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1.
Joseph W. Duke Jonathon L. Stickford Joshua C. Weavil Robert F. Chapman Joel M. Stager Timothy D. Mickleborough 《European journal of applied physiology》2014,114(11):2387-2397
Introduction
Despite VO2peak being, generally, greater while running compared to cycling, ventilation (V E) during maximal exercise is less while running compared to cycling. Differences in operating lung volumes (OLV) between maximal running and cycling could be one explanation for previously observed differences in V E and this could be due to differences in body position e.g., trunk/hip angle during exercise.Purpose
We asked whether OLV differed between maximal running and cycling and if this difference was due to trunk/hip angle during exercise.Methods
Eighteen men performed three graded maximal exercise tests; one while running, one while cycling in the drop position (i.e., extreme hip flexion), and one while cycling upright (i.e., seated with thorax upright). Resting flow-volume characteristics were measured in each body position to be used during exercise. Tidal flow-volume loops were measured throughout the exercise.Results
V E during maximal running (148.8 ± 18.9 L min?1) tended to be lower than during cycling in the drop position (158.5 ± 24.7 L min?1; p = 0.07) and in the upright position (158.5 ± 23.7 L min?1; p = 0.06). End-inspiratory and end-expiratory lung volumes (EILV, EELV) were significantly larger during drop cycling compared to running (87.1 ± 4.1 and 35.8 ± 6.2 vs. 83.9 ± 6.0 and 33.0 ± 5.7 % FVC), but only EILV was larger during upright cycling compared to running (88.2 ± 3.5 % FVC). OLV and V E did not differ between cycling positions.Conclusion
Since OLV are altered by exercise mode, but cycling position did not have a significant impact on OLV, we conclude that trunk/hip angle is likely not the primary factor determining OLV during maximal exercise. 相似文献2.
Guido E. Pieles Gergely Szantho Jonathan C. L. Rodrigues Christopher B. Lawton A. Graham Stuart Chiara Bucciarelli-Ducci Mark S. Turner Craig A. Williams Robert M. R. Tulloh Mark C. K. Hamilton 《European journal of applied physiology》2014,114(5):1013-1023
Purpose
Increased oxygen uptake and utilisation during exercise depend on adequate adaptations of systemic and pulmonary vasculature. Recent advances in magnetic resonance imaging techniques allow for direct quantification of aortic and pulmonary blood flow using phase-contrast magnetic resonance angiography (PCMRA). This pilot study tested quantification of aortic and pulmonary haemodynamic adaptations to moderate aerobic supine leg exercise using PCMRA.Methods
Nine adult healthy volunteers underwent pulse gated free breathing PCMRA while performing heart rate targeted aerobic lower limb exercise. Flow was assessed in mid ascending and mid descending thoracic aorta (AO) and main pulmonary artery (MPA) during exercise at 180 % of individual resting heart rate. Flow sequence analysis was performed by experienced operators using commercial offline software (Argus, Siemens Medical Systems).Results
Exercise related increase in HR (rest: 69 ± 10 b min?1, exercise: 120 ± 13 b min?1) resulted in cardiac output increase (from 6.5 ± 1.4 to 12.5 ± 1.8 L min?1). At exercise, ascending aorta systolic peak velocity increased from 89 ± 14 to 122 ± 34 cm s?1 (p = 0.016), descending thoracic aorta systolic peak velocity increased from 104 ± 14 to 144 ± 33 cm s?1 (p = 0.004), MPA systolic peak velocity from 86 ± 18 to 140 ± 48 cm s?1 (p = 0.007), ascending aorta systolic peak flow rate from 415 ± 83 to 550 ± 135 mL s?1 (p = 0.002), descending thoracic aorta systolic peak flow rate from 264 ± 70 to 351 ± 82 mL s?1 (p = 0.004) and MPA systolic peak flow rate from 410 ± 80 to 577 ± 180 mL s?1 (p = 0.006).Conclusion
Quantitative blood flow and velocity analysis during exercise using PCMRA is feasible and detected a steep exercise flow and velocity increase in the aorta and MPA. Exercise PCMRA can serve as a research and clinical tool to help quantify exercise blood flow adaptations in health and disease and investigate patho-physiological mechanisms in cardio-pulmonary disease. 相似文献3.
