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At least 919 records · Page 51Linked to original sources
PubMed1987

Perceived exertion and gas exchange after calcium and beta-blockade in atrial fibrillation.

Nine male patients (mean age 65 yr) with chronic atrial fibrillation underwent maximal exercise testing during placebo, beta-adrenergic (celiprolol, 600 mg), or calcium (diltiazem, 30 or 60 mg four times daily) channel blockade. The results were analyzed to determine which factors most closely related to ratings of perceived exertion (RPE) during exercise. Heart rate (HR), blood pressure (BP), oxygen uptake (VO2), minute ventilation (VE), and carbon dioxide production (VCO2) were evaluated at rest, 3.0 mph/0% grade, the gas exchange anaerobic threshold (ATge), 80% of placebo maximal O2 uptake, and maximal exercise. Both beta-adrenergic and calcium channel blockade significantly reduced heart rate and systolic blood pressure relative to placebo; these effects were more profound during beta-adrenergic blockade and as exercise progressed. Correlation coefficients and estimates of slope were derived for changes in RPE during exercise vs. changes in HR, VO2, VE, and VCO2 during the three treatments (r = 0.76 to 0.92, P less than 0.001). Although RPE was significantly correlated with HR during placebo and diltiazem therapy (r = 0.45, P less than 0.01), this was not the case during beta-adrenergic blockade (r = 0.31, NS). Slope of the regression lines between RPE and VO2, VE, and VCO2 did not differ between the three treatments. Slope of the regression lines between RPE and HR differed only during calcium channel blockade. Because the presence of atrial fibrillation and beta-adrenergic blockade altered the associations between RPE, VO2, and HR, these results suggest that VE is more closely related to RPE than the other parameters.

Adrenergic beta-Antagonists↗
PubMed2004

Exertional heat injury and gene expression changes: a DNA microarray analysis study.

This study examined gene expression changes associated with exertional heat injury (EHI) in vivo and compared these changes to in vitro heat shock responses previously reported by our laboratory. Peripheral blood mononuclear cell (PBMC) RNA was obtained from four male Marine recruits (ages 17-19 yr) who presented with symptoms consistent with EHI, core temperatures ranging from 39.3 to 42.5 degrees C, and elevations in serum enzymes such as creatine kinase. Controls were age- and gender-matched Marines from whom samples were obtained before and several days after an intense field-training exercise in the heat ("The Crucible"). Expression analysis was performed on Affymetrix arrays (containing approximately 12,600 sequences) from pooled samples obtained at three times for EHI group (at presentation, 2-3 h after cooling, and 1-2 days later) and compared with control values (average signals from two chips representing pre- and post-Crucible samples). After post hoc filtering, the analysis identified 361 transcripts that had twofold or greater increases in expression at one or more of the time points assayed and 331 transcripts that had twofold or greater decreases in expression. The affected transcripts included sequences previously shown to be heat-shock responsive in PBMCs in vitro (including both heat shock proteins and non-heat shock proteins), a number of sequences whose changes in expression had not previously been noted as a result of in vitro heat shock in PBMCs (including several interferon-induced sequences), and several nonspecific stress response genes (including ubiquitin C and dual-specificity phosphatase-1). We conclude that EHI produces a broad stress response that is detectable in PBMCs and that heat stress per se can only account for some of the observed changes in transcript expression. The molecular evidence from these patients is thus consistent with the hypothesis that EHI can result from cumulative effects of multiple adverse interacting stimuli.

Adolescent↗
PubMed2005

Altered secretion of growth hormone and luteinizing hormone after 84 h of sustained physical exertion superimposed on caloric and sleep restriction.

