively. eHSP70 was increased from rest after HOT70 (p < 0.05), but not HOT50 (p > 0.05) or HYP50 (p > 0.05) when analysed using ENZ-KIT. It is recommended that future studies requiring the precise determination of resting plasma eHSP70 use the ENZ-KIT (i.e. HSP70 Amp’d® ELISA) instead of the EKS-715 assay, despite additional assay development time and cost required.  相似文献   

4.

Background

Despite the widely accepted health benefits of regular physical activity, only a small percentage of the population meets the current recommendations. The reasons include a wide use of technology and a lack of enjoyment while exercising. The purpose of this study was to compare the physiological, perceptual and enjoyment responses between a single bout of (I) conventional cycling and (II) interactive cycling video game at a matched workload.

Methods

A cross-sectional study in 34 healthy participants was performed. Initially, participants completed an incremental maximal cycling test to measure peak oxygen uptake and to determine ventilatory threshold. In random order, participants carried out a 30 min interactive cycling trial and a 30 min conventional cycling trial at 55% of peak power output. During the trials, oxygen uptake and energy expenditure were measured by open-circuit spirometry and heart rate was measured by radiotelemetry. RPE and enjoyment were measured every 10 minutes with Borg scale and a modified PACES scale.

Results

Interactive cycling resulted in a significantly greater %V̇O2Reserve (68.2% ± 9.2% vs 64.7% ± 8.1%), rate of energy expenditure (505.8±75.2 vs 487.4±81.2 j·kg-1·min-1), and enjoyment (63.4% ± 17 vs 42% ± 13.6), P&lt;0.05. Participants were working at a higher intensity in relation to the individual’s ventilatory threshold during the interactive cycling video game trial (M = 11.86, SE = 3.08) than during the Conventional cycling trial (M = 7.55, SE = 3.16, t(33) = -2.69, P&lt;0.05, r = .42). No significant differences were found for heart rate reserve (72.5 ± 10.4 vs 71.4±10.1%) and RPE (13.1 ± 1.8 vs 13.2 ± 1.7).

Conclusion

Interactive cycling games can be a valid alternative to conventional exercise as they result in a higher exercise intensity than conventional cycling and a distraction from aversive cognitive and physiological states at and above the ventilatory threshold.  相似文献   

5.
This study aimed to compare the effects of 8-week self-paced high-intensity interval training (HIIT) vs. self-paced moderate-intensity continuous training (MICT) on the physical performance and psychophysiological responses of young adults. Twenty-eight recreationally active young adults (age: 21.1 ± 1.6 years) were randomly assigned to either the self-paced HIIT (n = 14) or the MICT (n = 14) group training protocol. The HIIT consisted of two 12–24 x 30 seconds of high-intensity runs interspersed by 30 seconds of recovery. The MICT completed 24–48 minutes of continuous running. Before and after the 8-week interventions the following tests were completed: maximum oxygen consumption (V̇O2max) estimated from the Yo-Yo Intermittent Recovery Test level 1 (YYIRTL-1), repeated sprint ability (RSA), 10–30-m sprint test, change of direction test (T-drill), countermovement jump (CMJ) and squat jump (SJ), and triple hop distance test (THD). Training rating of perceived exertion (RPE) and physical activity enjoyment scale (PACES) were assessed during the training programme. The HIIT resulted in greater improvement in YYIRTL-1, V̇O2max, RSA and T-drill performances compared to the MICT. Furthermore, RPE and PACES values were higher in the HIIT than the MICT. This study suggested that self-paced HIIT may be a more effective training regime to improve aerobic fitness with greater physical enjoyment in recreationally active young adults.  相似文献   

6.
This article presents the biochemical intra-skeletal-muscle basis of exercise intensity domains: moderate (M), heavy (H), very heavy (VH) and severe (S). Threshold origins are mediated by a ‘Pi double-threshold’ mechanism of muscle fatigue, which assumes (1) additional ATP usage, underlying muscle V̇O2 and metabolite slow components, is initiated when inorganic phosphate (Pi) exceeds a critical value (Picrit); (2) exercise is terminated because of fatigue, when Pi reaches a peak value (Pipeak); and (3) the Pi increase and additional ATP usage increase mutually stimulate each other forming a positive feedback. M/H and H/VH borders are defined by Pi on-kinetics in relation to Picrit and Pipeak. The values of the ATP usage activity, proportional to power output (PO), for the M/H, H/VH and VH/S borders are lowest in untrained muscle and highest in well-trained muscle. The metabolic range between the M/H and H/VH border (or ‘H space’) decreases with muscle training, while the difference between the H/VH and VH/S border (or ‘VH space’) is only weakly dependent on training status. The absolute magnitude of the muscle V̇O2 slow-component, absent in M exercise, rises gradually with PO to a maximal value in H exercise, and then decreases with PO in VH and S exercise. Simulations of untrained, physically active and well-trained muscle demonstrate that the muscle M/H border need not be identical to the whole-body M/H border determined from pulmonary V̇O2 on-kinetics and blood lactate, while suggesting that the biochemical origins of the H/VH border reside within skeletal muscle and correspond to whole-body critical power.  相似文献   

