Gender and ethnic differences in health behaviors and risk factors for coronary disease among urban teenagers: the PATH program.

OBJECTIVE: To assess gender and ethnic differences among teenagers in heart health behaviors, risk factors for coronary heart disease (CHD), and cardiovascular fitness. DESIGN: Observations consist of cross-sectional data collected prior to a school-based health promotion intervention program. PARTICIPANTS: Teenage girls (N = 865) and boys (N = 497) from three New York City high schools. The ethnic composition of this sample was 20% Asian-American, 40% African-American, 25% Hispanic, and 15% white. METHOD: Subjects were compared on the following: height, weight, body mass index, percentage body fat, total cholesterol, blood pressure, heart health knowledge, family history, socioeconomic status, dietary habits, smoking, physical activity, and estimated aerobic capacity. Differences were assessed with independent t tests, analysis of variance, and chi-square statistical techniques. RESULTS: Compared with girls, boys were more active and had higher estimated aerobic capacity, higher systolic blood pressure, and better self-perception of health. Compared with boys, girls had higher cholesterol, percentage body fat, and heart health knowledge scores and ate fewer foods high in saturated fat, cholesterol, salt, and simple sugars. Among girls, African-Americans had the highest blood pressure, cholesterol, body mass index, and intake of foods high in saturated fat, cholesterol, and sugar. Among boys, Hispanics had the highest body mass index and percentage body fat and the lowest heart health knowledge scores. White girls and white boys were the most frequent smokers. CONCLUSIONS: Poor health behaviors and risk factors for CHD occurred frequently among urban teenagers. In general, teenage girls had poorer health behaviors and a greater prevalence of risk factors than teenage boys, even though they scored better in heart health knowledge testing. Ethnic comparisons revealed poorer health behaviors and higher prevalence of risk factors in African-American and Hispanic teens compared with white and Asian-American teens. Results support the need for health promotion intervention among urban teenagers.

Coronary disease risk factor reduction and behavior modification in minority adolescents: the PATH program.

PURPOSE: To evaluate the impact of a unique school-based program of exercise, health education, and behavior modification on health knowledge, health behaviors, coronary risk factors, and cardiovascular fitness in minority adolescents. METHODS: A total of 346 students from an inner-city public high school participated in health promotion intervention or regular physical education volleyball classes. Subjects were African-American (47%), Asian-American (9%), Hispanic (21%), white (3%), and other (19%). The health promotion curriculum consisted of 11 weeks of daily circuit training exercise and health lecture-discussions. RESULTS: The groups were similar in age, height, weight, ethnicity, and socioeconomic status. Following intervention both boys (P < .001) and girls (P < .006) significantly improved health knowledge test scores. Significant benefits for girls included improved dietary habits (P < .05), reduced cholesterol (P < .004), and higher estimated V(O2)max (P < .0001). There were no other significant changes in boys. CONCLUSIONS: The results suggest that a school-based health promotion program of exercise and health lecture-discussion is beneficial for multiethnic, inner-city adolescents, especially females.

Health promotion in minority adolescents: a Healthy People 2000 pilot study.

PURPOSE: The purpose was to evaluate the effects of a health promotion curriculum on health knowledge, behavior, cardiovascular fitness, and cardiovascular risk factors. METHODS: A multi-ethnic, multi-cultural sample (n = 54) of 10th grade males and females participated in a study of cardiovascular health promotion and coronary risk factor reduction. The sample was comprised of Asian-Americans (39%), blacks (33%), Hispanics (11%), whites (2%), and others (15%). Intervention consisted of a 10-week health promotion curriculum of classroom education modules in physical activity, nutrition, smoking cessation, stress management and personal problem solving, and an exercise program of walking and running. A nonintervention control group served as a basis for comparison. Classroom and exercise sessions met on alternate days. RESULTS: Following intervention, a significant treatment effect (P = .007) was observed in lowered total cholesterol, and significant within group improvements (P < .01) were observed in diet habits, percent body fat, and cardiovascular health knowledge. Comparisons of knowledge and social effects revealed higher cardiovascular health knowledge (P < .05) in subjects of nonsmoking compared to smoking parents, higher self-perception of health (P < .01) in more active vs less active subjects and better dietary habits (P < .07) in children whose parents were college educated compared to parents who did not attend college. CONCLUSIONS: Preliminary findings suggest that a health promotion curriculum consisting of health education, behavior modification, and regular aerobic exercise lowers cholesterol, improves health behavior and increases health knowledge.

Thermal responses of men and women during cold-water immersion: influence of exercise intensity.

The influence of exercise intensity on thermoregulation was studied in 8 men and 8 women volunteers during three levels of arm-leg exercise (level I: 700 ml oxygen (O2).min-1; level II: 1250 ml O2.min-1; level III: 1700 ml O2.min-1) for 1 h in water at 20 and 28 degrees C (Tw). For the men in Tw 28 degrees C the rectal temperature (Tre) fell 0.79 degree C (P less than 0.05) during immersion in both rest and level-I exercise. With level-II exercise a drop in Tre of 0.54 degree C (P less than 0.05) was noted, while at level-III exercise Tre did not change from the pre-immersion value. At Tw of 20 degrees C, Tre fell throughout immersion with no significant difference in final Tre observed between rest and any exercise level. For the women at rest at Tw 28 degrees C, Tre fell 0.80 degree C (P less than 0.05) below the pre-immersion value. With the two more intense levels of exercise Tre did not decrease during immersion. In Tw 20 degrees C, the women maintained higher Tre (P less than 0.05) during level-II and level-III exercise compared to rest and exercise at level I. The Tre responses were related to changes in tissue insulation (I(t)) between rest and exercise with the largest reductions in I(t) noted between rest and level-I exercise across Tw and gender. For mean and women of similar percentage body fat, decreases in Tre were greater for the women at rest and level-I exercise in Tw 20 degrees C (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Thermal adjustment to cold-water exposure in resting men and women.

