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1.
The present study was designed to investigate the interrelationships of pulmonary diffusing capacity for CO ( \(D_{L_{{\text{CO}}} } \) ), pulmonary capillary blood flow ( \(\dot Q_c \) ), oxygen uptake ( \(\dot V_{{\text{O}}_{\text{2}} } \) ), and related functions in exercise. Six young adult men were tested on a bicycle ergometer on 9–20 occasions at various intensities of exercise up to the maximal level that could be sustained for 5 min. Measurements at each exercise level included work load (kgm/min), heart rate (HR), minute ventilation (V I ), \(\dot Q_c \) , \(D_{L_{{\text{CO}}} } \) , and \(\dot V_{{\text{O}}_{\text{2}} } \) . Using regression analysis, it was established that \(\dot Q_c \) and D L CO increased linearly with \(\dot V_{{\text{O}}_{\text{2}} } \) throughout the work range in each subject and no tendency toward a plateau was observed. While the maximal value varied from subject to subject, there was no difference between individuals in the coefffcient describing the relationship of D L and \(\dot Q_c \) to \(\dot V_{{\text{O}}_{\text{2}} } \) . Combining all subjects, D L was found to increase linearly with \(\dot Q_c \) the regression equation being: $$D_L = 26.4 + 1.03{\text{ }}\dot Q_c ,{\text{ }}r = .79$$ These results suggest that high-intensity short-duration exercise (5 min) is probably not limited by either of these functions in normals.  相似文献   

2.
The cardiac frequency (f H ) and oxygen intake ( \(\dot V_{O_2 } \) ) responses to submaximal and maximal work with 1- and 2-arms and 1- and 2-legs on suitably modified bicycle ergometers in relation to the prediction of maximal aerobic power output ( \(\dot V_{{\text{O}}_{{\text{2max}}} }\) ) have been examined in 12 healthy male subjects. The results showed that the physiological responses to the different forms of submaximal and maximal exercise were distinct and dependent upon the effective muscle mass used to perform the work. The observed \(\dot V_{{\text{O}}_{{\text{2max}}} }\) of 1-limb could be converted to respective 2-limb value with a coefficient of variation ranging from 4 to 7%, but maximal work with the arms gave no guide to that of the legs. Extrapolation of the \(\dot V_{O_2 } \) /f H curve to the f H max in 1-leg (175 beats/min) and 2-arm (165 beats/min) resulted in an overestimation of \(\dot V_{{\text{O}}_{{\text{2max}}} }\) of +70 ± 200 ml · min?1 and +70 ± 240 ml · min?1; but in 1-arm work (153 beats/min), \(\dot V_{{\text{O}}_{{\text{2max}}} }\) was underestimated by ?70 ± 270 ml · min?1. The bias in predictions for the 3 forms of exercise could be removed by applying the appropriate regression equations relating predicted to observed \(\dot V_{{\text{O}}_{{\text{2max}}} }\) , but the overall accuracy of the extrapolation method was limited to ± 8%, ± 15% and ± 23% in 1-leg, 2-arm and 1-arm work respectively. It was concluded that maximal work with the upper and lower limbs should be treated separately and if an accuracy of greater than ± 8 to ± 23% is required in situations where through injury, two limb exercise cannot be performed, attempts should be made to ascertain the \(\dot V_{{\text{O}}_{{\text{2max}}} }\) of a single limb directly.  相似文献   

