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PubMed1987

Exercise tolerance changes following renal transplantation.

Maximal exercise capacity was measured in 20 nondiabetic patients with end-stage renal disease before and soon after successful renal transplantation. Maximal oxygen consumption increased significantly in all patients posttransplant. Increases in maximal heart rate and heart rates at 70% of maximal levels were also observed. The changes in maximal oxygen consumption were not significantly correlated with changes in hematocrit. The removal of uremia may result in improved functioning of one or more of the systems involved in oxygen transport and utilization that determine exercise capacity.

Adrenergic beta-Antagonists↗
PubMed1994

Detection of restenosis following percutaneous coronary angioplasty in single-vessel coronary artery disease: the value of clinical assessment and exercise tolerance testing.

Chest pain and submaximal exercise testing were prospectively assessed over a 6-month period, for detecting the evolution of restenosis in patients undergoing percutaneous coronary angioplasty, following either acute myocardial infarction or treatment of an anginal syndrome. Seventy-eight patients with one-vessel coronary artery disease underwent a modified treadmill exercise test at the 1-week, 3-month and 6-month follow-up after angioplasty, when a final angiogram was also performed. Forty-four patients (group A) were examined after myocardial infarction; in 34 patients (group B) angioplasty was done for incapacitating angina. Both groups showed similar results with low sensitivity and relatively moderate specificity of both chest pain and exercise tests; this was also the case for the time of restenosis to occur. It is thus concluded that the parameters examined are somewhat limited markers of restenosis following coronary angioplasty.

Adult↗
PubMed2000

L-carnitine moderately improves the exercise tolerance in chronic stable angina.

OBJECTIVES: To study the safety and efficacy (with reference to exercise ECG testing) of oral L-carnitine in chronic stable angina. METHODS: Forty-seven patients, 30 men and 17 women, aged 56 +/- 8 years, were randomized to receive L-carnitine (n = 28) or placebo (n = 19) in the dose of 2 g/day for 3 months. The adjuvant treatment was not changed during the study. Patients were evaluated by computerized stress test (CST) done at the beginning and end of the trial. The parameters assessed were exercise duration, time to onset of ST changes, total ST score at peak exercise, rate-pressure product at peak exercise, and time needed for the ST changes to recover to baseline. RESULTS: The two groups were comparable at the beginning of the study. There was no change in the CST parameters in the placebo group at the end of 3 months. In the L-carnitine group there was a statistically significant improvement in the exercise duration from 7.8 +/- 2.2 min to 8.6 +/- 1.8 min (p = 0.006) and in the time needed for the ST changes to revert to baseline from 7.2 +/- 3.9 min to 5.7 +/- 3.8 min (p = 0.019). No change was noted in the time to onset for ST depression, ST score and double product. There were no systemic adverse effects or coronary events in either group. CONCLUSION: Oral L-carnitine is safe and moderately improves the duration of exercise and time to recovery of ST changes in patients with chronic stable angina.

Adult↗
PubMedDate not supplied

Rate-responsive pacing improves exercise tolerance in heart transplant recipients: a pilot study.

BACKGROUND: Chronotropic incompetence is one cause of diminished exercise capacity in heart transplant recipients. If reinnervation occurs, it often is late after transplantation and is not always accompanied by functional improvements in peak heart rate and appropriate tachycardia during exercise. To determine the efficacy of rate-responsive pacing on peak heart rate and exercise capacity, the authors studied eight male heart transplant recipients (age 57 +/- 12 years; 23 +/- 9 months after transplantation) that had either atrial or dual-chambered pacemakers. METHODS: All subjects completed two maximal graded exercise tests (GXT) using the Naughton treadmill protocol. During the first GXT, pacemakers were programmed for bradycardia support only and without rate responsiveness (unpaced). After a 14-day regimen of beta blockade with metoprolol to nullify the influence of circulating catecholamines on heart rate, subjects performed the second GXT with pacemakers programmed to respond optimally in the rate-responsive mode (paced). RESULTS: Peak heart rate (149 versus 129 bpm), peak oxygen uptake (18.9 versus 15.4 mL/kg/min), treadmill time to exhaustion (14.6 versus 12.4 min), and minute ventilation (76.7 versus 66.2 L/min) were significantly increased (P < or = 0.05) during the paced versus unpaced GXT. CONCLUSIONS: The results of this study demonstrate that chronotropic support of the transplanted heart using a rate-responsive pacemaker, with activity-based sensors programmed for maximal sensitivity, improves both peak heart rate and exercise capacity in heart transplant recipients significantly more than circulating catecholamines alone.

