The effect of physical training on hormonal status and exertional hormonal response in patients with chronic congestive heart failure.
(49/6923)
BACKGROUND: Physical training improves exercise capacity in patients with chronic heart failure. It decreases plasma noradrenaline at rest, which may be prognostically favourable. The effect on atrial natriuretic peptide, another prognostic factor, and on catabolic and anabolic hormones remains unknown. Furthermore, to our knowledge, the contribution of exertional hormonal responses to the improved exercise capacity has not been evaluated. METHODS: 27 patients with stable chronic heart failure (New York Heart Association class II-III) were randomized to training (n=12) and control (n=15) groups. The training group exercised on a bicycle ergometer for 30 min three times a week for 3 months. The load corresponded to 50-60% of their peak oxygen consumption. For the next 3 months they exercised at home according to personal instructions. The control group did not change its physical activities. The levels of hormones regulating the cardiovascular system and metabolism were determined at rest and after graded maximal exercise and during exercise with constant submaximal workload. RESULTS: Submaximal exercise capacity increased significantly and peak oxygen consumption tended to improve by 12% in the training group. The plasma noradrenaline at rest tended to decrease by 19%. The plasma level of N-terminal pro atrial natriuretic peptide did not change. Serum cortisol, a catabolic hormone, was normal at baseline and remained unchanged. The serum levels of anabolic hormones, growth hormone and insulin, as well as dehydroepiandrosteronesulfate and free testosterone were within a normal range at baseline. They were not altered by training. The dehydroepiandrosteronesulfate/cortisol, and the free testosterone/cortisol ratios, reflecting anabolic/catabolic balance, did not change, either. Training resulted in a higher peak noradrenaline response during graded maximal exercise. The rise in serum cortisol during exercise tended to attenuate. CONCLUSION: Physical training, which improves exercise capacity, does not have an unfavourable effect on anabolic/catabolic balance or neurohumoral activation in patients with congestive heart failure. It decreases plasma noradrenaline at rest. Minor changes in hormonal responses during exercise emerged after physical training which unlikely contribute to the improved exercise capacity. (+info)
Direct evidence of endothelial injury in acute myocardial infarction and unstable angina by demonstration of circulating endothelial cells.
(50/6923)
Circulating endothelial cells (CECs) have been detected in association with endothelial injury and therefore represent proof of serious damage to the vascular tree. Our aim was to investigate, using the technique of immunomagnetic separation, whether the pathological events in unstable angina (UA) or acute myocardial infarction (AMI) could cause desquamation of endothelial cells in circulating blood compared with effort angina (EA) and noncoronary chest pain. A high CEC count was found in AMI (median, 7.5 cells/mL; interquartile range, 4.1 to 43.5, P <.01 analysis of variance [ANOVA]) and UA (4.5; 0.75 to 13.25 cells/mL, P <.01) within 12 hours after chest pain as compared with controls (0; 0 to 0 cells/mL) and stable angina (0; 0 to 0 cells/mL). CEC levels in serial samples peaked at 15.5 (2.7 to 39) cells/mL 18 to 24 hours after AMI (P <.05 repeated measures ANOVA), but fell steadily after UA. Regardless of acute coronary events, the isolated cells displayed morphologic and immunologic features of vascular endothelium. The CECs were predominantly of macrovascular origin. They did not express the activation markers intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, and E-selectin, although some were positive for tissue factor. CECs failed to exhibit characteristics of apoptosis (TUNEL assay) excluding this event as a possible mechanism of cell detachment. The presence of CECs provides direct evidence of endothelial injury in AMI and UA, but not in stable angina, confirming that these diseases have different etiopathogenic mechanisms. (+info)
Decreased activity of the L-arginine-nitric oxide metabolic pathway in patients with congestive heart failure.
