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Biomedical subjects

W L Haskell

Publications and source records attributed to W L Haskell.

At least 109 records · Page 6Linked to original sources
PubMed1988

Effects of weight loss on clinic and ambulatory blood pressure in normotensive men.

Obesity and physical inactivity are associated with both elevated cardiovascular risk and blood pressure (BP), but the interrelation of exercise, weight loss and BP is poorly understood. This study examines the independent effects of exercise and weight loss on both standard clinic and automated, ambulatory BP in 115 overweight, sedentary, normotensive men (aged 30 to 59 years) who were randomly assigned to control status or to lose weight over 1 year by moderate caloric restriction (dieting) or by increased caloric expenditure (exercise). Median daytime and evening BP were determined from measurements made every 20 minutes while the subjects were awake. After 1 year, the control group gained (mean +/- standard deviation) 0.5 +/- 3.8 kg while the diet group lost 6.9 +/- 4.4 kg and the exercise group lost 4.6 +/- 3.5 kg. Clinic BP decreased similarly in all 3 groups, but daytime and evening ambulatory BP decreased in both intervention groups and increased in the control group. Relative to the 1-year change in control subjects, net change in daytime ambulatory BP averaged -2 to -3 mm Hg in both dieters and exercisers, while net change in evening ambulatory BP averaged -3 to -4 mm Hg. These changes were all statistically significant (p less than 0.05) when compared with control subjects except for daytime systolic BP in both intervention groups and evening diastolic BP in dieters. Weight loss achieved through caloric restriction or expenditure may cause important decreases in BP in normotensive men; exercise appears to confer no unique benefit. If confirmed, these results have important public health implications for the prevention of cardiovascular disease.

Adult↗
PubMed1988

Strategies for increasing early adherence to and long-term maintenance of home-based exercise training in healthy middle-aged men and women.

Two studies were undertaken to compare strategies for the adoption and maintenance of moderate-intensity, home-based exercise training. In the study of adoption, 52 men and women who had served for 6 months as controls for a study of moderate-intensity, home-based exercise training received 30 minutes of baseline instruction. They were then randomized to receive continuing instruction and support through 10 staff-initiated telephone contacts of 5 minutes each every 2 weeks, or to receive no telephone contacts. In subjects receiving telephone contacts, peak oxygen uptake increased significantly after 6 months, whereas no increase was observed in subjects receiving no staff support (p less than 0.05). In the maintenance study, 51 men and women who had significantly increased their peak oxygen uptake by 6 months of moderate-intensity, home-based exercise training were randomized to undergo daily self-monitoring and receive adherence instructions, or undergo weekly self-monitoring only, during a second 6-month period of training. Subjects performing daily self-monitoring reported completing significantly more exercise training sessions during the 6 months of training than subjects performing weekly self-monitoring; functional capacity in both groups remained higher than before training (p less than 0.05). Taken together, these studies suggest that brief baseline instruction followed by continuing telephone contact with staff can be used to help people adopt a moderate-intensity, home-based exercise training program that can be maintained by simple self-monitoring strategies.

Behavior↗
PubMed1988

Increasing exercise among blue-collar employees: the tailoring of worksite programs to meet specific needs.

Despite increasing interest in worksite exercise programs, little attention has been focused on the blue-collar segment of the workforce. Because of their low participation in traditional exercise classes and programs, blue-collar workers at a university were targeted for an exercise program tailored specifically to their preferences and needs. Thirty-eight sedentary males employed in operations and maintenance shops on the university campus were evaluated with regard to their current exercise behavior, other health habits, and their preferred types of physical activity programs. A pre- and postprogram submaximal exercise test, weight, and blood pressure measurements were also completed on-site. Twenty-two men (23% of the total blue-collar population) subsequently participated in a 16-week exercise program using an on-site parcourse, and incorporating such motivational strategies as public monitoring, intershop competition, and activity-based incentives. Participation rates were substantially higher than those recorded for previous worksite exercise classes. Participants showed increases in fitness levels (P less than 0.0001) and decreases in weight (P less than 0.05) compared with nonparticipants. Suggestions concerning recruitment of such individuals into low-cost exercise programs and subsequent participation maintenance are discussed.

Adult↗
PubMed1988

Smoking cessation after acute myocardial infarction: the effects of exercise training.

