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1.
Hiroshi Takaki Kenji Sunagawa Masaru Sugimachi Yasushi Hara Toru Kawada Takashi Kurita Yoichi Goto 《European journal of applied physiology and occupational physiology》1998,78(4):333-339
The transient response of oxygen uptake (V˙O2) to submaximal exercise, known to be abnormal in patients with cardiovascular disorders, can be useful in assessing the functional
status of the cardiocirculatory system, however, a method for evaluating it accurately has not yet been established. As an
alternative approach to the conventional test at constant exercise intensity, we applied a random stimulus technique that
has been shown to provide relatively noise immune responses of system being investigated. In 27 patients with heart failure
and 24 age-matched control subjects, we imposed cycle exercise at 50 W intermittently according to a pseudo-random binary
(exercise-rest) sequence, while measuring breath-by-breath V˙O2. After determining the transfer function relating exercise intensity (W˙) to V˙O2 and attenuating the high frequency ranges (>6 exercise-rest cycles · min−1), we computed the high resolution band-limited (0–6 cycles · min−1) V˙O2 response (0–120 s) to a hypothetical step exercise. The V˙O2 response showed a longer time constant in the patients than in the control subjects [47 (SD 37) and 31 (SD 8) s, respectively,
P < 0.05]. Furthermore, the amplitude of the V˙O2 response after the initial response was shown to be significantly smaller in the patients than in the control subjects [176
(SD 50) and 267 (SD 54) ml · min−1 at 120 s]. The average amplitude over 120 s correlated well with peak V˙O2 (r = 0.73) and ΔV˙O2/ΔW˙ (r = 0.70), both of which are well-established indexes of exercise tolerance. The data indicated that our band-limited V˙O2
step response using random exercise was more markedly attenuated and delayed in the patients with heart failure than in the normal controls
and that it could be useful in quantifying the overall functional status of the cardiocirculatory system.
Accepted: 6 January 1998 相似文献
2.
3.
D. Habedank I. Reindl G. Vietzke U. Bauer A. Sperfeld S. Gl?ser K. D. Wernecke F. X. Kleber 《European journal of applied physiology and occupational physiology》1998,77(5):421-426
The ventilatory equivalent for CO2 defines ventilatory efficiency largely independent of metabolism. An impairment of ventilatory efficiency may be caused by
an increase in either anatomical or physiological dead space, the latter being the most important mechanism in the hyperpnoea
of heart failure, pulmonary embolism, pulmonary hypertension and the former in restrictive lung disease. However, normal values
for ventilatory efficiency have not yet been established. We investigated 101 (56 men) healthy volunteers, aged 16–75 years,
measuring ventilation and gas exchange at rest (n = 64) and on exercise (modified Naughton protocol, n = 101). Age and sex dependent normal values for ventilatory efficiency at rest defined as the ratio ventilation:carbon dioxide
output (V˙
E:V˙CO2), exercise ventilatory efficiency during exercise, defined as the slope of the linear relationship between ventilation and
carbon dioxide output (V˙
E vs V˙CO2 slope), oxygen uptake at the anaerobic threshold and at maximum (V˙O2AT,V˙O2max, respectively) and breathing reserve were established. Ventilatory efficiency at rest was largely independent of age, but
was smaller in the men than in the women [V˙
E:V˙CO2 50.5 (SD 8.8) vs 57.6 (SD 12.6) P<0.05]. Ventilatory efficiency during exercise declined significantly with age and was smaller in the men than in the women
(men: (V˙
E vs V˙CO2 slope = 0.13 × age + 19.9; women: V˙
E vs V˙CO2 slope = 0.12 × age + 24.4). The V˙O2AT and V˙O2max were 23 (SD 5) and 39 (SD 7) ml O2 · kg · min−1 in the men and 18 (SD 4) and 32 (SD 7) in the women, respectively, and declined significantly with age. The V˙O2AT was reached at 58 (SD 9)% V˙O2max. Breathing reserve at the end of exercise was 41% and was independent of sex and age. It was concluded from this study that
ventilatory efficiency as well as peak oxygen uptake are age and sex dependent in adults.
Accepted: 11 June 1997 相似文献
4.