(51/6923)
BACKGROUND: Impaired endothelium-dependent, nitric oxide (NO)-mediated vasodilation may contribute to increased vasomotor tone in patients with heart failure. Whether decreased endothelium-dependent, NO-mediated vasodilation in patients with heart failure is due to decreased synthesis or increased degradation of NO is unknown. METHODS AND RESULTS: To specifically assess the synthetic activity of the L-arginine-NO metabolic pathway, urinary excretion of [15N]nitrates and [15N]urea was determined after a primed continuous intravenous infusion of L-[15N]arginine (40 micromol/kg) in 16 patients with congestive heart failure and 9 age-matched normal control subjects at rest and during submaximal treadmill exercise. After infusion of L-[15N]arginine, 24-hour urinary excretion of [15N]nitrates was decreased in patients with congestive heart failure at rest (2.2+/-0.5 versus 8.0+/-2.3 micromol/24 h) and during submaximal exercise (2.4+/-1.2 versus 11. 4+/-4.0 micromol/24 h) compared with control subjects (both P<0.01). After infusion of L-[15N]arginine, 24-hour urinary excretions of [15N]urea at rest in patients with congestive heart failure and control subjects were not different (1.1+/-0.3 versus 1.2+/-0.2 mmol/24 h, P>0.20). CONCLUSIONS: A specific decrease in synthetic activity of the L-arginine-NO metabolic pathway contributes to decreased endothelium-dependent vasodilation in patients with congestive heart failure. (+info)
Exercise four hour redistribution thallium-201 single photon emission computed tomography and exercise induced ST segment elevation in detecting the viable myocardium in patients with acute myocardial infarction.
(52/6923)
OBJECTIVE: To investigate the specificity and sensitivity of the combination of redistribution in exercise thallium-201 single photon emission computed tomography (SPECT) and exercise induced ST elevation for detecting the viable myocardium in patients with acute myocardial infarction. DESIGN: 37 patients were studied within seven weeks of onset of Q wave myocardial infarction (anterior in 22, inferior in 15). All patients underwent exercise four hour redistribution thallium-201 SPECT and positron emission tomography using fluorine-18-fluorodeoxyglucose (FDG) and nitrogen-13 ammonia under fasting conditions. RESULTS: Sixteen patients showed exercise induced ST elevation >/= 1.5 mm, and 15 of these had increased FDG uptake in the infarct region. Eleven of 16 patients (10 of 11 patients with anterior infarctions) with irreversible thallium-201 defects and increased FDG uptake showed exercise induced ST elevation. The sensitivity, specificity, and predictive accuracy of redistribution, exercise induced ST segment elevation, or both for detecting increased FDG uptake were 82%, 75%, and 67% (94%, 75%, and 91% for anterior infarctions), respectively. CONCLUSIONS: In patients with acute Q wave myocardial infarction, the combination of redistribution in exercise thallium-201 SPECT and exercise induced ST elevation can detect the viable myocardium in the infarct region with high sensitivity and specificity, especially in patients with anterior infarctions. (+info)
Improvements in thoracic movement following lung volume reduction surgery in patients with severe emphysema.
(53/6923)
In twelve patients with severe emphysema who underwent lung volume reduction surgery (LVRS), we assessed the results of dyspnea scale, pulmonary function, 6-minute walk distance (6MD), and thoracic movement prior to and 6 months following LVRS. Postoperatively, forced expiratory volume (FEV1), maximum inspiratory mouth pressures (MIP), maximum expiratory mouth pressures (MEP), maximum voluntary ventilation (MVV), diffusing capacity for carbon monoxide (DLCO), partial pressure of oxygen (PaO2) and 6MD were significantly increased with the decrease in dyspnea scale and lung hyperinflation. Thoracic movement, as assessed by the bilateral lung area ratio of the mid-sagittal dimension of dynamic magnetic resonance imaging (MRI) at full inspiration to that at full expiration, was significantly increased. The improvement in thoracic movement was significantly correlated with the increases in FEV1, MVV, and MIP, and with the decrease in residual volume (RV), and with the improvement in the dyspnea scale. These findings suggest that LVRS is an effective procedure for improving not only the airflow limitation and gas exchange but also the thoracic movement in severe emphysema, and these improvements may contribute to an increase in exercise performance and relief of dyspnea. (+info)
Exercise VE and physical performance at altitude are not affected by menstrual cycle phase.
