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At least 685 records · Page 38Linked to original sources
PubMed1984

Maximal exercise tolerance after induced alkalosis.

Eight healthy males performed two rides to exhaustion at a work load corresponding to 125 VO2 max, 1 h after ingesting either 0.2 g NaHCO3/kg body weight (E) or NaCl (C). Mean +/- SE pre-exercise blood pH, HCO-3, and base excess (BE) values were respectively 7.42 +/- 0.01, 28.2 +/- 1.5 mmol/l, and 2.02 +/- 0.10 mmol/l for the E condition, and 7.39 +/- 0.01, 24.4 +/- 0.07 mmol/l, and -0.40 +/- 0.07 mmol/l for the C condition (P less than 0.05 for all variables). Cycling time to exhaustion (E = 100.6 +/- 6.1; C = 98.6 +/- 5.7 s) and total VO2 during recovery (E = 17.7 +/- 0.9; C = 17.3 +/- 0.8 1/30 min) did not differ significantly between treatments. Blood pH, HCO-3, and BE were significantly higher while the hydrogen ion to lactate ratio (nmol/mmol) was significantly lower in E than in C during recovery. Blood LA levels were also greater in E than in C during the latter part of recovery although peak individual values were not significantly different between trials (E = 14.4 +/- 0.4; C = 13.3 +/- 0.0 mmol/l). In view of the insignificant differences in cycling time, peak individual LA, and total recovery VO2, it is not likely that LA production was greater in E than in C. Rather it appears that LA efflux was enhanced by the NaHCO3 feeding. Additionally, the return of the acid-base status in blood to resting conditions was more rapid during alkalosis. Given this protocol, alkalosis does not help to sustain an intense exercise bout. These data suggest, however, that NaHCO3 may be of benefit following repeated work bouts.

Bicarbonates↗
PubMed1998

Daytime functioning in obstructive sleep apnea patients: exercise tolerance, subjective fatigue, and sleepiness.

A sample of 32 obstructive sleep apnea patients (27 males, 5 females) was assessed with overnight polysomnography and the Multiple Sleep Latency Test (MSLT), an objective measure of daytime sleepiness. Patients also participated in a maximal exercise test, which served as an objective indicator of physical fatigue. The Fatigue Severity Scale (FSS) was used as a subjective measure of fatigue. Subjective fatigue ratings were significantly correlated with percent of predicted maximum heart rate achieved during exercise testing, suggesting that self-reported fatigue in apnea patients may refer to reduced physical fitness. FSS scores and exercise testing results were not significantly correlated with the MSLT, indicating that daytime fatigue and daytime sleepiness are independent problems in apnea patients. Participants self-reported a high level of fatigue, and exercise testing revealed decreased physical work capacity among apnea patients, but objective and subjective indicators of fatigue were not significantly correlated with apnea severity. A higher percentage of REM sleep predicted greater work capacity.

Adult↗
PubMed1985

Acute and long-term effects of enalapril on the cardiovascular response to exercise and exercise tolerance in patients with congestive heart failure.

Enalapril is a recently developed angiotensin-converting enzyme inhibitor that improves cardiac function at rest in patients with congestive heart failure. This study investigated the acute effects of enalapril on the cardiovascular response to exercise, and then evaluated the long-term effects of enalapril on exercise capacity and functional status during a 12 week placebo-controlled trial in patients with heart failure. Ten patients underwent hemodynamic monitoring while at rest and during incremental bicycle exercise before and after 5 to 10 mg of enalapril orally. At rest, enalapril decreased mean blood pressure 13% (p less than 0.01) and systemic vascular resistance 20% (p less than 0.05) and increased stroke volume index 21% (p less than 0.01). During maximal exercise, enalapril decreased systemic vascular resistance and increased both cardiac and stroke volume indexes. Enalapril acutely increased exercise duration (p less than 0.05) and maximal oxygen consumption (p less than 0.001). These 10 patients and an additional 13 patients were then randomized to either placebo or enalapril treatment and followed up for 12 weeks. Of the 11 patients assigned to active treatment, 73% considered themselves improved compared with 25% of the patients assigned to placebo treatment (p less than 0.02). During long-term treatment, exercise capacity increased in patients receiving enalapril (p less than 0.001) but was unchanged in patients receiving placebo (intergroup difference, p less than 0.05). During long-term treatment, no adverse effects of enalapril occurred. Thus, enalapril improves cardiac function at rest and during exercise. Compared with placebo, maintenance therapy with enalapril results in symptomatic improvement and increased exercise capacity.

Adult↗
PubMed1990

Exercise tolerance after anaemia correction with recombinant human erythropoietin in end-stage renal disease.

The aim of this study was to evaluate the effect of correction of chronic anaemia on the physical performance and the cardiovascular response to effort in children with end-stage renal disease (ESRD) maintained by haemodialysis. Seven patients (mean age 13.9 years) underwent triangular-type treadmill exercise testing before [haemoglobin (Hb) 6.3 +/- 0.9 g/dl] and after (Hb 11.2 +/- 1.2 g/dl) anaemia correction with recombinant human erythropoietin (rHuEPO). After treatment, the work-load reached, the peak oxygen uptake and average ventilatory anaerobic threshold (VAT) values were significantly increased (P less than 0.01, P less than 0.001, P less than 0.05 respectively). VAT values, expressed as a percentage of normal values, increased from 55.7 +/- 16.6% to 82.4 +/- 21%. This improvement correlated well with the increase in Hb (r = 0.79). Oxygen pulse also increased significantly, when tested after anaemia correction. In conclusion, these data demonstrate that when the anaemia of children with ESRD is corrected with rHuEPO, there is a clear improvement in aerobic work capacity and effort tolerance.

Adolescent↗
PubMed1981

Antihypertensive therapy with prazosin in patients with left ventricular dysfunction. Improvement in cardiac performance and exercise tolerance.

Although the relationship between blood pressure and cardiac performance has been widely recognized, there are few published clinical observations concerning the effect of blood pressure control on cardiac function. We evaluated the effect of prazosin, an antihypertensive agent which also improves hemodynamic measurements in normotensive patients with heart failure, in 16 patients with moderate hypertension and reduced ejection fractions. Therapy with digoxin and diuretics was continued throughout the study, but other antihypertensive agents were withdrawn at least one week prior to the initiation of the study. Measurements of ejection fraction, cardiothoracic ratio and the duration of maximal treadmill exercise were made before and after two months of antihypertensive therapy with prazosin. On prazosin, blood pressure fell from a mean of 169/103 to 141/84. Excellent control was achieved in 13/16 patients and significant reductions were noted in the remaining three. Concomitantly, ejection fraction rose from .38 +/- .02 (SEM) to .43 +/- .03 (P less than .02), cardiothoracic ratio decreased from .55 +/- .02 to .53 +/- .02 (P less than .05) and exercise capacity increased from 9.2 +/- 0.9 to 11.9 +/- 1.1 minutes (P less than .005). Prazosin was well tolerated except in one patient who experienced worsening angina. These findings emphasize the importance of rigorous blood pressure control in hypertensive patients with left ventricular dysfunction and indicate that prazosin is effective in this setting.

Aged↗