Physician advice and individual behaviors about cardiovascular disease risk reduction--seven states and Puerto Rico, 1997.
Cardiovascular disease (CVD) (e.g., heart disease and stroke) is the leading cause of death in the United States and accounted for 959,227 deaths in 1996. Strategies to reduce the risk for heart disease and stroke include lifestyle changes (e.g., eating fewer high-fat and high-cholesterol foods) and increasing physical activity. The U.S. Preventive Services Task Force and the American Heart Association (AHA) recommend that, as part of a preventive health examination, all primary-care providers counsel their patients about a healthy diet and regular physical activity. AHA also recommends low-dose aspirin use as a secondary preventive measure among persons with existing CVD. To determine the prevalence of physician counseling about cardiovascular health and changes in individual behaviors, CDC analyzed data from the Behavioral Risk Factor Surveillance System (BRFSS) for seven states and Puerto Rico. This report summarizes the results of that analysis, which indicate a lower prevalence of counseling and behavior change among persons without than with a history of heart disease or stroke. (+info)
Reliability of information on physical activity and other chronic disease risk factors among US women aged 40 years or older.
Data on chronic disease risk behaviors and related variables, including barriers to and attitudes toward physical activity, are lacking for women of some racial/ethnic groups. A test-retest study was conducted from July 1996 through June 1997 among US women (n = 199) aged 40 years or more who were white, black, American Indian/Alaska Native, or Hispanic. The sample was selected and interviews were conducted using a modified version of the methods of the Behavioral Risk Factor Surveillance System. For behavioral risk factors such as physical inactivity, smoking, and low fruit and vegetable consumption, group prevalences were generally similar between interviews 1 and 2. However, kappa values for selected physical activity variables ranged from 0.26 to 0.51 and tended to be lower for black women. Discordance was low for variables on cigarette smoking and exposure to environmental tobacco smoke (kappa = 0.64-0.92). Discordance was high (kappa = 0.33) for low consumption of fruits and vegetables. Additional variables for barriers to and access to exercise ranged widely across racial/ethnic groups and in terms of measures of agreement. These methods illustrate an efficient way to sample and assess the reliability of data collected from women of racial/ethnic minority groups. (+info)
Prognostic value of myocardial perfusion imaging in patients with high exercise tolerance.
BACKGROUND: Although high exercise tolerance is associated with an excellent prognosis, the significance of abnormal myocardial perfusion imaging (MPI) in patients with high exercise tolerance has not been established. This study retrospectively compares the utility of MPI and exercise ECG (EECG) in these patients. METHODS AND RESULTS: Of 388 consecutive patients who underwent exercise MPI and reached at least Bruce stage IV, 157 (40.5%) had abnormal results and 231 (59.5%) had normal results. Follow-up was performed at 18+/-2.7 months. Adverse events, including revascularization, myocardial infarction, and cardiac death, occurred in 40 patients. Nineteen patients had revascularization related to the MPI results or the patient's condition at the time of MPI and were not included in further analysis. Seventeen patients (12.2%) with abnormal MPI and 4 (1.7%) with normal MPI had adverse cardiac events (P<0.001). Cox proportional-hazards regression analysis showed that MPI was an excellent predictor of cardiac events (global chi2=13.2; P<0.001; relative risk=8; 95% CI=3 to 23) but EECG had no predictive power (global chi2=0.05; P=0.8; relative risk=1; 95% CI=0.4 to 3.0). The addition of Duke's treadmill score risk categories did not improve the predictive power of EECG (global chi2=0.17). The predictive power of the combination of EECG (including Duke score categories) and MPI was no better than that of MPI alone (global chi2=13.5). CONCLUSIONS: Unlike EECG, MPI is an excellent prognostic indicator for adverse cardiac events in patients with known or suspected CAD and high exercise tolerance. (+info)
Glucose kinetics during prolonged exercise in highly trained human subjects: effect of glucose ingestion.