Greg J. Wilson Andrew D. Walshe Mark R. Fisher 《European journal of applied physiology and occupational physiology》1997,75(5):455-461
The aims of the present study were: (1) to assess aerobic metabolism in paraplegic (P) athletes (spinal lesion level, T4–L3)
by means of peak oxygen uptake (V˙O2peak) and ventilatory threshold (VT), and (2) to determine the nature of exercise limitation in these athletes by means of cardioventilatory
responses at peak exercise. Eight P athletes underwent conventional spirographic measurements and then performed an incremental
wheelchair exercise on an adapted treadmill. Ventilatory data were collected every minute using an automated metabolic system:
ventilation (l · min−1), oxygen uptake (V˙O2, l · min−1, ml · min−1 · kg−1), carbon dioxide production (V˙CO2, ml · min−1), respiratory exchange ratio, breathing frequency and tidal volume. Heart rate (HR, beats · min−1) was collected with the aid of a standard electrocardiogram. V˙O2peak was determined using conventional criteria. VT was determined by the breakpoint in the V˙CO2−V˙O2 relationship, and is expressed as the absolute VT (V˙O2, ml · min−1 · kg−1) and relative VT (percentage of V˙O2peak). Spirometric values and cardioventilatory responses at rest and at peak exercise allowed the measurement of ventilatory
reserve (VR), heart rate reserve (HRr), heart rate response (HRR), and O2 pulse (O2 P). Results showed a V˙O2peak value of 40.6 (2.5) ml · min−1 · kg−1, an absolute VT detected at 23.1 (1.5) ml · min−1 · kg−1
V˙O2 and a relative VT at 56.4 (2.2)% V˙O2peak. HRr [15.8 (3.2) beats · min−1], HRR [48.6 (4.3) beat · l−1], and O2 P [0.23 (0.02) ml · kg−1 · beat−1] were normal, whereas VR at peak exercise [42.7 (2.4)%] was increased. As wheelchair exercise excluded the use of an able-bodied
(AB) control group, we compared our V˙O2peak and VT results with those for other P subjects and AB controls reported in the literature, and we compared our cardioventilatory
responses with those for respiratory and cardiac patients. The low V˙O2peak values obtained compared with subject values obtained during an arm-crank exercise may be due to a reduced active muscle
mass. Absolute VT was somewhat comparable to that of AB subjects, mainly due to the similar muscle mass involved in wheelchair
and arm-crank exercise by P and AB subjects, respectively. The increased VR, as reported in patients with chronic heart failure,
suggested that P athletes exhibited cardiac limitation at peak exercise, and this contributed to the lower V˙O2peak measured in these subjects.
Accepted: 22 April 1997 相似文献
5.
M. Faina V. Billat R. Squadrone M. De Angelis J. P. Koralsztein A. Dal Monte 《European journal of applied physiology and occupational physiology》1997,76(1):13-20
Using 23 elite male athletes (8 cyclists, 7 kayakists, and 8 swimmers), the contribution of the anaerobic energy system to
the time to exhaustion (t
lim) at the minimal exercise intensity (speed or power) at which maximal oxygen uptake (V˙O2
max) occurs (I
V˙O2
max) was assessed by analysing the relationship between the t
lim and the accumulated oxygen deficit (AOD). After 10-min warming up at 60% of V˙O2
max, the exercise intensity was increased so that each subject reached his I
V˙O2max
in 30 s and then continued at that level until he was exhausted. Pre-tests included a continuous incremental test with 2 min
steps for determining the I
V˙O2max
and a series of 5-min submaximal intensities to collect the data that would allow the estimation of the energy expenditure
at I
V˙O2max
. The AOD for the t
lim exercise was calculated as the difference between the above estimation and the accumulated oxygen uptake. The mean percentage
value of energy expenditure covered by anaerobic metabolism was 15.2 [(SD 6)%, range 8.9–24.1] with significant differences
between swimmers and kayakists (16.8% vs 11.5%, P≤0.05) and cyclists and kayakists (16.4% vs 11.5%, P≤0.05). Absolute AOD values ranged from 26.4 ml · kg−1 to 83.6 ml · kg−1 with a mean value of 45.9 (SD 18) ml · kg−1. Considering all the subjects, the t
lim was found to have a positive and significant correlation with AOD (r = 0.62, P≤0.05), and a negative and significant correlation with V˙O2
max (r = −0.46, P≤0.05). The data would suggest that the contribution of anaerobic processes during exercise performed at I
V˙O2max
should not be ignored when t
lim is used as a supplementary parameter to evaluate specific adaptation of athletes.
Accepted: 17 December 1996 相似文献
6.