The pulsatile release of growth hormone (GH) and luteinizing hormone (LH) from the anterior pituitary gland is integral for signaling secretion of insulin-like growth factor (IGF)-I and testosterone, respectively. This study examined the hypothesis that 84 h of sustained physical exertion with caloric and sleep restriction alters the secretion of GH and LH. Ten male soldiers [22 yr (SD 3), 183 cm (SD 7), 87 kg (SD 8)] had blood drawn overnight from 1800 to 0600 every 20 min for GH, LH, and leptin and every 2 h for IGF-I (total and free), IGF binding proteins-1 and -3, testosterone (total and free), glucose, and free fatty acids during a control week and after 84 h of military operational stress. Time-series cluster and deconvolution analyses assessed the secretion parameters of GH and LH. Significant results (P < or = 0.05) were as follows: body mass (-3%), fat-free mass (-2.3%), and fat mass (-7.3%) declined after military operational stress. GH and LH secretion burst amplitude (approximately 50%) and overnight pulsatile secretion (approximately 50%), IGF binding protein-1 (+67%), and free fatty acids (+33%) increased, whereas leptin (-47%), total (-27%) and free IGF-I (-32%), total (-24%) and free testosterone (-30%), and IGF binding protein-3 (-6%) decreased. GH and LH pulse number were unaffected. Because GH and LH positively regulate IGF-I and testosterone, these data imply that the physiological strain induced a certain degree of peripheral resistance. During periods of energy deficiency, amplitude modulation of GH and LH pulses may precede alterations in pulse numbers.

Adaptation, Physiological↗
PubMed2005

Functional predictors of exertional dyspnea, 6-min walking distance and HRCT fibrosis score in idiopathic pulmonary fibrosis.

BACKGROUND: Exertional dyspnea and exercise incapacity are the most prominent and disabling symptoms and the main contributors to health-related quality of life in patients with idiopathic pulmonary fibrosis (IPF). OBJECTIVES: There are no comprehensive studies on pulmonary function tests (PFTs), dyspnea, exercise capacity and radiographic scores in IPF. We therefore sought to investigate the functional variables that can predict dyspnea, exercise capacity and disease extent in IPF. METHODS: Thirty-four patients with IPF according to the ATS/ERS criteria underwent PFTs, Medical Research Council (MRC) dyspnea scoring, 6-min walking distance (6-MWD) and radiographic evaluation of fibrosis (HRCT score). RESULTS: The 6-MWD (% pred.) was more impaired than PFTs. Residual volume (RV) showed the best correlation with the extent of fibrosis (r = -0.67, p = 0.0001) and, together with the alveolar-arterial gradient for O(2) [DeltaP(A - a)O(2)], was an independent predictor of disease extent (R(2) = 0.44). PFTs showed significant though weak correlations with MRC score and 6-MWD. According to the regression analysis, DL(CO) and the HRCT fibrosis score were independent predictors of dyspnea, though they explained only 28% of the overall variance. FEV(1) and DeltaP(A - a)O(2) were independent predictors of 6-MWD (R(2) = 0.31). CONCLUSIONS: PFTs and lung volumes in particular are closely related to the HRCT score, a measure of the extent of IPF. The correlation of dyspnea score and 6-MWD to PFTs is limited, due to the complexity of mechanisms leading to exercise limitation in IPF. Therefore dyspnea and exercise performance are largely independent indices and should be followed together with PFTs and HRCT score in order to better assess the status and progress of IPF patients.

Aged↗
PubMed1992

Role of creatine phosphokinase in predicting acute renal failure in hypocalcemic exertional heat stroke.

Recruits frequently develop hypocalcemia in exertional heat stroke (ExHS) with rhabdomyolysis and acute renal failure (ARF) from intensive training. It usually indicated severe skeletal muscle damage. However, the relative risk of ARF in ExHS patients complicated with hypocalcemia was unknown. The present study was undertaken to evaluate the value of peak serum creatine phosphokinase (CPK) level in predicting ARF in ExHS patients with hypocalcemia. Sixty-eight army recruits with ExHS were hospitalized at the Tri-Service General Hospital, Taiwan: 17 with ARF and hypocalcemia (group A); 7 with ARF but without hypocalcemia (group B); 20 without ARF but with hypocalcemia (group C); and 24 without ARF or hypocalcemia (group D). In the 24 patients with ARF (groups A and B) the serum phosphate and peak CPK levels were significantly higher than in patients without ARF (groups C and D; p < 0.001), serum calcium levels were also significantly lower in the former (p < 0.001). In the 37 patients with hypocalcemia (groups A and C), the peak serum CPK levels were significantly higher than in those without hypocalcemia (groups B and D; p < 0.001). There was a higher proportion of hypocalcemic patients with peak serum CPK levels greater than 10,000 U/l among ARF compared with patients without ARF (chi 2 = 12.48, p < 0.001). In 24 patients with ARF, there was a negative correlation between serum Ca and peak CPK levels (t = 3.37, r = -0.58, p < 0.01). However, a positive correlation was found between serum creatinine and peak serum CPK levels in 37 patients with hypocalcemia (t = 2.47, r = 0.39, p < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1992

