Biomedical subjects

C Préfaut

Publications and source records attributed to C Préfaut.

At least 73 records · Page 4Linked to original sources

PubMed1997

Effectiveness of individualized aerobic training at the ventilatory threshold in the elderly.

This study was designed to specify whether an individualized training program at the ventilatory threshold in elderly subjects produces greater training adaptations than a standardized training program performed at 50% of heart rate reserve. Sixteen subjects participated in the study. Maximal exercise tests were performed on a treadmill before and after the training program. Eight subjects trained at the ventilatory threshold (ITG) and eight trained at 50% of heart rate reserve (STG). The mean training heart rate was 129 +/- 14.2 bpm and 115 +/- 7.9 bpm in the individualized training group (ITG) and the standardized training group (STG), respectively. The maximal O2 uptake (VO2max) was improved significantly by 20% in ITG (within group p < .05), whereas no significant improvement was noted in STG. The improvement in ITG compared to the nonsignificant change in STG was significant (p < .05). In addition, submaximal ventilation and heart rate were more decreased in ITG than STG. We conclude that for elderly people an individualized training program at the level of the ventilatory threshold is significantly more effective in terms of VO2max and submaximal cardiorespiratory adaptations.

Adaptation, Physiological↗

PubMed1997

Inhibition of histamine release by nedocromil sodium reduces exercise-induced hypoxemia in master athletes.

During exercise in highly-trained older master athletes (MA), the impairment of pulmonary gas exchanges has been shown to be associated with a concomitant increase in histamine release (2). To determine the role of the histamine released (% H) during exercise-induced hypoxemia, seven MA (age 63.2 yr +/- 1.9), all of whom were known to develop exercise-induced hypoxemia, performed two maximal incremental exercise tests at a one-month interval after administration of nedocromil sodium (which inhibits histamine and other mediator release) or placebo in random double-blind order. During exercise testing, blood samples for arterial blood gas analysis and histamine assay were drawn at rest, exercise and recovery. Nedocromil sodium induced an inhibition in % H (0.57 +/- 0.03 at maximal load (Pmax) with placebo vs 0.24 +/- 0.02 with nedocromil sodium) linked with an improvement of pulmonary gas exchange (PaO2: 71.1 +/- 1.4 at Pmax with placebo vs 83.4 +/- 3 with nedocromil sodium; D(Ai-a)O2: 37.5 +/- 1.4 at Pmax vs 19.1 +/- 3.1, respectively). These results confirm the link established between the increase in histamine and exercise-induced hypoxemia in master athletes.

Aged↗

PubMed1997

Wingate test performance in children with asthma: aerobic or anaerobic limitation?

To investigate the anaerobic capacity in children with bronchial asthma, eight male children with atopic asthma (age: 12 +/- 1.7 yr) and seven healthy control subjects (age: 12 +/- 1 yr) performed a 30-s all-out exercise test: the Wingate anaerobic test (WanT). Post-exercise plasma epinephrine (E), norepinephrine (NE), venous blood lactate (La), and blood pH levels were determined. Peak power (Ppeak), mean power (Pm), and total energy expenditure (Wtot) during the WanT were assessed. The relative importance of aerobic (WO2) and anaerobic (Wana) energy release during the WanT was also evaluated. In comparison with control subjects, the children with asthma exhibited lower Ppeak (W.kg-1): 6 +/- 1.14 vs 7.3 +/- 0.5, P < 0.05; lower Pm (W.kg-1): 4.7 +/- 0.8 vs 5.9 +/- 0.5, P < 0.05; and lower Wtot (Jg-1): 140.3 +/- 25 vs 176.9 +/- 19, P < 0.05. The relative contribution of WO2 (26%) and Wana (74%) to the Wtot was identical in both groups. Blood lactate and pH kinetics revealed significantly lower La values and less acidosis in the asthmatic group (P < 0.001). Lastly, E (pg.ml-1) concentrations were lower in the asthmatic group: 274.96 +/- 84.58 vs 901.28 +/- 604.76, P < 0.05. These results suggest a reduced anaerobic capacity in children with asthma. A diminished adrenergic response to exhausting exercise, leading to a decreased anaerobic glycolysis, could partly account for this phenomenon.