Acute exercises induce disorders of the gastrointestinal integrity in a murine model 总被引:1,自引:0,他引:1
Katrin Gutekunst Karsten Krüger Christian August Martin Diener Frank-Christoph Mooren 《European journal of applied physiology》2014,114(3):609-617
Purpose
Many endurance athletes complain about gastrointestinal (GI) symptoms. It is assumed that exercise-induced shift of perfusion with consecutive hypoperfusion of the enteral vascular system leads to an increased GI permeability and tissue damage. Therefore, the aim of the study was to investigate permeability, apoptosis, electrogenic ion transport (Isc), and tissue conductance (Gt) of the small intestine in a murine exercise model.Methods
After spirometry, male Swiss CD-1 mice were subjected to an intensive treadmill exercise (80 % VO2max). Sedentary mice served as controls. The small intestine was removed at several time intervals post-exercise. Apoptotic cells were determined by the TUNEL method, while fluorescein isothiocyanate dextran permeation indicated intestinal permeability. The Gt and Isc measurements were carried out in a modified Ussing chamber.Results
Apoptosis of epithelial cells increased continuously until 24 h post exercise (0.8 ± 0.42 versus 39.2 ± 26.0 %; p < 0.05). Compared with the control group the permeability increased 2 h after exercise (0.47 ± 0.07 versus 0.67 ± 0.14 FU/min; p < 0.05). Isc measurements of the ileum were augmented after 24 h (3.33 ± 0.56 versus 5.77 ± 1.16 μEq/h/cm2; p < 0.05). At this time the Gt increased as well (28.8 ± 3.37 versus 32.5 ± 2.59 mS/cm2; p < 0.05).Conclusion
In the murine exercise model there is evidence that after intense endurance exercise repair processes occur in small intestinal epithelial cells, which affect permeability, Gt, and Isc. The formation of lamellipodia to close the “leaky” tight junctions caused by apoptosis might be an underlying mechanism. 相似文献4.
Benjamin Kelly James A. King Jonas Goerlach Myra A. Nimmo 《European journal of applied physiology》2013,113(12):3039-3047
Introduction
High-intensity intermittent exercise training (HIT) may favourably alter body composition despite low training volumes and predicted energy expenditure (EE).Purpose
To characterise the acute impact of two common HIT protocols on EE and post-exercise oxygen consumption (11 h EPOC).Methods
Oxygen consumption (l min?1), respiratory exchange ratio (RER) and EE were measured in nine healthy, lean males over 12 h under three conditions: control (CON), HIT1 (10 × 1 min high-intensity cycling bouts followed by 1 min rest) and HIT2 (10 × 4 min high-intensity cycling bouts followed by 2 min rest).Results
Total exercise period EE during HIT1 (1,151 ± 205 kJ) (mean ± SD) was significantly lower than HIT2 (2,788 ± 322 kJ; p < 0.001). EE within the 60 min after exercise was significantly albeit marginally higher after HIT1 (388 ± 44 kJ; p = 0.02) and HIT2 (389 ± 39 kJ; p = 0.01) compared with CON (329 ± 39 kJ), with no difference between exercise conditions (p = 0.778). RER during this period was significantly lower in HIT1 (0.78 ± 0.06; p = 0.011) and HIT2 (0.76 ± 0.04; p = 0.004) compared with CON (0.87 ± 0.06). During the ‘slow phase’ of EPOC (1.25–9.75 h), there were no significant differences in EE (p = 0.07) or RER (p = 0.173) between trials.Conclusions
Single HIT sessions notably increases EE during exertion; however, the influence on metabolic rate post-exercise is transient and relatively minor. 相似文献5.
Davinia Vicente-Campos Aurora Martín López María Jesús Nuñez Jose López Chicharro 《European journal of applied physiology》2014,114(6):1123-1128
Background
Despite a growing clinical interest in determining the heart rate recovery (HRR) response to exercise, the limits of a normal HRR have not yet been well established.Purpose
This study was designed to examine HRR following a controlled maximal exercise test in healthy, physically active adult men.Methods
The subjects recruited (n = 789) performed a maximal stress test on a treadmill. HRR indices were calculated by subtracting the first and third minute heart rates (HRs) during recovery from the maximal HR obtained during stress testing and designated these as HRR-1 and HRR-3, respectively. The relative change in HRR was determined as the decrease in HR produced at the time points 1 and 3 min after exercise as a percentage of the peak HR (%HRR-1/HRpeak and %HRR-3/HRpeak, respectively). Percentile values of HRR-1 and HRR-3 were generated for the study population.Results
Mean HHR-1 and HHR-3 were 15.24 ± 8.36 and 64.58 ± 12.17 bpm, respectively, and %HRR-1/HRpeak and %HRR-3/HRpeak were 8.60 ± 4.70 and 36.35 ± 6.79 %, respectively. Significant correlation was detected between Peak VO2 and HRR-3 (r = 0.36; p < 0.001) or %HRR-3/HRpeak (r = 0.23; p < 0.001).Conclusions
Our study provides normality data for HRR following a maximal Ergometry test obtained in a large population of physically active men. 相似文献6.