Blood lactate is reduced following successful treatment of anaemia in haemodialysis patients with recombinant human erythropoietin both at rest and after maximal exertion.

The effect of increasing haemoglobin by erythropoietin therapy on exercise capacity was investigated in 11 regular haemodialysis patients, previously transfusion dependent. Exercise work load increased from a median of 100 W (95% confidence limit, 25-135) to 120 (45-180; p < 0.05) following erythropoietin, and the duration of the exercise test from 13 (3.5-20) to 15.5 min (4-22; p < 0.05). Resting blood lactate concentration decreased from 0.8 (0.6-1.6) to 0.3 mmol/l (0.3-0.4), p < 0.05, following treatment with erythropoietin, as did blood lactate concentration at maximal exertion from 2.0 (1.0-4.1) to 1.8 mmol/l (0.5-2.8; p < 0.05). In association with the increase in haemoglobin from a median of 6 (5.1-6.8) to 11.1 g/dl (11-11.9) following erythropoietin therapy, patients were able to achieve greater exercise capacity both in terms of maximum work load and duration of exercise in association with a reduced resting arterial lactate and a similar exercise-induced lactate production. This suggests that treatment had improved muscle function in terms of lactate production and/or utilisation. This was probably due to the increase in tissue oxygen delivery, as there was an increase in the median arterial oxygen content from 79 (65-85) to 150 ml O2 (144-157) following erythropoietin treatment.

Adult↗
PubMed1995

A prospective study of calcium metabolism in exertional heat stroke with rhabdomyolysis and acute renal failure.

Intensive training in a humid and warm environment can cause exertional heat stroke (ExHS) and rhabdomolysis (RBD) in military recruits. To investigate the role of vitamin D and monomeric calcitonin (CT) on the calcium metabolism in ExHS with RBD and acute renal failure (ARF), we studied 21 recruits with ExHS (mean age 21.4 years), 7 of which had ARF. Another 11 age-matched recruits with heat exhaustion (HE) and 11 healthy subjects were selected as controls. Our results showed that in 14 ExHS patients without ARF, mean serum creatinine (Cr) levels were significantly higher (151.16 vs. 106.08 mumol/l, p < 0.01), whereas serum osteocalcin (OC) levels were significantly lower (2.22 vs. 4.65 micrograms/l, p < 0.01) than in healthy controls. In 7 patients with ExHS and ARF, the mean serum Cr (774.38 vs. 105.20 mumol/l, p < 0.01), phosphorus (P) (2.26 vs. 1.26 mmol/l, p < 0.05), creatine phosphokinase (CPK) 274,143.97 vs. 85.78 IU/l, p < 0.05), intact parathyroid hormone (I-PTH) (299.81 vs. 18.66 ng/l, p < 0.05) and CT (13.58 vs. 6.63 ng/l, p < 0.01) levels on admission were significantly higher while the mean ionized calcium (iCa) levels were significantly lower than the healthy controls (0.9 vs. 1.18 mmol/l, p < 0.01). The mean serum 25-hydroxyvitamin D [25(OH)D] levels were not significantly different from healthy controls. However, mean serum 1,25-dihydroxyvitamin D [1,25(OH)2D] levels and the ratio of 1,25(OH)2D to 25(OH)D were significantly lower than healthy controls throughout the whole course of ARF. None of the 7 patients with ExHS and ARF developed hypercalcemia during the diuretic phase. Their mean serum I-PTH levels decreased significantly from 299 to 18 ng/l during the recovery phase (p < 0.05). Our study seems to suggest that the abnormal calcium metabolism in this unique patient group is in part caused by persistently decreased renal production of 1,25(OH)2D, although increased monomeric CT levels were associated with hypocalcemia. However, whether or not a causal relationship exists merits further investigation.

