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PubMed2002

Effect of increased fat availability on metabolism and exercise capacity.

Several procedures have been utilized to elevate plasma free fatty acid (FFA) concentration and increase fatty acid (FA) delivery to skeletal muscle during exercise. These include fasting, caffeine ingestion, L-carnitine supplementation, ingestion of medium-chain and long-chain triglyceride (LCT) solutions, and intravenous infusion of intralipid emulsions. Studies in which both untrained and well-trained subjects have ingested LCT solutions or received an infusion of intralipid (in combination with an injection of heparin) before exercise have reported significant reductions in whole-body carbohydrate oxidation and decreased muscle glycogen utilization during both moderate and intense dynamic exercise lasting 15-60 min. The effects of increased FA provision on rates of muscle glucose uptake during exercise are, however, equivocal. Despite substantial muscle glycogen sparing (15-48% compared with control), exercise capacity is not systematically improved in the face of increased FA availability.

Caffeine↗

PubMed1981

The prolonged effect of pentaerythritol tetranitrate on exercise capacity in stable effort angina pectoris.

We studied the effect of a single oral dose of 40 mg of pentaerythritol tetranitrate (PETN) on the exercise capacity of ten patients with angina pectoris. The study design was a randomized double-blind crossover comparing the effects of 40 mg of oral PETN with placebo on exercise tolerance. Patients were exercised to moderate angina pectoris before and 2 1/2 and 4 1/2 hours after receiving the placebo or PETN at seven-day intervals during the double-blind crossover period. Exercise tolerance time was measured using a multistage, progressive treadmill test. Exercise times were greater 2 1/2 hours and 4 1/2 hours following PETN compared with placebo (P less than 0.05). Heart rate, systolic and diastolic blood pressure, and double product at rest (supine and standing) and at point of angina pectoris did not change significantly.

Administration, Oral↗

PubMed1985

Failure of transdermal nitroglycerin to improve exercise capacity in patients with angina pectoris.

Sixteen patients with stable angina pectoris were studied in a double blind crossover manner utilizing treadmill exercise testing with the direct measurement of total body oxygen uptake, 1 and 24 hours after application of a 20 cm2 transdermal nitroglycerin system and identical placebo. Testing was performed after a 3 day lead-in period of treatment with either an active patch or placebo. Points of analysis were peak angina and the submaximal work load occurring at 4 minutes of exercise. No statistically significant differences were observed between nitroglycerin and placebo treatment in any of the rest hemodynamic or peak angina variables at 1 or 24 hours. A significant increase in the rate-pressure product at the submaximal work load was observed 1 hour after transdermal nitroglycerin relative to placebo application. However, no significant differences were observed in any of the other measured variables at the submaximal work load, 1 or 24 hours after nitroglycerin application. The once daily application of a 20 cm2 transdermal nitroglycerin system was ineffective in altering the exercise capacity of patients with angina pectoris. The lack of efficacy at 1 hour appears to be due to inadequate nitroglycerin blood levels; at 24 hours it may be due to tolerance.

Adult↗

PubMed1994

Relation between coronary artery stenosis assessed by visual, caliper, and computer methods and exercise capacity in patients with single-vessel coronary artery disease. The Veterans Affairs ACME Investigators.

BACKGROUND: Practitioners often assume a close relation between angiographic coronary artery stenosis and patient functional capacity. To test this unproven hypothesis, we analyzed the relation between coronary artery stenosis measured by different methods and maximal treadmill exercise tolerance in patients with single-vessel disease before and after intervention by percutaneous transluminal coronary angioplasty (PTCA). METHODS AND RESULTS: Coronary angiography and maximal exercise testing off anti-ischemic medication were performed before random assignment of 227 patients with single-vessel coronary artery disease to PTCA or drug therapy. Six months later, angiography and exercise testing were repeated with patients assigned to PTCA off anti-ischemic therapy so that the altered coronary stenosis was the only consistent variable. Patients assigned to drug therapy were exercised on drug therapy. Coronary stenosis was assessed visually by the local investigator and quantitatively by blinded caliper and computer methods in central laboratories. Variabilities of caliper and computer measurements were established in a subset read twice. Visually estimated stenosis > or = 90% at baseline was associated with shorter exercise duration (7.9 versus 9.2 minutes, P < .04). Similar segregation at baseline was not observed with caliper or computer methods. Regardless of the method of measurement used, correlation between changes of lesion severity and exercise duration from baseline to follow-up was poor. Patients were angiographically classified as "better," "unchanged," or "worse" if follow-up stenosis was below, within, or above 2 SD of mean technical variability from baseline (+/- 18.8%, caliper, +/- 14.6%, computer). Exercise duration for PTCA patients improved among those with better lesions (+2.4 minutes, n = 50, P = .001) but also among those with unchanged lesions (+1.9 minutes, n = 41, P < or = .001). Unchanged medically treated patients improved less (+0.5 minutes, n = 86, P = .04). Results were similar when patients were angiographically classified by minimum lumen diameter. CONCLUSIONS: Handheld calipers and quantitative coronary angiography are equivalent techniques for making anatomic measurements. Neither method identified patients having reduced exercise capacity at baseline as well as visual estimation. The relation between changes of coronary stenosis and exercise duration is highly variable, at least in part because of the insensitivity of angiographic methods for detecting small but potentially important changes. Minimal anatomic improvement 6 months after PTCA does not preclude a good functional outcome. Contrary to common belief, angiographic stenosis does not correlate well with functional capacity, even in patients with single-vessel disease.