7.
The generation of reactive nitrogen/oxygen species (RN/OS) represents an important mechanism in erythropoietin (EPO) expression and skeletal muscle adaptation to physical and metabolic stress. RN/OS generation can be modulated by intense exercise and nutrition supplements such as α-lipoic acid, which demonstrates both anti- and pro-oxidative action. The study was designed to show the changes in the haematological response through the combination of α-lipoic acid intake with running eccentric exercise. Sixteen healthy young males participated in the randomised and placebo-controlled study. The exercise trial involved a 90-min run followed by a 15-min eccentric phase at 65% VO2max (-10% gradient). It significantly increased serum concentrations of nitric oxide (NO), hydrogen peroxide (H2O2) and pro-oxidative products such as 8-isoprostanes (8-iso), lipid peroxides (LPO) and protein carbonyls (PC). α-Lipoic acid intake (Thiogamma: 1200 mg daily for 10 days prior to exercise) resulted in a 2-fold elevation of serum H2O2 concentration before exercise, but it prevented the generation of NO, 8-iso, LPO and PC at 20 min, 24 h, and 48 h after exercise. α-Lipoic acid also elevated serum EPO level, which highly correlated with NO/H2O2 ratio (r = 0.718, P < 0.01). Serum total creatine kinase (CK) activity, as a marker of muscle damage, reached a peak at 24 h after exercise (placebo 732 ± 207 IU · L-1, α-lipoic acid 481 ± 103 IU · L-1), and correlated with EPO (r = 0.478, P < 0.01) in the α-lipoic acid group. In conclusion, the intake of high α-lipoic acid modulates RN/OS generation, enhances EPO release and reduces muscle damage after running eccentric exercise.  相似文献   

8.
In order to better understand the specificity of training adaptations, we compared the effects of two different anaerobic training regimes on various types of soccer-related exercise performances. During the last 3 weeks of the competitive season, thirteen young male professional soccer players (age 18.5±1 yr, height 179.5±6.5 cm, body mass 74.3±6.5 kg) reduced the training volume by ~20% and replaced their habitual fitness conditioning work with either speed endurance production (SEP; n = 6) or speed endurance maintenance (SEM; n = 7) training, three times per wk. SEP training consisted of 6–8 reps of 20-s all-out running bouts followed by 2 min of passive recovery, whereas SEM training was characterized by 6–8 x 20-s all-out efforts interspersed with 40 s of passive recovery. SEP training reduced (p<0.01) the total time in a repeated sprint ability test (RSAt) by 2.5%. SEM training improved the 200-m sprint performance (from 26.59±0.70 to 26.02±0.62 s, p<0.01) and had a likely beneficial impact on the percentage decrement score of the RSA test (from 4.07±1.28 to 3.55±1.01%) but induced a very likely impairment in RSAt (from 83.81±2.37 to 84.65±2.27 s). The distance covered in the Yo-Yo Intermittent Recovery test level 2 was 10.1% (p<0.001) and 3.8% (p<0.05) higher after SEP and SEM training, respectively, with possibly greater improvements following SEP compared to SEM. No differences were observed in the 20- and 40-m sprint performances. In conclusion, these two training strategies target different determinants of soccer-related physical performance. SEP improved repeated sprint and high-intensity intermittent exercise performance, whereas SEM increased muscles’ ability to maximize fatigue tolerance and maintain speed development during both repeated all-out and continuous short-duration maximal exercises. These results provide new insight into the precise nature of a stimulus necessary to improve specific types of athletic performance in trained young soccer players.  相似文献   

9.

Aim

Our study aimed to investigate changes of different markers for routine assessment of fatigue and recovery in response to high-intensity interval training (HIIT).