Acute Kidney Injury↗
PubMed1987

Reversal of exertional hypotension by prolonged exercise training in selected patients with ischemic heart disease.

The effect of prolonged intense endurance exercise training on exertional hypotension was investigated in 16 patients with coronary artery disease who had a 10 mm Hg or greater fall in systolic blood pressure (SBP) during progressive exercise testing. Training consisted of walking, running, or cycling at 50% to 60% of peak oxygen uptake (peak VO2) for 30 min 3 days per week for an initial 3 months and was followed by an additional 9 months of similar exercise performed at 70% to 90% of peak VO2 for 50 to 60 min 5 days per week. The 1 year program resulted in a 41% increase in peak VO2 and lower heart rate and blood pressure responses to submaximal work. Before conditioning, SBP attained a maximal value of 162 +/- 5 mm Hg but fell 21 +/- 3 mm Hg, to 141 +/- 7 mm Hg, at peak effort (p less than .01). After training, maximal SBP was achieved at a faster heart rate (157 +/- 5 vs 132 +/- 6 beats/min; p less than .001) and was 7.4% higher (174 +/- 6 vs 162 +/- 5 mm Hg; p less than .005), while SBP at peak exercise had increased by 21% (171 +/- 6 vs 141 +/- 7 mm Hg; p less than .001) and ST segment depression was slightly reduced. Left ventricular ejection fraction (LVEF) before training declined from 56 +/- 4% at rest to 52 +/- 3% at peak exercise (p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Exertional oxygen of limited benefit in patients with chronic obstructive pulmonary disease and mild hypoxemia.

It is unclear whether short-term benefits from supplemental oxygen translate into improved quality of life in patients with severe COPD. In a 12 wk double-blind randomized crossover study, we assessed the effects of supplemental air and oxygen on exercise performance (step tests and 6 min walking distance [6MWD]) initially and after two 6 wk periods at home using exertional cylinder air or oxygen. We measured quality of life at baseline and after the two 6 wk domiciliary periods. The 26 patients (24 males) had a mean age of 73 +/- 6 yr; mean FEV1, 0.9 +/- 0.4 L; mean DLCO, 10.6 +/- 2.4 ml/min/mm Hg; mean resting PO2, 69 +/- 8.5 (range 58 to 82) mm Hg; mean PCO2, 41 +/- 3.3 mm Hg; and mean resting SaO2, 94 +/- 2.1 (mean +/- SD). Laboratory tests were performed breathing intranasal air or oxygen at 4 L/min, and measurements were made of SaO2 and Borg dysnea scores. Supplemental oxygen increased 6MWD and steps by small, statistically significant increments acutely at baseline and after 6 and 12 wk, without corresponding falls in Borg score. Degree of desaturation at baseline did not correlate with increase in 6MWD or steps achieved at baseline or at 6 or 12 wk, nor with the domiciliary gas used. There was no difference in 6MWD or steps achieved while breathing supplemental oxygen after 6 wk of domiciliary oxygen compared with domiciliary air. Small improvements in quality of life indices were found after domiciliary oxygen, and mastery also improved after domiciliary air. There were no differences in quality of life, however, when domiciliary oxygen was compared with domiciliary air. Although oxygen supplementation induced small acute increments in laboratory exercise performance, such improvements had little impact on the patients' daily lives.

Aged↗
PubMedDate not supplied

Cardiac displacement with a congenital complete left-sided pericardial defect in a patient with exertional angina pectoris--a case report.

A 71-year-old man with exertional chest pain was admitted to the hospital. A chest roentgenogram exhibited levoposition of the heart. An electrocardiogram showed clockwise rotation in the precordial leads and ST depression in V6, V7, V8, and V9 as well as in II, III, aVF leads associated with chest pain in a treadmill exercise test. The congenital complete left-sided pericardial defect could not be diagnosed preoperatively, but it was confirmed by thoracotomy.

Aged↗
PubMed1990

Hemodynamic effects of nebivolol at rest and on exertion in patients with heart failure.

