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Lipoprotein(a) (Lp(a)) is bound to apolipoprotein B-100 by disulfide linkage and is associated in the upper density range of low density lipoprotein cholesterol. Persons with elevated concentrations of Lp(a) are regarded as having an increased risk for premature coronary artery disease. Although many studies exist evaluating the effects of a single session of exercise on lipids and lipoproteins, little information is available concerning the effects of exercise on Lp(a). Therefore, the purpose of this study was to determine the effects of a single exercise session on plasma Lp(a). Twelve physically active men completed two 30-min submaximal treadmill exercise sessions: low intensity (LI, 50% VO2max) and high intensity (HI, 80% VO2max). Blood samples were obtained immediately before and after exercise. Total cholesterol (LI: before 4.22 +/- 0.26, after 4.24 +/- 0.28; HI: before 4.24 +/- 0.31, after 4.11 +/- 0.28 mmol.l-1, mean +/- SE) and triglyceride (LI: before 1.14 +/- 0.16, after 1.06 +/- 0.16; HI: before 1.12 +/- 0.19, after 1.21 +/- 0.19 mmol.l-1) concentrations did not differ immediately after either exercise session, nor did Lp(a) concentrations differ immediately after either exercise session (LI: before 4.1 +/- 2.2, after 4.0 +/- 2.1: HI: before 3.9 +/- 2.2, after 3.7 +/- 2.0 mg.dl-1). These results suggest that neither a low nor a high intensity exercise session lasting 30 min in duration has an immediate effect on plasma Lp(a).

Initial information on the newly discovered hormone leptin suggests a primary role in energy balance and body weight maintenance. Recent published information suggests that leptin has an impact on several physiological systems, including neuroendocrine and immune function, as well as being involved in growth and development. Although the role of leptin in these areas is only partially understood at best, even less is known about the effect of exercise on plasma leptin concentrations. Further, if exercise has an impact on leptin concentration, how then does exercise affect overall leptin function? This article considers leptin function and the impact that exercise has on blood leptin concentrations, and suggests future directions for research on exercise and leptin. Leptin, a hormone synthesized primarily by adipose tissue and secreted into the circulatory system, is a purported satiety factor with receptors in the hypothalamus. Human leptin is a relatively small protein (16 kDa) which shares a high degree of homology with other species such as mice (84%) and rats (83%). Although rare in humans, leptin mutations in mice result in leptin deficiency and lead to early onset obesity, hyperphagia, and hypothalamic hypogonadism. Unlike leptin deficient mice, humans deficient in leptin do not suffer from hyperinsulinaemia, hyperglycaemia, hypercorticism, or hypothermia. Although regulation of leptin synthesis and release is poorly understood, a distinct circadian pattern for plasma leptin concentrations has been observed and is similar to that of prolactin and thyroid stimulating hormone.1 Conflicting …

OBJECTIVE: The purpose of this study was to determine the association between moderate-intensity physical activity (PA) and fasting insulin levels among African-American (n = 47), Native American (n = 46), and Caucasian women (n = 49), aged 40-83 years, enrolled in the Cross-Cultural Activity Participation Study. Associations by race/ethnicity, levels of central obesity, and cardiorespiratory fitness were also examined. RESEARCH DESIGN AND METHODS: Physical activity scores were obtained from detailed PA records that included all PA performed during two consecutive 4-day periods scheduled 1 month apart. Using MET intensity (the associated metabolic rate for a specific activity divided by a standard resting metabolic rate), PA was expressed as MET-min (the product of the minutes for each activity times the MET intensity level) per day of energy expended in moderate (3-6 METs) and moderate/vigorous (> or = 3 METs) PA. Fasting insulin levels were determined by radioimmunoassay. Data were analyzed by multiple linear regression analysis. RESULTS: After adjusting for race/ethnicity, age, educational attainment, and site, an increase of 30 min of moderate-intensity PA was associated with a 6.6% lower fasting insulin level (P < 0.05). The association was similar among races/ethnicities, centrally lean and centrally obese women, and women with low and high cardiorespiratory fitness levels. CONCLUSIONS: These findings lend support to the 1995 Centers for Disease Control and Prevention and American College of Sports Medicine recommendations for an accumulation of 30 min/day in moderate-intensity PA. They also contribute to the growing literature suggesting that moderate amounts of PA have a significant role in reducing the burden of hyperinsulinemia and diabetes among ethnic populations at highest risk for these conditions.

PURPOSE Cardiac rehabilitation (CR) programs have been shown to promote numerous health benefits among patients with active coronary heart disease (CHD), but little is known about the percentage of eligible CHD patients who enroll in CR. METHODS A survey was performed of 500 randomly chosen CR programs in operation in the United States during 1990. Patient characteristics and enrollment data were combined with data from the 1990 National Hospital Discharge Survey to estimate the percentage of eligible patients who participated in early outpatient (Phase II) CR programs after myocardial infarction (MI), after coronary angioplasty (PTCA), or after coronary artery bypass surgery (CABS). RESULTS Completed surveys were returned by 163 programs (32.6%) with information on 1,322 women and 1,418 men who enrolled in their programs in 1990. Women were older, more likely to be single, and had more traditional CHD risk factors than men. Only a minority of MI, PTCA, and CABS survivors enrolled in CR programs (10.8%, 10.3% and 23.4%, respectively). Enrollment was particularly low for post-MI and post-CABS women as compared with men: 6.9% versus 13.3% (P < .001), and 20.2% versus 24.6% (P < .001), respectively. Enrollment was generally lowest for nonwhites, those over age 65, and those living in the southern United States. CONCLUSIONS Cardiac rehabilitation programs are used by a minority of eligible patients, particularly among women, nonwhites, and the elderly. To meet newly released national guidelines that recommend CR services for most patients recovering from MI, PTCA, or CABS, and to still contain costs, new methods need to be explored that can expand the delivery of CR services in clinical settings.

