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At least 883 records · Page 49Linked to original sources
PubMed1987

[Exercise 13NH3-positron emission computed tomography (PET) versus exercise single photon emission computed tomography (SPECT)].

The value of exercise positron emission computed tomography (PET) was determined by comparing it with exercise T1-201 single photon emission computed tomography (SPECT) using graded ergometer exercise in 10 anginal patients with left anterior descending coronary (LAD) involvement (stenosis greater than or equal to 75%) with or without other coronary stenosis. The distribution of N-13 ammonia or T1-201 was determined and expressed as percent count ot the highest count on the circumferential profile curve (CPC) in the transaxial image. Two standard deviations below the mean counts of six normal hearts for PET and ten for SPECT were considered as the lower limit of normal, and these were determined separately during exercise and at rest. The ischemic areas per total myocardial areas (%C), the accuracy in diagnosing coronary involvement and the identification of coronary branch involvement were determined by CPC analysis in three corresponding slices. Regional analyses revealed that accuracy in diagnosing proximal left anterior descending artery (LAD) involvement was higher with PET (9/10) than with SPECT (7/10), but the difference was not statistically significant. The accuracy in diagnosing right coronary or circumflex artery stenosis was 9/10 with PET and 8/10 with SPECT (NS); the %C was significantly higher with PET than with SPECT during exercise (PET: mean +/- SD = 56 +/- 21%, SPECT: 35 +/- 21%, p less than .01) in spite of smaller double products (x10(3] (PET: 18.9 +/- 4.7, SPECT: 23.5 +/- 5.7, p less than .02). Thus, exercise PET was more reliable in evaluating regional ischemia and in semiquantifying the ischemic area in the myocardium.

Ammonia↗
PubMed1986

Exercise physiology in the 1990's: mechanistically defining the exercise model.

Definition of the exercise model via a mechanistic approach is a goal which should be of high priority among sport researchers in the 1990's, in an attempt to further qualify previous phenomenological observations of exercising man. Prolonged argument on the "theory-versus-practice" issue is one which is counter-productive in the advancement of knowledge in our discipline, and must be addressed and resolved. With specific emphasis on the neuromuscular control of movement, current research literature suggests that the components limiting to human performance may reside in the muscle, motoneurone and in the supraspinal of movement. Mechanistically defining the limits in each component, related to patterns of movement during exercise, may soon herald a reclassification of exercise types and their limits, defined by the particular system involved. Similarly, new evidence on adaptations throughout the neuromuscular system calls for a systematic study of these adaptations, how they influence structure and function of cell and organ systems, and their effects on the performance of the voluntarily exercising human. A mechanistic approach to these problems, using "simple" experimental models to more precisely define cause-effect, are justifiable and necessary in our field on the basis of the potential applicability of such information in the fields of design of exercise programmes, and the evaluation of their effectiveness, for normal and special populations. The problems associated with increased academic specialization and the communication gap which might result, are not inevitable. An enhancement of the proliferation of this knowledge and its interpretation in practical terms will result through our own awareness of the necessity of doing this, and through sensitization of our students to this issue.

Humans↗
PubMed1980

Segmental wall-motion analysis in the right anterior oblique projection: comparison of exercise equilibrium radionuclide ventriculography and exercise contrast ventriculography.

Thirty-nine patients with known or suspected coronary artery disease were studied at rest and during supine bicycle exercise with radionuclide and contrast left ventriculography. Analysis of regional wall motion was made by visual evaluation of the five standard 30 degrees right anterior oblique (RAO) wall segments in the contrast images and the corresponding 10 degrees RAO radionuclide segments. The radionuclide studies were evaluated independently by three observers using a five-point grading system. The interobserver wall-motion grading agreed completely in more than 80% of segments at rest and exercise, and agreed within one wall-motion grade in more than 95% of segments. The comparison of wall-motion grades between radionuclide and contrast ventriculograms showed complete agreement in 86% of segments at rest and in 78% during exercise, and agreement within one wall-motion grade in 97% of rest and 96% of exercise segments. Visual evaluation of 10 degrees RAO rest and exercise radionuclide ventriculograms compares favorably with rest and exercise 30 degrees RAO contrast ventriculograms and demonstrates satisfactory interobserver agreement.

Coronary Disease↗
PubMed1998

Heart rate deflection compared to 4 mmol x l(-1) lactate threshold during incremental exercise and to lactate during steady-state exercise on an arm-cranking ergometer in paraplegic athletes.