Jerzy A. Zoladz Zbigniew Szkutnik Joanna Majerczak Krzysztof Duda 《European journal of applied physiology and occupational physiology》1998,78(4):369-377
The purpose of this study was to develop a method to determine the power output at which oxygen uptake (V˙O2) during an incremental exercise test begins to rise non-linearly. A group of 26 healthy non-smoking men [mean age 22.1 (SD
1.4) years, body mass 73.6 (SD 7.4) kg, height 179.4 (SD 7.5) cm, maximal oxygen uptake (V˙O2max) 3.726 (SD 0.363) l · min−1], experienced in laboratory tests, were the subjects in this study. They performed an incremental exercise test on a cycle
ergometer at a pedalling rate of 70 rev · min−1. The test started at a power output of 30 W, followed by increases amounting to 30 W every 3 min. At 5 min prior to the first
exercise intensity, at the end of each stage of exercise protocol, blood samples (1 ml each) were taken from an antecubital
vein. The samples were analysed for plasma lactate concentration [La]pl, partial pressure of O2 and CO2 and hydrogen ion concentration [H+]b. The lactate threshold (LT) in this study was defined as the highest power output above which [La−]pl showed a sustained increase of more than 0.5 mmol · l−1 · step−1. The V˙O2 was measured breath-by-breath. In the analysis of the change point (CP) of V˙O2 during the incremental exercise test, a two-phase model was assumed for the 3rd-min-data of each step of the test: X
i
=at
i
+b+ɛ
i
for i=1,2,…,T, and E(X
i
)>at
i
+b for i =T+1,…,n, where X
1, … , X
n
are independent and ɛ
i
∼N(0,σ2). In the first phase, a linear relationship between V˙O2 and power output was assumed, whereas in the second phase an additional increase in V˙O2 above the values expected from the linear model was allowed. The power output at which the first phase ended was called the
change point in oxygen uptake (CP-V˙O2). The identification of the model consisted of two steps: testing for the existence of CP and estimating its location. Both
procedures were based on suitably normalised recursive residuals. We showed that in 25 out of 26 subjects it was possible
to determine the CP-O2 as described in our model. The power output at CP-V˙O2 amounted to 136.8 (SD 31.3) W. It was only 11 W – non significantly – higher than the power output corresponding to LT. The
V˙O2 at CP-V˙O2 amounted to 1.828 (SD 0.356) l · min−1 was [48.9 (SD 7.9)% V˙O2
max
]. The [La−]pl at CP-V˙O2, amounting to 2.57 (SD 0.69) mmol · l−1 was significantly elevated (P<0.01) above the resting level [1.85 (SD 0.46) mmol · l−1], however the [H+]b at CP-V˙O2 amounting to 45.1 (SD 3.0) nmol · l−1, was not significantly different from the values at rest which amounted to 44.14 (SD 2.79) nmol · l−1. An increase of power output of 30 W above CP-V˙O2 was accompanied by a significant increase in [H+]b above the resting level (P=0.03).
Accepted: 25 March 1998 相似文献
7.
This study investigated the effects on running economy (RE) of ingesting either no fluid or an electrolyte solution with
or without 6% carbohydrate (counterbalanced design) during 60-min running bouts at 80% maximal oxygen consumption (V˙O2max). Tests were undertaken in either a thermoneutral (22–23°C; 56–62% relative humidity, RH) or a hot and humid natural environment
(Singapore: 25–35°C; 66–77% RH). The subjects were 15 young adult male Singaporeans [V˙O2max = 55.5 (4.4 SD) ml kg−1 min−1]. The RE was measured at 3 m s−1 [65 (6)% V˙O2max] before (RE1) and after each prolonged run (RE2). Fluids were administered every 2 min, at an individual rate determined
from prior tests, to maintain body mass (group mean = 17.4 ml min−1). The V˙O2 during RE2 was higher (P < 0.05) than that during the RE1 test for all treatments, with no differences between treatments (ANOVA). The mean increase
in V˙O2 from RE1 to RE2 ranged from 3.4 to 4.7 ml kg−1 min−1 across treatments. In conclusion, the deterioration in RE at 3 m s−1 (65% V˙O2max) after 60 min of running at 80% V˙O2max appears to occur independently of whether fluid is ingested and regardless of whether the fluid contains carbohydrates or
electrolytes, in both a thermoneutral and in a hot, humid environment.
Accepted: 30 October 1997 相似文献
8.
