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The Activity Counseling Trial (ACT) is a multicenter, randomized controlled trial to evaluate the effectiveness of interventions to promote physical activity in the primary health care setting. ACT has recruited, evaluated, and randomized 874 men and women 35-75 yr of age who are patients of primary care physicians. Participants were assigned to one of three educational interventions that differ in amount of interpersonal contact and resources required: standard care control, staff-assisted intervention, or staff-counseling intervention. The study is designed to provide 90% power in both men and women to detect a 1.1 kcal.kg-1.day-1 difference in total daily energy expenditure between any two treatment groups, and over 90% power to detect a 7% increase in maximal oxygen uptake, the two primary outcomes. Primary analyses will compare study groups on mean outcome measures at 24 months post-randomization, be adjusted for the baseline value of the outcome measure and for multiple comparisons, and be conducted separately for men and women. Secondary outcomes include comparisons between interventions at 24 months of factors related to cardiovascular disease (blood lipids/lipoproteins, blood pressure, body composition, plasma insulin, fibrinogen, dietary intake, smoking, heart rate variability), psychosocial effect, and cost-effectiveness, and at 6 months for primary outcome measures. ACT is the first large-scale behavioral intervention study of physical activity counseling in a clinical setting, includes a generalizable sample of adult men and women and of clinical setting, and examines long-term (24 months) effects. ACT has the potential to make substantial contributions to the understanding of how to promote physical activity in the primary health care setting.

Most studies of physical fitness change have been relatively small, not population-based, and lacking in women and nonwhites. The purpose of this analysis was to evaluate the 7-yr change in physical fitness in a biracial (black and white) population of young men and women.We evaluated change in exercise treadmill test performance in a biracial (black and white) population of 1,962 young adults, ages 18-30 yr at baseline, who completed symptom-limited graded exercise treadmill tests at the baseline (1985-1986) and year 7 (1992-1993) examinations of the CARDIA study.Mean test duration decreased 58 s (9.5%) over 7 yr (black men, 13.6% decrease, white men, 7.4%; black women, 11.1%; white women, 7.0%). Mean time to heart rate 130 (WL130), a measure of submaximal performance, decreased 31 s (11.3%) (black men, 16.9%; white men, 10.0%; black women, 12.3%; white women, 6.1%). Baseline body mass index (BMI) and physical activity were not statistically significant predictors of test duration change in any race-gender group, but change in BMI and activity were. Seven-year weight gain20 lbs (31% of cohort) was associated with a large decrease in fitness (18.5% decrease in mean duration, 21.8% decrease in WL130).These data suggest that fitness declines during young adulthood in blacks and whites and that fitness changes are related to changes in weight and physical activity.

Physical activity performed by patients with coronary heart disease is a two-edged sword. A number of biological changes produced by regular exercise may reduce the risk of future cardiac events, while the increase in cardiac work produced by this same exercise can predispose the patient to sudden cardiac death. Data from observational studies as well as randomized clinical trials demonstrate a lower cardiac mortality rate for men participating in exercise rehabilitation programs vs nonparticipants. Overall, exercise program participants appear to experience a reduction of approximately 25% in cardiac and all-cause mortality, but no single study has provided definitive results. During medically supervised exercise, the risk of cardiac death based on reports of programs in the United States is approximately one event in every 60,000 participant-hours of exercise. At this rate, a typical rehabilitation program that has 95 patients exercising 3 h.wk-1 could expect a sudden cardiac death during an exercise session once every 4 yr. No data have been published on the morbidity or mortality benefits or risks of home-based exercise or for women participants. Also, the contribution of continuous electrocardiographic monitoring to the safety of exercise training of cardiac patients is yet to be defined.

The Guidelines for Exercise Training initially developed by the American College of Sports Medicine in 1978 and updated in 1990 have served as the foundation for most recommendations regarding physical activity program design for the general public. These guidelines have proven to be very useful by providing a specific regimen for enhancing aerobic capacity and body composition. As data supporting a causal link between increased activity or fitness and health status have evolved, questions have been raised about potential limitations of these guidelines for promoting physical activity to increase the health status of sedentary adults. The major issues have involved the necessity to achieve the values for each of the program parameters, especially the intensity, duration, and frequency of exercise, in order to improve health status. To address these issues, a paradigm shift from exercise training to promote physical fitness to physical activity to promote health has been introduced. This new paradigm is based on the results from numerous studies indicating that a generally active life style is associated with better health and performance and greater longevity and a certain set of assumptions, yet to be fully tested. The following article provides some background leading to the development of the ACSM guidelines and presents some of those issues we understand and some we do not regarding the characteristics of daily physical activity or exercise training that are likely to improve the physical health status of sedentary persons.