Adolescent↗

PubMed1997

Comparison of two training programmes in chronic airway limitation patients: standardized versus individualized protocols.

This study tested the effect of two methods of training, one individualized at the heart rate corresponding to the gas exchange threshold (GET) and the other at the heart rate corresponding to 50% of maximal heart rate reserve, on maximal and submaximal cardiorespiratory response in 24 patients with chronic airway limitation (CAL). The patients were randomly assigned to either the individualized training group (IT; n = 12) or the standardized training group (ST; n = 12). The training programme consisted of 4 weeks of stationary bicycle exercise, 5 days.week-1. Before reconditioning began, the target level based on heart rate was not significantly different between groups (109 +/- 4 versus 110 +/- 3 beats.min-1, in IT and ST, respectively). Post-training, a significant increase in symptom-limited oxygen uptake (V'O2.sl) and maximal O2 pulse was found in IT, whereas ST exhibited no significant change. In each group, GET was statistically increased in much the same way as V'O2,sl, with a higher increase in IT (p < 0.01) than ST (p < 0.05). Nevertheless, IT exhibited a concomitant and gradual decrease in minute ventilation (V'E), carbon dioxide production (V'CO2), and venous lactate concentration ([La]), whereas ST presented no significant change in these parameters (intergroup p < 0.01). Breathing pattern was also altered after IT, at the same metabolic level and at the same ventilation level (intergroup p < 0.05). Cardiac responses were modified in the two groups. At the same metabolic level, a significantly lower cardiac frequency was found both for IT and ST (intragroup p < 0.05 after training). In contrast, the increase in O2 pulse was only significantly higher in It after training. These data show the greater efficiency of an individualized training protocol based on determination of gas exchange threshold as compared to a standardized protocol, in improving exercise performance, when applied to a patient group. Despite an apparently similar target training level, the individualized method clearly optimized the physiological training effects in patients with chronic airway limitation and, more particularly, decreased their ventilatory requirement.

Bicycling↗

PubMed1997

High-resolution CT scan in the evaluation of exercise-induced interstitial pulmonary edema in cardiac patients.

OBJECTIVE: To evaluate the onset of exercise-induced interstitial pulmonary edema in cardiac patients by high-resolution CT (HRCT). DESIGN: Prospective, normal controlled. PARTICIPANTS: Thirty subjects divided into three groups: group 1--10 outpatients with chronic congestive heart failure (CCHF), New York Heart Association (NYHA) class I; group 2--10 outpatients with CCHF, NYHA class II/III; and group 3 (control)--10 normal subjects. METHOD: HRCT scans were obtained at rest and 4, 8, 12, 16, and 20 min after progressive treadmill exercise test. RESULTS: The following HRCT findings consistent with interstitial edema were significantly different (p<0.05) in group 2 when compared with groups 1 and 3: artery/bronchus ratio > 1 in the upper lobes, peripheral increase in the vascular markings, interlobular septal thickening, and peribronchial "cuffing." These differences were maximal at 12 min after exercise and returned to normal values after 20 min. CONCLUSION: Interstitial pulmonary edema was present immediately after exercise in CCHF patients. It may be important in the genesis of dyspnea of these patients.

Adult↗

PubMed1997

[Diaphragm kinetics coupled with spirometry. M-mode ultrasonographic and fluoroscopic study; preliminary results].