Keren Constantini Surendran Sabapathy Troy J. Cross 《European journal of applied physiology》2014,114(6):1153-1161
Purpose
Critical power (CP), and the finite capacity to perform work above CP (W′), can be determined using a 3-min “all-out” cycling test (3MT). This protocol requires two laboratory visits: an incremental exercise test, followed by a 3MT on a separate day. The purpose of this study was to establish whether an incremental exercise test and a 3MT performed during a single laboratory visit can be used to accurately determine CP and W′.Methods
Twelve participants completed two experimental protocols: (1) Combined protocol: an incremental exercise test followed by a 3MT, with 20 min of recovery between exercise bouts; and (2) Independent protocol: the conventional 3MT protocol, performed on a separate day.Results
CP determined from the Combined (254 ± 117 W) and Independent (256 ± 118 W) protocols were not different (p = 0.40). Similarly, W′ was not different (p = 0.96) between the Combined (13.7 ± 3.9 kJ) and Independent (13.7 ± 4.5 kJ) protocols. Linear regression revealed a strong level of measurement agreement between the protocols for CP and W′, evidenced by high R 2 values (≥0.85) and marginal standard errors of the estimates (CP = 5 W; W′ = 1.81 kJ).Conclusion
A Combined protocol, consisting of an incremental exercise test followed by a 3MT, provides an accurate and valid method to determine an individual’s CP and, to a lesser extent, W′. Furthermore, this protocol permits the measurement of the gas-exchange threshold and peak O2 uptake and, consequently, the moderate, heavy, and severe exercise-intensity domains may be defined within a single exercise-testing session. 相似文献7.
Andreas D. Flouris Andrea Bravi Heather E. Wright-Beatty Geoffrey Green Andrew J. Seely Glen P. Kenny 《European journal of applied physiology》2014,114(4):785-792
Purpose
We assessed the efficacy of different treatments (i.e., treatment with ice water immersion vs. natural recovery) and the effect of exercise intensities (i.e., low vs. high) for restoring heart rate variability (HRV) indices during recovery from exertional heat stress (EHS).Methods
Nine healthy adults (26 ± 3 years, 174.2 ± 3.8 cm, 74.6 ± 4.3 kg, 17.9 ± 2.8 % body fat, 57 ± 2 mL·kg·?1 min?1 peak oxygen uptake) completed four EHS sessions incorporating either walking (4.0–4.5 km·h?1, 2 % incline) or jogging (~7.0 km·h?1, 2 % incline) on a treadmill in a hot-dry environment (40 °C, 20–30 % relative humidity) while wearing a non-permeable rain poncho for a slow or fast rate of rectal temperature (T re) increase, respectively. Upon reaching a T re of 39.5 °C, participants recovered until T re returned to 38 °C either passively or with whole-body immersion in 2 °C water. A comprehensive panel of 93 HRV measures were computed from the time, frequency, time–frequency, scale-invariant, entropy and non-linear domains.Results
Exertional heat stress significantly affected 60/93 HRV measures analysed. Analyses during recovery demonstrated that there were no significant differences between HRV measures that had been influenced by EHS at the end of passive recovery vs. whole-body cooling treatment (p > 0.05). Nevertheless, the cooling treatment required statistically significantly less time to reduce T re (p < 0.001).Conclusions
While EHS has a marked effect on autonomic nervous system modulation and whole-body immersion in 2 °C water results in faster cooling, there were no observed differences in restoration of autonomic heart rate modulation as measured by HRV indices with whole-body cold-water immersion compared to passive recovery in thermoneutral conditions. 相似文献8.