Symptom-limited, graded exercise treadmill testing was performed by 4,968 white and black adults, ages 18-30 yr, during the baseline examination for the Coronary Artery Risk Development in Young Adults (CARDIA) study. Compared with nonsmokers, the mean exercise test duration of smokers was 29-64 s shorter depending on race/gender group (all P0.001), but mean duration to heart rate 130 (beats.min-1) ranged from 20-50 s longer (P0.05). In each race/gender group, test duration to heart rates up to 150 was 15-35 s longer (P0.05) in smokers than in nonsmokers after adjustment for age, sum of skinfolds, hemoglobin, and physical activity score. The mean maximum heart rate was lower in smokers than in nonsmokers (difference ranging from 6.7 beats.min-1 in white men to 11.2 beats.min-1 lower in black women, P0.001), although maximum rating of perceived exertion was nearly identical in smokers and nonsmokers. Chronic smoking appears to blunt the heart rate response to exercise, so that exercise duration to submaximal heart rates is increased even though maximal performance is impaired. This may result from downloading of beta-receptors caused by smoking. Smoking status should be considered in the evaluation of physical fitness data utilizing submaximal test protocols, or else the fitness of smokers relative to nonsmokers is likely to be overestimated.

Heart rate, determined by palpation of the carotid, radial, or temporal artery, is commonly used to monitor exercise intensity. It is known that massage of the carotid artery has a baroreceptor reflex effect on the heart rate. The heart rate, monitored with and without carotid palpation, at rest, during exercise, and immediately post-exercise was determined in 60 male cardiac patients (39-65 years of age) following either myocardial infarction (n=52), bypass surgery (n=6), or those with angina pectoris (n=2). The mean changes in heart rate with carotid palpation in the testing group were -3.5 bpm at rest and -2.2 bpm during exercise; in the training group the changes were +0.8 bpm at rest -3.1 bpm post exercise. While the mean decrease at rest in the testing group was statistically significant, each of the decreases in resting, during, and post-exercise heart rates were too small to be accurately monitored by palpation over a 10- or 15-sec count, a usual procedure in exercise rehabilitation programs. Provided the patients are correctly instructed and technique regularly checked, there appears to be no reason why carotid palpation should not be used in cardiac exercise rehabilitation programs to determine resting, exercise, or post-exercise heart rates.

Runners and other active individuals typically have plasma lipoprotein patterns different than their more sedentary peers. In an attempt to determine if these patterns could be explained by dietary differences, we studied nutrient intake in middle-aged (35-59 yr) men and women runners averaging 55-65 km/wk, and inactive controls. The runners were leaner (P less than or equal to 0.0001) and had higher caloric intakes (40-60% higher on a weight-adjusted basis); they also ate more fat and carbohydrate (P less than or equal to 0.01), and were more likely to consume alcoholic beverages. When nutrient intake was expressed as a percent of total calories, the runners ate less protein (P less than or equal to 0.001). The runners obtained a smaller percentage of calories from starch and a greater percentage from other carbohydrates. Differences in nutrient intake seemed unlikely to account for observed differences in plasma lipids and lipoproteins between the runners and controls.

Cardiorespiratory characteristics, relative body fat, grip strength and selected skinfolds, circumferences and bone diameters were determined in 25 males and 25 females (31--55 yr) whose exclusive mode of regular exercise was tennis (9.7--11.1 hr/wk). Mean resting heart rates were 54 beats/min for the males and 61 beats/min for the females. Mean resting blood pressures were 117/75 and 107/68 mmHg for the males and females, respectively. Compared to normally active populations of the same age and sex, the tennis players displayed an above average maximal oxygen uptake (mean values equal 50.2 ml/kg.min-1 for the males and 44.2 ml/kg.min-1 for the females), below average relative body fat (mean values equal 19.3% and 20.3% for the males and females, respectively), greater dominant grip strengths, and similar non-dominant grip strengths. The results indicate that either physically superior individuals choose to play tennis, or that regular tennis participation produces above average levels of fitness, or both.