A. S. Weller C. E. Millard P. L. Greenhaff I. A. Macdonald 《European journal of applied physiology and occupational physiology》1998,77(3):217-223
In a previous study, rectal temperature (T
re) was found to be lower, and oxygen consumption (V˙O2) and the respiratory exchange ratio (R) were higher in a cold (+5°C), wet and windy environment (COLD), compared with a thermoneutral environment during intermittent
walking at ≈30% of peak V˙O2 (Weller AS, Millard CE, Stroud MA et al. Am J Physiol 272:R226–R233, 1997). The aim of the present study was to establish
whether these cold-induced responses are influenced by prior fasting, as impaired thermoregulation has been demonstrated in
cold-exposed, resting men following a 48-h fast. To address this question, eight men attempted a 360-min intermittent (15 min
rest, 45 min exercise) walking protocol under COLD conditions on two occasions. In one condition, the subjects started the
exercise protocol ≈120 min after a standard meal (FED/COLD), whereas in the other the subjects had fasted for 36 h (FASTED/COLD).
The first two exercise periods were conducted at a higher intensity (HIGHER, 6 km · h−1 and 10% incline), than the four subsequent exercise periods (LOW, 5 km · h−1 and 0% incline). There was no difference in the time endured in FED/COLD and FASTED/COLD. In FASTED/COLD com pared with FED/COLD,
R was lower during HIGHER and LOW, and T
re was lower during LOW, whereas there was no difference in V˙O2, mean skin temperature and heart rate. Therefore, although the 36-h fast impaired temperature regulation during intermittent
low-intensity exercise in the cold, wet and windy environment, it was unlikely to have been the principal factor limiting
exercise performance under these experimental conditions.
Accepted: 26 August 1997 相似文献
9.
Y. Bhambhani R. Maikala S. Buckley 《European journal of applied physiology and occupational physiology》1998,78(5):422-431
The purpose of this study was to compare the rates of muscle deoxygenation in the exercising muscles during incremental arm
cranking and leg cycling exercise in healthy men and women. Fifteen men and 10 women completed arm cranking and leg cycling
tests to exhaustion in separate sessions in a counterbalanced order. Cardiorespiratory measurements were monitored using an
automated metabolic cart interfaced with an electrocardiogram. Tissue absorbency was recorded continuously at 760 nm and 850 nm
during incremental exercise and 6 min of recovery, with a near infrared spectrometer interfaced with a computer. Muscle oxygenation
was calculated from the tissue absorbency measurements at 30%, 45%, 60%, 75% and 90% of peak oxygen uptake (V˙O2) during each exercise mode and is expressed as a percentage of the maximal range observed during exercise and recovery (%Mox).
Exponential regression analysis indicated significant inverse relationships (P < 0.01) between %Mox and absolute V˙O2 during arm cranking and leg cycling in men (multiple R = −0.96 and −0.99, respectively) and women (R =−0.94 and −0.99, respectively). No significant interaction was observed for the %Mox between the two exercise modes and
between the two genders. The rate of muscle deoxygenation per litre of V˙O2 was 31.1% and 26.4% during arm cranking and leg cycling, respectively, in men, and 26.3% and 37.4% respectively, in women.
It was concluded that the rate of decline in %Mox for a given increase in V˙O2 between 30% and 90% of the peak V˙O2 was independent of exercise mode and gender.
Accepted: 31 March 1998 相似文献
10.
George Havenith John M. L. Coenen Lyda Kistemaker W. Larry Kenney 《European journal of applied physiology and occupational physiology》1998,77(3):231-241
Multiple heterogeneous groups of subjects (both sexes and a wide range of maximal oxygen uptake V˙O2
max
, body mass, body surface area (A
D),% body fat, and A
D/mass coefficient) exercised on a cycle ergometer at a relative (%V˙O2max, REL) or an absolute (60 W) exercise intensity in a cool (CO 21°C, 50% relative humidity), warm humid (WH 35°C, 80%) and
a hot dry (HD 45°C, 20%) environment. Rectal temperature (T
re) responses were analysed for the influence of the individual's characteristics, environment and exercise intensity. Exposures
consisted of 30-min rest, followed by 60-min exercise. The T
re was negatively correlated with mass in all conditions. Body mass acted as a passive heat sink in all the conditions tested.
While negatively correlated with V˙O2
max
and V˙O2
max
per kilogram body mass in most climates, T
re was positively correlated with V˙O2
max
and V˙O2
max
per kilogram body mass in the WH/REL condition. Thus, when evaporative heat loss was limited as in WH, the higher heat production
of the fitter subjects in the REL trials determined T
re and not the greater efficiency for heat loss associated with high V˙O2
max
. Body fatness significantly affected T
re only in the CO condition, where, with low skin blood flows (measured as increases in forearm blood flow), the insulative
effect of fat was pronounced. In the warmer environments, high skin blood flows offset the resistance offered by peripheral
adipose tissue. Contrary to other studies, T
re was positively correlated with A
D/mass coefficient for all conditions tested. For both exercise types used, being big (a high heat loss area and heat capacity)
was apparently more beneficial from a heat strain standpoint than having a favourable A
D/mass coefficient (high in small subjects). The total amount of variance in T
re responses which could be attributed to individual characteristics was dependent on the climate and the type of exercise.