Most techniques used so far for the evaluation of diaphragm kinetics are either invasive (electromyography, fluoroscopy), or indirect (respiratory pressures, impedance plethysmography). The aim of this study was to determine whether assessment with ultrasound or fluoroscopy differed, and which technique appeared more suitable in the investigation of quantitative hemidiaphragmatic displacement. Six patients (3 female, 3 male, aged 29 to 40) without respiratory disease were studied during systematic X-Ray chest examination, spirometry, and abdominal sonography. The amplitude of the right diaphragm motion could be measured in all patients with M-mode sonography as well as with fluoroscopy. The vertical ascending motion of the diaphragm measured by M-mode sonography, reached 60% of its maximum amplitude at 50% of inspiratory capacity. There was a significant correlation between the maximum amplitude of diaphragm motion as measured by M-mode sonography (5.8 +/- 0.4 cm; r = 0.89; p = 0.019) or fluoroscopy (5.6 +/- 0.7 cm; r = 0.84; p = 0.036) and the inspiratory capacity (2.73 +/- 0.39 l). M-mode sonography has technical, quantitative and qualitative advantages over fluoroscopy and should be the method of choice in the investigation of suspected diaphragmatic movement disorder. When coupled with other techniques like spirometry, this technique could represent a useful adjunct to functional respiratory studies.

Adult↗

PubMed1997

[Value and indications of exercise test in pneumology].

Exercise testing is the only integrate exploration technique, i.e., a technique which tests pulmonary, cardiac and muscular function, currently available in pneumology. The first indication for exercise testing in pneumology is to evaluate the exercise capacity of dyspnea patients. This can be done by measuring exercise tolerance and by differentiating each of the elements in the oxygen transport chain which can contribute to the dyspea, from a classical diagnostic standpoint, the exercise test can be used to screen for post-exercise asthma or a right-left shunt, estimate the severity of respiratory disease by demonstrating, for example, exercise-induced hypoxia. The exercise test also plays a fundamental role in preoperative evaluation prior to surgical resection of lung transplantation. It can also serve as a natural follow-up for treatment of respiratory diseases. One final and fundamental indication for exercise.

Exercise Test↗

PubMed1997

[Factors limiting exertion in respiratory diseases].

Factors limiting exercise capacity in patients with respiratory disease are determined in part by their response to an exercise test. Exercise tests evaluate the overall oxygen transport chain, i.e. exercise tolerance. The basic parameter is maximal oxygen consumption, VO2max which is very low in respiratory diseases. Decreased exercise tolerance results first from limited ventilatory capacity at maximal exercise: ventilatory reserve in these patients is low. At submaximal exercise, ventilation is on the contrary increased for a given exercise load. This relative hyperventilation is the consequence of the patient's general poor physical condition. In these patients the cardiovascular response to exercise is impaired because of decreased systolic ejection fraction related to bronchial obstruction. Finally, whatever investigation method is used, the metabolic response in patients with respiratory disease, i.e. peripheral muscle response, is greatly impaired. The aerobic is deficient and the anaerobic pathway predominates, sign that the sedentary status of these patients has altered their metabolic response.

Exercise Test↗

PubMed1997

[Interpreting exercise tests].

The main objective of the maximal exercise test is to measure a patient's exercise limit and to identify the cause. The test to be interpreted is evaluated first by judging exercise tolerance on the basis of maximal oxygen consumption (VO2max or symptom-limited VO2(VO2 SL). Intolerance is moderate if VO2 is under 85% of the theoretical level and severe when it is under 60%. Interpretation then consists in identifying the cause of the limitation. Ventilatory reserve is the main element for determining whether the limitation is due to ventilatory or cardiac impairment. In case of a ventilatory limitation, ventilatory reserve falls and the ventilatory pattern and gasometric values orient the diagnosis to emphysema, diffuse interstitial lung disease or bronchopneumopathy. If the ventilatory reserve rises, the limitation has cardiac as origin and in this case the oxygen pool is decreased. Persistence of chronotrope reserve can indicate coronary artery disease while the VD/VT ratio is useful for differentiating cardiac and vascular limitations. Peripheral limitations usually produce an early major increase in blood lactate, a high lactate/pyruvate ratio, with lactate or ventilatory thresholds under 40% of theoretical VO2max, especially in case of muscle pain and low watt equivalent. Nevertheless, these parameters cannot be used to confirm a precise diagnosis. The only positive diagnosis given by the exercise test concerns glycogenolysis disorders (por example McArdle's disease) seen as a total absence of increased lactate level. In conclusion, the exercise test is a means of assessing a patient's exercise tolerance and provides arguments for determining the origin of the limitation. However, as no one argument is truly pathognomonic, the diagnosis hypothesis must be based on all the elements available from clinical examination and complementary explorations.