3.
The change in plasma catecholamine concentration (ΔC) has been studied in four healthy male subjects during work, involving different muscle groups, whilst breathing air and 45% oxygen. The results show that during arm and (1- and 2-) leg(s) work ΔC was more closely associated with relative (expressed as a % of \(\dot V_{{\text{O}}_{{\text{2max}}} }\) ) than absolute work load; a rise in C occurred at ~ 60% \(\dot V_{{\text{O}}_{{\text{2max}}} }\) in all 3 forms of exercise. However, in arm and 1-leg work the curves relating ΔC to % \(\dot V_{{\text{O}}_{{\text{2max}}} }\) were displaced to the right indicating the independence of the two variables. Further, breathing 45% oxygen reduced ΔC but was without effect on either \(\dot V_{O_2 } \) at a given work load or \(\dot V_{{\text{O}}_{{\text{2max}}} }\) . For a given \(\dot V_{O_2 } \) , ΔC was inversely related to the effective muscle (plus bone) volume used to perform the work and associated with change of blood lactic acid (LA) concentration, but again the use of exercise involving different muscle groups indicated that the changes in C and LA were essentially independent. This was also true of the changes of C with cardiac output but not cardiac frequency (f H ). Plasma C changed as a curvilinear function of f H , the association between the two variables being independent of type of exercise and inspired O2 concentration within the range used in this study. This suggests that the rise in C and f H in exercise may be closely related to circulatory stress and may reflect the degree of vasoconstriction present in ‘non-active’ tissues and efficacy of the body's ability to maintain the integrity of systemic blood pressure in the face of increased demands of the exercising muscles for blood and the transport of oxygen.  相似文献   

4.
In male elite swimmers \(\dot V_{{\text{O}}_{\text{2}} } \) at a given velocity in freestyle and backstroke was on average 1 to 2 l x min?1 lower as compared with breaststroke and butterfly. Except for breaststroke, swimming with arm strokes only demanded a lower \(\dot V_{{\text{O}}_{\text{2}} } \) at a given submaximal velocity than the whole stroke. In freestyle and backstroke the submaximal \(\dot V_{{\text{O}}_{\text{2}} } \) of leg kick at a given velocity was clearly higher than the whole stroke. The highest velocity during maximal swimming was always attained with the whole stroke, and the lowest with the leg kick, except for breast stroke, where the leg kick was most powerful. At a given submaximal \(\dot V_{{\text{O}}_{\text{2}} } \) , heart rate and \(\dot V_{\text{E}} :\dot V_{{\text{O}}_{\text{2}} } \) tended to be higher during swimming with arm strokes only as compared with the whole stroke. Highest values for \(\dot V_{{\text{O}}_{\text{2}} } \) , heart rate and blood lactate during maximal exercise were almost always attained when swimming the whole stroke, and lowest when swimming with arm strokes only. At higher velocities body drag was 0.5 to 0.9 kp lower when arms or legs were supported by a cork plate as compared with body drag without support.  相似文献   

5.
The maximal aerobic power of six highly trained young cyclist, mean age 16.3 years and mean \(\dot V_{O_2 \max } \) 4.9 l/min, was directly measured at intervals of 4 hrs. A Latin square design was used for the test order. At submaximal work of O2-consumption 2.4 to 4.4 l/min no circadian variation of any single function was found. However, at maximal work load the differences between the maxima and minima values were 12.4% for maximal work output ( \(\dot W_{\max } \) ), 7.8% for expiratory minute volume ( \(\dot V_{E\max } \) ), 5.7% for maximal aerobic power ( \(\dot V_{O_2 \max } \) ) and 3.4% for maximal heart rate (HR max). All the functions—with the exception of \(\dot V_{O_2 \max } \) —had their minima at 0300 hrs; the minima of \(\dot V_{O_2 \max } \) was reached already at 2300 hours. The maxima-values of \(\dot V_{E\max } \) and \(\dot V_{O_2 \max } \) were measured at 1500 hrs, of \(\dot W_{\max } \) andHR max at 0700 and ofHR rest at 1900 hrs correspondingly. A one-tailed test showed significant differences between the maxima and minima values of all variables (P<0.05). The results suggest a decreased cardiopulmonary working capacity at night. However, this impairment is only of practical importance if the work will be done near the limit of endurance capacity. Besides it will suggest, that the indirect methods for assessing the cardiopulmonary capacity based on \(\dot V_{O_2 \max } \) and \(\dot W_{170} \) are not useful at nighttime, because the presuppositions for these methods are limited of the time of day.  相似文献   

