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1.
Maria D. Koskolou Donald C. McKenzie 《European journal of applied physiology and occupational physiology》1994,68(1):80-86
In order to determine the level of hypoxemia which is sufficient to impair maximal performance, seven well-trained male cyclists [maximum oxygen consumption (VO2max)51·min–1 or 60 ml·kg–1·min–1] performed a 5-min performance cycle test to exhaustion at maximal intensity as controlled by the subject, under three experimental conditions: normoxemia [percentage of arterial oxyhemoglobin saturation (%S
a O2)>94%], and artificially induced mild (%S
aO2=90±1%) and moderate (%S
aO2=87±1%) hypoxemia. Performance, evaluated as the total work output (Worktot) performed in the 5-min cycle test, progressively decreased with decreasing %S
aO2 [mean (SE) Worktot=107.40 (4.5) kJ, 104.07 (5.6) kJ, and 102.52 (4.7) kJ, under normoxemia, mild, and moderate hypoxemia, respectively]. However, only performance in the moderate hypoxemia condition was significantly different than in normoxemia (P=0.02). Mean oxygen consumption and heart rate were similar in the three conditions (P=0.18 andP=0.95, respectively). End-tidal partial pressure of CO2 was significantly lower (P=0.005) during moderate hypoxemia compared with normoxemia, and ventilatory equivalent of CO2 was significantly higher (P=0.005) in both hypoxemic conditions when compared with normoxemia. It is concluded that maximal performance capacity is significantly impaired in highly trained cyclists working under an %S
aO2 level of 87% but not under a milder desaturation level of 90%. 相似文献
2.
T. B. R. J. Smith W. G. Hopkins N. A. S. Taylor 《European journal of applied physiology and occupational physiology》1994,69(1):44-49
The position of the body and use of the respiratory muscles in the act of rowing may limit ventilation and thereby reduce maximal aerobic power relative to that achieved in cycling or running, in spite of the greater muscle mass involved in rowing. This hypothesis was investigated for three groups of male subjects: nine elite senior oarsmen, eight former senior oarsmen and eight highly trained athletes unskilled in rowing. The subjects performed graded exercise to maximal effort on a rowing ergometer, cycle ergometer and treadmill while respiratory minute volume
and oxygen consumption
were monitored continuously. The VE at a given
during intense submaximal exercise (greater than 75% of maximal
) was not significantly lower in rowing compared with that in cycling and treadmill running for any group, which would suggest that submaximal rowing does not restrict ventilation. At maximal effort,
and
for rowing were less than those for the other types of exercise in all the groups, although the differences were not statistically significant in the elite oarsmen. These data are consistent with a ventilatory limitation to maximal performance in rowing that may have been partly overcome by training in the elite oarsmen. Alternatively, a lower maximal VE in rowing might have been an effect rather than a cause of a lower maximal
if maximal
was limited by the lower rate of muscle activation in rowing. 相似文献
3.
J. Orysiak P. Zmijewski A. Klusiewicz P. Kaliszewski J. Malczewska-Lenczowska J. Gajewski A. Pokrywka 《Biology of sport / Institute of Sport》2013,30(4):249-253
The aim of the study was to examine the possible relationship between I/D polymorphism of ACE gene and selected indices of aerobic capacity among male and female athletes practising winter endurance sports. Sixty-six well-trained athletes (female n = 26, male n = 40), aged 18.4 ± 2.8 years, representing winter endurance sports (cross-country skiing, n = 48; biathlon, n = 8; Nordic combined, n = 10) participated in the study. Genotyping for ACE I/D polymorphism was performed using polymerase chain reaction. Maximal oxygen consumption (VO2max), maximal running velocity (Vmax) and running velocity at anaerobic threshold (VAT4) were determined in an incremental test to volitional exhaustion on a motorized treadmill. The ACE genotype had no significant effect on absolute VO2max, relative VO2max (divided by body mass or fat free body mass), VAT4 or Vmax. No interaction effect of gender x ACE genotype was found for each of the examined aerobic capacity indices. ACE gene variation was not found to be a determinant of aerobic capacity in either female or male Polish, well-trained endurance athletes participating in winter sports. 相似文献
4.
5.