To determine the influence of exercise training on smoking after acute myocardial infarction (AMI), smoking rates in 42 pre-AMI smokers assigned to exercise training were compared with 26 pre-AMI smokers assigned to no training. Exercise training occurred 3-26 weeks after AMI. The increase in functional capacity in 3-26 weeks was significantly greater in training than in no-training patients: 1.8 vs. 1.2 METs respectively (p less than 0.05). Adherence to exercise training was higher in non-smokers and former smokers than in those who continued to smoke: 89% and 88% vs. 80% respectively (NS). The prevalence of smoking 6 months post-AMI was lower in training than in no-training patients: 31% vs. 39% respectively (NS). Plasma thiocyanates collected on a random sample of 42 patients suggested that 19% of patients who are smoking after MI fail to report doing so. Self-reported cigarette consumption at 28 weeks was half as great in training as in no-training patients: 11 +/- 7 vs. 22 +/- 16 cigarettes per day (p less than 0.03). Firm advice to stop smoking followed by medically supervised exercise training with frequent followup reduces self-reported cigarette consumption in patients after AMI.

Aged↗
PubMed1988

New methodologies for studying the prevention of atherosclerosis.

To determine if multiple risk factor modification favorably alters the rate of progression of coronary atherosclerosis, 300 patients with established atherosclerosis have been randomized into a clinical trial; 155 to usual care and 145 to special intervention. All patients have medical/risk examinations at baseline and annually for 4 years. The special intervention patients undergo aggressive risk factor management with emphasis on lipoprotein modification, dietary management, smoking abatement, blood pressure control, weight loss and increased physical activity. To measure progression of atherosclerosis, a quantitative, computer-assisted coronary arteriographic system was developed to analyze the baseline and 4-year follow-up arteriograms. This procedure uses a catheter with a metallic calibration cylinder at its tip to determine absolute artery size and automated computer edge detection techniques to define the internal border of the artery. The analysis system detects artery borders using changes in cine film density and measures distances between these borders. For each segment the minimum, maximum and mean diameters are measured and percent stenosis and atheroma area calculated. This system provides precise and reproducible measures of coronary artery segment diameter. Using this technique, we estimate a 33% reduction in the rate of coronary artery progression over 4 years, defined as mean segment diameter, can be detected at a power of 0.80 and an alpha of 0.05 (one tailed test) with a sample size of 120 in each of 2 groups.

Coronary Angiography↗
PubMed1987

Effectiveness of self-monitored, home-based, moderate-intensity exercise training in middle-aged men and women.

The effects of 6 months of self-monitored, home-based exercise training on maximal oxygen uptake (VO2 max), body composition and plasma lipid levels of healthy, sedentary, middle-aged persons were evaluated in 60 men, aged 49 +/- 6 years, and 60 women, aged 47 +/- 5 years. Moderate-intensity training was performed 5 times per week in sessions of 47 +/- 7 minutes and 54 +/- 8 minutes for men and women, respectively. The individually prescribed range of heart rate corresponded to 65 to 77% of the peak value during symptom-limited treadmill testing (mean of 72% for men and 69% for women). Caloric expenditure per training session was approximately 345 kcal for men and 235 kcal for women. VO2 max increased 15% in men and 9% in women (both p less than 0.01). The greater increase in VO2 max in men than in women primarily reflected greater adherence to training in men (greater than or equal to 90% vs greater than or equal to 75%). The increase in VO2 max in women who showed very high adherence was comparable to that of men. Body weight decreased, by 1.5 +/- 10 kg, in men (p less than 0.05) but not in women undergoing training. No significant training-induced changes in plasma lipid levels were noted in either men or women. Baseline orientation and follow-up telephone calls required less than 1 hour of staff time per participant. Self-monitored, moderate-intensity, home-based exercise training significantly increases functional capacity in healthy, middle-aged men and women. Such training provides an alternative to group-based exercise training.

Adult↗
PubMed1987

Assessment by a microprocessor of adherence to home-based moderate-intensity exercise training in healthy, sedentary middle-aged men and women.

