ISSN:0195-9131    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The effects of supervised physical training (PT) and lifestyle education(LSE) on risk factors for coronary artery disease and non-insulin-dependent diabetes mellitus were compared in obese 7- to 11-yr-old black girls. The subjects were divided into two groups. The PT group (N= 12) completed a 5-d·wk-1, 10-wk, aerobic training program; and the LSE group participated in weekly lifestyle discussions to improve exercise and eating habits. The PT group showed a significant increase in aerobic fitness(P< 0.05) and decrease in percent body fat (P< 0.05), while the LSE group declined significantly more in dietary energy and percent of energy from fat (P< 0.05). Fasting insulin did not change significantly. The LSE group declined significantly more than the PT group in glucose (P< 0.05), and glycohemoglobin declined from baseline in both groups (P< 0.05). Lipid changes were similar in the two groups: total cholesterol/high density lipoprotein cholesterol(P< 0.01) and triglycerides (P< 0.05) declined, the low density lipoprotein (LDL)/apoproteinB ratio increased (which indicates a decrease in small dense LDL) (P< 0.05) and lipoprotein(a) increased (P< 0.05). Thus, the interventions were similarly effective in improving some diabetogenic and atherogenic factors, perhaps through different pathways; i.e., the PT improved fitness and fatness, while the LSE improved diet. Exercise and diet-induced changes in lipoprotein(a) require further investigation.

ISSN:0195-9131    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

We investigated: 1) the mechanism of the hypotensive effect of a single bout of dynamic exercise in hypertensive subjects by measuring hemodynamic parameters before and for 2 h after treadmill exercise, and 2) the duration of the effect using ambulatory blood pressure (BP) monitoring once the subjects left the test site. Ten minutes after exercise there was a significant decrease from baseline systolic pressure (SP; -14 ± 3 mm Hg), mean arterial pressure (MAP; -7 ± 2 mm Hg), total peripheral resistance(TPR; -3.7 ± 1.2 units), calf vascular resistance (CVR; -25.4 ± 4.1 units), and an increase in HR (19 ± 2 bpm). The changes in SP, DP, MAP, and HR were maintained during the 2 h of post-exercise monitoring; CVR remained decreased for 1 h; TPR returned to baseline within 20 min and then tended to be slightly elevated. CO was significantly decreased at 50, 60, and 120 min after exercise. We conclude that the early decline in BP after dynamic exercise in hypertensive subjects follows a biphasic pattern: 1) an initial decrease in total and regional vascular resistance with maintained CO, 2) followed by increasing resistance and decrease CO. Pre-exercise hypertensive BP values returned during subsequent ambulatory monitoring.

ISSN:0195-9131    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Previous studies have suggested a reduced glucose uptake by the athlete's heart at rest. To examine whether there is a compensatory increase in the myocardial fatty acid utilization, we studied nine male endurance-trained athletes (age 26 ± 2 yr, ˙VO2max60 ± 1 ml·kg-1·min-1, mean ± SEM) and eight sedentary subjects (age 26 ± 1 yr, ˙VO2max38 ± 2 ml·kg-1·min-1) by single photon emission tomography using123I-heptadecanoic acid (HDA) and mathematical modeling. Magnetic resonance imaging (MRI) and echocardiography were performed for the measurements of cardiac dimensions and left ventricular (LV) mass. No significant differences were found in the myocardial HDA beta-oxidation index(5.2 ± 2.0 vs 7.4 ± 1.6 μmol·min-1·100 g-1,P= NS) between endurance-trained and sedentary subjects. Fractional amounts of HDA beta-oxidation, backdiffusion, and esterification were also similar. In MRI study, LV mass was greater in the trained subjects (213 ± 9 vs 179 ± 10 g,P< 0.01) and in particular, LV long-axis diameter measured from the mitral valve level to the apex was increased (102 ± 2 vs 88 ± 2 mm,P< 0.001, trained vs sedentary subjects). ˙VO2maxcorrelated with LV long-axis diameter (r = 0.77,P< 0.001). In contrast to our hypothesis, myocardial HDA utilization was not enhanced in endurance-trained athletes at rest. Increases in LV mass and especially in LV long-axis diameter were observed in the athletes, indicating LV longitudinal remodeling.

ISSN:0195-9131    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

This study examined the plasma glucose, free fatty acids (NEFA), lactate, triglyceride, cortisol, and insulin responses of pregnant women (22-28 wk) to a 40-min aerobic dance program and 40-min treadmill walking at similar heart rate intensities. The heart rates during exercise averaged 135 ± 5 bt·min-1for both trials. Immediate post-exercise plasma glucose levels were lower than resting levels for both exercise trials (P< 0.05), and remained below resting levels 20 min after exercise. Plasma triglycerides and NEFA were increased immediately post-exercise (P< 0.05), and returned toward rest 20 min after exercise. The NEFA responses at the end of the walking trials were significantly greater than at the end of the aerobic dance trials (P< 0.05). For both trials, immediate post-exercise plasma insulin levels were below resting levels (P< 0.05) and remained attenuated 20 min post-exercise. Plasma cortisol concentrations were unchanged throughout the aerobic dance trial. However, a mean increase of 105 nmol·l-1immediately post-exercise was evident during the walking trials (P< 0.05). The results suggest that 40 min of walking or aerobic dance reduces blood glucose but does not cause hypoglycemia. Further, the results suggest that 40 min of walking or aerobic dance does not expose the mother to serious metabolic consequences that might adversely affect the fetus.