Exercise Test↗

PubMed1996

Lactate uptake by forearm skeletal muscles during repeated periods of short-term intense leg exercise in humans.

We investigated the role of the forearm skeletal muscles in the removal of lactate during repeated periods of short-term intensive leg exercise, i.e. a force-velocity (FV) test known to induce a marked accumulation of lactate in the blood. The leg FV test was performed by seven untrained male subjects. Arterial and venous blood samples for determination of arterial ([la-]a) and venous ([la-]v) plasma lactate concentrations were concomitantly taken at rest before the test, during the FV test at the end of each period of intensive exercise just before the 5-min between-sprint recovery period, and after the completion of the test at 2, 4, 6, 8, 10, 15, and 20 min of the final recovery. The arteriovenous difference in concentration for plasma lactate ([la-]a-v) was determined for each blood sample. During the test, [la-]a and [la-]v increased significantly (P < 0.001; P < 0.001) with significantly higher values for [la-]a (P < 0.001). At the onset of the test, [la-]a-v became positive and increased up to a braking force of 6 kg, correlating significantly with [la-]a (r = 0.61, P < 0.001) with power (r = 0.58, P < 0.001) during the test. At the end of the test, [la-]a, [la-]v and [la-]a-v decreased (P < 0.001; P < 0.001; P < 0.001 respectively) but were still higher than the basal values after 20-min of passive recovery. In conclusion, forearm skeletal muscles would seem to have been involved in the removal of lactate from the blood during the leg FV test, with an increase in lactate uptake proportional to the increase in plasma lactate concentration and power.

Adult↗

PubMed1996

Anaerobic exercise components during the force-velocity test in sickle cell trait.

Incremental exercise tests have shown no difference in exercise capacity (EC), maximal oxygen uptake (VO2max), and ventilatory threshold (VT) in subjects with sickle cell trait (SCT) when compared to controls with normal hemoglobin (Hb). Nevertheless, during long and strenuous exercise testing, subjects with SCT exhibit comparable EC but lower oxygen uptake (VO2). Consequently, specific metabolic adaptations in subjects with SCT have been suggested during endurance exercise, consisting of a slight "handicap" in oxygen consumption and compensation by the hypothetical development of a higher anaerobic metabolism. The purpose of the present study was to research differences in the anaerobic exercise performance, and the anaerobic exercise metabolism between 9 sedentary black males with SCT and 9 controls with normal Hb. The two groups of subjects were matched for morphological and hematological variables and for aerobic fitness. The subjects were tested using the force-velocity test (FV test) characterized by the repetition of 6-s maximal exercise bouts on a cycle ergometer. The anaerobic exercise performance parameters were peak anaerobic power (PAnP), maximal velocity (V0), and maximal braking force (F0). The anaerobic exercise metabolism parameters were blood lactate concentration at PAnP and peak lactate, and blood lactate kinetics during the FV test and the recovery period. The results indicated no significant difference between the SCT and control groups for PAnP (792.3 +/- 63.3 watts vs 763.8 +/- 52.5 watts), V0 (185.5 +/- 8.9 rev.min-1 vs 173.7 +/- 5.8 rev.min-1), F0 (17.1 +/- 1.2 kg vs 17.2 +/- 1.1 kg), blood lactate concentration at PAnP (5.3 +/- 0.9 mmol.l-1 vs 4.8 +/- 0.4 mmol.l-1), at peak lactate (7.0 +/- 0.9 mmol.l-1 vs 6.7 +/- 0.7 mmol.l-1), and blood lactate kinetics during the test and the recovery period. The present study indicated that sedentary subjects with SCT and controls with normal Hb had similar anaerobic exercise performance and similar anaerobic exercise metabolism. It did not confirm the hypothetical higher anaerobic metabolism suggested in subjects with SCT.