The deflection point (DP) of the heart rate in relation to the work rate (WR) of 8 male endurance-trained paraplegics and 11 male physically active sports students was investigated during nonsteady-state incremental arm cranking ergometry (IT) and compared to the 4 mmol x l(-1) blood lactate concentration threshold and to blood lactate concentration in steady-state exercise (SST). Heart rate, and lactate concentration from capillary blood, were determined at rest, during IT and SST. The DP was calculated by linear regression analysis of the heart rate during IT. The SST consisted of three consecutive exercise intensities over a period of 8 min at exercise intensities of 10 W below, and at 10 W above the work rate at deflection point (WRDP). No difference was found between the paraplegics and non-handicapped subjects regarding heart rate and blood lactate concentration at rest and during exercise. A DP was established in all the paraplegics and in 72.7% of the non-handicapped subjects, but lactate accumulation was observed in 75% of the paraplegics and in 62.5% of the non-handicapped subjects at the lowest intensity of SST. In summary, endurance-trained paraplegics with an injury level below T5 showed heart rate and blood lactate concentration values comparable to non-handicapped subjects during IT. A linear increase at moderate exercise intensities and a levelling-off at higher to maximal intensities could be identified in all the paraplegics and in 72.7% of non-handicapped subjects. The determination of the anaerobic threshold by DP should be applied with caution, since no causal relationship of DP and the anaerobic threshold was found and the WRDP tended to overestimate threshold values.

Adult↗
PubMed1989

Exercise prescription in pregnancy: weight-bearing versus non-weight-bearing exercise.

Bicycle ergometry (non-weight-bearing exercise) and treadmill (weight-bearing exercise) were compared to assess physiologic responses to similar work loads. A total of 22 subjects at 29.3 +/- 1.6 (+/- SEM) weeks' gestation who performed non-weight-bearing exercise were compared with 15 similarly fit subjects at 26.1 +/- 2.3 weeks' gestation who performed weight-bearing exercise at three submaximal levels. Measurements by indirect calorimetry indicate preferential carbohydrate use during non-weight-bearing exercise at submaximal levels.

Adult↗
PubMed1984

Changes in rest and exercise myocardial perfusion and left ventricular function 3 to 26 weeks after clinically uncomplicated acute myocardial infarction: effects of exercise training.

The effects of exercise training on exercise myocardial perfusion and left ventricular (LV) function in the first 6 months after clinically uncomplicated acute myocardial infarction (AMI) were assessed in 53 consecutive men aged 55 +/- 9 years. Symptom-limited treadmill exercise with thallium myocardial perfusion scintigraphy and symptom-limited upright bicycle ergometry with equilibrium gated radionuclide ventriculography were performed 3, 11 and 26 weeks after AMI by 23 men randomized to training and 30 randomized to no training. Peak cycle capacity increased in both groups between 3 and 26 weeks (p less than 0.01), but reached higher levels in trained than in untrained patients (803 +/- 149 vs 648 +/- 182 kg-m/min, p less than 0.01). Reversible thallium perfusion defects were significantly more frequent at 3 than at 26 weeks: 59% and 36% of patients, respectively (p less than 0.05), without significant inter-group differences. Values of LV ejection fraction at rest, submaximal and peak exercise did not change significantly in either group. The increase in functional capacity, i.e., peak treadmill or bicycle workload, that occurred 3 to 26 weeks after infarction was significantly correlated with the increase in peak exercise heart rate (p less than 0.001), but not with changes in myocardial perfusion or LV function determined by radionuclide techniques. Changes in myocardial perfusion or LV function do not appear to account for the improvement in peak functional capacity that occurs within the first 6 months after clinically uncomplicated AMI.

Coronary Circulation↗
PubMed2000

Exercise-induced laryngochalasia: an imitator of exercise-induced bronchospasm.

BACKGROUND: Patients with exercise-induced laryngochalasia present with dyspnea and stridor during exercise. Symptoms are due to a subtotal occlusion of the larynx resulting from mucosal edema from the aryepiglottic folds being drawn into the endolarynx. METHODS: We report on three patients with exercise-induced bronchospasm, refractory to standard therapy. RESULTS: Spirometry with flow-volume loops revealed truncation of the inspiratory limb. Abnormal movement of the arytenoid region was visualized on laryngoscopy. A diagnosis of exercise-induced laryngochalasia was made. CONCLUSIONS: Evaluation of laryngeal motion in patients with refractory exercise-induced bronchospasm is important. Surgical correction with laser laryngoplasty is effective in carefully selected cases.