Research in exercise training of healthy persons, which has been conducted almost exclusively in supervised group programs, is relatively expensive for the investigator and inconvenient for the participant. To overcome these obstacles, self-monitored moderate-intensity home-based exercise training was prescribed for 28 middle-aged men and 26 middle-aged women. The median energy expenditure prescribed for each of 5 weekly exercise sessions was 4 cal/kg body weight, or 317 kcal for men and 265 kcal for women, corresponding to a median duration of 45 and 60 minutes, respectively. In the next 24 weeks, peak oxygen uptake increased 13.7% in men who exercised, from 31 +/- 4 to 37 +/- 4 ml/kg/min, and 10% in women who exercised, from 26 +/- 4 to 29 +/- 5 ml/kg/min (p less than 0.001 for both comparisons). The proportion of prescribed caloric expenditure per session, which was documented by a solid-state heart rate recorder, was 108% in men and 90% in women. The duration of training at heart rates above the prescribed range approximated 10 minutes per session for both men and women; the proportion of total caloric expenditure represented by exercise at heart rates exceeding the prescribed limit was 9% for men and 4% for women. The proportion of time spent within the prescribed heart rate range during training sessions was 76% for men and 84% for women. Training-induced musculoskeletal problems were reported by 6 men and no women. No subject sought medical attention and all resumed training within 1 week.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Improved insulin action in muscle, liver, and adipose tissue in physically trained human subjects.

The present studies were initiated to assess the effect of insulin on muscle, liver, and adipose tissue in eight control and eight physically trained individuals matched for age and body mass index. Results indicated that percent body fat was 53% lower and maximal oxygen consumption 50% higher in physically trained subjects. Although the plasma glucose response to a standard oral glucose challenge was similar in the two groups, the insulin response was significantly lower in the trained individuals (P less than 0.001). Mean (+/- SE) insulin-stimulated glucose uptake, quantified in vivo by the euglycemic hyperinsulinemic clamp technique, was significantly greater in physically trained individuals at steady-state plasma insulin concentrations of approximately 10 microU/ml (3.41 +/- 0.14 vs. 2.73 +/- 0.22 mg.kg fat free mass-1.min-1, P less than 0.05) and 50 microU/ml (13.58 +/- 0.75 vs. 9.82 +/- 0.53 mg.kg fat free mass-1.min-1, P less than 0.001). In addition, mean (+/- SE) hepatic glucose production rate was lower in physically trained subjects at insulin levels of 10 microU/ml (0.63 +/- 0.19 vs. 1.19 +/- 0.22 mg.kg body wt-1.min-1, P less than 0.05) and 50 microU/min (0.18 +/- 0.14 vs. 0.60 +/- 0.17 mg.kg body wt-1.min-1, P less than 0.05). Finally, the ability of insulin to stimulate mean (+/- SE) glucose uptake above basal levels was greater in adipocytes isolated from trained individuals (94 +/- 10 vs. 56 +/- 14 fl.cell-1.s-1, P less than 0.01). On the other hand, no difference in specific binding of insulin to its receptor on monocytes was noted between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1986

Assessment of prescribed increases in physical activity: application of a new method for microprocessor analysis of heart rate.

A portable solid-state recorder-display system was used to measure and analyze heart rate during the waking hours of 3 consecutive days in free-living sedentary normal middle-aged men who were randomized to undergo 3 regimens of physical activity during a 12-week period: low-intensity exercise training at home (n = 21), high-intensity exercise training at home (n = 23) and customary activity (n = 20). This was done to determine whether the system could detect changes in heart rate and, indirectly, in physical activity within the 3 groups. In both training groups the percentage of total recorded time spent within the prescribed high or low heart rate range recorded at 6 or 12 weeks increased significantly (p less than 0.05), whereas control subjects showed no increase above baseline values. Peak oxygen consumption increased by 8% and 17% in men undergoing low- and high-intensity training, whereas in control subjects it did not change. This solid-state system reliably measures prescribed increases in heart rate and provides an indirect measure of physical activity in normal sedentary men undergoing exercise training at home.

Ambulatory Care↗
PubMed1986

Effects of low- and high-intensity home-based exercise training on functional capacity in healthy middle-aged men.

The effects of 12 weeks of home-based exercise training on peak oxygen consumption (VO2 max) in healthy sedentary middle-aged men, mean age 49 +/- 6 years, were evaluated. Twenty-one men trained at low intensity, 23 trained at high intensity and 20 were control subjects. Individually prescribed low- and high-intensity training was performed 5 times per week within a range of 42 to 60% and 63 to 81% of baseline VO2 max, corresponding to average heart rates of 102 to 122 and 128 to 148 beats/min, respectively. Caloric expenditure per training session approximated 350 kcal in both groups; adherence was at least 90% in both groups. VO2 max increased 8% in patients who trained at low intensity, 17% in those who trained at high intensity (both p less than 0.001), and not at all in control subjects. Low-intensity exercise training at home significantly augments functional capacity in healthy sedentary middle-aged men.