Adrenergic beta-Antagonists↗
PubMed1996

Influence of intrinsic limb vasodilator capacity on exercise tolerance in patients with recent myocardial infarction.

To investigate the influence of intrinsic limb vasodilator capacity on exercise performance, limb reactive hyperemic flows and their relations to exercise capacity during upright bicycle exercise were examined in 52 patients with recent myocardial infarction. Reactive hyperemic flow was measured in the forearm and the calf by venous occlusive plethysmography after 5 min of arterial occlusion. Calf reactive hyperemic flow correlated significantly with cardiac output, systemic vascular resistance, and oxygen consumption at peak exercise, whereas flow in the forearm did not. In patients with preserved exercise capacity (group 1, n = 20) compared with those with exercise impairment (group 2, n = 32), calf reactive hyperemic flow was significantly augmented, but forearm flow was similar in the two groups. There were no significant differences in hemodynamic parameters at rest between the two groups. At peak exercise, however, cardiac output was lower and systemic vascular resistance was higher in group 2 than in group 1, whereas arterial blood pressure was maintained identically in the two groups. Thus, intrinsic calf but not forearm vasodilator capacity was linked to exercise hemodynamic responses and exercise capacity in patients with recent myocardial infarction. In addition, reduced calf vasodilation and concomitant enhanced vascular tone seemed to be useful for preserving arterial blood pressure in the setting of decreased cardiac output response to exercise in patients with exercise impairment.

Adult↗
PubMed1997

[Mechanism of increase in exercise tolerance in patients with acute myocardial infarction].

The contribution of cardiac output reserve and the skeletal muscle to exercise capacity was investigated in 24 patients with acute myocardial infarction. Symptom-limited exercise tests with a cycle ergometer were performed at 1 week, 3 weeks, and 3 months after the onset of the first infarction. Ventilatory gas was analyzed throughout the testing, and peak oxygen uptake (peak VO2) and anaerobic threshold (AT) were determined. During the test, the cardiac index (CI) was measured by the dye dilution method and the change in CI during exercise (delta CI) was calculated as an index of cardiac output reserve. The cross-sectional area of the thigh muscles (CSA) at the level of 10 cm above the patella was measured using computed tomography. Peak VO2 and AT increased significantly from 1 week to 3 months after the onset of infarction. delta CI increased significantly from 1 week to 3 weeks, and CSA increased significantly from 3 weeks to 3 months. Peak VO2 correlated significantly with both delta CI and CSA at each measurement point, as was AT with delta CI and CSA. Change in peak VO2 correlated with change of delta CI from 1 week to 3 weeks, and also with both delta CI and CSA from 3 weeks to 3 months. These results suggest that both cardiac output reserve and peripheral factors contribute to the exercise capacity up to 3 months after the onset of myocardial infarction. In particular, peripheral factors such as muscle volume are important to improve exercise capacity from 3 weeks to 3 months.

Aged↗
PubMed1986

Ventricular pacing improves exercise tolerance in patients with chronic heart block.

Exercise capacity was assessed by means of a simple six minute walking test in a group of 18 patients with heart block whose only presenting symptom was breathlessness. None was in overt cardiac failure. Patients were studied before and after implantation of a transvenous, ventricular, demand pacing system (study group). Eight patients with an implanted pacemaker admitted for elective generator replacement were assessed in the same manner (control group). Exercise capacity in the study group was significantly increased within 48 hours of pacing, and this improvement was maintained in most patients during the follow up period of up to 30 months. In contrast, exercise capacity was unaffected by generator replacement in the control group. Simple ventricular pacing produces symptomatic benefit in patients with heart block accompanied by breathlessness. This benefit is apparent within 48 hours of pacing and is maintained; it can be assessed objectively by a six minute walking test.

Aged↗
PubMed2005

The reliability of an aerobic and an anaerobic exercise tolerance test in patients with juvenile onset dermatomyositis.