Adolescent↗
PubMed2000

The effects of exercising muscle mass on post exercise hypotension.

Nine recreationally active, borderline hypertensive subjects completed 30 min of arm ergometry (ARM) at 65% VO2 peak and 30 min of leg ergometry (LEG) at 70% VO2 Peak (randomised order). Blood pressure was monitored before and for 1 h after exercise using the Finapres method. Systolic, diastolic and mean blood pressures were significantly reduced for the entire 1 h post exercise. This reduction was independent of exercise modality, but there was an indication for the duration of the effect to be prolonged following the leg exercise. We conclude that the mass of the working muscle does not directly effect the magnitude of post-exercise hypotension (PEH) but may influence the duration of the response. These results suggest that a central mechanism or decreased vascular responsiveness is responsible for PEH.

Adult↗
PubMed2001

Treadmill exercise testing with increasing inclination as exercise protocol for wheelchair athletes.

STUDY DESIGN: Treadmill testing on a progressive incline of 11 wheelchair athletes. OBJECTIVE: To determine if a novel treadmill exercise protocol which uses increments in inclination, rather than the standard increments in velocity, can be used to effectively determine maximum oxygen uptake VO2max for elite wheelchair athletes. SETTING: Nottwil, Switzerland. METHODS: Eleven elite wheelchair basketball players (29.3+/-6.3 years, 72.7+/-16.9 kg and 177+/-9.6 cm) performed an exercise protocol with increasing inclination on the treadmill. Eight players had a spinal cord injury (SCI), two had no lesion of the central nervous system and one had poliomyelitis. VO2max and heart rate were measured continuously, while serum lactate was determined immediately after the exercise protocol. RESULTS: Athletes reached a maximal heart rate of 185+/-11.4 bpm and maximal lactate of 10.2+/-2.1 mmol/l. VO2max was 35.1+/-4.9 ml/min/kg. The correlation between heart rate and VO(2) at different inclinations was statistically significant and comparable to able-bodied subjects. CONCLUSIONS: An exercise protocol with increasing inclination is a valid alternative to an exercise protocol with increasing velocity.

Adult↗
PubMed2005

Effect of exercise-induced dehydration on lactate parameters during incremental exercise.

Cyclists often use heart rate limits or power output zones, obtained from lactate parameters during incremental exercise testing, to control training intensity. However, the relationship between heart rate or power output, and blood lactate can be changed by several factors including dehydration. Therefore, in the current study we investigated the impact of exercise-induced dehydration on lactate parameters during graded exercise. Nine triathletes completed two test sessions in random order, with a 1-week interval. Each session consisted of 2 graded cycling tests to exhaustion (pretest, posttest), interspersed by a 2-h endurance exercise bout. In one session the cyclists received adequate fluid replacement (EH, 1350 ml . h (-1)) whilst in the other session dehydration was not prevented (DH, 225 ml . h (-1)). Subjects received equal amounts of carbohydrates (150 g) during either condition. The 4-mmol lactate threshold (OBLA) and the d (max) lactate threshold (TH-Dm) were calculated from the power : lactate curves. Weight loss was 0.5 +/- 0.3 kg in EH versus 2.5 +/- 0.2 kg in DH (p < 0.05). Heart rate (HR) at TH-Dm remained unchanged in all test occasions. Conversely, HR at OBLA increased by approximately 10 beats . min (-1) from the pretest to the posttest (p < 0.05), in both EH and DH. Compared to the pretest, in the posttest power output at TH-Dm was reduced (minus approximately 12 %, p < 0.05) in DH, but not in EH. Gross mechanical efficiency at TH-Dm was 20.7 +/- 1 % in the pretest in EH and was not different from the pretest value in DH (21.4 +/- 0.7 %, n.s.). Gross efficiency decreased in the posttest in DH (18.4 +/- 0.6 %, p < 0.05), but not in EH (20.2 +/- 0.8 %, n.s.). It is concluded that heart rate rather than power output should be used to monitor training load in cyclists exercising in environmental conditions predisposing to dehydration. Furthermore, in the latter condition, adequate rehydration is essential to preserve optimal mechanical efficiency.