Pitkänen HT Oja SS Rusko H Nummela A Komi PV Saransaari P Takala T Mero AA 《Amino acids》2003,25(1):85-94
This study described the effect of leucine supplementation on serum amino acid concentration during two different exercise sessions in competitive male power athletes. The subjects performed a strength exercise session (SES; n = 16; 26 +/- 4 years) or a maximal anaerobic running exercise session (MARE; n = 12; 27 +/- 5 years) until exhaustion twice at a 7-day interval. The randomized subjects consumed drinks containing leucine (100 mg x kg/body weight before and during SES or 200 mg x kg/body weight before MARE) or placebo. Blood specimens taken 10 min before (B) and after (A) the sessions were analyzed for serum amino acids. In SES the concentration of leucine was distinctly higher in the leucine supplemented group than in the placebo group in both B (p < 0.001) and A (p < 0.001) samples. The leucine concentration decreased in placebo but not in the leucine supplemented group following the exercise session. Isoleucine (p = 0.017) and valine (p = 0.006) concentration decreased more in the leucine supplemented group than in placebo in A samples. In MARE the concentration of leucine was higher in the leucine supplemented group than in placebo in both B (p < 0.001) and A (p < 0.001) samples and increased (p < 0.001) in the supplemented group following the session. Isoleucine (p = 0.020) and valine (p = 0.006) concentration decreased in the supplemented group in A samples. There were no differences in a counter movement jump after SES or in the running performance in MARE between the leucine supplemented group and placebo. These findings indicate that consuming leucine before or before and during exercise sessions results in changes in blood amino acid concentration. However, the supplementation does not affect an acute physical performance. 相似文献
6.
Knowledge of daily boron (B) intakes will assist researchers in establishing B requirements and elucidating the metabolic
role of B in humans. B concentrations in commonly consumed foods were utilized to approximate the B intake of selected US
populations. Triplicate food samples were digested at low temperatures with 16M HNO3 and 30% H2O2, and analyzed by inductively coupled plasma spectroscopy (ICP). Milk and dairy products, juices, and beverages were the largest
contributors to dietary B. Total B content of average daily diets ranged from 548 μg for toddlers (2 yr old) to 883 μg for
mature males (60–65 yr old), excluding tap water contributions. Toddlers consumed 3.7 times more B than mature males when
adjusted for body weight (body wt) and consumed the diet with the highest boron density (1.8 μg/kJ or 0.43 μg/kcal). Adolescent
females consumed a diet with the lowest B density (1.12 μg/kJ or 0.26 μg/kcal). Food B concentrations applied to diet records
(1020 μg/d) and ICP analysis of the corresponding food composites (1170 μg/d) were comparable (p < 0.05). Current estimations of B in US diets are consistent with reports in the literature stating that normal adult daily
B intakes are approx 1 mg.
Presented at the symposium “Second International Symposium on the Health Effects of Boron and Its Compounds” held in Irvine,
CA, on October 23, 1997. This symposium was presented by the University of California, Irvine. The publication of the symposium
was supported by U.S. Borax Inc. Guest editors for this symposium were B. Dwight Culver (University of California, Irvine,
CA) and James R. Coughlin (Coughlin and Associates, Newport Coast, CA).
US Department of Agriculture, Agricultural Research Service, Northern Plains Area is an equal opportunity/affirmative action
employer, and all agency services are available without discrimination. 相似文献
7.
Puerta RC Aliz EL Lopez-Calleja MA Ramirez RR Pena GP 《Indian pacing and electrophysiology journal》2011,11(3):73-80
Background
Few studies have been performed on P wave indices in athletes. The aim of this study was to determine the behaviour of maximum P wave duration (Pmax), minimum P wave duration (Pmin) and P wave dispersion (PWD) in young high performance athletes, as well as the relationship of PWD with training history, heart rate (HR) and echocardiographic parameters.Methods
We performed a cross-sectional observational study in 38 athletes of high performance in sports: water polo, distance running and weight lifting compared with 34 sedentary controls.Results
The average age in both groups was 20.6 years. Note that PWD was increased in athletes (57 ± 14 ms vs. 40 ± 12 ms, p <0.001) while Pmin was significantly lower (57 ± 13 ms vs. 72 ± 13 ms, p <0.001), and there was no difference when comparing Pmax (114 ± 9 ms vs. 117 ± 14 ms, p> 0.05). The correlation between the duration of training (r = 0.511) and resting HR (r = 0.461) with PWD was significant (p <0.01).Conclusions
PWD is increased in young athletes of high performance and was positively correlated with duration of training and baseline HR. The increase in PWD was secondary to a significant decrease in Pmin. 相似文献8.