Nebivolol is a novel B-1-adrenoceptor-blocking drug with an unusual hemodynamic profile unlike classical B-blockers. In dogs and in healthy volunteers it decreases blood pressure and heart rate but improves left ventricular function. The authors studied 10 male patients with coronary artery disease and heart failure (ejection fraction mean = 46%). A Swan-Ganz catheter was placed into the pulmonary artery, and the mean blood pressure, the heart rate, the pulmonary artery pressure, the pulmonary wedge pressure, the right atrial pressure, the cardiac output, and the stroke volume were measured at rest and on exertion before and after seven days' treatment with oral nebivolol (5 mg/day). While the blood pressure and the heart rate decreased significantly, the pulmonary artery and wedge pressures, as well as the right atrial pressure and the cardiac output, did not change during treatment. The stroke volume increased significantly. The maintained cardiac output cannot be explained by any changes in preload or afterload; instead a positive inotropic mechanism must be assumed. Unlike other B-blockers it seems to be possible to treat patients with heart failure with nebivolol without causing the hemodynamic situation to deteriorate.

Adrenergic beta-Antagonists↗
PubMed1997

Left ventricular diastolic filling dynamics during isometric exertion in syndrome X assessed with Doppler flowmetry.

To study left ventricular diastolic properties in syndrome X, we analyzed transmitral filling dynamics during handgrip exertion. In 14 normal subjects (N), 17 with syndrome X (Syn X), 16 with single-vessel disease (SVD), and 8 with multiple-vessel disease (MVD), transmitral inflow was recorded at baseline and during handgrip (50% of maximal effort for one minute) using pulsed Doppler echocardiography. We measured early diastolic (E) and late atrial (A) inflow velocities, A/E ratio and percent change of A/E from baseline (%A/E). Blood pressure and heart rate increased to the same degree in each group during handgrip. In normal subjects, E did not change with handgrip; A (51 +/- 10 vs 54 +/- 11 cm/sec, P < 0.05) and A/E (1.16 +/- 0.22 vs 1.25 +/- 0.33, P < 0.05) increased minimally. In Syn X subjects, E decreased (51 +/- 10 vs 38 +/- 10 cm/sec, P < 0.0001), A increased (52 +/- 11 vs 60 +/- 14 cm/sec, P < 0.005), and A/E increased markedly (1.07 +/- 0.31 vs 1.68 +/- 0.51, P < 0.0001). The %A/E in Syn X and MVD were significantly larger than that in SVD and N (Syn X: 58 +/- 29%; MVD: 45 +/- 25%; SVD: 22 +/- 21%; N: 8 +/- 13%). Handgrip-induced changes in diastolic filling in syndrome X and are similar to those in MVD and more marked than in SVD. These changes are consistent with impaired ventricular relaxation and support a generalized left ventricular (LV) abnormality in syndrome X.

Adult↗
PubMed1994

Attentional style in ratings of perceived exertion during physical exercise.

This study assessed the effects of associative and dissociative psychological strategies of attention on heart rate and self-report ratings of perceived exertion (RPE) during cycling performance. Seven trained cyclists performed a control ride, a dissociation ride, and an association ride on a bicycle ergometer at a work rate corresponding to 75% of their maximal heart rate. For the dissociation ride, subjects watched a videotape unrelated to cycling and responded to a key word each time it occurred on tape. For the association ride, subjects focused attention on heart-rate feedback available throughout the ride. During the control ride, attentional focus was not intentionally manipulated. Analysis indicated that the deliberate application of an attentional strategy did not significantly affect heart rate or RPE scores; however, the dissociation condition yielded somewhat higher RPE scores. From a postexperimental interview, four subjects responded that the association ride was the easier to complete, while three subjects responded the control ride was the easier one, matching a possible trend in the data.

Adolescent↗
PubMedDate not supplied

The use of magnetic resonance imaging in exertional compartment syndromes.