Adult↗
PubMed2005

Pre-exercise antioxidant enzyme activities determine the antioxidant enzyme erythrocyte response to exercise.

Free radical production increases during exercise and oxidative damage occurs in several tissues. We examined the effects of three different exercise tests on the pattern of change of erythrocyte enzyme antioxidant activities. The tests were a short maximal exercise test, a submaximal prolonged exercise test and a cycling stage during competition. The participants were amateur and professional cyclists with different training statuses and different basal erythrocyte antioxidant enzyme activities. The maximal test produced no changes in the erythrocyte antioxidant enzyme activities of amateur sportsmen. The submaximal test, performed at 80% of maximal oxygen uptake, decreased erythrocyte catalase (12%), glutathione peroxidase determined with H2O2 (14%) and glutathione reductase (16%); superoxide dismutase activity increased by about 25%. The cycling stage performed by professional cyclists increased erythrocyte catalase (29%) and glutathione reductase (10%) activities. The in vivo changes in glutathione reductase activity were confirmed by in vitro measurements: hydrogen peroxide decreased and the presence of catalase increased the activity of this enzyme. In conclusion, we suggest that the different erythrocyte antioxidant enzyme responses to diverse exercise tests can be explained by the effects of hydrogen peroxide and the superoxide anion on the antioxidant enzyme activities in erythrocytes.

Adult↗
PubMed1991

Multicentre study of the determination of peak oxygen uptake and ventilatory threshold during bicycle exercise in chronic heart failure. Comparison of graphical methods, interobserver variability and influence of the exercise protocol. The VO2 French Study Group.

Assessment of the ventilatory threshold (VT) has been proposed to assess exercise tolerance more objectively, particularly in clinical trials, but reproducibility, interobserver variability and feasibility of the graphical methods for determination of VT have not been properly studied in patients with chronic heart failure (CHF). Fifty-one patients with mild to moderate CHF (mean peak oxygen uptake (VO2): 20.5 ml.min-1.kg-1) were assessed during two consecutive bicycle exercise tests within 8 days. Two graded exercise protocols were compared with stages of 30 W every 3 min (22 patients) or 10 W/min (29 patients). VT was determined separately by five trained physicians using five different graphical methods. The 'crossing method' (first crossing of the VCO2 and VO2 curves) yielded the highest rate of determination (88%) but tended to overestimate the mean VT. The VE method (disproportionate increase of ventilation relative to VO2) produced the best interobserver agreement (coefficient of variation = 78%). Peak VO2 was very highly reproducible in both exercise protocols (relative difference 2-test 1/test 1 = -0.32% for the 30 W 3 min protocol; +2.18% for the 10 W.min-1 protocol). The reproducibility of VT was slightly lower regardless of the graphical method used to determine it (relative differences varied from -3.3% to +7.3%). Therefore, peak VO2 appears more suitable than VT for assessment of exercise tolerance in CHF.

Adult↗
PubMed1997

Cardiovascular response to sudden strenuous exercise: an exercise echocardiographic study.

We studied the response in left ventricular (LV) internal dimensions and posterior wall thickness during the performance of sudden strenuous exercise without warm-up (SSE) and sudden strenuous exercise with warm-up (SSEw) in 15 healthy, untrained college-aged males (26 +/- 5.0 yr). Measurements of left ventricular end-diastolic dimension (LVEDD), left ventricular end-systolic dimension (LVESD), stroke dimension (SD = LVEDD-LVESD), fractional shortening (FS = SD/EDD) and posterior wall thickness (PWT) were obtained from continuous 2-D targeted on M-mode echocardiography. Continuous EKG and blood pressure were obtained at rest and during the final 10 s of SSE (30 s of upright leg cycle ergometry of 400 W at 80 rpm). SSEw was preceded by warm-up exercise (6 min of graded leg cycle exercise of 2-min stages initial load 30 W, increasing in 30-W increments at 60 rpm, followed immediately by SSE). Our findings revealed that there were no significant differences in the LV internal dimensions (LVEDD, LVESD, FS, PWT), HR max, RPP max, ECG, and MAP max between SSE and SSEw. Sudden strenuous exercise without warm-up is not associated with a reduced LV function. The results of this study are contradictory to previous findings that have suggested that SSE is associated with transient global left ventricular (LV) dysfunction.

