Poor Exercise Performance Research Articles

Evaluation of the effects of exercise and a mild hypocaloric diet on cardiovascular risk factors in obese subjects.

A weight reduction program to improve cardiovascular risk factors was implemented in obese subjects. The program consisted of exercise training corresponding to the anaerobic threshold (AT) and a mild hypocaloric diet for 12 weeks. In this program, we evaluated the effects of a combination of exercise training and a diet on cardiovascular risk factors such as obesity, dyslipidemia, and poor exercise performance in obese subjects. In addition, we also evaluated the independent effects of exercise training and dietary modification. For this purpose, we adopted a relative training time and a diet score. A relative training time was calculated as the number of times that the subject performed exercises divided by all of the training sessions scheduled, and the diet score was calculated from information which each subject provided on a self-assessment questionnaire. Twenty three obese subjects (Age: 24-54 years old, 19 men and 4 women, body mass index (BMI) > 26 kg/m2) participated in this study. After the 12-week intervention, the mean reductions in body weight, body mass index and body fat were 4.7 kg, 1.7 kg/m2 and 2.9%, respectively (P < 0.0001). The % change in body weight was significantly associated with the diet score and with the relative training time. The mean reductions in total cholesterol, triglyceride and low density lipoprotein cholesterol were 21 mg/dl (P < 0.002), 34 mg/dl (P < 0.01) and 15.9 mg/dl (P < 0.01), respectively, and the % change in triglyceride was significantly associated with the diet score (P = 0.0056) and tended to correlate with the relative training time (P = 0.0596). Oxygen uptake at AT and at peak exercise were increased from 14.1 +/- 1.6 to 16.0 +/- 3.1 ml/min/kg (P < 0.005) and from 26.3 +/- 4.8 to 28.4 +/- 4.9 ml/min/kg (P < 0.002), respectively. A combination of aerobic exercise and a mild hypocaloric diet significantly contributed not only to weight loss but also to the improvement of dyslipidemia and exercise performance, but either hypocaloric diet or mild exercise independently did less. The diet score and the relative training time were useful for evaluating separately dietary modification and the quantity of exercise.

Gender differences in use of stress testing and coronary heart disease mortality: a population-based study in Olmsted County, Minnesota

Objectives. We sought to examine the utilization of exercise stress testing in relation to age and gender in a population-based setting.Background. The utilization of noninvasive procedures has been shown to be associated with the subsequent use of invasive procedures. Yet, there are no population-based data on the utilization of stress testing; in particular, although gender differences in the use of invasive procedures have been reported, the use of noninvasive procedures has not been examined in relation to gender.Methods. In Olmsted County, Minnesota, passive surveillance of the medical care of the community is provided through the Rochester Epidemiology Project. A population-based cohort of Olmsted County residents undergoing exercise tests was identified. The medical records of residents with prevalent and incident exercise tests in 1987 and 1988 were reviewed. For persons with an initial test (incidence cohort), data on clinical presentation, test indications and results were abstracted. Stress test utilization rates were calculated, and crude rates were directly adjusted to the age distribution of the 1980 U.S. population. To help interpret patterns of use at the population level, coronary heart disease mortality rates (International Classification of Diseases, 9th revision, codes 410 to 414) were calculated (crude and directly adjusted to the overall age distribution of the 1980 U.S. population) and used as an indicator of coronary disease burden.Results. A total of 2,624 tests were performed. The crude utilization rate (per 100,000) was 1,888 for men and 703 for women (rate ratio for men over women 2.7, 95% confidence interval [CI] 2.5 to 2.9); it remained significantly higher in men across all age strata. The crude incidence rate (per 100,000) of initial stress tests was 1,112 for men and 517 for women (rate ratio 2.2, 95% CI 1.9 to 2.4). For both men and women, the incidence increased with age; however, incidence remained lower in women in all age strata. At the time that they underwent an initial test, women were more symptomatic and had poorer exercise performance than men. The rate ratio of men over women for coronary heart disease mortality was 1.1 (95% CI 0.9 to 1.2). The age-adjusted rate ratios for stress test utilization were 2.8 (95% CI 2.5 to 3.0), and that for coronary heart disease mortality was 1.9 (95% CI 1.7 to 2.2).Conclusions. These population-based data show that during the study period, the utilization of stress testing in Olmsted County was lower in women than in men. Women in the incidence cohort were older and more symptomatic and had poorer exercise performance than men. Such differences should be considered when examining the utilization of subsequent invasive procedures according to gender.

Lymphangioleiomyomatosis: the pathophysiology of diminished exercise capacity.