6.
The responses to 1-leg submaximal and maximal exercise have been studied in four male subjects before and after a 5 week training programme. One leg was trained under normoxic conditions and the other under hypoxic ( \(F_{IO_2 } \) =0.12) conditions for 30 min/day, 3 times/week at a fixed absolute work load which approximated to 75% of the limb's normoxic \(\dot V_{O_2 \max } \) . Before and after training both limbs were measured in normoxia, one limb was additionally measured in hypoxia. The aim of the experiments being to use each subject as his own control and to try and elucidate the effects of hypoxia per se as a training stimulus to the improvement of maximal aerobic power output ( \(\dot V_{O_2 \max } \) ) measured in normoxia. The results showed that before training the responses to exercise at submaximal and maximal levels were identical in each limb; the effects of hypoxia being to raise V E1.5 and f H1.5, to reduce \(\dot V_{O_2 \max } \) and to leave \(\dot V_{O_2 450} \) unchanged. The effects of the two types of training were to reduce \(\dot V_{O_2 450} \) , decrease f H1.5 and increase \(\dot V_{O_2 \max } \) , the effects being independent of the \(F_{IO_2 } \) . The changes in \(\dot V_{O_2 \max } \) of the hypoxic and normoxic trained legs were related to the initial \(\dot V_{O_2 \max } \) of each subjects' limb. It was concluded that our investigation lends no support to the view that hypoxia has either an additive or potentiating effect with exercise during a training programme on the improvement of aerobic power output measured under normoxic conditions.  相似文献   

7.
The purpose of this study was to consider which characteristics are related to a high velocity in water during swimming. The study was performed on 13 of the best competition swimmers of the region of Lyon (France). The collected data were: \(\dot V_{O_2 } \) max, measured during leg-work ( \(\dot V_{O_2 } \) max LW), during arm-work ( \(\dot V_{O_2 } \) max AW), and the hydrodynamic resistances measured when the swimmers were towed at the speed of 1.80 m/sec. The cardiac output was measured for four of the subjects. The swimmers were characterized by a mean \(\dot V_{O_2 } \) max LW of 56 ml/kg/min and by a high value of the ratio \(\frac{{\dot V_{O_2 } \max {\text{ }}AW}}{{\dot V_{O_2 } \max {\text{ }}LW}}\) which reached 99% for three of them. There was a very high correlation (r = 0.90 and 0.91) between the mean speed calculated from the best performances in competition swims of 400 m and 1500 m and a value which is thought to express the aerobic energy available to the swimmer: $$\dot V_{O_2 } \max water:\dot V_{O_2 } \max {\text{ }}AW + \frac{{\dot V_{O_2 } \max {\text{ }}LW - \dot V_{O_2 } \max {\text{ }}AW}}{6}$$   相似文献   

8.
The criteria of max \(\dot V_{O_2 } \) and max O2 D which are traditionally used in studying aerobic and anaerobic work capacity, have the different dimensions. While max \(\dot V_{O_2 } \) is an index of the power of aerobic energy output, max O2 D assesses the capacity of anaerobic sources. For a comprehensive assessment of physical working capacity of athletes, both aerobic and anaerobic capabilities should be represented in three dimensions,i.e. in indexes of power, capacity and efficiency. Experimental procedures have been developed for assessing these three parameters in treadmill running tests. It is proposed to assess anaerobic power by measuring excess CO2, concurrently with determination of max \(\dot V_{O_2 } \) . Maximal aerobic capacity is established as the product of max \(\dot V_{O_2 } \) by the time of max \(\dot V_{O_2 } \) maintenance determined in a special test with running at critical speed. The ergometric criteria derived on the basis of the tests proposed, may be used for systematization of various physical work loads.  相似文献   