Though substantial for absolute exercise intensities (52%–58%) the variance explained in T
re differed markedly for relative intensities: 72% for the WH climate with its limited evaporative capacity, and only 10%–26%
for the HD and CO climates. The results showed that individual characteristics play a significant role in determining the
responses of body core temperature in all conditions tested, but their contribution was low for relative exercise intensities
when evaporative heat loss was not restricted. This study demonstrated that effects of individual characteristics on human
responses to heat stress cannot be interpreted without taking into consideration both the heat transfer properties of the
environment and the metabolic heat production resulting from the exercise type and intensity chosen. Their impact varies substantially
among conditions.
Accepted: 4 July 1997 相似文献
11.
S. Grant W. Davidson T. Aitchison J. Wilson 《European journal of applied physiology and occupational physiology》1998,78(4):324-332
The aim of this study was to compare the exercise intensity and rating of perceived exertion (RPE) of a high-impact (HIP)
and a low-impact (LIP) university aerobic dance session. Ten women [mean (SD) age 22.9 (2.6) years] took part in the study.
An incremental treadmill test was performed by each subject to determine maximum oxygen consumption (V˙O2
max
) and maximum heart rate (HR
max
). The measured V˙O2
max
[mean (SD)] was 49.0 (7.5) ml · kg−1 · min−1. The subjects were randomly assigned to LIP and HIP sessions (i.e. five of the subjects participated in the HIP session first,
and the other five participated in the LIP session first). In a laboratory, heart rate, oxygen uptake and RPE were measured
throughout each session for each subject. Expired air was collected continuously throughout the sessions using Douglas bags
(ten bags over a 30-min period). The sessions consisted of 20 min of aerobic exercise (bags 1–7) followed by 5 min of local
muscular endurance exercise (bags 8 and 9) and 5 min of flexibility exercises (bag 10). The mean intensity of the aerobic
section of the LIP and HIP sessions was 51.6% and 64.7% V˙O2
max
, respectively. Ninety-five percent confidence intervals for the average difference between the HIP and LIP sessions demonstrate
that the %V˙O2
max
was between 12% and 14% higher for the HIP session. The mean %HR
max
for the LIP and HIP sessions was 71.4% and 76.7%, respectively, with the %HR
max
in the HIP session being between 5.4% and 7.2% higher on average than that of the LIP session. On average, the RPE for the
aerobic section of the HIP session (12.1) was consistently higher than that of the LIP session (11.1). HIP activity has the
potential to maintain/improve the aerobic fitness of its participants. According to the literature, the exercise intensity
elicited by LIP activity may have a limited training effect for the population utilised in this study, and for some individuals
may result in detraining. Conversely, LIP activities may be an appropriate mode of exercise for overweight and unfit individuals.
Accepted: 5 January 1998 相似文献
12.
Thierry Weissland P. Pelayo Jacques Vanvelcenaher Ga?lle Marais Jean-Marc Lavoie Hervé Robin 《European journal of applied physiology and occupational physiology》1997,76(5):428-433
The aims of the present study were: first, to assess the interindividual variations of a spontaneously chosen crank rate
(SCCR) in relation to the power developed during an incremental upper body exercise on an arm ergometer set at a constant
power regime, and second, to compare heart rate (HR) responses, expired minute ventilation (V˙
E) and oxygen consumption (V˙O2) when the pedal rates were chosen spontaneously (TSCCR) or set at ±10% of the freely chosen rates (T+10% and T−10%, respectively). The mean pedal rate values were linearly related (P < 0.01) with the power developed during arm cranking (r = 0.96), although large variations of pedalling rate strategies were observed between subjects. Maximal power (MP) and time
to exhaustion values were significantly higher (P < 0.05) during TSCCR than during T+10% and T−10%. Peak V˙O2 values were significantly higher (P < 0.05) in T+10% than in TSCCR and T−10%. The increase in HR, V˙
E, and V˙O2 mean values, in relation to the increase in the power developed, was significantly higher (P < 0.05) when the pedal rate was set at plus 10% of the SCCR (T±10%) than in the two other conditions. The findings of the present study suggest that the use of an electromagnetically braked
ergometer, which automatically adjusts the resistance component to maintain a constant work rate, should be used in order
to achieve the highest MP values during an incremental upper body exercise. A 10% increase of the SCCR should be used in order
to provide the highest peak V˙O2 value.