M. Glaister John R. Pattison Bernadette Dancy Gillian McInnes 《European journal of applied physiology》2014,114(11):2447-2454
Purpose
The aims of this study were to evaluate the recovery kinetics of peak power output (PPO) following a maximal sprint, and to evaluate the influence of aerobic fitness on that recovery process.Methods
On separate occasions, 16 well-trained men (age: 21 ± 3 years; height: 1.84 ± 0.05 m; and body mass: 78.8 ± 7.8 kg) performed a 30 s maximal sprint on a cycle ergometer, followed by a predetermined stationary rest period (5, 10, 20, 40, 80, and 160 s) and a subsequent 5 s sprint to determine PPO recovery kinetics. On another occasion, \({\dot V}{{\rm O}_{2}}\) was monitored during recovery from a 30 s sprint to provide a comparison with the recovery of PPO. Finally, subjects completed a \({\dot V}{{\rm O}_{2{\rm max}}}\) test to evaluate the influence of aerobic fitness on the recovery of PPO.Results
Despite following similar time courses (F = 0.36, p = 0.558), and being well described by double-exponential models, the kinetic parameters of PPO and \({\dot V}{{\rm O}_{2}}\) in recovery were significantly different (p < 0.05). There was no significant relationship (r = 0.15; p = 0.578) between \({\dot V}{\rm O}_{2{\rm max}}\) and the time to achieve 50 % recovery of PPO. Moreover, there was no difference (p = 0.61) between the recovery kinetics of participants classified according to their \({\dot V}{\rm O}_{2{\rm max}}\) (59.4 ± 1.3 vs 48.5 ± 2.2 ml·kg?1·min?1).Conclusion
Despite similar overall recovery kinetics, \({\dot V}{{\rm O}_{2}}\) and PPO show differences in key model parameters. Moreover, the recovery of PPO does not appear to be affected by aerobic fitness. 相似文献9.
The effect of prior eccentric exercise on heavy-intensity cycling: the role of gender and oral contraceptives 总被引:1,自引:0,他引:1
Sarah Joyce Surendran Sabapathy Andrew C. Bulmer Clare Minahan 《European journal of applied physiology》2014,114(5):995-1003
Purpose
To determine if gender and/or the use of oral contraceptives alter cycling performance with exercise-induced muscle damage (EiMD).Methods
Nine male adults (MEN), nine normally menstruating female adults (WomenNM), and nine female adults using oral contraceptives (WomenOC) participated. Gas exchange and time to exhaustion were measured during continuous cycling performed at three distinct power outputs before (pre) and 48 h after (post) 240 maximal effort eccentric contractions of the quadriceps muscles designed to induce muscle damage (i.e., EiMD).Results
The change in muscle damage (i.e., range of motion about the knee joint and serum creatine kinase activity) from pre- compared to post-EiMD was greater in MEN and WomenOC compared to the WomenNM. Time to exhaustion decreased after EiMD in MEN (5.19 ± 4.58 min, p = 0.01) and in WomenOC (2.86 ± 2.83 min, p = 0.02) but did not change in WomenNM (0.98 ± 2.28 min, p = 0.43). Accordingly, the slow component of O2 uptake, expressed relative to time to exhaustion (i.e., % min?1), was greater in post- compared to pre-EiMD for MEN (p = 0.02) and the WomenOC (p = 0.03), but not for the WomenNM (p = 0.12).Conclusion
The preservation of exercise tolerance during heavy-intensity cycling performed after intense eccentric exercise is improved in women compared to men. Furthermore, the preservation of exercise tolerance is exclusive to 17β-estradiol and cannot be replicated with an exogenous synthetic estrogen replacement delivered in an oral contraceptive. 相似文献10.
Introduction
The upper limit of brachial artery (BA) flow-mediated dilation (FMD) has not been thoroughly interrogated, and long duration occlusion + handgrip exercise may create larger shear stress stimuli than previous manipulations.Purpose
To determine whether novel combinations of occlusion + handgrip exercise can extend the range of FMD stimulus–response relationship characterization and permit identification of a BA-FMD response ceiling.Methods
Ten healthy subjects performed eight reactive hyperemia (RH) FMD trials: 5, 10, and 15 min of occlusion (5RH, 10RH, 15RH); 5, 10 and 15 min of occlusion + 3-min ischemic exercise (IE) (5IE, 10IE, 15IE); 10 and 15 min of occlusion + 3-min IE + 4-min post-occlusion exercise (PE) (10IEPE, 15IEPE). Shear stress was estimated as shear rate (SR = blood velocity/BA diameter; (ultrasound assessment)) (SR stimulus = area under the curve (AUC) until peak diameter). Data are mean ± SE.Results
There were no differences in SR-AUC among IE and IEPE trials (p > 0.70), however, IE consistently increased the SR-AUC (IE + IEPE trial average 17,845.1 ± 2,023.3 a.u.) vs. the 5RH and 10RH trials (4,943.0 ± 428.4 a.u., 6,800.6 ± 805.9 a.u.) (p < 0.05). The %FMD ranged from 7.3 ± 0.8 % (5RH) to 19.1 ± 2.0 % (15IEPE) (p < 0.001) with no differences among IE and IEPE trials (p > 0.16). FMD increased with increasing SR-AUC (all subjects, all trials: r 2 0.36, p < 0.001)Conclusions
The stimulus created by brief (5 min) occlusion + ischemic exercise was not significantly enhanced by prolonging occlusion or continuing to exercise post-occlusion. The FMD response did not clearly plateau with increasing stimulus magnitude; however, the FMD capacity was shown to be more than double the FMD magnitude that was elicited with a standard 5-min occlusion test. 相似文献11.