9.
Tonic and phasicI Na blockade by antiarrhythmics   总被引:6,自引:0,他引:6  
Drug-induced depression ofI Na was studied in microelectrode experiments on papillary muscles of guinea pigs by taking \(\dot V_{\max } \) of the fast Naü action potential as an estimate forg max thereby systematically discriminating between tonic and phasic blockade.
  1. The antiarrhythmic compound propafenone and its derivatives butafenone and Sa 76, which are structurally related to local anesthetics, exerted a tonic and phasic \(\dot V_{\max } \) blockade. At a given drug concentration, the strength as well as the kinetics of development and removal of phasic block are functions of the interstimulus interval. The slope of the curve relating the strength to the interstimulus interval indicates the sensitivity of phasic block to changes in stimulation rate. It depends on the molecular structure of the drug and can be also affected by the resting potential. With increasingly shorter interstimulation intervals, phasic inhibition became more marked and developed faster. However, when the development kinetics are considered as an event-dependent process, the fraction of complete phasic block that is installed per single excitation decreases.
  2. Each type of drug-induced \(\dot V_{\max } \) block possesses its own individual apparent dissociation constant and apparentn H coefficient. In the case of propafenone, for instance, the apparentK m's for tonic and phasic inhibition (at a frequency of 120/min) were 4.4×10?5 mol/l and 1×10?5 mol/l, respectively, and the apparentn H's amounted to 1.76 and 0.84, respectively. The apparentK m for the phasic block depends on the interstimulus interval and decreases with an increase in stimulation rate. The stoichiometry of the underlying drugreceptor interaction, however, remains virtually unaffected since the apparentn H of the phasic \(\dot V_{\max } \) block proved insensitive to frequency changes.
  3. Propafenone wash-out experiments revealed that tonic and phasic \(\dot V_{\max } \) block disappeared with individual time constants differing by a factor of 3–5 from each other.
  4. TTX (5×10?6 mol/l) enhanced the propafenone action and intensified tonic and phasic \(\dot V_{\max } \) blockade. Each block exhibited an individual quantitative response. Tonic blockade became stronger by a factor of 3.1±0.72, but phasic block by a factor of 1.9±0.1.
  5. Chemical channel modification induced by formaldehyde increased the inhibitory efficacy of propafenone. Again, tonic \(\dot V_{\max } \) blockade responded more sensitive than phasic blockade and the former rose by a factor of 6.9 but the latter by a factor of only 1.5.
  6. These results can be satisfactorily accounted for in terms of the modulated single receptor hypothesis (HHK model).
  相似文献   

10.
Criteria for the identification of maximal steady state as related to state of conditioning were evaluated. 13 volunteers walked and/or ran during a series of 15 min tests on a treadmill. The speeds ranged from mild to exhaustive. Heart rate was monitored continuously; \(\dot V_{O_2 } \) was determined from 6 min to 9 min; and venous blood was obtained at 10 min and 15 min for lactate analyses. Max \(\dot V_{O_2 } \) was established for each subject. Subjects were classified on level of conditioning according to the quantity and quality of their activity record for the previous 6 months. The 10 min heart rate associated with a blood lactate level of 2.2 mM/L (MSSHR) was the best predictor of conditioning. The relative \(\dot V_{O_2 } \) (% of max \(\dot V_{O_2 } \) ) found with a 10 min blood lactate concentration of 2.2 mM/L (RMSS \(\dot V_{O_2 } \) ) was almost as accurate as MSSHR in predicting state of conditioning. Changes in blood lactate levels between 10 min and 15 min were not significantly related to conditioning.  相似文献   

11.
The effect of an increased body temperature (T r) elicited by prolonged heavy exercise at normal ambient temperature in absence of any heat stress, on the maximal aerobic power ( \(\dot V_{O_2 \max } \) ) and on heart rate (HR) has been studied. The prolonged exercise consisted in running for 1 hr on a motor driven treadmill, this leading to an average increase of T r of 1.2° C. Oxygen consumption ( \(\dot V_{O_2 } \) ), ventilation (V I ), HR and T r were measured at rest and every 10 min during the prolonged exercise. Before and after this exercise indirect measurement of \(\dot V_{O_2 \max } \) were made. After the exercise, HR in submaximal exercise was increased, the increase being less pronounced the heavier the exercise. The HR increment was 17.5 beats/min per 1° C rise in T r in the exercise involving an oxygen comsumption of 22 ml/kg·min and it dropped to 7.5 b/min · °C when the O2 consumption increased to 32.4 ml/kg · · min. \(\dot V_{O_2 \max } \) as calculated indirectly from HR values in submaximal exercise remained essentially the same before and after the treadmill run.  相似文献   