Accepted: 5 May 1997 相似文献
13.
Jerzy A. Zoladz Krzysztof Duda Joanna Majerczak 《European journal of applied physiology and occupational physiology》1998,77(5):445-451
A group of 12 healthy non-smoking men [mean age 22.3 (SD 1.1) years], performed an incremental exercise test. The test started
at 30 W, followed by increases in power output (P) of 30 W every 3 min, until exhaustion. Blood samples were taken from an antecubital vein for determination of plasma concentration
lactate [La−]pl and acid-base balance variables. Below the lactate threshold (LT) defined in this study as the highest P above which a sustained increase in [La−]pl was observed (at least 0.5 mmol · l−1 within 3 min), the pulmonary oxygen uptake (V˙O2) measured breath-by-breath, showed a linear relationship with P. However, at P above LT [in this study 135 (SD 30) W] there was an additional accumulating increase in V˙O2 above that expected from the increase in P alone. The magnitude of this effect was illustrated by the difference in the final P observed at maximal oxygen uptake (V˙O2max) during the incremental exercise test (P
max,obs at V˙O2max) and the expected power output at V˙O2max(P
max,exp at V˙O2max) predicted from the linear V˙O2-P relationship derived from the data collected below LT. The P
max,obs at V˙O2max amounting to 270 (SD 19) W was 65.1 (SD 35) W (19%) lower (P<0.01) than the P
max,exp at V˙O2max
. The mean value of V˙O2max reached at P
max,obs amounted to 3555 (SD 226) ml · min−1 which was 572 (SD 269) ml · min−1 higher (P<0.01) than the V˙O2 expected at this P, calculated from the linear relationship between V˙O2 and P derived from the data collected below LT. This fall in locomotory efficiency expressed by the additional increase in V˙O2, amounting to 572 (SD 269) ml O2 · min−1, was accompanied by a significant increase in [La−]pl amounting to 7.04 (SD 2.2) mmol · l−1, a significant increase in blood hydrogen ion concentration ([H+]b) to 7.4 (SD 3) nmol · l−1 and a significant fall in blood bicarbonate concentration to 5.78 (SD 1.7) mmol · l−1, in relation to the values measured at the P of the LT. We also correlated the individual values of the additional V˙O2 with the increases (Δ) in variables [La−]pl and Δ[H+]b. The Δ values for [La−]pl and Δ[H+]b were expressed as the differences between values reached at the P
max,obs at V˙O2max and the values at LT. No significant correlations between the additional V˙O2 and Δ[La−]pl on [H+]b were found. In conclusion, when performing an incremental exercise test, exceeding P corresponding to LT was accompanied by a significant additional increase in V˙O2 above that expected from the linear relationship between V˙O2 and P occurring at lower P. However, the magnitude of the additional increase in V˙O2 did not correlate with the magnitude of the increases in [La−]pl and [H+]b reached in the final stages of the incremental test.
Accepted: 30 October 1997 相似文献
14.
Takeshi Yamauchi Takeshi Harada Masashi Kurono Nobuo Matsui 《European journal of applied physiology and occupational physiology》1998,77(5):409-412
The present study was carried out to elucidate whether an exercise-induced increase in plasma hydrogen ion concentration
influences aldosterone secretion. Six healthy men (aged 22–25 years) performed two intermittent exercise tests with and without
drug administration. The intensities of these exercise tests were 40% maximal oxygen uptake (V˙O2max) and 90% V˙O2max, respectively. Administration of 2-mg Dexamethasone and 50-mg Captopril caused an almost complete suppression of adrenocorticotropic
hormone (ACTH) and an enhancement of the elevation in renin concentration during exercise, indicating successful inhibition
of ACTH release and angiotensin II production during exercise. While the magnitude of the increase in aldosterone in the drug
experiment was depressed compared with the control experiment, a significant increase in aldosterone concentration was observed
at the end of the 90% V˙O2max exercise. Whilst the change in aldosterone concentration did not correlate with the change in plasma potassium concentration,
there was a significant correlation between aldosterone and plasma hydrogen ion concentrations in the drug experiment. Since
the correlation coefficient was low (r=0.455), the biological meaning of this correlation should be further investigated. These results would suggest that an elevation
of plasma hydrogen ion concentration induced by exercise per se appears to be related, at least in part, with increased aldosterone
secretion, independent of the pituitary-adrenal axis, and the renin-angiotensin system.