Methods

22 well-trained male and female team sport athletes (age, 23.0 ± 2.7 years; V̇O2max, 57.6 ± 8.6 mL·min·kg−1) participated in a six-day running-based HIIT-microcycle with a total of eleven HIIT sessions. Repeated sprint ability (RSA; criterion measure of fatigue and recovery), countermovement jump (CMJ) height, jump efficiency in a multiple rebound jump test (MRJ), 20-m sprint performance, muscle contractile properties, serum concentrations of creatinkinase (CK), c-reactive protein (CRP) and urea as well as perceived muscle soreness (DOMS) were measured pre and post the training program as well as after 72 h of recovery.

Results

Following the microcycle significant changes (p < 0.05) in RSA as well as in CMJ and MRJ performance could be observed, showing a decline (%Δ ± 90% confidence limits, ES = effect size; RSA: -3.8 ± 1.0, ES = -1.51; CMJ: 8.4 ± 2.9, ES = -1.35; MRJ: 17.4 ± 4.5, ES = -1.60) and a return to baseline level (RSA: 2.8 ± 2.6, ES = 0.53; CMJ: 4.1 ± 2.9, ES = 0.68; MRJ: 6.5 ± 4.5, ES = 0.63) after 72 h of recovery. Athletes also demonstrated significant changes (p < 0.05) in muscle contractile properties, CK, and DOMS following the training program and after the recovery period. In contrast, CRP and urea remained unchanged throughout the study. Further analysis revealed that the accuracy of markers for assessment of fatigue and recovery in comparison to RSA derived from a contingency table was insufficient. Multiple regression analysis also showed no correlations between changes in RSA and any of the markers.

Conclusions

Mean changes in measures of neuromuscular function, CK and DOMS are related to HIIT induced fatigue and subsequent recovery. However, low accuracy of a single or combined use of these markers requires the verification of their applicability on an individual basis.  相似文献   

10.
The purpose of this study was to determine both the independent and additive effects of prior heavy-intensity exercise and pacing strategies on the VO2 kinetics and performance during high-intensity exercise. Fourteen endurance cyclists (VO2max  = 62.8±8.5 mL.kg−1.min−1) volunteered to participate in the present study with the following protocols: 1) incremental test to determine lactate threshold and VO2max; 2) four maximal constant-load tests to estimate critical power; 3) six bouts of exercise, using a fast-start (FS), even-start (ES) or slow-start (SS) pacing strategy, with and without a preceding heavy-intensity exercise session (i.e., 90% critical power). In all conditions, the subjects completed an all-out sprint during the final 60 s of the test as a measure of the performance. For the control condition, the mean response time was significantly shorter (p<0.001) for FS (27±4 s) than for ES (32±5 s) and SS (32±6 s). After the prior exercise, the mean response time was not significantly different among the paced conditions (FS = 24±5 s; ES = 25±5 s; SS = 26±5 s). The end-sprint performance (i.e., mean power output) was only improved (∼3.2%, p<0.01) by prior exercise. Thus, in trained endurance cyclists, an FS pacing strategy does not magnify the positive effects of priming exercise on the overall VO2 kinetics and short-term high-intensity performance.  相似文献   

11.
To investigate the changes in the reflectance of human cone photoreceptors by an adaptive optics scanning laser ophthalmoscope (AO-SLO) during photobleaching. A custom-built AO-SLO with an observation light of 840-nm was used to measure the cone densities and the reflectance changes during bleaching by 630 nm red light emitting diodes. Measurements were made at 1° and 3° temporal to the fovea within an area of 1° × 1° in 8 eyes of 8 normal subjects. After dark-adaptation, images of the cone mosaics were recorded continuously for 5-min before, 5-min during, and after 5-min of light stimulation with a sampling rate of 5-Hz. The first positive peak (P1) was observed at 72.2 ± 15.0-s and a second positive peak (P2) at 257.5 ± 34.5-s at 1°. The increase of the reflectance of P1 was significantly larger at 1° (34.4 ± 13.9%) than at 3° (26.0 ± 10.5%; P = 0.03, Wilcoxon’s signed rank test). The average cone density at 1° (51123.13 ± 1401.23 cells/mm2) was significantly larger than that at 3° (30876.13 ± 1459.28 cells/mm2; P <0.001, Wilcoxon’s signed rank test). The changes in the reflectance of the cones during bleaching by red light had two peaks. The two peaks may be caused by regeneration of cone photopigment during bleaching.  相似文献   

12.
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   

13.