Angioplasty, Balloon, Coronary↗

PubMed2007

The efficacy of a 9-month treadmill walking program on the exercise capacity and weight reduction for adolescents with severe autism.

This study evaluated the efficacy of a 9-month treadmill walking (TW) program on exercise capacity and body mass index (BMI) for adolescents with severe autism. Ten youth residing in a residential/school treatment facility were assigned to either a supplemental treadmill walking (TW) or control group. Both groups continued to participate in their regular physical education curriculum. Monthly records were maintained for the following: (a) TW progression in frequency, duration, speed and elevation; (b) caloric expenditure; and (c) BMI. The TW program resulted in significant increases in mean monthly TW frequency, speed, elevation, and calories expended coupled with a reduction in BMI.

Adolescent↗

PubMed2000

Prognostic value of changes over time in exercise capacity and echocardiographic measurements in patients with chronic heart failure.

AIMS: This study sought to examine the predictive values of changes over time in exercise capacity and echocardiographic measurements of ventricular dimensions or function in predicting mortality in patients with chronic heart failure. METHODS AND RESULTS: Sixty-two patients with chronic heart failure (58 men, mean [+/-SD] age 60+/-10 years, mean peak oxygen consumption (VO(2)) 18.2+/- 5.9 ml. kg(-1). min(-1), mean left ventricular ejection fraction 38.9+/-15. 8%) who underwent both treadmill exercise testing and echocardiographic examination on two occasions, separated by 19+/-15 months were followed-up for a mean of 17 months (interquartile range 9-30 months). During the follow-up period, 19 patients (30%) died and three (4.8%) underwent heart transplantation. Of measurements taken at a single time-point (visit 2) exercise duration, peak VO(2), ventilatory response to exercise (VE/VCO(2)), left atrial diameter and left ventricular ejection fraction were found, by Cox proportional-hazard analysis, to predict the outcome in these patients (all P<0.05). Of the changes in parameters between visit 1 to visit 2, only changes in peak VO(2)per year (P=0.026) predicted non-transplanted survival (independent of changes in left ventricular ejection fraction and VE/VCO(2)). In Kaplan-Meier survival analysis patients with increased peak VO(2)over time (n=28) showed a better prognosis at 2 years (cumulative survival 75% [95% confidence interval: 56-95%] than those with a decrease in peak VO(2)(n=34, cumulative survival 50% [95% confidence interval: 31-68%]). CONCLUSIONS: Although single estimates of peak VO(2), VE/VCO(2)and left ventricular ejection fraction have significant prognostic importance in patients with chronic heart failure, when monitoring changes over time only peak VO(2)remains a significant predictor of outcome.

Adult↗

PubMed2005

Relationships among exercise capacity, hypertrophy, and left ventricular diastolic function in nonobstructive hypertrophic cardiomyopathy.