Andrew D. Govus Chris R. Abbiss Laura A. Garvican-Lewis Dorine W. Swinkels Coby M. Laarakkers Christopher J. Gore Peter Peeling 《European journal of applied physiology》2014,114(10):2183-2191
Purpose
This study measured the influence of acute hypoxic exercise on Interleukin-6 (IL-6), hepcidin, and iron biomarkers in athletes.Methods
In a repeated measures design, 13 moderately trained endurance athletes performed 5 × 4 min intervals at 90 % of their peak oxygen consumption velocity (vVO2peak) in both normoxic [NORM, fraction of inspired oxygen (F IO2) = 0.2093, 15.3 ± 1.7 km h?1] and simulated hypoxic (HYP, F IO2 = 0.1450, 13.2 ± 1.5 km h?1) conditions. Venous blood samples were obtained pre-, post-, and 3 h post-exercise, and analysed for serum hepcidin, IL-6, ferritin, iron, soluble transferrin receptor (sTfR), and transferrin saturation.Results
Peak heart rate was significantly lower in HYP compared with NORM (p = 0.01); however, the rating of perceived exertion was similar between trials (p = 0.24). Ferritin (p = 0.02), transferrin (p = 0.03), and IL-6 (p = 0.01) significantly increased immediately post-exercise in both conditions, but returned to baseline 3 h later. Hepcidin levels significantly increased in both conditions 3 h post-exercise (p = 0.05), with no significant differences between trials. A significant treatment effect was observed between trials for sTfR (p = 0.01), but not iron and transferrin saturation.Conclusion
Acute exercise in hypoxia did not influence post-exercise IL-6 production, hepcidin activity or iron metabolism compared with exercise at the same relative intensity in normoxia. Hence, acute exercise performed at the same relative intensity in hypoxia poses no further risk to an athlete’s iron status, as compared with exercise in normoxia. 相似文献12.
J. Kappenstein A. Ferrauti B. Runkel J. Fernandez-Fernandez K. Müller J. Zange 《European journal of applied physiology》2013,113(11):2769-2779
Purpose
The aim of the present study was to test the hypotheses that a greater oxidative capacity in children results in a lower phosphocreatine (PCr) depletion, a faster PCr resynthesis and a lower muscle acidification during high-intensity intermittent exercise compared to adults.Methods
Sixteen children (9.4 ± 0.5 years) and 16 adults (26.1 ± 0.3 years) completed a protocol consisting of a dynamic plantar flexion (10 bouts of 30-s exercise at 25 % of one repetition maximum separated by 20-s recovery), followed by 10 min of passive recovery. Changes of PCr, ATP, inorganic phosphate, and phosphomonoesters were measured by means of 31Phosphorous-magnetic resonance spectroscopy during and post-exercise.Results
Average PCr (percentage of [PCr] at initial rest (%[PCr]i)) at the end of the exercise (adults 17 ± 12 %[PCr]i, children 38 ± 17 %[PCr]i, P < 0.01) and recovery periods (adults 37 ± 14 %[PCr]i, children 57 ± 17 %[PCr]i, P < 0.01) was significantly lower in adults compared to children, induced by a stronger PCr decrease during the first exercise interval (adults ?73 ± 10 %[PCr]i, children ?55 ± 15 %[PCr]i, P < 0.01). End-exercise pH was significantly higher in children compared to adults (children 6.90 + 0.20, ?0.14; adults 6.67 + 0.23, ?0.15, P < 0.05).Conclusions
From our results we suggest relatively higher rates of oxidative ATP formation in children’s muscle for covering the ATP demand of high-intensity intermittent exercise compared to adults, enabling children to begin each exercise interval with significantly higher PCr concentrations and leading to an overall lower muscle acidification. 相似文献13.