Koury JC de Oliveira CF Portella ES Oliveira AV Donangelo CM 《Biological trace element research》2005,107(3):201-211
The purpose of this study was to evaluate the effect of the resting period on hematological and copper-zinc-dependent antioxidant
indices in Brazilian elite judo athletes (n=7). Venous blood samples were collected after 24-h and 5-d periods of resting following a competition, with an interval of
30 d between collections. Two months prior to and during the study, each athlete received an individualized adequate diet.
Body composition was determined at both study periods. The following were analyzed: in whole blood, hemoglobin, hematocrit,
red cell count, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, red cell
distribution width, and white cell count; in plasma, zinc, copper, iron, ceruloplasmin, and total iron-binding capacity; in
erythrocytes, metallothionein, copper/zinc superoxide dismutase, and osmotic fragility. Dietary intake and body composition
did not affect the biochemical measurements. A significant reduction in ceruloplasmin and superoxide dismutase activity was
found after 5 d compared to 24 h of resting. A significant correlation between erythrocyte metallothionein and red cell distribution
width was observed after 24 h of resting (r=−0.83, p=0.02) whereas positive correlations of metallothionein with hemoglobin, red cell count, and mean corpuscular hemoglobin concentration
were observed after 5 d of resting (r≥0.76, p≤0.05). Our results suggest that a longer resting period favors homeostatic adjustments in the erythrocyte population and
in the copper/zinc-dependent antioxidant system in elite judo athletes. 相似文献
9.
Patrick Mucci Jacques Prioux Maurice Hayot Michèle Ramonatxo Christian Préfaut 《European journal of applied physiology and occupational physiology》1998,77(4):343-351
Exercise-induced hypoxaemia (EIH) in master athletes may be related to a diminished exercise hyper- pnoea. The aim of this
study was to determine whether EIH is associated with a change in the sensitivity of the ventilation response to activation
of the central chemoreceptors. The ventilation response to CO2 was measured in nine elderly untrained men (UT) [mean age 66.3 (SEM 3.1) years] and nine master athletes (MA) [mean age 62.7
(SEM 0.8) years] at rest, during moderate exercise (40% maximal oxygen uptake, V˙O2max), and during strenuous exercise (70% V˙O2max) using the rebreathing method. Our results showed that the ventilation response to CO2 did not differ with endurance training and/or exercise, that the threshold of the CO2 response (Th) increased with exercise (P < 0.001), that the increase in Th in MA was higher than in UT between rest and moderate exercise [ΔTh0–40: 8.55 (SEM 1.8) vs 3.06 (SEM 1.72) mmHg, P < 0.05], and that ΔTh0–40 and Th during moderate exercise were negatively correlated with arterial O2 saturation during maximal exercise (r = 0.50, P<0.05). We concluded therefore that exercise-induced hypoxaemia in master athletes may not be due to a lower ventilation response
to CO2, but may be partly related to a greater increase in Th during moderate exercise.
Accepted: 18 August 1997 相似文献
10.
Craig A. Williams Peter Bale 《European journal of applied physiology and occupational physiology》1998,77(3):271-277
Previous research has often used correlations as a statistical method to show agreement; however, this is not a valid use
of the statistic. The purpose of this study was to investigate the bias and limits of agreement for three methods of estimating
percentage body fat for 117 male and 114 female university athletes: hydrodensitometry (HYD), bioelectrical impedance (BIA)
and skinfold calipers (SKF). The mean (SD) percentage body fat for males as assessed by HYD, BIA and SKF methods, respectively,
were 13.2 (3.3)%, 14.1 (3.3)% and 13.0 (3.2)%. Female body fat measurements were 22.5 (3.9)%, 23.7 (4.3)% and 23.8 (4.2)%,
respectively. Pearson product moment correlations for male and female body fat percentages between the three methods were
high, ranging from 0.81 to 0.86 (P < 0.05). However, compared to the criterion measure of body fat percentage (HYD), the magnitude of agreement BIA and SKF
revealed a different pattern. The mean absolute difference between HYD and BIA measurements of body fat for males was −0.8
(2.0)% fat, and between HYD and SKF was it was 0.2 (1.7)% fat. The mean absolute difference for females between HYD and BIA
was −1.2 (2.5)%; for HYD and SKF it was −1.4 (2.2)%. Compared to the HYD measures for males and females, the BIA and SKF measures
were as much as a 3.8% underestimation and a 6.2% overestimation of body fat. This study provides evidence that the strength
of a correlation does not indicate agreement between two methods. In future, reliability and validity studies should examine
the absolute differences between two variables and calculate limits of agreement around which a practitioner can appreciate
the precision of the methodologies.
Accepted: 26 August 1997 相似文献