12.
From a population of 20 healthy male volunteers, half performed constant speed, incremental load maximal aerobic capacity ( \(\dot V_{O_2 \max } \) ) tests on a motor-driven treadmill, while the other half performed similar \(\dot V_{O_2 \max } \) tests on a bicycle ergometer. The two groups, matched for size and age, showed no significant differences in \(\dot V_{O_2 \max } \) , maximum heart rate, or in post-exercise (4 min) peripheral venous blood concentrations of lactate or pyruvate. However, post-exercise peripheral venous blood ammonia levels were significantly higher in the group tested on the bicycle ergometer than in the treadmill group.  相似文献   

13.
The predictability of maximum oxygen uptake ( \(\dot V_{O_2 }\) max) was tested on 78 male subjects taken from four different age-groups (ages: 9 to 10, 13 to 14, 17 to 18, 20 to 52). \(\dot V_{O_2 }\) max and W170 were measured during the same experiment, both with stepwise respectively continuously increasing loads on the bicycle ergometer. Oxygen uptake and heart rate were measured at submaximal and maximal workloads. We examined the predictability of \(\dot V_{O_2 }\) max by following the methods described by åstrand and Ryhming (1954), Margaria et al. (1965), and Rutenfranz (1971). We also examined the W170-test which gives a direct information on submaximal criteria and requires no further extrapolation and the equation given by Müller (1961 a, b), which allows to compare results of the LPI-method for assessing the endurance limit at submaximal work with the method of I. åstrand (1960) to determine the endurance limit as percentage of maximal aerobic power. When we used the methods mentioned above we observed a considerable underestimation of the measured \(\dot V_{O_2 }\) max. The results obtained by Müller's equation, however, deviated unsystematically from measured \(\dot V_{O_2 }\) max. By means of age-correcting factors according to I. åstrand (1960) respectively to von Döbeln et al. (1967) it is possible to adjust the prediction of \(\dot V_{O_2 }\) max without inquiring into the sources of the observed deviations. By means of special factors to correct extrapolation we were, however, able to avoid an error that is typical of all methods which determine \(\dot V_{O_2 }\) max based on the linear relationship between pulse frequency and oxygen uptake during work by extrapolation to maximal heart rate. This error is due to an underestimation of \(\dot V_{O_2 }\) max as there is no linear relationship between heart rate and O2-consumption in the upper performance section. In this section O2-consumption increases more with increasing workload than heart rate. In order to compare the above mentioned procedures we transformed the original formulas and adapted them to the conditions we met in our own experiments. The coefficients of validity with the exception of those calculated according to Müller show that there do not exist any striking differences. The cardio-vascular performance capacity was estimated equally well by means of W170. In predicting \(\dot V_{O_2 }\) max the standard deviation was 7 to 10,5%. The mean error of a single determination was 4 to 7%, whether \(\dot V_{O_2 }\) max was measured or predicted.  相似文献   

14.
Comparisons have been made in 7 dogs between maximum oxygen consumption recorded before (N dogs) and after thyroidectomy (T dogs). The comparisons were performed under two conditions 1) during severe cold stress (C \(V_{O_2 }\) max), 2) during a short period of exhaustive work (Ex \(\dot V_{O_2 }\) max). Heart rate, plasma catecholamine and substrate concentrations (glucose, lactic acid, FFA) were measured under each condition.
  1. Thyroidectomy induced a more substantial decrease in C \(\dot V_{O_2 }\) max than in Ex \(\dot V_{O_2 }\) max.
  2. At C \(\dot V_{O_2 }\) max, average plasma epinephrine and norepinephrine concentrations rose to a higher level in T dogs than in N dogs. In T dogs, correlations were found between plasma epinephrine concentrations and C \(\dot V_{O_2 }\) max values, and between plasma norepinephrine concentrations and C \(\dot V_{O_2 }\) max values. At Ex \(V_{O_2 }\) max, average plasma norepinephrine concentrations were similar in N dogs and in T dogs, and average plasma epinephrine concentrations were not significantly different from each other.
  3. At Ex \(\dot V_{O_2 }\) max, average plasma concentrations of the various substrates were not significantly different in N dogs and T dogs. At C \(\dot V_{O_2 }\) max, plasma FFA levels were higher in T dogs.
It may be concluded that in dogs, thyroidectomy affects mechanisms which are more specifically involved in heat production than in muscular exercise. The increased catecholamine secretion in response to cold which occured in T dogs appeared merely to limit the decrease in heat production. It seems possible that increased catecholamine secretion compensates for the decreased sensitivity of β receptors to catecholamine but it cannot fully account for the effects of thyroidectomy.  相似文献   