Purpose

The purpose of the current study was to investigate the effects of adding strength training to normal endurance training on running performance and running economy in well-trained female athletes. We hypothesized that the added strength training would improve performance and running economy through altered stiffness of the muscle-tendon complex of leg extensors.

Methods

Nineteen female endurance athletes [maximal oxygen consumption (VO2max): 53±3 ml∙kg-1∙min-1, 5.8 h weekly endurance training] were randomly assigned to either normal endurance training (E, n = 8) or normal endurance training combined with strength training (E+S, n = 11). The strength training consisted of four leg exercises [3 x 4–10 repetition maximum (RM)], twice a week for 11 weeks. Muscle strength, 40 min all-out running distance, running performance determinants and patellar tendon stiffness were measured before and after the intervention.

Results

E+S increased 1RM in leg exercises (40 ± 15%) and maximal jumping height in counter movement jump (6 ± 6%) and squat jump (9 ± 7%, p < 0.05). This was accompanied by increased muscle fiber cross sectional area of both fiber type I (13 ± 7%) and fiber type II (31 ± 20%) in m. vastus lateralis (p < 0.05), with no change in capillary density in m. vastus lateralis or the stiffness of the patellar tendon. Neither E+S nor E changed running economy, fractional utilization of VO2max or VO2max. There were also no change in running distance during a 40 min all-out running test in neither of the groups.

Conclusion

Adding heavy strength training to endurance training did not affect 40 min all-out running performance or running economy compared to endurance training only.  相似文献   

14.
Here, we evaluated the influence of breathing oxygen at different partial pressures during recovery from exercise on performance at sea-level and a simulated altitude of 1800 m, as reflected in activation of different upper body muscles, and oxygenation of the m. triceps brachii. Ten well-trained, male endurance athletes (25.3±4.1 yrs; 179.2±4.5 cm; 74.2±3.4 kg) performed four test trials, each involving three 3-min sessions on a double-poling ergometer with 3-min intervals of recovery. One trial was conducted entirely under normoxic (No) and another under hypoxic conditions (Ho; FiO2 = 0.165). In the third and fourth trials, the exercise was performed in normoxia and hypoxia, respectively, with hyperoxic recovery (HOX; FiO2 = 1.00) in both cases. Arterial hemoglobin saturation was higher under the two HOX conditions than without HOX (p<0.05). Integrated muscle electrical activity was not influenced by the oxygen content (best d = 0.51). Furthermore, the only difference in tissue saturation index measured via near-infrared spectroscopy observed was between the recovery periods during the NoNo and HoHOX interventions (P<0.05, d = 0.93). In the case of HoHo the athletes’ Pmean declined from the first to the third interval (P < 0.05), whereas Pmean was unaltered under the HoHOX, NoHOX and NoNo conditions. We conclude that the less pronounced decline in Pmean during 3 x 3-min double-poling sprints in normoxia and hypoxia with hyperoxic recovery is not related to changes in muscle activity or oxygenation. Moreover, we conclude that hyperoxia (FiO2 = 1.00) used in conjunction with hypoxic or normoxic work intervals may serve as an effective aid when inhaled during the subsequent recovery intervals.  相似文献   

15.
In this study we have examined the effect of prolonged endurance training program on the pulmonary oxygen uptake (V’O2) kinetics during heavy-intensity cycling-exercise and its impact on maximal cycling and running performance. Twelve healthy, physically active men (mean±SD: age 22.33±1.44 years, V’O2peak 3198±458 mL ∙ min-1) performed an endurance training composed mainly of moderate-intensity cycling, lasting 20 weeks. Training resulted in a decrease (by ~5%, P = 0.027) in V’O2 during prior low-intensity exercise (20 W) and in shortening of τp of the V’O2 on-kinetics (30.1±5.9 s vs. 25.4±1.5 s, P = 0.007) during subsequent heavy-intensity cycling. This was accompanied by a decrease of the slow component of V’O2 on-kinetics by 49% (P = 0.001) and a decrease in the end-exercise V’O2 by ~5% (P = 0.005). An increase (P = 0.02) in the vascular endothelial growth factor receptor 2 mRNA level and a tendency (P = 0.06) to higher capillary-to-fiber ratio in the vastus lateralis muscle were found after training (n = 11). No significant effect of training on the V’O2peak was found (P = 0.12). However, the power output reached at the lactate threshold increased by 19% (P = 0.01). The power output obtained at the V’O2peak increased by 14% (P = 0.003) and the time of 1,500-m performance decreased by 5% (P = 0.001). Computer modeling of the skeletal muscle bioenergetic system suggests that the training-induced decrease in the slow component of V’O2 on-kinetics found in the present study is mainly caused by two factors: an intensification of the each-step activation (ESA) of oxidative phosphorylation (OXPHOS) complexes after training and decrease in the ‘‘additional” ATP usage rising gradually during heavy-intensity exercise.  相似文献   