Accepted: 23 September 1997 相似文献
15.
Gustave Savourey Jacques Bittel 《European journal of applied physiology and occupational physiology》1998,78(5):379-384
It has previously been demonstrated that metabolic heat production (M˙) during cold exposure at rest was related to maximal
oxygen uptake (O2max). Consequently, an increase in O2max could allow an increase M˙ in the cold. The aim of the present study was therefore to test this hypothesis. Eight male volunteers
undertook interval training (periods of 25% V˙O2max of 30-s duration and 110% V˙O2max of 60-s duration until exhaustion, five times a week over 8 weeks) to increase V˙O2max. Both before and after this physical training, they were subjected to a 10∘, 5∘ and 1∘C 2-h cold air test in a climatic chamber. During the cold exposure, rectal temperature (T
re), tympanic temperature (T
ty), mean skin temperature () and M˙ were measured as well as the time to onset of shivering (t) and body temperatures () at t. The results showed that physical training involved an increase in O2max (14%–15%, P < 0.05). During the cold exposure, T
re was higher after training both at 10∘,5∘ and 1∘C (P < 0.05) whereas were not significantly changed. However, an increase in the sensitivity of the thermoregulatory system was attested by a
decreased t at higher These slight physiological changes found after training were not related to the increases in V˙O2max. In conclusion, this study demonstrated that interval training induced slight thermoregulatory changes unrelated to changes
in V˙O2max and it suggested that M˙ during cold exposure could be related mainly to the level of V˙O2max observed before training, since increases in V˙O2max did not modify M˙.
Accepted: 8 April 1998 相似文献
16.
Olivier Bernard Frédéric Maddio Soualiho Ouattara Chantal Jimenez Annie Charpenet Bruno Melin Jacques Bittel 《European journal of applied physiology and occupational physiology》1998,78(6):578-585
During high-intensity running, the oxygen uptake (V˙O2) kinetics is characterised by a slow component which delays the attainment of the steady-state beyond the 3rd min of exercise.
To assess if the aerobic energy cost of running measured at the 3rd min (C
3) adequately reflects the variability of the true aerobic energy cost measured during the steady-state (C
ss), 13 highly-trained runners completed sessions of square-wave running at intensities above 80% maximal oxygen uptake (V˙O2max) on a level treadmill. To evaluate the time at which the steady-state V˙O2 was attained (t
ss), the V˙O2 responses were described using a general double-exponential equation and t
ss was defined as the time at which V˙O2 was less than 1% below the asymptotic value given by the model. All the subjects achieved a steady state for intensities
equal to or greater than 92% V˙O2max, and 8 out of 13 achieved it at 99% V˙O2max. In all cases, t
ss was less than 13 min. For intensities greater than 85% V˙O2max, C
ss was significantly higher than C
3 and was positively related to %V˙O2max (r= 0.44; P < 0.001) while C
3 remained constant. The C
3 only explained moderately the variability of C
ss (0.39 < r
2 < 0.72, depending on the velocity or the (relative intensity at which the relationship was calculated). Moreover, the excess
aerobic energy cost of running the (difference between C
ss and C
3) was well predicted by age (0.90 < r
2 < 0.93). Therefore, when the aerobic profile of runners is evaluated, it is recommended that their running efficiencies at
velocities which reflect their race intensities should be determined, with V˙O2 data being measured at the true steady-state.
Accepted: 1 June 1998 相似文献
17.
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
18.