Jon L. Oliver Mark B. A. De Ste Croix Rhodri S. Lloyd Craig A. Williams 《European journal of applied physiology》2014,114(11):2241-2249
Purpose
To examine changes to neuromuscular control of leg stiffness following 42 min of soccer-specific exercise.Methods
Ten youth soccer players, aged 15.8 ± 0.4 years, stature 1.73 ± 0.06 m and mass 59.8 ± 9.7 kg, hopped on a force plate at a self-selected frequency before and after simulated soccer exercise performed on a non-motorised treadmill. During hopping, muscle activity was measured using surface electromyography from four lower limb muscles and analysed to determine feedforward- and feedback-mediated activity, as well as co-contraction.Results
There was a small, non-significant change in stiffness following exercise (26.6 ± 10.6 vs. 24.0 ± 7.0 kN m?1, p > 0.05, ES = 0.25), with half the group increasing and half decreasing their stiffness. Changes in stiffness were significantly related to changes in centre of mass (CoM) displacement (r = 0.90, p < 0.01, extremely large correlation) but not changes in peak ground reaction force (r = 0.58, p > 0.05, large correlation). A number of significant relationships were observed between changes in stiffness and CoM displacement with changes in feedforward, feedback and eccentric muscle activity of the soleus and vastus lateralis muscles following exercise (r = 0.64–0.98, p < 0.05, large–extremely large correlations), but not with changes in co-contraction (r = 0.11–0.55, p > 0.05, small–large correlations).Conclusions
Following soccer-specific exercise individual changes in feedforward- and reflex-mediated activity of the soleus and vastus lateralis, and not co-contraction around the knee and ankle, modulate changes in CoM displacement and leg stiffness. 相似文献14.
Nicola Gerrett Yacine Ouzzahra Samantha Coleby Sam Hobbs Bernard Redortier Thomas Voelcker George Havenith 《European journal of applied physiology》2014,114(7):1451-1462
Purpose
The study aimed to compare thermal sensation in response to a fixed warm stimulus across 31 body locations in resting and active males and females.Methods
Twelve males (20.6 ± 1.0 years, 78.1 ± 15.6 kg, 180 ± 8.9 cm, 34.4 ± 5.2 ml kg?1 min?1) and 12 females (20.6 ± 1.4 years, 62.9 ± 5.5 kg, 167 ± 5.7 cm, 36.5 ± 6.6 ml kg?1 min?1) rested in a thermoneutral (22.2 ± 2.2 °C, 35.1 ± 5.8 % RH) room whilst a thermal probe (25 cm2), set at 40 °C was applied in a balanced order to 31 locations across the body. Participants reported their thermal sensation 10 s after initial application. Following this, participants began cycling at 50 % \(\dot{V}{\text{O}}_{{ 2 {\text{max}}}}\) for 20 min, which was then lowered to 30 % \(\dot{V}{\text{O}}_{{ 2 {\text{max}}}}\) and the sensitivity test repeated.Results
Females had significantly warmer magnitude sensations than males at all locations (4.7 ± 1.8 vs 3.6 ± 2.2, p < 0.05, respectively). Regional differences in thermal sensation were evident but were more prominent for females. Thermal sensation was greatest at the head then the torso and declined towards the extremities. In comparison to rest, exercise caused a significant reduction in thermal sensation for males (?thermal sensation; 0.86 ± 0.3, p < 0.05), but only at select locations in females (0.31 ± 0.56, p > 0.05).Conclusion
The data provide evidence that the thermal sensation response to warmth varies between genders and between body regions and reduces during exercise. These findings have important implications for clothing design and thermophysiological modelling. 相似文献15.
Josh Foster Lee Taylor Bryna C. R. Chrismas Samuel L. Watkins Alexis R. Mauger 《European journal of applied physiology》2014,114(1):41-48
Introduction
The aim of this study was to investigate the effect of acetaminophen on repeated sprint cycling performance.Methods
Nine recreationally active male participants completed a graded exercise test, a familiarisation set of Wingate Anaerobic Tests (WAnTs) and two experimental sets of WAnTs (8 × 30 s sprints, 2 min active rest intervals). In the experimental WAnTs, participants ingested either 1.5 g acetaminophen or a placebo in a double-blind, randomised, crossover design. During the WAnT trials, participants provided ratings of perceived pain 20 s into each sprint. Mean and peak power output and heart rate were recorded immediately following each sprint, and percentage decrement in mean power output was subsequently calculated.Results
Participants cycled at a significantly greater mean power output over the course of 8 WAnTs (p < 0.05) following the ingestion of acetaminophen (391 ± 74 vs. 372 ± 90 W), due to a significantly greater mean power output during sprints 6, 7 and 8 (p < 0.05). Percentage decrements in mean power output were also significantly reduced (p < 0.05) following acetaminophen ingestion (17 ± 14 vs. 24 ± 17 %). No significant differences in peak power output, perceived pain or heart rate were observed between conditions.Conclusion
Acetaminophen may have improved performance through the reduction of pain for a given work rate, thereby enabling participants to exercise closer to a true physiological limit. These results suggest that exercise may be regulated by pain perception, and that an increased pain tolerance can improve exercise performance. 相似文献16.