This prospective, double-blind study was carried out to assess the usefulness of magnetic resonance imaging (MRI) as a noninvasive method in the diagnosis of chronic compartment syndrome (CCS). As well, a new radiopharmaceutical known as methoxy isobutyl isonitrile that has been shown to be taken up by muscle in direct proportion to its blood flow was used to illustrate the possible pathophysiology of this syndrome. Twenty patients with a history of chronic leg pain and possible diagnosis of CCS and five normal volunteers had preexercise and postexercise MRI, nuclear medicine imaging, and static and dynamic slit catheter pressure studies. Nine patients had classic symptoms; only five of these nine had abnormal pressure studies. The other 11 patients had an element of pain at rest and had normal pressure studies. The nuclear blood flow studies were normal in all 25 legs tested in this study. Measurement of intrinsic MRI parameters T1 and T2 in the normal legs as well as in those with an atypical history showed a marked elevation with exercise and a gradual return to baseline postexercise that was similar to the pressure curves. In the five patients with a clinical history and elevated pressures, four had abnormal MRI studies with failure of T1 to return to baseline values. Although these results demonstrate the potential of MRI as a tool for noninvasively monitoring muscle status, clinical history and examination remain important in the diagnosis of CCS. This study indicates that the pathophysiology of exertional compartment syndrome does not appear to be related to ischemia.

Adolescent↗
PubMed2005

Factors limiting maximal oxygen uptake in exertional monoparesis.

Strength and maximal oxygen uptake (VO2max) for each leg were compared in a trained multiple sclerosis (MS) patient with exertional left monoparesis. Left quadriceps strength and left leg VO2max were 22% and 30% lower, respectively, compared to the right (control) leg. Because the same O2 delivery system served each leg during exercise, VO2max of the paretic leg was not limited by cardiorespiratory factors but rather by strength and/or muscle oxidative capacity. However, training with monoparesis likely enhanced O2 extraction and aerobic work capacity of the right leg.

Adult↗
PubMed1996

Changes in thyroid hormone metabolism in exertional heat stroke with or without acute renal failure.

The effects of exertional heat stroke (ExHS), with or without acute renal failure (ARF), on thyroid hormone metabolism were investigated. Eighteen ExHS patients were recruited and divided into two groups based on the presence or absence of ARF. Eleven age-matched healthy subjects served as a control group. Serum values of T3, T4, TSH, free T4 (FT4), rT3, and sulfated T3 (T3S) were measured in these groups during the acute and recovery stages of ExHS. Serum T3, T4, and FT4 levels were reduced, with reciprocal increases in rT3 and T3S levels as the severity of ExHS increased. The following mean levels of thyroid hormones were found (controls vs. ExHS without ARF vs. with ARF): T3, 1514 vs. 1164 vs. 393 pmol/L (P < 0.05 each); T4, 97 vs. 79 vs. 49 nmol/L (P = NS and P < 0.05, respectively); FT4, 20.5 vs. 19.5 vs. 19.0 pmol/L (P = NS each); rT3, 371 vs. 617 vs. 805 pmol/L (P < 0.05 and P = NS, respectively); and T3S, 30.1 vs. 34.2 vs. 71.1 pmol/L (P = NS and P < 0.05, respectively). The serum TSH levels were not significantly different among the three groups. Significantly negative correlations were found between serum creatinine and T3 (r = -0.75; P < 0.001) and T4 levels (r = -0.65; P < 0.001), whereas no relationship was noted between serum creatinine and rT3 values (r = 0.11; P < 0.05). In contrast, a correlation was observed between serum glutamic pyruvic transaminase and rT3 (r = 0.45; P < 0.01). Thyroid function tests returned to normal after patients recovered. In conclusion, our results show that patients suffering from ExHS, with or without ARF, displayed altered serum thyroid function in proportion to the severity of their condition. No significant changes in serum levels of rT3 were observed between the two groups, whereas a positive relationship was observed between serum rT3 and serum glutamic pyruvic transaminase values, suggesting that the changes in serum rT3 levels were more dependent on extrarenal illness than on renal disease per se. The moderate increase in serum T3S levels found in patients suffering from both ExHS and ARF may represent a decrease in tissue 5'-monodeiodinase activity as found in other nonthyroidal illnesses. A return of serum thyroid function tests to normal values after recovery from ExHS suggests that the low T3 state may play a protective role to prevent undesirable catabolic effects. Replacement therapy is thus not recommended.

Acute Kidney Injury↗