1. The objectives of this study were (1) to investigate whether glucose ingestion during prolonged exercise reduces whole body muscle glycogen oxidation, (2) to determine the extent to which glucose disappearing from the plasma is oxidized during exercise with and without carbohydrate ingestion and (3) to obtain an estimate of gluconeogenesis. 2. After an overnight fast, six well-trained cyclists exercised on three occasions for 120 min on a bicycle ergometer at 50 % maximum velocity of O2 uptake and ingested either water (Fast), or a 4 % glucose solution (Lo-Glu) or a 22 % glucose solution (Hi-Glu) during exercise. 3. Dual tracer infusion of [U-13C]-glucose and [6,6-2H2]-glucose was given to measure the rate of appearance (Ra) of glucose, muscle glycogen oxidation, glucose carbon recycling, metabolic clearance rate (MCR) and non-oxidative disposal of glucose. 4. Glucose ingestion markedly increased total Ra especially with Hi-Glu. After 120 min Ra and rate of disappearance (Rd) of glucose were 51-52 micromol kg-1 min-1 during Fast, 73-74 micromol kg-1 min-1 during Lo-Glu and 117-119 micromol kg-1 min-1 during Hi-Glu. The percentage of Rd oxidized was between 96 and 100 % in all trials. 5. Glycogen oxidation during exercise was not reduced by glucose ingestion. The vast majority of glucose disappearing from the plasma is oxidized and MCR increased markedly with glucose ingestion. Glucose carbon recycling was minimal suggesting that gluconeogenesis in these conditions is negligible. (+info)
Reduced cytosolic acidification during exercise suggests defective glycolytic activity in skeletal muscle of patients with Becker muscular dystrophy. An in vivo 31P magnetic resonance spectroscopy study.
Becker muscular dystrophy is an X-linked disorder due to mutations in the dystrophin gene, resulting in reduced size and/or content of dystrophin. The functional role of this subsarcolemma protein and the biochemical mechanisms leading to muscle necrosis in Becker muscular dystrophy are still unknown. In particular, the role of a bioenergetic deficit is still controversial. In this study, we used 31p magnetic resonance spectroscopy (31p-MRS) to investigate skeletal muscle mitochondrial and glycolytic ATP production in vivo in 14 Becker muscular dystrophy patients. Skeletal muscle glycogenolytic ATP production, measured during the first minute of exercise, was similar in patients and controls. On the other hand, during later phases of exercise, skeletal muscle in Becker muscular dystrophy patients was less acidic than in controls, the cytosolic pH at the end of exercise being significantly higher in Becker muscular dystrophy patients. The rate of proton efflux from muscle fibres of Becker muscular dystrophy patients was similar to that of controls, pointing to a deficit in glycolytic lactate production as a cause of higher end-exercise cytosolic pH in patients. The maximum rate of mitochondrial ATP production was similar in muscle of Becker muscular dystrophy patients and controls. The results of this in vivo 31P-MRS study are consistent with reduced glucose availability in dystrophin-deficient muscles. (+info)
Addition of angiotensin II receptor blockade to maximal angiotensin-converting enzyme inhibition improves exercise capacity in patients with severe congestive heart failure.
BACKGROUND: Incomplete suppression of the renin-angiotensin system during long-term ACE inhibition may contribute to symptomatic deterioration in patients with severe congestive heart failure (CHF). Combined angiotensin II type I (AT1) receptor blockade and ACE inhibition more completely suppresses the activated renin-angiotensin system than either intervention alone in sodium-depleted normal individuals. Whether AT1 receptor blockade with losartan improves exercise capacity in patients with severe CHF already treated with ACE inhibitors is unknown. METHODS AND RESULTS: Thirty-three patients with severe CHF despite treatment with maximally recommended or tolerated doses of ACE inhibitors were randomized 1:1 to receive 50 mg/d losartan or placebo for 6 months in addition to standard therapy in a multicenter, double-blind trial. Peak aerobic capacity (V(O2)) during symptom-limited treadmill exercise and NYHA functional class were determined at baseline and after 3 and 6 months of double-blind therapy. Peak V(O2) at baseline and after 3 and 6 months were 13.5+/-0.6, 15.1+/-1.0, and 15.7+/-1.1 mL. kg-1. min-1, respectively, in patients receiving losartan and 14.1+/-0.6, 14.3+/-0.9, and 13.6+/-1.1 mL. kg-1. min-1, respectively, in patients receiving placebo (P<0.02 for treatment group-by-time interaction). Functional class improved by at least one NYHA class in 9 of 16 patients receiving losartan and 1 of 17 patients receiving placebo. CONCLUSIONS: Losartan enhances peak exercise capacity and alleviates symptoms in patients with CHF who are severely symptomatic despite treatment with maximally recommended or tolerated doses of ACE inhibitors. (+info)
Influences of low intensity exercise on body composition, food intake and aerobic power of sedentary young females.