AIM: The aim of this study was to analyze the relationships among exercise capacity (EC), hypertrophy, and diastolic function in nonobstructive hypertrophic cardiomyopathy (NOHCM). METHODS AND RESULTS: Twenty-seven patients with NOHCM were studied. Left ventricular hypertrophy (LVH) was determined by appropriate echocardiographic indexes. For diastolic function evaluation, the following were measured: the early (E) and late (A) waves, E/A, and deceleration time of E of the mitral flow; the systolic (S), diastolic (D), and atrial reversal (AR) waves, S/D, and the atrial systolic filling fraction of the pulmonary vein flow; and the early (Ea), late (Aa) waves, Ea/Aa, and E/Ea by tissue Doppler imaging. The difference between the duration of AR and A waves (DurAR - DurA), the peak VO2, and anaerobic threshold (AT) were also determined. In these patients, the E/Ea ratio was 8.9 +/- 3.2 and DurAR - DurA was 22.6 +/- 32.6 milliseconds. The peak VO2 and AT correlated with D (r = 0.55, P = .003 and .51, P = .007, respectively) and Ea/Aa (r = 0.56, P = .007 and .45, P = .03, respectively). There was no correlation between EC and LVH. CONCLUSIONS: Patients with NOHCM demonstrated evidences of elevated left ventricular (LV) end-diastolic pressure with normal filling pressure. EC compromise may be attributed to relaxation changes with inadequate filling of the left ventricle.

Adolescent↗

PubMed1992

Exercise capacity after complete repair of tetralogy of Fallot: deleterious effects of residual pulmonary regurgitation.

OBJECTIVE: To determine the effects of residual pulmonary regurgitation on exercise tolerance after complete repair of tetralogy of Fallot. DESIGN: Prospective study of symptom free patients more than five years after complete repair. Graded exercise performance was measured with standard Bruce protocol. Maximal oxygen uptake and ventilatory anaerobic threshold were measured by respiratory mass spectrometry. Measurement of pulmonary regurgitant fraction was from pressure-volume loops constructed from measurements of right ventricular volume obtained from biplane angiograms and simultaneous pressures measured with a micromanometer. SETTING: Tertiary referral centre. PATIENTS: 16 patients were studied. Two patients had been excluded because of residual cardiac lesions or inadequate data from cardiac catheterisation. Four were later excluded because they failed to reach a respiratory quotient of greater than 1.0 during graded exercise. RESULTS: There was a significant negative correlation between the degree of residual regurgitation and both total duration of exercise and maximal heart rate achieved. Maximal heart rate and total duration of exercise were significantly lower in the patients than in normal controls. Patients with an abnormal maximal oxygen uptake (less than 85% of the predicted normal value) had significantly greater residual pulmonary regurgitation than those in whom oxygen uptake was normal. CONCLUSIONS: Impaired exercise capacity after complete repair of tetralogy of Fallot is directly related to the degree of residual pulmonary regurgitation. These data should be taken into account when deciding the optimal timing and nature of corrective surgery.

Adolescent↗

PubMedDate not supplied

Patients with dilated cardiomyopathy and less than 20% ejection fraction increase exercise capacity and have less severe arrhythmia after controlled exercise training.

The results of this pilot study suggest that patients with a diminished ejection fraction as low as 16% can safely perform an exercise program. A significant improvement in peak VO2 and maximal work rate was achieved. Moreover, this study suggests that exercise training might diminish the severity of asymptomatic ventricular arrhythmia; however a larger controlled study is needed to confirm these findings.

Arrhythmias, Cardiac↗

PubMed1982

Exercise capacity and cardiac function of rats with drug-induced cardiac enlargement.

A study was undertaken to determine if sustained administration of isoproterenol (ISO) alters biochemical and functional properties of hearts and the submaximal and maximal exercise capacity of rodents. Compared with sham-treated controls of the same age, sex, and body weight, 4 wk of ISO (0.2--0.4 mg/kg sc) produced an approximate 30% increase in combined ventricle wet weight (P less than 0.001). Respiratory capacity of homogenates, total muscle protein concentration, and actomyosin and myofibril ATPase of heart muscle of the ISO-treated group were the same as in the control group. Various cardiac function parameters in situ, obtained under control conditions and in response to tyramine-induced norepinephrine release, were similar for the two groups. ISO-treated rats had slightly greater endurance for running submaximally on a treadmill than the control rats (P less than 0.10), but their maximal capacity to utilize oxygen (VO2max) was not different from controls. These findings suggest that rodent hearts moderately enlarged by relatively low doses of isoproterenol possess normal metabolic and functional capacity. However, this cardiac enlargement had no apparent effect on maximal exercise performance of the whole animal.

Actomyosin↗

PubMed1999

Repetitive hemodilution in chronic obstructive pulmonary disease and pulmonary hypertension: effects on pulmonary hemodynamics, gas exchange, and exercise capacity.