Nicolas Bourdillon Jui-Lin Fan Bengt Kayser 《European journal of applied physiology》2014,114(5):1037-1048
Background
The Richalet hypoxia sensitivity test (RT), which quantifies the cardiorespiratory response to acute hypoxia during exercise at an intensity corresponding to a heart rate of ~130 bpm in normoxia, can predict susceptibility of altitude sickness. Its ability to predict exercise performance in hypoxia is unknown.Objectives
Investigate: (1) whether cerebral blood flow (CBF) and cerebral tissue oxygenation (O2Hb; oxygenated hemoglobin, HHb; deoxygenated hemoglobin) responses during RT predict time-trial cycling (TT) performance in severe hypoxia; (2) if subjects with blunted cardiorespiratory responses during RT show greater impairment of TT performance in severe hypoxia.Study design
Thirteen men [27 ± 7 years (mean ± SD), Wmax: 385 ± 30 W] were evaluated with RT and the results related to two 15 km TT, in normoxia and severe hypoxia (FIO2 = 0.11).Results
During RT, mean middle cerebral artery blood velocity (MCAv: index of CBF) was unaltered with hypoxia at rest (p > 0.05), while it was increased during normoxic (+22 ± 12 %, p < 0.05) and hypoxic exercise (+33 ± 17 %, p < 0.05). Resting hypoxia lowered cerebral O2Hb by 2.2 ± 1.2 μmol (p < 0.05 vs. resting normoxia); hypoxic exercise further lowered it to ?7.6 ± 3.1 μmol below baseline (p < 0.05). Cerebral HHb, increased by 3.5 ± 1.8 μmol in resting hypoxia (p < 0.05), and further to 8.5 ± 2.9 μmol in hypoxic exercise (p < 0.05). Changes in CBF and cerebral tissue oxygenation during RT did not correlate with TT performance loss (R = 0.4, p > 0.05 and R = 0.5, p > 0.05, respectively), while tissue oxygenation and SaO2 changes during TT did (R = ?0.76, p < 0.05). Significant correlations were observed between SaO2, MCAv and HHb during RT (R = ?0.77, ?0.76 and 0.84 respectively, p < 0.05 in all cases).Conclusions
CBF and cerebral tissue oxygenation changes during RT do not predict performance impairment in hypoxia. Since the changes in SaO2 and brain HHb during the TT correlated with performance impairment, the hypothesis that brain oxygenation plays a limiting role for global exercise in conditions of severe hypoxia remains to be tested further. 相似文献17.
Fernando G. Beltrami Christian Froyd Asgeir Mamen Timothy D. Noakes 《European journal of applied physiology》2014,114(5):941-950
Purpose
We investigated the accuracy of the Moxus Modular Metabolic System (MOXUS) against the Douglas Bag Method (DBM) during high-intensity exercise, and whether the two methods agreed when detecting small changes in $\dot{V}{\text{O}}_{2}$ between two consecutive workloads ( $\Delta {\dot{{V}}\text{O}}_{ 2}$ ).Methods
Twelve trained male runners performed two maximal incremental running tests while gas exchange was analyzed simultaneously by the two systems using a serial setup for four consecutive intervals of 30 s on each test. Comparisons between methods were performed for $\dot{V}{\text{O}}_{2}$ , ${\dot{{V}}}_{\text{E}}$ , fractions of expired O2 (FeO2) and CO2 (FeCO2) and $\Delta {\dot{{V}}\text{O}}_{ 2}$ .Results
The MOXUS produced significant higher (mean ± SD, n = 54) readings for $\dot{V}{\text{O}}_{2}$ (80 ± 200 mL min?1, p = 0.005) and ${\dot{{V}}}_{\text{E}}$ (2.9 ± 4.2 L min?1, p < 0.0001), but not FeO2 (?0.01 ± 0.09). Log-transformed 95 % limits of agreement for readings between methods were 94–110 % for $\dot{V}{\text{O}}_{2}$ , 97–108 % for $\dot{V}_{\text{E}}$ and 99–101 % for FeO2. $\Delta \dot{V}{\text{O}}_{2}$ for two consecutive measurements was not different between systems (120 ± 110 vs. 90 ± 190 mL min?1 for MOXUS and DBM, respectively, p = 0.26), but agreement between methods was very low (r = 0.25, p = 0.12).Discussion
Although it was tested during high-intensity exercise and short sampling intervals, the MOXUS performed within the acceptable range of accuracy reported for automated analyzers. Most of the differences between equipments were due to differences in $\dot{V}_{\text{E}}$ . Detecting small changes in $\dot{V}{\text{O}}_{2}$ during an incremental test with small changes in workload, however, might be beyond the equipment’s accuracy. 相似文献18.