Dyspnea with exertion is nearly always present in patients with pulmonary lymphangioleiomyomatosis, but the mechanisms underlying exercise impairment have not been well defined. Spirometry, lung volumes, lung mechanics, and exercise physiology were performed on a cohort of 16 patients. We determined the relative contribution of airflow limitation, gas exchange abnormalities, and pulmonary vascular abnormalities to the exercise performance achieved. The patients had normal TLC and Vtg, but RV was elevated in 88% of the subjects. A moderate to severe obstructive pattern was present in 69% of the subjects, and the DLCO was reduced, often markedly, in 81% of the subjects. Exercise performance was limited (work load, 68% +/- 6) with abnormalities of ventilatory function and gas exchange present. Strong correlations between overall exercise performance (percent predicted VO2max and maximal work load achieved) and indices of airflow and vascular involvement were present. Poor exercise performance was due primarily to ventilatory limitation. The etiology of this ventilatory limitation appears twofold. First, subjects had a reduced ventilatory ceiling because of airflow limitation. Second, subjects demonstrated an excessive ventilatory response as a result of increased dead-space ventilation thought to be due to disease-associated cystic changes and associated pulmonary vascular dysfunction or destruction.

Changes in airway inflammatory cell populations in Standardbred racehorses after interferon-alpha administration

Natural human interferon-alpha (nHuIFNα) was administered to actively training Standardbred racehorses with inflammatory airway disease (IAD). Inflammatory airway disease was characterized by poor exercise performance and inflammation and exudate in the upper and lower airway. Placebo, 50, 150, or 450 units (U) of nHuIFNα was administered orally for 5 consecutive days to eight horses per treatment group in a double-blind, randomized block design. Response to nHuIFNα was monitored by semiquantitative endoscopic examination score and cytologic examination of bronchoalveolar lavage fluid (BALF) performed at baseline (Day 1), Day 8 and Day 15 after initiation of nHuIFNα administration. Neutrophil, macrophage, lymphocyte, and nucleated cell counts in BALF were lower ( P < 0.05), compared with BALF cell counts in placebo-treated horses, 8 days after administration of 50 U and 150 U nHuIFNα, and 15 days after administration of 50 U nHuIFNα. Neutrophil, lymphocyte and nucleated cell counts were lower than cell counts from placebo-treated horses, 8 days following administration of 450 U nHuIFNα. The proportion CD4-, CD5-, and CD8-positive lymphocytes in BALF was not affected by administration of nHuIFNα. Oral administration of low-dose nHuIFNα reduced inflammation of the lower respiratory tract in Standardbred racehorses with IAD.

Review Article: Echocardiography

SummaryEchocardiography encompasses a number of specific imaging techniques. The two‐dimensional (2‐D) echocardiogram is used to identify lesions of the heart and great vessels, assess myocardial function and provide a template for guiding contrast echocardiography, colour‐coded Doppler echocardiography and spectral Doppler studies. M‐mode echocardiography is used to measure cardiac size and ventricular function and can be combined with contrast or colour‐coded Doppler studies for accurate timing of flow events. Pulsed wave and continuous wave Doppler echocardiography display the direction and velocity of red blood cells within the heart and circulation. Continuous wave Doppler studies are used to calculate pressure gradients in the circulation. Any of the Doppler techniques can be used to identify abnormal or high velocity flow responsible for pathologic heart murmurs. Each Doppler format is complementary to the others: colour‐coded Doppler is used to screen large areas for flow disturbances; pulsed wave Doppler can pinpoint regions of abnormal flow; and continuous wave Doppler quantifies the maximal velocities of blood flow across cardiac lesions. Echocardiographic studies are very useful for the diagnosis and assessment of horses with cardiac murmurs, arrhythmias, and poor exercise performance. A number of cardiac disorders can be evaluated by echocardiography, including: cardiac malformation, valvular heart disease, cardiomyopathy, bacterial endocarditis, pericardial effusion, and congestive heart failure. When combined with a careful clinical examination, exercise evaluation and results of electrocardiography, the echocardiogram provides the best overall clinical assessment of the equine heart.

Cyclosporine A decreases rat skeletal muscle mitochondrial respiration in vitro.

Cyclosporine A (CsA) is a potent immunosuppressant used to decrease organ rejection after transplantation surgery. Reported limitations to use of CsA have been hepatotoxicity and nephrotoxicity. Additionally, exercise capacity is much less than expected following transplantation even if arterial oxygen transport capacity is repaired. Purposes of the present study were to determine the effects of CsA on skeletal muscle mitochondrial respiration in vitro and to determine the site of the CsA skeletal muscle mitochondrial lesion. Mitochondria were isolated from rat hind limb muscle homogenates after differential centrifugation. Mitochondrial respiration was determined using a Rank oxygen polarograph at 37 degrees C in a sucrose and mannitol respiration medium. CsA inhibited maximal respiration (ADP stimulated) in the presence of succinate and rotenone by 18.3% and in the presence of malate and pyruvate by 34.7%. CsA decreased the rate of uncoupled respiration (addition of carbonyl cyanide p-trifluoromethozyphenylhydrazone) by 19.6% and 32.0% for succinate and rotenone, or pyruvate plus malate, respectively. No significant effect of CsA on ADP/O for either substrate was observed. We conclude that CsA inhibits maximal coupled and uncoupled skeletal muscle mitochondrial respiration in vitro. Moreover, although the effects of CsA were greater on electron flux through Complex I, mitochondrial lesions caused by CsA were not specific to either Complex I or Complex II of the electron transport chain (ETC). Poor exercise performance despite adequate arterial oxygenation and systemic and regional oxygen deliveries in transplant patients may be attributed, in part, to the effects of immunosuppressive therapy on ETC capacity of skeletal muscle mitochondria.