BACKGROUND: In cor pulmonale associated with severe chronic obstructive pulmonary disease (COPD), disturbances of pulmonary microcirculation may contribute significantly to hypoxemia, pulmonary hypertension, and exercise intolerance. OBJECTIVE: It was tested whether reduction of blood viscosity induced by repetitive hemodilution might improve pulmonary hemodynamics and oxygen uptake. METHODS: Seven patients with stable COPD (forced expiratory volume in 1 s 33 +/- 3 % of predicted, means +/- SE) and pulmonary hypertension were phlebotomized 5-6 times over a period of 3 months with substitution of 6% hydroxyethyl starch (molecular weight 40, 000). This resulted in a stepwise reduction of the hematocrit from 53.3 +/- 2.6 to 45.8 +/- 3.1% and a reduction of whole blood viscosity from 9.8 +/- 0.6 to 8.8 +/- 0.7 mPa x s at a shear rate of 2.0 s-1. Before and after the treatment period, patients underwent cardiopulmonary exercise testing and right heart catheterization. RESULTS: Mean pulmonary artery pressure (PAm) decreased from 30 +/- 3 to 22 +/- 2 mm Hg and arterial oxygen partial pressure (PaO2) increased from 63.2 +/- 2.2 to 71.8 +/- 3.7 mm Hg at rest. During peak exercise, PAm decreased from 59 +/- 7 to 53 +/- 7 mm Hg and PaO2 increased from 54.0 +/- 5.7 to 63.2 +/- 2.4 mm Hg after hemodilution. Peak oxygen consumption rose from 573 +/- 84 to 750 +/- 59 ml x min-1, corresponding to an increase in cardiac index from 4.25 +/- 0.5 to 5.88 +/- 0.76 liters x min-1 x m-2. Pulmonary vascular resistance fell from 345 +/- 53 to 194 +/- 32 dyn x s x cm-5. The patients' peak exercise capacity increased from 9.2 +/- 2. 0 before to 13.5 +/- 3.2 kJ at the end of the study (p < 0.05 for all differences, paired t test). CONCLUSION: The findings suggest that a prolonged improvement of pulmonary microcirculation by reducing blood viscosity may improve pulmonary gas exchange, central hemodynamics, and exercise tolerance in patients with severe COPD and pulmonary hypertension.

Aged↗

PubMed1991

Importance of coronary collateral circulation for increased treadmill exercise capacity by nitrates in patients with stable effort angina pectoris.

The purpose of this study was to elucidate the mechanism that induces an improvement in exercise capacity by nitrates in patients with stable effort angina pectoris. The study population was composed of 19 patients: group A, 10 patients with chronic stable effort angina who had a well-developed coronary collateral circulation to the potentially ischemic region; group B, 9 patients with chronic stable effort angina who had no collateral circulation to the jeopardized myocardium. Treadmill exercise was performed according to the standard Bruce protocol with and without pretreatment with orally administered 10 mg isosorbide dinitrate. Percent increases (mean +/- SE) in exercise duration were not significantly different between groups A and B (25 +/- 6 vs. 14 +/- 6%). Percent increases in the maximal rate-pressure product tended to be greater in group A than in group B (27 +/- 6 vs. 10 +/- 6%). Percent increases in the rate-pressure product at the onset of angina pectoris were significantly greater in group A than in group B (37 +/- 7 vs. 7 +/- 6%; p less than 0.01). Percent increases in the rate-pressure product at 0.1 mV S-T segment depression were also significantly greater in group A than in group B (26 +/- 6 vs. 1 +/- 5%; p less than 0.01). These results suggest that isosorbide dinitrate dilates epicardial collateral vessels with smooth muscle layers, but fails to dilate the coronary arteries with significant organic stenoses.

Angina Pectoris↗

PubMed1982

Normal exercise capacity in patients with severe left ventricular dysfunction: compensatory mechanisms.

About one-third of patients who have severe left ventricular dysfunction can achieve normal levels of exercise. To elucidate the mechanisms that permit this to occur, we studied six patients with severe left ventricular dysfunction (average left ventricular ejection fraction 17 +/- 2.5% [mean +/- SEM]) who achieved nearly normal levels of exercise tolerance (greater than 11 minutes of treadmill exercise, Sheffield protocol). All patients had normal pulmonary function at rest and during exercise. Hemodynamics were measured at rest and during supine and upright exercise. The major mechanisms of the preserved exercise capacity in these patients were chronotropic competence, ability to tolerate elevated wedge pressures (33 +/- 3 mm Hg) without dyspnea, ventricular dilation, and increased levels of plasma norepinephrine at rest and during exercise. Also, whereas peripheral vascular resistance was unchanged during supine exercise, it decreased by 50% during similar levels of upright exercise. As a consequence, increases in cardiac output from rest to exercise were greater during upright than supine exercise (100% vs 50%, respectively) (p less than 0.05), and pulmonary wedge pressures were lower during upright than supine exercise (21 +/- 5 mm Hg vs 33 +/- 3 mm Hg). Thus, multiple mechanisms permit some patients with severe left ventricular dysfunction to achieve normal levels of exercise. These studies emphasize that left ventricular function must be assessed by direct means rather than inferring function of the left ventricle from the results of an exercise tolerance test.

