Successful recruitment strategies for school-based health promotion: experiences from CATCH.

School-based research designs in the 1990s often require that a large number of schools be recruited to participate in studies. Therefore, effective recruitment and maintenance of schools becomes an important activity for ensuring the integrity of the study design. The Child and Adolescent Trial for Cardiovascular Health (CATCH) is the largest school-based health promotion research project yet undertaken; 96 schools (24 per field site) were successfully recruited and retained for this cardiovascular disease risk reduction project. This article describes general recruitment strategies used at the four CATCH sites, a description of how Social Learning Theory guided these activities, a discussion of logistical considerations, and recommended recruitment strategies for future school-based research.

CATCH: process evaluation of environmental factors and programs.

The Child and Adolescent Trial for Cardiovascular Health (CATCH) is a multicenter trial designed to test the effectiveness of school and family-based cardiovascular health promotion for preadolescents. CATCH interventions target multiple cardiovascular health behaviors such as dietary intake of fat and sodium, physical activity, and tobacco use. Evaluation includes physiological, psychosocial, behavioral, and process measures. An important aspect of the process evaluation is the assessment of environmental factors and "secular events" in both intervention and control schools that may affect outcomes independently of the CATCH interventions. With such information, CATCH investigators are able to isolate the impact of the CATCH intervention from competing (non-CATCH) factors as well as "track" proximal (i.e., immediate and short term) changes related to the intervention that may in turn lead to "distal" (long-term) behavior change. The School Health Questionnaire, the major process evaluation tool for monitoring secular and environmental changes in the schools, is described in detail, and data describing tobacco-related environmental factors and secular events are presented.

CATCH: challenges of conducting process evaluation in a multicenter trial.

This paper discusses the challenges faced when collecting process evaluation information in a school-based, multicenter field trial. Experiences from the Child and Adolescent Trial for Cardiovascular Health (CATCH) are shared as a means of illustrating the challenges that are presented and ways of meeting the challenges. The scope and magnitude of the trial (96 schools across four sites) and the diverse population participating in the trial (including children and adults representing a cultural and socioeconomic mix) present challenges that are compounded by conducting research in a highly structured school setting. In such a trial, thoughtful consideration must be paid to what data should be collected, how data should be collected, how to collect data on tailored interventions, gaining and maintaining schools' cooperation, collecting data in year-round schools, and assuring data quality.

Effects of propranolol and pindolol on cardiac output during extended periods of low-intensity physical activity.

The effects of a nonselective beta-adrenergic blocking agent with (pindolol) and without (propranolol) intrinsic sympathomimetic activity properties, compared with placebo-controlled conditions, on metabolic and cardiorespiratory function during long-duration (2 hours) physical activity were examined. After initial cardiorespiratory testing, subjects performed 2-hour walks at 25 and 45% of maximal oxygen consumption (VO2max) under each of the following 3 treatments: pindolol, propranolol and placebo. Medication distribution was randomized and double-blinded. A supine resting blood pressure and electrocardiogram were obtained before each exercise trial. Oxygen consumption, heart rate, stroke volume, cardiac output and blood pressure were determined after 5 minutes of quiet sitting and every 30 minutes during each 2-hour exercise trial. Cardiac output was not significantly different at rest or during exercise, comparing pindolol and propranolol with placebo conditions. Cardiac output tended to decrease over time earlier during propranolol treatment for the 25% VO2max trials in trained normotensive subjects than for the other treatments. Cardiac output decreased at approximately the same time across treatments during the 45% VO2max trials in trained normotensive and untrained hypertensive groups. Finally, owing to the observation that a reduction in cardiac output was delayed or prevented in trained normotensive subjects when compared with that in untrained hypertensives while exercising at 25% VO2max, developing a subject's cardiovascular fitness level may be important in the maintenance of cardiac output during extended periods of low-to-moderate physical activities while under the influence of beta-adrenergic blockade.

Is there energy conservation in amenorrheic compared with eumenorrheic distance runners?

The female distance runner is considered at high risk for secondary amenorrhea and reduced spinal bone mineral, and recent studies have suggested that these disturbances might be nutritionally or metabolically linked. The present study investigated 1) whether there is a physiological basis by which the amenorrheic runner might maintain weight at a lower than expected caloric intake, i.e., conservation of energy, and 2) the potential interactions of reduced energy intake, secondary amenorrhea, and reductions in bone density. Subjects included 13 elite female distance runners, 8 amenorrheic and 5 eumenorrheic, and 5 untrained female controls. Body composition by hydrostatic weighing, bone density and mineral content by dual-photon absorptiometry, and blood samples for hormonal analyses (once per week for 4 wk) were obtained, as were duplicate measures for resting metabolic rate, thermic effect of a meal, and the energy cost of specific (treadmill) and nonspecific (cycle ergometer) physical activity. Energy intake and energy expenditure were estimated by 3-day logs. Energy intakes did not differ (1,781, 1,690, and 1,763 kcal), nor did energy expenditures (2,480, 2,314, and 2,268 kcal), for the amenorrheic and eumenorrheic runner and control groups, respectively. The difference between reported energy intake and estimated energy expenditure of 500-700 kcal was likely due to underreporting or restricting intake, inasmuch as there was no evidence of energy conservation. A possible link was suggested between disordered eating, secondary amenorrhea, and bone mineral loss.