16.
Sustained aerobic exercise not only affects the rate of force development but also decreases peak power development. The aim of this study was to investigate whether anaerobic power of amateur mountain bikers changes during the first half of the competition season. Eight trained cyclists (mean ± SE: age: 22.0 ±0.5 years; height: 174.6 ± 0.9 cm; weight: 70.7 ± 2.6 kg) were subjected to an ergocycle incremental exercise test and to the Wingate test on two occasions: before, and in the middle of the season. After the incremental exercise test the excess post-exercise oxygen consumption was measured during 5-min recovery. Blood lactate concentration was measured in the 4th min after the Wingate test. Maximum oxygen uptake increased from 60.0 ± 1.5 ml min-1 kg-1 at the beginning of the season to 65.2 ± 1.4 ml min-1 kg-1 (P < 0.05) in the season. Neither of the mechanical variables of the Wingate test nor excess post-exercise oxygen consumption values were significantly different in these two measurements. However, blood lactate concentration was significantly higher (P < 0.001) in season (11.0 ± 0.5 mM) than before the season (8.6 ± 0.4 mM). It is concluded that: 1) despite the increase of cyclists’ maximum oxygen uptake during the competition season their anaerobic power did not change; 2) blood lactate concentration measured at the 4th min after the Wingate test does not properly reflect training-induced changes in energy metabolism.  相似文献   

17.
The aim of this study was to assess the plasma adrenaline and noradrenaline concentrations as well as whole blood β2-adrenoceptor gene (ADRB2) expression in young ice hockey players before and immediately after exercise in relation to performed work. Nineteen Youth National Team ice hockey players were subjected to the maximal incremental cycloergometer exercise. The test was done in the pre-competitive phase of training. Among many parameters the plasma adrenaline and noradrenaline concentrations and ADRB2 gene expression in peripheral blood mononuclear cells (PBMC) were determined before and after exercise. The average performed work was 3261.3 ± 558.3 J · kg−1 and maximal oxygen consumption (VO2max) for all players was 53.85 ± 3.91 mL · kg−1 min−1. The geometric mean of the ADRB2 gene expression was statistically significantly different before and after exercise (P ≤ 0.05), while adrenaline and noradrenaline levels in plasma significantly increased after exercise. In the analysed group of athletes we found that initial level of plasma noradrenaline correlated with the performed work (r = - 0.55, P < 0.014) and normalized ADRB2 expression before the exercise correlated with the work done by them (r = 0.48, P<0.039). However, no statistically significant correlations were found between the plasma adrenaline or noradrenaline concentrations and ADRB2 gene expression in peripheral blood of the players. The performed work in the maximal incremental exercise test of regularly training young ice hockey players depends on the initial levels of noradrenaline in plasma and ADRB2 mRNA in PBMC.  相似文献   

18.

Background

Pulmonary hyperinflation has the potential for significant adverse effects on cardiovascular function in COPD. The aim of this study was to investigate the relationship between dynamic hyperinflation and cardiovascular response to maximal exercise in COPD patients.

Methods

We studied 48 patients (16F; age 68 yrs ± 8; BMI 26 ± 4) with COPD. All patients performed spirometry, plethysmography, lung diffusion capacity for carbon monoxide (TLco) measurement, and symptom-limited cardiopulmonary exercise test (CPET). The end-expiratory lung volume (EELV) was evaluated during the CPET. Cardiovascular response was assessed by change during exercise in oxygen pulse (ΔO2Pulse) and double product, i.e. the product of systolic blood pressure and heart rate (DP reserve), and by the oxygen uptake efficiency slope (OUES), i.e. the relation between oxygen uptake and ventilation.