Adult↗

PubMed1996

Pulse wave velocity measurement by cross-correlation of Doppler velocity signals. Application to elderly volunteers during training.

Pulse wave velocity (PWV) measurement is widely used for the indirect assessment of arterial wall distensibility. In order to improve its measurement technique, we built a system performing the calculation of the cross-correlation function of Doppler velocity signals. In 12 normal subjects and 10 patients, the mean difference between duplicate measurements was 0.7 +/- 7.8% (NS). We tested this technique in 15 elderly volunteers before and after a three months training period. Brachial and tibial systolic blood pressure decreased respectively from 18.1 +/- 2.2 kPa to 16.7 +/- 1.9 kPa (p = 0.008) and from 21.1 +/- 3.4 kPa to 18.4 +/- 2.5 kPa (p = 0.003), while lower limb PWV decreased from 8.96 +/- 1.26 to 7.92 +/- 1.22 m.s-1 (p = 0.016). Therefore, automatic PWV measurement using the cross-correlation technique allows to demonstrate training induced changes in PWV, although concomitant changes in blood pressure must be considered in their interpretation.

Adult↗

PubMed1996

Exercise tolerance in patients with mitral stenosis before and after acute percutaneous mitral valvuloplasty. Role of lung diffusing capacity limitation?

The aim of this study was to specify in patients with tight mitral stenosis whether lung diffusing capacity could play a role in their exercise intolerance. A similar study was recently carried out in patients with moderate chronic heart failure. Ten patients with tight mitral stenosis were studied before and 6 months after successful percutaneous transvenous balloon valvuloplasty and compared to six control subjects. Measurements of diffusing capacity, evaluated by the lung transfer factor (TLCO) and by the transfer coefficient (TLCO/VA), obtained at rest and during early recovery after cardiopulmonary exercise testing were performed. Cardiac output was determined non-invasively, both at rest and during exercise, using the carbon dioxide exponential rebreathing technique. Prior to valvuloplasty, TLCO and TLCO/VA were not different at rest between the two groups. During exercise, patients differed from control subjects, with lower oxygen uptake (P < 0.001) and lower cardiac output at peak exercise (P < 0.001). These values at peak exercise were significantly correlated (P = 0.02; r = 0.75). Moreover, patients differed from control subjects at early recovery after peak exercise with an absence of increase in TLCO (P < 0.05). Six months after valvuloplasty, a decrease of both TLCO (P < 0.01) and TLCO/VA (P < 0.05) was observed at rest. During exercise, comparison of patients demonstrated a significant increase of both peak exercise oxygen uptake (SLVO2, P < 0.01) and cardiac output (P < 0.001). At early recovery after peak exercise there was a significant increase in TLCO (P < 0.05) and TLCO/VA (P < 0.01), such that a delta TLCO and a delta TLCO/VA appeared (P < 0.05) identical to that observed in control subjects. Moreover, delta SLVO2 was significantly correlated in patients with delta Q+ delta TLCO/VA (P = 0.02; r = 0.72). In conclusion, this study suggests a role, at least partial, of lung diffusing capacity in exercise intolerance in patients with tight mitral stenosis and in the improvement of their aerobic exercise capacity demonstrated after successful percutaneous balloon valvuloplasty.

Adult↗

PubMed1996

Influence of post-surgery time after cardiac transplantation on exercise responses.