Stroke volume during submaximal exercise in endurance-trained normotensive subjects and in untrained hypertensive subjects with beta blockade (propranolol and pindolol).

The effect of beta-adrenergic blockade on stroke volume (SV) at increasing submaximal exercise intensities was studied in 12 endurance-trained normotensive and 12 untrained hypertensive (diastolic blood pressure greater than 95 mm Hg) men, aged 18 to 34 years. Subjects were assigned to each of 3 treatments in a double-blind, randomized order: placebo, propranolol (80 mg twice daily) and pindolol (10 mg twice daily) for 10 days, with a period of 48 to 60 hours from the initial dose to the first treadmill test and a 4-day washout period between drugs. Cardiac output was measured using the carbon dioxide rebreathing method and SV was calculated from cardiac output and heart rate as follows: SV = cardiac output/heart rate. Cardiac outputs were estimated at rest and while walking on a treadmill at 25, 45, 60 and 75% of the subject's previously determined maximal oxygen uptake (VO2max). No significant differences were found in cardiac output between either of the drugs and placebo at rest, or at any of the 4 rates of work. Propranolol significantly increased SV above placebo values (p less than 0.05) for both trained and untrained groups at the intensities of 45, 60 and 75%. Significant differences in SV were found between pindolol and placebo only at the intensities of 60 and 75% in the trained group. Contrary to expectations, SV showed no indication of a plateau with propranolol in the trained subjects throughout the 4 different exercise intensities, whereas a plateau was established under placebo conditions by 45% of VO2max in both trained and untrained subjects. These results suggest that both trained and untrained hypertensive persons can exercise with beta-adrenergic blockade at submaximal levels without compromised cardiac function.

Changes in plasma free fatty acids and glycerols during prolonged exercise in trained and hypertensive persons taking propranolol and pindolol.

The extent to which lipolysis is attenuated during prolonged submaximal exercise during beta blockade was determined in 12 normotensive endurance-trained and 12 hypertensive sedentary men using nonselective drugs with and without intrinsic sympathomimetic activity (ISA). Initially, subjects performed a graded treadmill test to determine maximal oxygen uptake (VO2max). This was followed by 2-hour walks at 25 and 45% of the subject's VO2max under each of 3 treatments: pindolol (ISA), propranolol (non-ISA) and placebo. The distribution of medication was randomized and double blinded. Blood samples taken at rest and every 30 minutes during the 2-hour walks were analyzed to determine the concentrations of free fatty acids (FFA) and glycerol. On the basis of the respective changes in FFA, glycerols and the respiratory exchange ratio, beta-adrenergic blockade did not attenuate lipolysis in the untrained hypertensive subjects when compared with the placebo administration. However, beta blockade did demonstrate a tendency to attenuate lipolysis in the trained, normotensive subjects when compared with results after placebo administration. This was particularly evident at 30 minutes of exercise, when both glycerol and FFA concentrations were not increased above resting values under both conditions of beta blockade. No differences between pindolol and propranolol were observed. Therefore, a beta-blocking agent with ISA properties appears to have no clear benefit with respect to lipid metabolism during low and moderate intensity exercise. Furthermore, these data demonstrate that beta blockade does not inhibit exercise-induced lipolysis at low and moderate intensities of exercise as formerly believed, and is unlikely to be the cause of fatigue normally observed during work in patient populations taking beta-blocking medication.

Comparison of the effects of pindolol and propranolol on exercise performance in young men with systemic hypertension.

To determine the effect of intrinsic sympathomimetic activity (ISA) on exercise performance during beta blockade, 12 hypertensive men were studied. The subjects underwent graded treadmill testing while taking pindolol (a beta blocker with ISA), propranolol (a beta blocker without ISA) and placebo, in a double-blind, crossover fashion. Blood pressure, heart rate, oxygen consumption (VO2), cardiac output and stroke volume were determined at 25, 45, 60 and 75% of each subject's VO2 max. Heart rate was significantly lower with pindolol compared with placebo at all stages of exercise, but significantly higher compared with propranolol at all stages of exercise except at 75% of VO2 max and at VO2 max (no significant differences between the 2 beta blockers were recorded at these stages). Mean arterial pressure was statistically equivalent with pindolol and propranolol at all stages of exercise and significantly lower while beta-blocked compared with placebo conditions at 45, 60 and 75% of VO2 max. Cardiac output and VO2 were statistically equivalent across all 3 treatments at all submaximal levels of exercise. It was concluded that, although heart rate was significantly higher with pindolol compared with propranolol at the 3 lower rates of work, cardiac output and VO2 were not different between the drugs, thus making little impact on exercise performance.