ISSN:0195-9131    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

In the Training Levels Comparison Trial, 197 male coronary heart disease patients were randomized to low or high intensity training with target heart rates, which corresponded to 50% and 85% of the ˙VO2maxachieved on the previous exercise test, respectively. Patients were to exercise at their assigned intensity level at three 1-h long supervised sessions per week for 2 yr. This paper reports on two components of adherence: attendance at exercise sessions and achievement of heart rates in the target range. During the first year of training, the average percent of exercise sessions attended (mean± SE) for the low intensity group (64.0% ± 2.5%) was significantly higher than for the high intensity group (55.5% ± 2.7%). At the end of 1 yr of training, 54% and 37% of the low and high intensity patients, respectively, achieved heart rates within 5 beats·min-1of their target heart rates. Although the low intensity program was preferable to achieve maximum attendance, attenders on the high intensity program achieved higher heart rates. These results suggest that to maximize the achieved heart rate, it would be optimal to motivate a cardiac rehabilitation patient to train at the high intensity level for a prolonged period of time.

ISSN:0195-9131    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Malignant ventricular arrhythmias account for a significant number of deaths annually. Improved therapies have increased survival for this patient population. These patients, however, remain at high risk due to their history of sudden cardiac death and the preponderance of poor ventricular function in this population. This high risk status may have excluded them from participation in cardiac rehabilitation programs or from undergoing exercise testing in some medical centers. Although the risk of complications, especially arrhythmias, is quite real, the experience in some centers has indicated that it is manageable. This experience and some guidelines for exercise testing and training of patients with malignant ventricular arrhythmias are reviewed in this paper.

ISSN:0195-9131    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

This study tested the hypothesis that an α-adrenergic coronary constrictor tone increases with the intensity of exercise and imposes a limitation on transmural myocardial blood flow and contractile function during strenuous levels of exercise. Nine (9) dogs were chronically instrumented to measure left circumflex blood flow (CBF), global myocardial contractile function (dP/dtmax), and regional myocardial contractile function(maximal rate of segmental shortening, dL/dtmax). The dogs were subjected to a graded submaximal exercise test with increasing workloads encompassing 4.8 kph and 6.4 kph, 0, 4, 8, 12, and 16% incline. On separate days, either vehicle (sterile water) or the specificα1-adrenergic receptor antagonist prazosin (1μg·kg-1·min-1) was infused into the circumflex artery during exercise. Removal of an α1-receptor mediated coronary constrictor tone resulted in a 15 ± 7%, 24 ± 9%, and 35± 10% greater increase in CBF compared with vehicle at the three most strenuous levels of exercise, respectively. Regional left ventricular blood flow was measured using labeled microspheres in four (4) additional dogs. Endocardial and epicardial blood flow increased equally by 16% during exercise after prazosin, such that the endocardial/epicardial flow ratio did not change. The augmentation in CBF after α1-blockade was associated with significant increases in both regional and global left ventricular contractile function. These studies indicate that a uniformly distributed transmural coronary α1-constrictor tone increases in magnitude with increasing levels of exercise intensity and, as a result, imposes a significant limitation on myocardial function.

ISSN:0195-9131    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

During constant-rate high-intensity (CRHI) exercise lasting longer than 3 min, ˙VO2has been reported to exceed ˙VO2maxmeasured with a traditional graded exercise test (GXT). This could be because˙VO2maxwas not achieved on the GXT or because the factors responsible for the slow-component rise in ˙VO2alter˙VO2max. The objective of this study was to test the hypothesis that the slow-component rise in ˙VO2measured during CRHI running leads to a total ˙VO2that exceeds ˙VO2maxmeasured during a running GXT. ˙VO2maxwas determined in eight highly trained individuals using data collected from five grade-incremented, treadmill-running GXT. Each subject demonstrated a definitive plateau of˙VO2as a function of exercise intensity. Three ˙VO2maxvalues based on different approaches for representing the ˙VO2maxplateau were obtained. Subjects also completed two exhaustive CRHI bouts of treadmill running lasting 7-13 min at speeds estimated from the ACSM equation to elicit an average of 99 ± 5% ˙VO2max. The mean(±SD) ˙VO2peakdetermined during the CRHI runs (4.17± 0.9 l·min-1) was not different from or less than the three ˙VO2maxvalues (4.19-4.32 ± 0.09 l·min-1). We conclude that in highly trained individuals, the slow-component rise in ˙VO2during CRHI treadmill running does not lead to a total ˙VO2that exceeds the ˙VO2maxmeasured during a running graded exercise test.

ISSN:0195-9131    

出版商:OVID    

年代:1996

数据来源: OVID