The present study was designed to investigate the influences of aerobic training on the body composition, aerobic power and food intake of sedentary young females in relation to the initial levels of these variables. Thirty one untrained college females (age = 19.8 +/- 0.2 yr, stature = 154.4 +/- 0.8 cm, body mass = 53.3 +/- 1.2 kg, mean +/- SEM) participated in an exercise regimen consisting of 40% of maximum oxygen uptake (VO2max) for 30 minutes per day on a bicycle ergometer 5 times a week in a training period of 12 weeks. Food consumption was ad libitum but the content of daily food intake was recorded accurately throughout the whole training period and analyzed weekly. The average body mass index (BMI) and fat mass relative to body mass (% FM), estimated from the data of skinfold thickness, decreased significantly after the 12 wk training. There were significant negative correlations between the relative changes (% delta s) and initial levels of both body mass (r = -0.447, p < 0.05) and fat mass (r = -0.638, p < 0.05), but the corresponding correlation for lean body mass (LBM) was not significant (r = 0.186, p > 0.05). While the energy intake during the training period did not differ significantly from that during the control period on the average, the % delta value in energy intake between the two periods was negatively correlated to the energy intake during the control period (r = -0.604, p < 0.05). In addition, there were low but significant negative correlations between both the initial levels of BMI and %FM and % delta in energy intake; r = -0.413 (p < 0.05) for BMI and r = -0.393 (p < 0.05) for %FM. However, no significant correlations were found between % delta in energy intake and those in body composition variables (r = 0.116 to 0.237, p > 0.05). On the average VO2max relative to body mass (VO2max/BM) increased significantly, but VO2max relative to LBM (VO2max/LBM) did not. However, not only VO2max/BM but also VO2max/LBM was negatively correlated to the initial level; r = -0.671 (p < 0.05) for VO2max/BM and r = -0.625 for VO2max/LBM. Thus, the present results indicate that whether the body composition, food intake and aerobic power of sedentary young females can be modified by the exercise regimen eliciting 40% of VO2max depends on their initial levels. (+info)
Stroke volume decline during prolonged exercise is influenced by the increase in heart rate.
This study determined whether the decline in stroke volume (SV) during prolonged exercise is related to an increase in heart rate (HR) and/or an increase in cutaneous blood flow (CBF). Seven active men cycled for 60 min at approximately 57% peak O2 uptake in a neutral environment (i.e., 27 degrees C, <40% relative humidity). They received a placebo control (CON) or a small oral dose (i.e., approximately 7 mg) of the beta1-adrenoceptor blocker atenolol (BB) at the onset of exercise. At 15 min, HR and SV were similar during CON and BB. From 15 to 55 min during CON, a 13% decline in SV was associated with an 11% increase in HR and not with an increase in CBF. CBF increased mainly from 5 to 15 min and remained stable from 20 to 60 min of exercise in both treatments. However, from 15 to 55 min during BB, when the increase in HR was prevented by atenolol, the decline in SV was also prevented, despite a normal CBF response (i.e., similar to CON). Cardiac output was similar in both treatments and stable throughout the exercise bouts. We conclude that during prolonged exercise in a neutral environment the decline in SV is related to the increase in HR and is not affected by CBF. (+info)