Adult↗
PubMed2006

Statement on cardiopulmonary exercise testing in chronic heart failure due to left ventricular dysfunction: recommendations for performance and interpretation. Part I: definition of cardiopulmonary exercise testing parameters for appropriate use in chronic heart failure.

Cardiopulmonary exercise testing (CPET) provides a global assessment of the integrated response to exercise involving the pulmonary, cardiovascular, haematopoietic, neuropsychological, and skeletal muscle systems. This information cannot be obtained through investigation of the individual organ systems in isolation. The non-invasive, dynamic physiological overview permits the evaluation of both submaximal and peak exercise responses, providing the physician with relevant information for clinical decision making. The use of CPET in management of the chronic heart failure patient is increasing with the understanding that resting pulmonary and cardiac function testing cannot reliably predict exercise performance and functional capacity and that, furthermore, overall health status and prognosis are predicted better by indices of exercise tolerance than by resting measurements. Our aim is to produce a statement which provides recommendations on the interpretation and clinical application of CPET in heart failure, based on contemporary scientific knowledge and technical advances: the focus is on clinical indications, issues of standardization, and interpretative strategies for CPET.

Cardiac Output↗
PubMed2004

Transforming the nature of fatigue through exercise: qualitative findings from a multidimensional exercise programme in cancer patients undergoing chemotherapy.

The objective of this study was to explore the nature of fatigue in cancer patients with advanced stages of disease undergoing chemotherapy and concurrently participating in a 6-week multidimensional exercise programme (physical exercise, relaxation, massage and body-awareness training). Semi-structured qualitative interviews were conducted with 23 patients between 18 and 65 years of age prior to, during, and at termination of the programme. The findings endorsed that physical debilitation, fatigue, and uncertainty of physical capacity were the patients' motivation for participation. Throughout the programme the patients experienced exercise-induced fatigue, which they associated with a sense of increased physical strength, improvement in energy and physical well-being. This positive sense of fatigue can be seen as a contrast to the negative chemotherapy-induced fatigue, which is characterized by physical discomfort and uncontrollable exhaustion. The patients learned to manoeuvre through periods of intense fatigue by using exercise as a strategy to adjust their sense of physical debilitation. Visibility of fatigue's qualitative aspects is necessary if patients are to be encouraged to stay active and to set realistic goals. The transformation process of fatigue identified in this study supports the theory of exercise as a beneficial intervention strategy in the treatment of cancer-related fatigue.

Activities of Daily Living↗
PubMed1994

Plasma glucose levels after prolonged strenuous exercise correlate inversely with glycemic response to food consumed before exercise.

It was hypothesized that slowly digested carbohydrates, that is, low glycemic index (GI) foods, eaten before prolonged strenuous exercise would increase the blood glucose concentration toward the end of exercise. Six trained cyclists pedaled on a cycle ergometer at 65-70% VO2max 60 min after ingestion of each of four test meals: a low-GI and a high-GI powdered food and a low-GI and a high-GI breakfast cereal, all providing 1 g of available carbohydrate per kilogram of body mass. Plasma glucose levels after more that 90 min of exercise were found to correlate inversely with the observed GI of the foods (p < .01). Free fatty acid levels during the last hour of exercise also correlated inversely with the GI (p < .05). The findings suggest that the slow digestion of carbohydrate in the prevent food favors higher concentrations of fuels in the blood toward the end of exercise.

Adult↗
PubMed1995

Effects of carbohydrate feeding before and during prolonged exercise on subsequent maximal exercise performance capacity.

The study examined the effect of carbohydrate ingestion on exercise performance capacity. Nine male cyclists performed two separate trials at 70% VO2max for 60 min followed by a maximal ride for 10 min. During trials subjects were fed either an 8% glucose solution (CHO) or a placebo solution (PL), which were administered at rest and during and immediately after submaximal exercise. Statistical analyses indicated that glucose levels at rest increased significantly 15 min after the ingestion of CHO compared to PL. At 30 and 60 min during submaximal exercise, plasma glucose levels decreased significantly in the CHO but not in the PL trial. Following the performance ride, glucose levels increased significantly only during the CHO test trial. Free fatty acids did not change significantly during testing trials. The maximal performance ride results showed that in the CHO trial, a significantly greater external work load was accomplished compared to the PL trial. It is concluded that CHO ingestion improves maximal exercise performance after prolonged exercise.

Adult↗