(54/6923)
We hypothesized that progesterone-mediated ventilatory stimulation during the midluteal phase of the menstrual cycle would increase exercise minute ventilation (VE; l/min) at sea level (SL) and with acute altitude (AA) exposure but would only increase arterial O2 saturation (SaO2, %) with AA exposure. We further hypothesized that an increased exercise SaO2 with AA exposure would enhance O2 transport and improve both peak O2 uptake (VO2 peak; ml x kg-1 x min-1) and submaximal exercise time to exhaustion (Exh; min) in the midluteal phase. Eight female lowlanders [33 +/- 3 (mean +/- SD) yr, 58 +/- 6 kg] completed a VO2 peak and Exh test at 70% of their altitude-specific VO2 peak at SL and with AA exposure to 4,300 m in a hypobaric chamber (446 mmHg) in their early follicular and midluteal phases. Progesterone levels increased (P < 0.05) approximately 20-fold from the early follicular to midluteal phase at SL and AA. Peak VE (101 +/- 17) and submaximal VE (55 +/- 9) were not affected by cycle phase or altitude. Submaximal SaO2 did not differ between cycle phases at SL, but it was 3% higher during the midluteal phase with AA exposure. Neither VO2 peak nor Exh time was affected by cycle phase at SL or AA. We conclude that, despite significantly increased progesterone levels in the midluteal phase, exercise VE is not increased at SL or AA. Moreover, neither maximal nor submaximal exercise performance is affected by menstrual cycle phase at SL or AA. (+info)
Explosive-strength training improves 5-km running time by improving running economy and muscle power.
(55/6923)
To investigate the effects of simultaneous explosive-strength and endurance training on physical performance characteristics, 10 experimental (E) and 8 control (C) endurance athletes trained for 9 wk. The total training volume was kept the same in both groups, but 32% of training in E and 3% in C was replaced by explosive-type strength training. A 5-km time trial (5K), running economy (RE), maximal 20-m speed (V20 m), and 5-jump (5J) tests were measured on a track. Maximal anaerobic (MART) and aerobic treadmill running tests were used to determine maximal velocity in the MART (VMART) and maximal oxygen uptake (VO2 max). The 5K time, RE, and VMART improved (P < 0.05) in E, but no changes were observed in C. V20 m and 5J increased in E (P < 0.01) and decreased in C (P < 0.05). VO2 max increased in C (P < 0.05), but no changes were observed in E. In the pooled data, the changes in the 5K velocity during 9 wk of training correlated (P < 0.05) with the changes in RE [O2 uptake (r = -0.54)] and VMART (r = 0.55). In conclusion, the present simultaneous explosive-strength and endurance training improved the 5K time in well-trained endurance athletes without changes in their VO2 max. This improvement was due to improved neuromuscular characteristics that were transferred into improved VMART and running economy. (+info)
Effects of feeding frequency and voluntary salt intake on fluid and electrolyte regulation in athletic horses.
(56/6923)
The effect of feeding frequency and voluntary sodium intake (VSI) on fluid shifts and plasma aldosterone concentration (PAC) were studied at rest and after exercise in six athletic horses. The horses were fed twice a day (2TD) and six times a day (6TD) for 25 days for each protocol, according to a changeover design. VSI was measured by weighing each horse's salt block daily. Feeding 2TD or 6TD caused no major alterations in fluid shifts, but in the 2TD treatment there was a postprandial increase in plasma protein concentration and osmolality that lasted <1 h. PAC and VSI were not affected by feeding frequency. VSI ranged from 0 to 62 mg x kg body weight-1 x day-1 and caused significant alterations in PAC. At VSI <26 mg x kg body weight-1 x day-1, a diurnal rhythm for PAC was noted. Water intake, fecal concentrations of sodium and potassium, and packed cell volume during exercise were influenced by VSI. The response to exercise did not differ between treatments. In conclusion, VSI, but not feeding frequency, has significant effects on fluid and electrolyte regulation in athletic horses. (+info)