Effects of cyclosporine A on skeletal muscle mitochondrial respiration and endurance time in rats.

We investigated the effects of 14 d of cyclosporine A (CsA) administration on skeletal muscle mitochondrial respiration and submaximal running endurance time in rats. Eight experimental (CsA) and eight control rats followed a 14-d feeding protocol of CsA (20 mg/kg/d) oral administration or placebo. Submaximal endurance exercise time (EET) was measured on a treadmill on Day 13 and mitochondria were isolated from the hind limb muscles homogenate on Day 15. The results showed (1) a significant decrease of EET in CsA versus control rats (29 +/- 8 min versus 60 +/- min, p < 0.001), (2) significantly lower state 3 and uncoupled mitochondrial respiration in CsA compared with control rats with pyruvate plus malate (p < 0.001, p < 0.01) as well as succinate plus rotenone (p < 0.01) as substrates, (3) no differences in coupling efficiency (ADP/O ratios), and (4) significant linear correlation between EET and state 3 respiration (r = 0.71, p < 0.05; r = 0.92, p < 0.001), and strong curvilinear relationship between EET and CsA state 3/mean control state 3 (r2 = 0.81, p < 0.001; r2 = 0.82, p < 0.001), respectively, with pyruvate plus malate and succinate plus rotenone. We conclude that 14 d of CsA oral administration decreases skeletal muscle mitochondrial electron chain capacity without changing coupling efficiency in rats. Results suggest that immunosuppressive therapy is responsible, in part, for poor exercise performance in transplant patients.

Muscle Metabolite Response to Exercise and Recovery in Yellow Perch (Perca flavescens): Comparison of Populations from Naturally Acidic and Neutral Waters

To test whether energy metabolism is responsive to changes in the aquatic environment and to better understand the exercise physiology of acid-tolerant fish species and populations, I compared metabolic responses to exercise and recovery in a population of perch from a naturally acidic lake (acid-lake perch, ALP) and a circumneutral lake (neutral-lake perch, NLP). White muscle from the two populations was sampled after 16 h of acclimation in a swim flume to either pH 4.0 or pH 7.8 water, after exhaustion induced by a critical swimming speed protocol, or after 6-12 h of recovery from exhaustive exercise. Extracts were analyzed for nucleotides, phosphagens, and glycolytic intermediates. Acid-lake perch had less severe postexercise metabolite perturbations and poorer exercise performance in neutral water than NLP, which suggests that fish that fully activate anaerobic metabolism during exercise may have been selected against in this population. Populations differed most in lactate and pyruvate levels, with ALP accumulating more pyruvate and less lactate after exercise than NLP. There was some support for my hypothesis that ALP are selected for minimal proton accumulation during recovery from exercise. Acid water altered the postexercise metabolic profile in NLP only. The significantly lower lactate, AMP, and IMP levels in "acid-naive" NLP signaled an inability of these fish to fully use anaerobic sources of ATP in acid water.

Acute elevation of blood carboxyhemoglobin to 6% impairs exercise performance and aggravates symptoms in patients with ischemic heart disease

Acute exposure to carbon monoxide has the potential to impair exercise capacity in patients with ischemic heart disease. The effect of sufficient inhalation of this compound to gradually produce a level of 6% carboxyhemoglobin was studied in 30 nonsmoking patients with obstructive coronary artery disease and evidence of exercise-induced ischemia. After an initial training session, subjects were exposed to air or carbon monoxide on successive days in a randomized double-blind crossover fashion. Cardiac function and exercise capacity were assessed during symptomlimited supine radionuclide ventriculography. On the carbon monoxide day, mean postexposure carboxyhemoglobin was 5.9 ± 0.1% compared with 1.6 ± 0.1% (p < 0.01) after air exposure.The mean duration of exercise was significantly longer after air compared with carbon monoxide exposure (626 ± 50 s for air versus 585 ± 49 s for carbon monoxide, p < 0.05). Actuarial methods suggested that subjects were likely to experience angina earlier during exercise on the day of carbon monoxide exposure (p < 0.05). Both the level (62 ± 2.4 versus 60 ± 2.4%, p = 0.05) and change in left ventricular ejection fraction at submaximal exercise (1.6 ± 1.6 versus −1.2 ± 1.6%, p = 0.05) were greater on the air exposure day compared with the carbon monoxide day. The peak exercise left ventricular ejection fraction was not different for the two exposures (57 ± 2.5% for both). These results demonstrate earlier onset of ventricular dysfunction, angina and poorer exercise performance in patients with ischemic heart disease after acute carbon monoxide exposure sufficient to increase blood carboxyhemoglobin to 6%.

Exercise testing in evaluation of patients for lung resection.

We studied, in a prospective fashion, whether exercise testing selected candidates for lung resection and predicted postoperative morbidity and mortality better than "standard" lung function tests. We confirmed that a low preoperative FEV1 and VC had prognostic significance for the development of postoperative complications. Poor exercise performance did not. Likewise, analysis of exercise performance did not discriminate in patients rejected for surgery from those in whom resection was successfully completed.