Influence of post-surgery time after cardiac transplantation on exercise responses. Med. Sci. Sports Exerc., Vol. 28, No. 2, pp. 171-175, 1996. To test the hypothesis that exercise response changes with time after cardiac transplantation, we investigated the cardiorespiratory responses of nine orthotopic heart transplant patients (52.4 +/- 2 yr) during graded exercise tests (30 W.3 min-1) done at 1, 3, 6, 9 and 12 months post-surgery. At peak exercise, 1) oxygen uptake per kg of body weight (VO2), minute ventilation (VE) and oxygen pulse (O2 pulse) did not change significantly between 1 and 12 months postsurgery; 2) transplanted heart rate (HRt) and delta heart rate (peak exercise heart rate--resting heart rate) increased significantly over time (P < 0.01; P < 0.05) with a marked increase between 1 and 3 months (P < 0.05); and (3) a significant negative correlation existed between O2 pulse and HRt (r = -0.36, P < 0.05), whereas no correlation was found between delta heart rate and delta VO2 (peak exercise VO2- resting VO2, l.min-1). During submaximal exercise, HRt increased significantly over time (P < 0.001); VO2, VE, and O2 pulse showed no significant change; and the VO2-HRt relationship shifted toward higher values of HRt. We conclude that, in the absence of formal physical training, the exercise response of denervated transplanted heart increases in relation to post-surgery time but does not affect oxygen uptake at submaximal and peak levels of exercise.

Blood Pressure↗

PubMed1996

Effect of 2-chloropropionate on initial lactate uptake by rat skeletal muscle sarcolemmal vesicles.

2-Chloropropionate (2-CP) is a halogenated monocarboxylic acid generally used to decrease blood lactate concentration in various metabolic states. To investigate whether it has an inhibitory effect on sarcolemmal lactate transport, we compared the initial rate of lactate transport in sarcolemmal membrane vesicles purified from 20 male Wistar rats with and without 2-CP. Transport by these vesicles was measured as uptake of L-(+)-[U-14C]lactate under pH gradient-stimulated cis inhibition. The time courses of 1 mM L-(+)-lactate uptake into vesicles both with and without 10 mM 2-CP (L- or D-) displayed saturation kinetics. Lactate uptake values were lower with 10 mM L-2-CP and 10 mM D-2-CP in comparison to the control values. Both 10 mM L-2-CP and 10 mM D-2-CP significantly inhibited 1 mM L-(+)-lactate uptake (55.8 +/- 9.1 and 53.5 +/- 12.1%, respectively; P < 0.001), whereas a smaller inhibition was observed with a higher lactate concentration of 50 mM (40.2 +/- 11.2 and 38.7 +/- 12.4%; P < 0.001 and P < 0.05, respectively). However, a higher D-2-CP concentration (50 mM) increased the inhibition of pH-stimulated 1 mM L-(+)-lactate uptake (77.0 +/- 9.4%; P < 0.001). D-2-CP had a trans-stimulation effect on the initial rate of lactate efflux of 1 mM L-(+)-lactate compared with baseline efflux (9.5 +/- 0.8 vs. 5.1 +/- 0.4 nmol.min-1.mg protein-1; P < 0.05). 2-CP significantly inhibited the initial rate of lactate uptake in skeletal muscle sarcolemmal membrane vesicles. This result suggests that 2-CP is a nonstereoselective substrate of the lactate muscle carrier that impairs lactate transport.

Animals↗

PubMed1995

Aerobic and anaerobic contribution to Wingate test performance in sprint and middle-distance runners.