C. B. O’Leary C. Lehman K. Koltun A. Smith-Ryan A. C. Hackney 《European journal of applied physiology》2013,113(9):2419-2424
Purpose
To examine the androgen response to exercise in women under conditions of high (H) and low (L) estrogen (E2) levels.Methods
Ten exercise trained eumenorrheic women (mean ± SD: 20.0 ± 2.2 years, 58.7 ± 8.3 kg, 22.3 ± 4.9 % body fat, VO2max = 50.7 ± 9.0 mL/kg/min) completed a 60 min treadmill run at ~70 % of VO2max during both the mid-follicular (L-E2, 69.7 ± 7.3 % VO2max) and mid-luteal (H-E2, 67.6 ± 7.9 % VO2max) phases of their menstrual cycle. Blood samples were taken pre-exercise (PRE), immediately post (POST), and 30 min into recovery (30R) from exercise and analyzed for total testosterone using ELISA assays. Results were analyzed using repeated measures ANOVA.Results
Testosterone responses were (mean ± SD: L-E2, pre = 1.41 ± 0.21, post = 1.86 ± 0.21, 30R = 1.75 ± 0.32 nmol/L; H-E2, pre = 1.27 ± 0.23, post = 2.43 ± 0.56, 30R = 1.69 ± 0.34 nmol/L). Statistical analysis indicated no significant interaction existed between high and low estrogen conditions across the blood sampling times (p = 0.138). However, a main effect occurred for exercise (p < 0.004) with the post-testosterone concentration being greater than pre, although pre vs. 30R was not different (p > 0.05). All testosterone hormonal concentrations immediately post-exercise greatly exceeded the level of hemoconcentration observed during the L-E2 and H-E2 exercise sessions.Conclusions
Prolonged aerobic exercise induces short-term elevations in testosterone in trained eumenorrheic women, which appears unrelated to estrogen levels and menstrual cycle phase. These increases may occur due to either increased androgen production and/or decreased degradation rates of the hormone, and are not solely the result of plasma fluid shifts from the exercise. 相似文献19.
Sam Esfandiari Zion Sasson Jack M. Goodman 《European journal of applied physiology》2014,114(2):331-343
Purpose
This study examined the effects of short-term high-intensity interval training (HIT) and continuous moderate-intensity training (CMT) on cardiac function in young, healthy men.Methods
Sixteen previously untrained men (mean age of 25.1 ± 4.1 years) were randomly assigned to HIT and CMT (n = 8 each) and assessed before and after six sessions over a 12-day training period. HIT consisted of 8–12 intervals of cycling for 60 s at 95–100 % of pre-training maximal aerobic power ( $\dot{V}$ O2max), interspersed by 75 s of cycling at 10 % $\dot{V}$ O2max. CMT involved 90–120 min of cycling at 65 % pre-training $\dot{V}$ O2max. Left ventricular (LV) function was determined at rest and during submaximal exercise (heart rate ~105 bpm) using two-dimensional and Doppler echocardiography.Results
Training resulted in increased calculated plasma volume (PV) in both groups, accompanied by improved $\dot{V}$ O2max in HIT (HIT: from 39.5 ± 7.1 to 43.9 ± 5.5 mL kg?1 min?1; CMT: from 39.9 ± 5.9 to 41.7 ± 5.3 mL kg?1 min?1; P < 0.001). Resting LV function was not altered. However, increased exercise stroke volume (P = 0.02) and cardiac output (P = 0.02) were observed, secondary to increases in end-diastolic volume (P < 0.001). Numerous Doppler and speckle tracking indices of diastolic function were similarly enhanced during exercise in both training groups and were related to changes in PV.Conclusion
Short-term HIT and CMT elicit rapid improvements in $\dot{V}$ O2max and LV filling without global changes in cardiac performance at rest. 相似文献20.
Tomoaki Matsuo Kousaku Saotome Satoshi Seino Miki Eto Nobutake Shimojo Akira Matsushita Motoyuki Iemitsu Hiroshi Ohshima Kiyoji Tanaka Chiaki Mukai 《European journal of applied physiology》2014,114(9):1963-1972