15.
The metabolic cost of one healthy male subject aged 31 years, running on a range of gradients from +5% to ?45% at speeds varying from 6.0 km · h?1 to 18.0 km · h?1, on a motor-driven treadmill, has been investigated. The results showed that the “apparent” efficiency of running increased with gradient from 0 to ?15% and then remained fairly constant at a value similar to that found for downhill walking (see Davies and Barnes [6]) of ?1.2 until a gradient of ?35% was reached. Beyond this gradient, there was a further rise in efficiency to reach ?1.41 at ?45%. The speed of running was controlled by stride length from 0 to ?20%, but at higher gradients there was an increase in step frequency which was speed dependent. The relationships of \(\dot V_E /\dot V_{O_2 } \) and \(f_H /\dot V_{O_2 } \) were similar to those previously decribed for downhill walking except that at gradients >?15% there was a parallel displacement of the \(f_H /\dot V_{O_2 } \) to the right. The relationship of \(\dot V_{O_2 } \) to speed of running uphill and downhill was essentially linear and thus for both forms of exercise, for a given gradient, the aerobic cost of running per unit distance covered was constant and independent of speed.  相似文献   

16.
Even though the electrical activity of the heart varies very slowly with time, a complete and thorough investigation of the heart activity in terms of time-varying potentials and fields has been studied. Starting from Maxwell's equations in their vector partial differential equation form, a vector partial differential equation of the electric Hertzian vector potential \(\bar \Pi \) is set up in terms of the assumed electric dipole moment per unit volume of the electrical heart activityP. The equation is solved in terms of an infinite series in \(\bar \Pi \) and then approximated only to its first term since it converges extremely fast. The potential distribution inside the body ?, the electric field intensity \(\bar E\) , and the magnetic field intensity \(\bar H\) , are derived from \(\bar \Pi \) in terms of \(\bar P\) . Thus ?, \(\bar E\) and \(\bar H\) are known in terms of \(\bar P\) , the source. Next, the inverse problem is investigated since it is of unique importance i.e. to determine \(\bar P\) knowing ?, \(\bar E\) or \(\bar H\) . This is done in two different ways: the ‘electric’, ECG, and the ‘magnetic’, MCG. A comparison between the ECG and MCG follows and, finally, ways of determining \(\bar P\) ‘electrically’ and ‘magnetically’ are given.  相似文献   

17.
A system for online compensation and differentiation of blood-pressure pulse waves was developed which compensates for pressure-waveform distortion due to transmission, in fluid-filled catheters and provides outputs of pressure P, \(\dot P\) , P/ \(\dot P\) and \(\dot P\) . The compensator can be tuned with the catheter in place by changing the natural frequency and damping ratio when these catheter parameters are altered by fibrin deposits, gas bubbles, and softening of the catheter wall. The compensator can be used with standard monitoring equipment and its output can be recorded or displayed on a cathode-ray-tube oscilloscope.  相似文献   