Results

Patients with a peak exercise EELV (%TLC) ≥ 75% had a significantly lower resting FEV1/VC, FEF50/FIF50 ratio and IC/TLC ratio, when compared to patients with a peak exercise EELV (%TLC) < 75%. Dynamic hyperinflation was strictly associated to a poor cardiovascular response to exercise: EELV (%TLC) showed a negative correlation with ΔO2Pulse (r = - 0.476, p = 0.001), OUES (r = - 0.452, p = 0.001) and DP reserve (r = - 0.425, p = 0.004). Furthermore, according to the ROC curve method, ΔO2Pulse and DP reserve cut-off points which maximized sensitivity and specificity, with respect to a EELV (% TLC) value ≥ 75% as a threshold value, were ≤ 5.5 mL/bpm (0.640 sensitivity and 0.696 specificity) and ≤ 10,000 Hg · bpm (0.720 sensitivity and 0.783 specificity), respectively.

Conclusion

The present study shows that COPD patients with dynamic hyperinflation have a poor cardiovascular response to exercise. This finding supports the view that in COPD patients, dynamic hyperinflation may affect exercise performance not only by affecting ventilation, but also cardiac function.  相似文献   

19.
The aim of this study was to compare: i) the physiological and perceptual responses of low-load exercise [(moderate intensity exercise (MI)] with different levels of blood flow restriction (BFR), and ii) MI with BFR on the bike with high intensity (HI) exercise without BFR. The protocol involved large muscle mass exercise at different levels of BFR, and this differentiates our study from others. Twenty-one moderately trained males (age: 24.6 ± 2.4 years; VO2peak: 47.2 ± 7.0 ml.kg-1.min-1, mean ± sd) performed one maximal graded exercise test and seven 5-min constant-load cycling bouts. Six bouts were at MI [40% peak power (Ppeak), 60%VO2peak], one without BFR and five with different levels of BFR (40%, 50%, 60%, 70%, 80% of estimated arterial occlusion pressure). The HI bout (70%Ppeak, 90%VO2peak) was without BFR. Oxygen uptake (VO2), heart rate (HR), blood lactate (BLa), rate of perceived exertion (RPE), and tissue oxygen saturation (TSI) were recorded. Regardless of pressure, HR, BLa and RPE during MI-BFR were higher compared to MI (p < 0.05, ES: moderate to very large), and TSI reduction was greater in MI-BFR than MI (p < 0.05, ES: moderate to large). The responses of VO2, HR, BLa, RPE and TSI induced by the different levels of BFR in MI-BFR were similar. Regardless of pressure, the responses of VO2, HR, BLa and RPE induced by MI-BFR were lower than HI (p < 0.05), except for TSI. TSI change was similar between MI-BFR and HI. It appears that BFR equal to 40% of arterial occlusion pressure is sufficient to reduce TSI when exercising with a large muscle mass.  相似文献   

20.

Background/Aims

Resveratrol has been demonstrated to be protective in the cardiovascular system. The aim of this study was to assess the effects of resveratrol on hydrogen peroxide (H2O2)-induced increase in late sodium current (I Na.L) which augmented the reverse Na+-Ca2+ exchanger current (I NCX), and the diastolic intracellular Ca2+ concentration in ventricular myocytes.

Methods

I Na.L, I NCX, L-type Ca2+ current (I Ca.L) and intracellular Ca2+ properties were determined using whole-cell patch-clamp techniques and dual-excitation fluorescence photomultiplier system (IonOptix), respectively, in rabbit ventricular myocytes.

Results

Resveratrol (10, 20, 40 and 80 µM) decreased I Na.L in myocytes both in the absence and presence of H2O2 (300 µM) in a concentration dependent manner. Ranolazine (3–9 µM) and tetrodotoxin (TTX, 4 µM), I Na.L inhibitors, decreased I Na.L in cardiomyocytes in the presence of 300 µM H2O2. H2O2 (300 µM) increased the reverse I NCX and this increase was significantly attenuated by either 20 µM resveratrol or 4 µM ranolazine or 4 µM TTX. In addition, 10 µM resveratrol and 2 µM TTX significantly depressed the increase by 150 µM H2O2 of the diastolic intracellular Ca2+ fura-2 fluorescence intensity (FFI), fura-fluorescence intensity change (△FFI), maximal velocity of intracellular Ca2+ transient rise and decay. As expected, 2 µM TTX had no effect on I Ca.L.

Conclusion

Resveratrol protects the cardiomyocytes by inhibiting the H2O2-induced augmentation of I Na.L.and may contribute to the reduction of ischemia-induced lethal arrhythmias.  相似文献   

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