M. De Angelis G. Vinciguerra A. Gasbarri C. Pacitti 《European journal of applied physiology and occupational physiology》1998,78(2):121-127
The aim of this research was to investigate the physiological responses and, in particular, the participation of lactic acid
anaerobic metabolism in aerobic dance, which is claimed to be pure aerobic exercise. In contrast to previous studies, that
have put subjects in very unfamiliar situations, the parameters were monitored in the familiar context of gymnasium, practice
routine and habitual instructor. A group of 30 skilled fairly well-trained women performed their usual routine,␣a combination
of the two styles: low (LI) and high impact (HI), and were continuously monitored for heart rate (HR) and every 8 min for
blood lactate concentration ([La−]b). Of the group, 15 were tested to determine their maximal aerobic power (V˙O2max) using a cycleergometer. They were also monitored during the routine for oxygen uptake (V˙O2) by a light telemetric apparatus. The oxygen pulses of the routine and of the corresponding exercise intensity in the incremental
test were not statistically different. The mean values in the exercise session were: peak HR 92.8 (SD 7.8)% of the subject's
maximal theoretical value, peak V˙O2 99.5 (SD 12.4)% of V˙O2max, maximal [La−]b 6.1 (SD 1.7) mmol · l−l, and mean 4.8 (SD 1.3) mmol · l−l. Repeated measures ANOVA found statistically significant differences between the increasing [La−]b values (P < 0.001). In particular, the difference between the [La−]b values at the end of the mainly LI phase and those of the LI-HI combination phase, and the difference between the samples
during the combination LI-HI phase were both statistically significant (both P= 0.002 and P= 0.002). The similar oxygen pulses confirmed the validity of the present experiment design and the reliability of HR monitoring
in this activity. The HR, V˙O2 and, above all, the increase of [La−]b to quite high values, showing a non steady state, demonstrated the high metabolic demand made by this activity that involved
lactic acid metabolism at a much higher level than expected.
Accepted: 23 September 1997 相似文献
19.
Roger Kaprielian Michael J. Plyley Panagiota Klentrou Leonard S. Goodman Jack M. Goodman 《European journal of applied physiology and occupational physiology》1998,78(2):141-147
Exercise intolerance in persons with paraplegia (PARAS) is thought to be secondary to insufficient venous return and a subnormal
cardiac output at a given oxygen uptake. However, these issues have not been resolved fully. This study utilized lower-body
positive pressure (LBPP) as an intervention during arm crank exercise in PARAS in order to examine this issue. Endurance-trained
(TP, n= 7) and untrained PARAS (UP, n= 10) with complete lesions between T6 and T12, and a control group consisting of sedentary able-bodied subjects (SAB, n= 10) were tested. UP and TP subjects demonstrated a diminished cardiac output (via CO2 rebreathing) during exercise compared to SAB subjects. Peak oxygen uptake (V˙O2peak) remained unchanged for all groups following LBPP. LBPP resulted in a significant decrease in heart rate (HR) in UP and TP
(P≤0.05), but not SAB subjects. LBPP produced an insignificant increase in cardiac output (Q˙) and stroke volume (SV). The significant decrease in HR in both PARA groups may indicate a modest hemodynamic benefit of
LBPP at higher work rates where circulatory sufficiency may be most compromised. We conclude that PARAS possess a diminished
cardiac output during exercise compared to the able-bodied, and LBPP fails to ameliorate significantly their exercise response
irrespective of the conditioning level. These results support previous observations of a lower cardiac output during exercise
in PARAS, but indicate that lower-limb blood pooling may not be a primary limitation to arm exercise in paraplegia.
Accepted: 11 December 1997 相似文献
20.
M. Sandsund M. Sue-Chu J. Helgerud R. E. Reinertsen L. Bjermer 《European journal of applied physiology and occupational physiology》1998,77(4):297-304
The effects of whole-body exposure to ambient temperatures of −15°C and 23°C on selected performance-related physiological
variables were investigated in elite nonasthmatic cross-country skiers. At an ambient temperature of −15°C we also studied
the effects of the selective β2-adrenergic agonist Salbutamol (0.4 mg × 3) which was administered 10 min before the exercise test. Eight male cross-country
skiers with known maximal oxygen uptakes (V˙O2
max
) of more than 70 ml · kg−1 · min−1 participated in the study. Oxygen uptake (V˙O2), heart rate (f
c), blood lactate concentration ([La−]b) and time to exhaustion were measured during controlled submaximal and maximal running on a treadmill in a climatic chamber.
Lung function measured as forced expiratory volume in 1 s (FEV1) was recorded immediately before the warm-up period and at the conclusion of the exercise protocol. Submaximal V˙O2 and [La−]b at the two highest submaximal exercise intensities were significantly higher at −15°C than at 23°C. Time to exhaustion was
significantly shorter in the cold environment. However, no differences in V˙O2
max
or f
c were observed. Our results would suggest that exercise stress is higher at submaximal exercise intensities in a cold environment
and support the contention that aerobic capacity is not altered by cold exposure. Furthermore, we found that after Salbutamol
inhalation FEV1 was significantly higher than after placebo administration. However, the inhaled β2-agonist Salbutamol did not influence submaximal and maximal V˙O2, f
c, [La−]b or time to exhaustion in the elite, nonasthmatic cross-country skiers we studied. Thus, these results did not demonstrate
any ergogenic effect of the β2-agonist used.
Accepted: 18 August 1997 相似文献