We investigated the aerobic and anaerobic contributions to performance during the Wingate test in sprint and middle-distance runners and whether they were related to the peak aerobic and anaerobic performances determined by two commonly used tests: the force-velocity test and an incremental aerobic exercise test. A group of 14 male competitive runners participated: 7 sprinters, aged 20.7 (SEM 1.3) years, competing in 50, 100 and 200-m events and 7 middle-distance runners, aged 20.0 (SEM 1.0) years, competing in 800, 1,000 and 1,500 m-events. The oxygen uptake (VO2) was recorded breath-by-breath during the test (30 s) and during the first 20 s of recovery. Blood samples for venous plasma lactate concentrations were drawn at rest before the start of the test and during the 20-min recovery period. During the Wingate test mean power (W) was determined and three values of mechanical efficiency, one individual and two arbitrary, 16% and 25%, were used to calculate the contributions of work by aerobic (Waer,ind,16%,25%) and anaerobic (Wan,ind,16%,25%) processes. Peak anaerobic power (Wan,peak) was estimated by the force-velocity test and maximal aerobic energy expenditure (Waer,peak) was determined during an incremental aerobic exercise test. During the Wingate test, the middle-distance runners had a significantly greater VO2 than the sprinters (P < 0.001), who had significantly greater venous plasma lactate concentrations (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Pulmonary gas exchange and ventilatory responses to brief intense intermittent exercise in young trained and untrained adults.

To investigate pulmonary gas exchange and ventilatory responses to brief intense intermittent exercise and to study the effects of physical fitness on these responses, nine trained and nine untrained healthy male subjects aged 18-33 years performed the force-velocity (F-v) exercise test. This test consisted of 6-s sprints against increasing braking forces (F) separated by 5-min recovery periods. Oxygen uptake (VO2), carbon dioxide output (VCO2), and ventilation (VE) were continuously measured during the test and the magnitudes of their responses to the sprints were then calculated. For all subjects VO2 increased rapidly after beginning the sprints, and the peaks of the responses (F = 13.4; P < 0.001), end of recovery values (F = 6.5; P < 0.01), and VO2 magnitudes of response (F = 12.4; P < 0.001) rose significantly with the repetition of the sprints. The VO2 magnitudes of response correlated with the corresponding sprint power outputs (r = 0.55; P < 0.001) and with the sprint repetitions (r = 0.51, P < 0.001). The VCO2 (F = 7.1; P < 0.01) and VE (F = 5.0; P < 0.01) peaks of response increased with the initial load incrementation, then stabilized when the subjects attained peak power output. End of recovery VCO2 (F = 18.0; P < 0.001) and VE (F = 14.1; P < 0.001) values rose with increasing F. The F-v peak VO2, VCO2, VE, tidal volume and respiratory frequency responses attained 53%, 40%, 44%, 66%, and 82% of the peak values measured at exhaustion of maximal graded exercise, respectively. (ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

Anaerobic and aerobic peak power output and the force-velocity relationship in endurance-trained athletes: effects of aging.

The aim of this investigation was to test the hypothesis that the anaerobic peak power output (Pan, peak) declines more than the peak aerobic power (Paer, peak) with increasing age. In addition, the force-velocity (F-v) relationship was studied to determine which of these two factors is primarily responsible for the expected alterations in anaerobic power. The Pan, peak, the maximal F when v is equal to zero (F0) and the maximal v when F is equal to zero (v0) were assessed by F-v test i.e. a brief intense intermittent exercise test using incremental braking forces. The Paer, peak was measured by a maximal increment exercise test. A group of 12 young athletes (YA) and 12 master athletes (MA) mean age 24.8 (SEM 1.3) and 65.1 (SEM 1.2) years, respectively, participated in this study. The YA and MA had similar body masses, heights and endurance training schedules. The results showed that Pan, peak was 42.7% lower in the older subjects, corresponding to mean values of 1089 (SEM 40) compared to 624 (SEM 33) W (t = 8.9, P < 0.001) for YA compared to MA, respectively. The F0 and V0 indices showed values that were lower by 30.3% and 15.2%, respectively. The Paer, peak was 35% lower with mean values of 323 (SEM 12) W for YA compared to 210 (SEM 6) W for MA (t = 8.3, P < 0.001). The mean maximal oxygen uptake was 34.7% lower with 4240 (SEM 160) ml.min-1 for YA compared to 2770 (SEM 120) ml.min-1 for MA (t = 7.2, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