Adult↗
PubMed1986

Vigorous physical activity and cardiovascular risk factors in young adults.

There are conflicting data regarding the effects of vigorous physical activity (PA) and cardiovascular disease risk factors. Representative samples of adults aged 20-35 from four northern California cities were studied both cross-sectionally and longitudinally in order to examine the relationships between vigorous PA and selected physiological risk factors. A self-report measure of habitual vigorous PA was validated by pulse rate. There were relationships, in both cross-sectional and longitudinal analyses between self-reported vigorous PA and HDL/LDL ratio, especially for women. Relationships in cross-sectional analyses only were found between PA and diastolic blood pressure, total cholesterol, HDL-cholesterol, triglycerides, and alveolar carbon monoxide. The results of the present study generally tend to confirm investigations of other samples.

Adult↗
PubMed1986

Predictors of adoption and maintenance of physical activity in a community sample.

Predictors of changes in three measures of physical activity over 1 year were examined in a community sample of 1,411 California adults. Five percent of women and 11% of men adopted vigorous activities (e.g., running), and 26% of men and 34% of women adopted regular moderate activity (e.g., walking). About 50% of vigorous exercisers and 25-35% of moderate exercisers dropped out in 1 year. About 9% reported large 1-year increases in globally rated activity level, while about 7% reported decreases in global activity. In multivariate analyses, adoption of vigorous activity was predicted by young age, male gender, and self-efficacy. Maintenance of vigorous activity was predicted by attitudes toward physical activity. Adoption of moderate activity was predicted by health knowledge, and maintenance was predicted by specific exercise knowledge, female gender, and self-efficacy.

Adult↗
PubMed1986

Personal and mediated health counseling for sustained dietary reduction of hypercholesterolemia.

Methods of effective cardiovascular risk reduction that are suitable for use in clinical settings are needed. Several behavioral interventions were designed to be compatible with office-based medical practice, to be delivered by paraprofessional counselors, and to be of low intensity and low cost. Eighty-three hypercholesterolemic volunteers were assigned to one of three experimental conditions (face-to-face counseling, mail and telephone counseling, initial session only). Twenty-six nonrandomized subjects served as a no-contact group and were followed for 1 year. Participants in the first three groups received risk factor education, behavioral recommendations, and a packet of materials, while those in the face-to-face and mail/telephone counseling groups were contacted for five brief follow-up sessions over a 4-month period. At the 1-year follow-up evaluation, subjects in the face-to-face and mail/telephone counseling conditions showed decreases in plasma cholesterol of 6.2 and 4.6%, respectively (P less than 0.01), while the other two groups evidenced small increases. There were no differences by condition for plasma triglycerides, systolic or diastolic blood pressure, or weight. Low-intensity, low-cost behavioral interventions delivered by paraprofessionals can produce long-term decreases in a major cardiovascular risk factor. Physicians are encouraged to incorporate similar interventions into their practices.

Adult↗
PubMed1986

Moderate-intensity physical activity and cardiovascular risk factors: the Stanford Five-City Project.

There is evidence that low to moderate levels of physical activity can reduce risk of cardiovascular disease, even though they do not produce substantial changes in cardiorespiratory function. In this study of a representative population sample of 5,930 adult men and women, participants in moderate-intensity activities, such as walking and climbing stairs, were compared with nonparticipants. Men and women who reported more moderate activities were less overweight than sedentary peers. Moderate activity was associated with more risk factor benefits in men than in women. The apparent health benefits of moderate-intensity physical activity have implications for public health education.

Adult↗
PubMed1986

Community surveillance of cardiovascular diseases in the Stanford Five-City Project. Methods and initial experience.

The Stanford Five-City Project is a long-term field evaluation of the effects of community health education on cardiovascular disease risk factors and event rates. One major end point of the project is the difference between treatment and control group trends in morbidity and mortality rates ascertained through community-wide surveillance of deaths and hospital discharges. This surveillance system includes continuous review of death certificates and hospital discharge records, interviews with the families and physicians of decedents who died outside the hospital, abstraction of the hospital records of possible myocardial infarction and stroke cases (fatal and nonfatal), and systematic validation of diagnosis by the use of standard criteria. Initial experience with information access, availability of diagnostic information, costs, and reliability are described. This standardized approach to community surveillance of cardiovascular disease events rates, both fatal and nonfatal, is a feasible method for evaluating large-scale intervention programs and may be applicable to monitoring secular trends in the absence of intervention.

Adult↗