Aged↗

PubMed1991

Reduced exercise capacity in senescent beagles: an evaluation of the periphery.

This study investigated the effect of age on peripheral factors involved in the systemic response to maximal exercise. Skeletal muscle was analyzed and regional blood flow distribution was determined at rest and during maximal exercise in senescent (old) and in younger mature (young) beagles. Maximal exercise capacity was significantly reduced (P less than 0.05) in old and was associated with a reduction in cardiac output (CO), as well as a tendency for arteriovenous O2 difference to be reduced, with a concomitant reduction in maximal O2 consumption. In each regional circulation evaluated, resting blood flow was similar in young and old. During exercise, blood flow was similar in young and old to the diaphragm, heart, tongue, and six of seven locomotory muscles. Concomitant blood flow reductions in splanchnic regions tended to be more pronounced in old than in young. Skeletal muscle analyses of triceps, semitendinosus, and gastrocnemius muscles disclosed similar percent fiber type distribution in young and old but a reduction in type II fiber area in old. In addition, both muscle capillary density and capillary-to-fiber ratio were reduced in old. These results demonstrate that age-related changes in blood flow distribution during maximal exercise enable skeletal muscle blood flow to be maintained in old, despite reductions in maximal CO and in muscle capillary density. However, this pattern of blood flow distribution only partially compensates for the combined effects of age-related changes in metabolic potential of the periphery, O2 content of arterial blood, and cardiac function during maximal exercise in old.

Aging↗

PubMed1999

[Exercise capacity in children late after aortic valve replacement using the Konno procedure].

Between 1980 and 1996, aortic valve replacements using the Konno procedure were performed in 10 patients. In order to assess the latent problems after this procedure, the exercise capacity was evaluated in 6 patients (3 males and 3 females). Exercise stress tests by a bicycle ergometer with ramp protocol were performed and gas exchange responses using the mixing chamber method were measured. The mean age at the time of operation was 6.6 years (range 3 to 11) and the mean age at the time of exercise test was 11.4 years (range 8 to 15). All patients were NYHA class I except 2 patients who had residual PH. Maximum oxygen consumptions were 37 to 39 ml/kg/min in males and 23 to 34 ml/kg/min in females. Maximum heart rates ranged from 166 to 184 bpm and O2 pulses ranged from 4.6 to 7.1 ml/beat/BSA. In the 2 patients who had residual pulmonary hypertension, HR bursting and O2 pulse plateau & decline occurred, which may indicate presence of decreased stroke volume. In conclusion, all patients late after the Konno procedure could tolerate exercise beyond respiratory compensation and there were no arrhythmia during exercise. HR was satisfactorily increased but maximum oxygen consumption was lowered at about 70% of the normal level.

Aortic Valve↗

PubMed1997

Long-term change in exercise capacity, body mass, and pulmonary function in adults with cystic fibrosis.

STUDY OBJECTIVES: Cross-sectional studies in patients with cystic fibrosis (CF) have shown that exercise capacity is correlated with pulmonary function and body mass. We have examined whether the same relationships are seen longitudinally in adults with CF. DESIGN: Subjects who first performed progressive maximal cycle ergometry between 1986 and 1989 were retested using an identical protocol a mean of 6.3 years later. PARTICIPANTS AND SETTING: Adults with CF attending a regional center. MEASUREMENTS AND RESULTS: The principal exercise measures were peak oxygen uptake (VO2peak), ventilation (VEpeak), oxygen saturation, and heart rate. Spirometry, weight, and height were also recorded at each time point. At baseline, subjects had a mean age of 19.8 years, body mass index (BMI) of 19.0, FEV1 of 69% predicted, VO2peak of 1.56 L/min, and VEpeak of 48.9 L/min. At repeated testing after a mean interval of 6.3 years, the FEV1 had fallen significantly to 54% predicted (p < 0.001) and the BMI had risen significantly to a mean of 20.9 (p < 0.001). There were no significant differences in VO2peak or VEpeak, although VEpeak was a significantly higher proportion (72% vs 61%) of predicted maximal voluntary ventilation. CONCLUSIONS: Adults with mild to moderate pulmonary dysfunction were able to increase body mass and maintain VO2peak despite a declining FEV1. VO2peak was not reduced by the decrease in FEV1 because VEpeak was unaffected. Improved nutrition may have contributed to maintaining fitness.