OBJECTIVE: To investigate the reliability of an aerobic and an anaerobic exercise test in patients with juvenile dermatomyositis (JDM). METHODS: Sixteen patients with JDM (mean age 13.85 +/- 6.4 yrs, range 6.7-27.2) participated. Anaerobic exercise capacity was measured using the Wingate Anaerobic Exercise Test (WAnT). Aerobic exercise test was performed using a graded exercise test to volitional exhaustion on an electronically braked cycle ergometer. Patients were tested and retested within 12.8 +/- 5.7 days. RESULTS: Correlation coefficients and other reliability statistics indicated that peak power and mean power on the WAnT and peak oxygen uptake (VO2peak) and maximal workload (Wmax) on the aerobic exercise test could be reliably assessed in patients with JDM. Pearson (R) and intraclass correlation coefficients (ICC) were > 0.85, and typical error was < 20% for the peak power and mean power on the WAnT. On the aerobic exercise test the R and ICC were > 0.95, and typical error was < 6% for the VO2peak and Wmax. CONCLUSION: We found acceptable reliability for the WAnT and very good reliability for the aerobic exercise test. This indicated that these exercise tests could be performed reliably in patients with JDM.

Adolescent↗
PubMed1996

Sequential assessment of exercise tolerance in heart transplantation compared with coronary artery bypass surgery after phase II cardiac rehabilitation.

To investigate the improvement in exercise capacity of transplant patients after an early postoperative (phase II) cardiac rehabilitation program during the first year after surgery, we analyzed retrospectively exercise capacity within 3 months (at the completion of phase II rehabilitation) and 1 year after surgery in 17 orthotopic heart transplantation patients (15 men and 2 women) and 17 age- and gender-matched coronary artery bypass graft (CABG) patients. All patients participated in a phase II cardiac rehabilitation exercise program followed by a home-based exercise program. At the completion of phase II cardiac rehabilitation, mean peak oxygen (VO2) adjusted for body weight in heart transplant patients was not significantly different from that in CABG patients (19.7 +/- 3.7 vs 21.9 +/- 4.1 ml/kg/min), and oxygen pulse at peak exercise did not differ between the 2 groups (11.5 +/- 2.5 vs 12.6 +/- 2.4 ml/beat). Between 3 months and 1 year after surgery, CABG patients had a marked increase in exercise time, increase in heart rate from rest to peak exercise (heart rate reserve), peak VO2, and oxygen pulse. In contrast, heart transplant patients had a significant but only modest increase in peak VO2, and were much more limited in exercise capacity at 1 year than were CABG patients (21.3 +/- 3.9 vs 27.4 +/- 4.7 ml/kg/min, p <0.0001). In our limited patient population, usual phase I rehabilitation with subsequent home-based exercise training was inadequate to improve the exercise capacity of heart transplant patients, and different rehabilitation protocols, such as long-term supervised exercise training, specific to this patient group may be indicated.

Blood Pressure↗
PubMed1995

The effect of oral coenzyme Q10 on the exercise tolerance of middle-aged, untrained men.

In order to determine the effect of oral Coenzyme Q10 (CoQ10) dosing on exercise capacity, 15 middle-aged men (44.7 +/- 2.0 years) received either CoQ10 (150 mg/day x 2 months-Q10 GRP) or placebo (2 months-CON GRP). Blood CoQ10 levels increased (p < 0.05) during the treatment in the Q10 GRP (Pre = 0.72 +/- 0.06, 2 months = 1.08 +/- 0.14 micrograms/ml) and were unchanged in the CON GRP (Pre = 0.91 +/- 0.05, 2 month = 0.69 +/- 0.05 microgram/ml). Similarly, the subjective perception of vigor (visual analog scale 1-10 where, 10 = very energetic, and 0 = very, very unenergetic) increased (p < 0.05) in the Q10 GRP (Pre = 5.73 +/- 0.35, 2 month = 6.64 +/- 0.45). However, maximal oxygen consumption (VO2max Pre = 2.97 +/- 0.18, 2 month = 3.05 +/- 0.15 l/min) and lactate threshold (LT Pre = 2.04 +/- 0.12, 2 month = 2.08 +/- 0.12 l/min), as measured on the cycle ergometer, were unchanged as a result of the CoQ10 treatment, Neither forearm oxygen uptake, nor forearm blood flow was found to be affected by the CoQ10. Although lactate release during hand-grip testing tended to decrease in the Q10 GRP (Pre = 227 +/- 49, 2 month = 168.3 +/- 40 mumole/min) this was not significant (p > 0.05). It can be concluded that short-term (2 months) oral dosing with CoQ10 increases circulating blood levels of CoQ10 and the subjective perceived level of vigor in middle-aged men. However, short-term dosing does not improve aerobic capacity or firearm exercise metabolism as measured in this investigation.

Administration, Oral↗