18.
An experimental increase in left atrial pressure (eLAP↗) leads to an increase in sodium excretion (UNa \(\dot V\) ). This ‘atrial natriuresis’ is probably involved in the adjustment of sodium balance, but the mechanism is not well understood. The present studies were undertaken to examine
  1. the influence of eLAP↗ on plasma renin activity (PRA) and UNa \(\dot V\) in conscious dogs, and
  2. the influence of eLAP↗ on UNa \(\dot V\) with and without the presence of adrenal glands.
Twenty-three female beagle dogs were kept under controlled environmental conditions. They had chronically implanted instruments (purse string around the mitral annulus, catheter in the left atrium, carotid loop; 5 dogs were adrenalectomized). PRA waselevated by a chronic low sodium intake (LSI). When eLAP↗ was performed (+1.0 kPa), PRA decreased by about 50% within at least 60 min. PRA was chronicallylowered by a high sodium intake (HSI). Even under HSI conditions a decrease of PRA could be demonstrated if eLAP↗ was performed (by about 50%). However both HSI and LSI dogs showed a marked increase in UNa \(\dot V\) if eLAP↗ was performed. After the removal of the adrenals a decrease in glomerular filtration rate was observed (40% of the control values), but eLAP↗ led to a similar increase in UNa \(\dot V\) to that found in intact dogs (Δ mean 110%). These results indicate that stretching of the left atrium leads to a reduction of tubular sodium reabsorption in a twofold manner: 1st by reduction of PRA, possibly followed by a reduction in aldosterone secretion and 2nd by activating an adrenal independent mechanism of unknown origin. This could be a direct influence of angiotensin II on the tubular reabsorption of sodium. These results are compatible with the hypothesis that reflexes out of the low pressure system are important for the adjustment of sodium balance independent of changes in mineralocorticoid activity.  相似文献   

19.

Purpose

To assess the validity of predicting peak oxygen uptake ( $ {\dot{\text{V}}}{\text{O}}_{{\text{2peak}}}$ ) from differentiated ratings of perceived exertion (RPE) obtained during submaximal wheelchair propulsion.

Methods

Three subgroups of elite male wheelchair athletes [nine tetraplegics (TETRA), nine paraplegics (PARA), eight athletes without spinal cord injury (NON-SCI)] performed an incremental speed exercise test followed by graded exercise to exhaustion ( $ {\dot{\text{V}}}{\text{O}}_{{\text{2peak}}}$ test). Oxygen uptake ( $ {\dot{\text{V}}}{\text{O}}_2$ ), heart rate (HR) and differentiated RPE (Central RPEC, Peripheral RPEP and Overall RPEO) were obtained for each stage. The regression lines for the perceptual ranges 9–15 on the Borg 6–20 scale ratings were performed to predict $ {\dot{\text{V}}}{\text{O}}_{{\text{2peak}}}$ .

Results

There were no significant within-group mean differences between measured $ {\dot{\text{V}}}{\text{O}}_{{\text{2peak}}}$ (mean 1.50 ± 0.39, 2.74 ± 0.48, 3.75 ± 0.33 L min?1 for TETRA, PARA and NON-SCI, respectively) and predicted $ {\dot{\text{V}}}{\text{O}}_{{\text{2peak}}}$ determined using HR or differentiated RPEs for any group (P > 0.05). However, the coefficients of variation (CV %) between measured and predicted $ {\dot{\text{V}}}{\text{O}}_{{\text{2peak}}}$ using HR showed high variability for all groups (14.3, 15.9 and 9.7 %, respectively). The typical error ranged from 0.14 to 0.68 L min?1 and the CV % between measured and predicted $ {\dot{\text{V}}}{\text{O}}_{{\text{2peak}}}$ using differentiated RPE was ≤11.1 % for TETRA, ≤7.5 % for PARA and ≤20.2 % for NON-SCI.

Conclusions

Results suggest that differentiated RPE may be used cautiously for TETRA and PARA athletes when predicting $ {\dot{\text{V}}}{\text{O}}_{{\text{2peak}}}$ across the perceptual range of 9–15. However, predicting $ {\dot{\text{V}}}{\text{O}}_{{\text{2peak}}}$ is not recommended for the NON-SCI athletes due to the large CV %s (16.8, 20.2 and 18.0 %; RPEC, RPEP and RPEO, respectively).  相似文献   

20.
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