Adolescent↗

PubMed2002

Effect of exercise training on skeletal muscle fibre characteristics in men with chronic heart failure. Correlation between skeletal muscle alterations, cytokines and exercise capacity.

BACKGROUND: In patients with congestive heart failure (CHF) there is a shift from aerobic type I muscle fibres to less aerobic type II fibres. Exercise training has been shown to have beneficial effects on exercise performance, peripheral pathology and the neurohumoral profile in stable patients with CHF. This study evaluated the effect of a 3 month exercise training program on skeletal muscle characteristics and the correlation of these to cytokines and exercise capacity in CHF patients. METHODS: Skeletal muscle biopsies for enzyme-histochemical analysis were performed in 15 CHF patients in New York Heart Association classes II-III, with a mean ejection fraction of 33+/-5% before and after a 12 week training period. The patients were trained for 30 min, five times a week at 80% of the peak heart rate achieved at baseline ergometer cycle test. Fifteen healthy men were used as controls. Plasma samples were examined by enzyme immunoassays for levels of pro-inflammatory cytokines. RESULTS: (a) At baseline we found muscle atrophy in five of the patients. The percent area of type I fibres (40.7+/-12.0 vs. 56.4+/-11.0%, P<0.05) and the thickness of type IIA (56.10+/-7.8 vs. 71.6+/-11.9 microm, P<0.001) and B-fibres (49.0+/-8.9 vs. 63.9+/-10.6 microm, P<0.001) were reduced, whereas the percent area of type IIA fibres (52.1+/-13.3 vs. 36.4+/-9.9%, P<0.05) was increased in heart failure patients compared to healthy controls. There was a modest correlation between fibre thickness and the level of interleukin 6 (r=-0.657, P=0.008). (b) After exercise training there was a reduction in muscle area examined by light-microscopy, measured as a percentage of field (-2.7, P=0.003) with an concomitant increase in interstitium. This reduction correlated to the increase in the 6-min walk test (r=-0.558, P=0.031). The thickness of type IIB fibres increased (+5.6 microm, P=0.068) and the area of type I fibres decreased (-6.1%, P=0.062). CONCLUSIONS: Patients with CHF have a relatively increased area of type IIA fibres and a relatively decreased area of type I fibres compared to healthy individuals. The thickness of type IIA and type IIB fibres is decreased compared to normal individuals. A modest negative correlation between the level of interleukin 6 and fibre thickness at baseline, suggests that inflammatory cytokines may be involved in the pathogenesis of the CHF related myopathy. A significant correlation between the reduction of muscle area, with increased interstitum, and the increase in the 6-min walk test may indicate that the improvement is due to increased capillary density permitting better flow reserve to exercising muscles.

Aged↗

PubMed1984

Effects of the oral hypoglycemic agent methyl palmoxirate on exercise capacity of rats.

The effect of the oral hypoglycemic agent methyl palmoxirate (methyl 2-tetradecylglycidate, McN-3716), a selective inhibitor of long chain fatty acid oxidation, on the exercise capacity of normal rats was evaluated. Daily administration of 2.5 mg/kg for 7 days, or of a single dose of 10 mg/kg, of methyl palmoxirate did not affect the ability of rats to perform strenuous exercise of an intensity that caused exhaustion in less than 30 min. The ability to perform prolonged, moderately strenuous exercise of an intensity that could be maintained for more than 60 min was decreased slightly (17%) in the methyl palmoxirate treated rats. This effect appeared to be mediated by a significant reduction in initial liver glycogen content in the methyl palmoxirate treated rats. As a consequence, the methyl palmoxirate treated rats became hypoglycemic during prolonged exercise. Inhibition of fatty acid oxidation in skeletal muscle was minimal. Treatment with methyl palmoxirate protected against the development of exercise-induced ketosis. It appears that the liver is the major site of action of methyl palmoxirate when given in low dosage.

Administration, Oral↗