The purposes of this study were to 1) characterize changes in fibrinolytic activity in response to maximal exercise and 5-min venous occlusion and 2) compare responses in men of various habitual physical activity levels. Tissue plasminogen activator (TPA) activity and plasminogen activator inhibitor 1 (PAI-1) activity were measured in 15 inactive, 15 regularly active, and 15 highly active men. Data were analyzed using a three-way analysis of variance with repeated measures. Pretest TPA activity was similar among groups. TPA activity increased postexercise with higher values seen in the active groups (P < 0.001). The highly active group also significantly increased TPA activity postvenous occlusion (P < 0.01). Pretest PAI-1 activity was different among groups, with the inactive group showing the highest activity and the highly active group the lowest (P < 0.05). PAI-1 activity decreased with exercise (P < 0.01) but did not change with venous occlusion. In conclusion, active men exhibited greater changes in fibrinolytic activity with maximal exercise and venous occlusion than inactive men. This enhanced fibrinolytic activity may be an important mechanism mediating the cardioprotective effect provided by regular physical activity.

The purpose of this investigation was to examine the immediate and delayed effects of prolonged strenuous exercise on plasma lipid and lipoprotein concentrations in female runners. Venous blood samples were collected from 12 female runners 24 h before, 10 min after, and 1, 3, and 5 d after running a 42 km marathon. Whole blood was analyzed for hematocrit and hemoglobin to determine plasma volume shifts. Plasma aliquots were assayed for total cholesterol, high-density lipoprotein cholesterol (HDL-C), and triglyceride concentrations, while low-density lipoprotein cholesterol (LDL-C) was estimated. Total cholesterol concentrations were significantly reduced 1 d following the exercise and were still lower 3 and 5 d post-marathon. LDL-C was lower immediately and 1 d after the marathon. HDL-C concentrations, corrected for changes in plasma volume, were elevated 24 h post-exercise. The ratio of HDL/total cholesterol was increased 24 h post-exercise. Triglyceride concentrations were elevated immediately following the marathon but returned to baseline levels by 24 h post-exercise. These results demonstrate that prolonged strenuous exercise in women produces changes in blood lipid profiles that can last for several days.

The purpose of this study was to examine the physiological responses of county jail inmates to running programs of 1-day, 3-day, and 5-day/week frequencies. Fifty-five volunteer male inmates, age 20 to 35 years, were evaluated on the following variables: resting heart rate and blood pressure; treadmill performance time; maximum oxygen intake ([Vdot]O2 max) and related metabolic measures; lung volumes; body composition; and serum lipids. Subjects were assigned randomly into a control, 1-day, 3-day, or 5-day/week conditioning group. The training were 30 min/session and were conducted at approximately 85 to 90% maximum heart rate for 20 weeks. Results indicated no significant changes in the four groups for resting and recovery blood pressures, maximum heart rates, spirometry measures, body weight, and serum lipids. Significant improvements occurred in direct proportion to frequency of training in resting and recovery heart rates, treadmill performance time, [Vdot]O2 max, max O2 pulse, and [Vdot]E ma...

Systolic blood pressure was determined weekly to assess the development of hypertension in sedentary and active Dahl salt-sensitive (S) rats that were exercised by running at 20 m/min, 60 min/day, 5 days/wk. The marked rise in blood pressure that occurred with feeding 8% NaCl (wt/wt) diet in Dahl S rats could be attenuated by chronically practiced endurance running, but only if exercise at 20 m/min was started at the beginning of salt feeding. Under the same dietary feeding conditions, running at 27 m/min resulted in incomplete attenuation of hypertension. Further, running for 30 min/day was not as beneficial as running 60 min/day at 20 m/min. Delaying the start of exercise for 6 wk after the beginning of salt feeding did not result in reduction of hypertension in the S rat. These experiments indicate that increases in blood pressure can be prevented in Dahl S rats for 12 wk if running is initiated concomitantly with salt feeding. Blood pressure is not reduced if hypertension due to salt feeding has been continued for 6 wk. The results also indicate that there is an optimal exercise intensity, duration, or both, for controlling hypertension in Dahl rats.

Previous studies have concluded that exercise training has resulted in increases in cholesterol associated with high-density lipoprotein (HDL). However, data regarding alterations in triglyceride, cholesterol, and the protein associated with the three major lipoproteins in a hyperlipoproteinemic state in response to exercise training are not available. Serum lipoprotein levels from normal and hyperlipoproteinemic Zucker rats were studied following 9 and 18 wk of treadmill running to determine the extent that the three major serum lipoprotein classes were affected. Nine weeks of treadmill running reduced serum triglyceride content in obese rats (sedentary, 294 +/- 19 [SE]; trained, 128 +/- 40 mg X dl-1) but did not affect total serum cholesterol (sedentary, 85 +/- 6; trained, 90 +/- 6 mg X dl-1). Serum very low-density lipoprotein from the trained obese rats contained lower levels of triglyceride (57%), cholesterol (46%), and protein (61%). HDL cholesterol (sedentary, 61 +/- 4; trained, 73 +/- 4 mg X dl-1) was increased by 14% in the obese rat. In the lean rat, HDL cholesterol was the only lipoprotein fraction altered following 9 wk of treadmill running. The data from this study indicate that hypertriglyceridemia can be reduced in the obese rat and that HDL cholesterol can be increased by physical activity requiring about 70% maximal aerobic capacity.