Thermoregulatory responses were studied in 10 men and 8 women at rest in air and during 1-h immersion in water at 20, 24, and 28 degrees C. For men of high body fat (27.6%), rectal temperature (Tre) and oxygen consumption (VO2) were maintained at air values at all water temperatures (Tw). For men of average (16.8%) and low (9.2%) fat the change in Tre (delta Tre) was inversely related to body fat at all Tw with VO2 increasing to 1.07 l X min-1 for a -1.6 degrees C delta Tre for lean men. For women of average (25.2%) and low (18.5%) fat Tre decreased steadily during immersion at all Tw. The greatest changes occurred at 20 degrees C with little differences in delta Tre and VO2 noted between these groups of women. In comparison with males of similar percent fat, Tre dropped to a greater extent (P less than 0.05) in females at 20 and 24 degrees C. Stated somewhat differently, lean women with twice the percentage of fat have similar delta Tre as lean men at all Tw. For delta Tre greater than -1.0 degree C men showed significantly greater (P less than 0.05) thermogenesis compared with women. The differences in thermoregulation between men and women during cold stress at rest may be due partly to the sensitivity of the thermogenic response as well as the significant differences in lean body weight and surface area-to-mass ratio between the sexes.

Thermal adjustment to cold-water exposure in exercising men and women.

Thermoregulatory responses were studied in 10 men and 8 women during 36-W exercise for 1 h in air and water at 20, 24, and 28 degrees C. Men were classified as high (27.6%; n = 2), average (16.8%; n = 4), and low (9.2%; n = 4) percent body fat, whereas women were classified as average (25.2%; n = 4) and low (18.5%; n = 4) fat. For both men and women, exercise of about 1.7 l O2 X min-1 was beneficial in either preventing or retarding the fall in rectal temperature (Tre) observed in a previous study for the same subjects at rest. The greatest thermal strain was noted for the leanest subjects. However, in no instance did exercise facilitate a drop in Tre compared with resting conditions. Despite a larger surface area-to-mass ratio (P less than 0.05) and less effective thermoregulation for women at rest compared with men, essentially similar thermoregulatory responses were observed for both sexes during exercise at each water temperature. For both the men and women, the thermoregulatory benefits of exercise were due largely to the added heat production from physical activity. For the female, an additional benefit of exercise may in part be derived from a more favorable distribution of subcutaneous fat over the active musculature.

Metabolic and cardiovascular adjustment to arm training.

Maximal and submaximal metabolic and cardiovascular measures and work capacity were studied in control (n = 7) and experimental (n = 9) subjects (S's) during arm work prior to and following 10 wk of interval arm training. These measures were oxygen uptake (VO2), minute ventilation (VE), heart rate (HR), respiratory exchange ratio (R), cardiac output (Q), stroke volume (SV), and arteriovenous oxygen difference ((a--v)O2 diff). In addition, maximal oxygen uptake (VO2max) was measured in both groups during treadmill running. Experimental S's showed significant increases (P less than 0.01) in peak VO2 (438 ml.min-1), max VE (17.7 l.min-1), max (a--v)O2 diff (20.8 ml.l-1), and work time (9.2 min) during arm ergometry, while maximum values of Q, SV, HR, and R remained unchanged. In addition, submaximal heart rates were significantly lower during arm ergometry after training. VO2max during treadmill running remained essentially unchanged. No changes in metabolic and physiological measures were noted for the controls after the 10-wk training period. The results support the concept of training specificity for VO2max, and indicate that the improvement in peak VO2 in arm ergometry reflects enhanced oxygen utilization due to an expanded (a--v)O2 diff.

Metabolic and cardiovascular adjustment to work in air and water at 18, 25, and 33 degrees C.

By use of successive increments of discontinuous work with an arm-leg cycle ergometer the VO2, Q, SV, and HR were studied in six male subjects at rest and during exercise in air and in water at 18, 25, and 33 degrees C. The Q values obtained by CO2 rebreathing were reproducible. VO2 was linearly related to work with the plots for air and 33 degrees C water being similar. However, during work in 25 and 18 degrees C water, the VO2 averaged 9.0% (150 ml) and 25.3% (400 ml) higher, respectively, than values observed in 33 degrees C water, with the largest differences observed in leaner subjects. The plot of HR-VO2 was linear and almost identical during work in air and 33 degrees C water, but shifted significantly to the right in cooler water. VO2 averaged 250-700 ml higher in cold water compared to air and 33 degrees C water at a given mean heart rate. The Q vs. VO2 line was similar during work in air and in water with no effect of water or temperature. At similar levels of VO2, SV was significantly larger (P less than 0.05) in 25 and 18 degrees C water than in air or 33 degrees C water. Consequently, the reduction in heart rate during work in cold water was entirely compensated for by a proportionate increase in the SV of the heart. Q was therefore maintained at similar levels of energy expenditure in air and in 18, 25, and 30 degrees C water.

Specificity of swim training on maximum oxygen uptake.

The present study was designed to evaluate the specificity-generality of the cardiorespiratory adaptation to swim training. Fifteen male, college age, recreational swimmers utilized interval swim training procedures 1 h/day, 3 days/wk for 10 wk. Maximum physiological measures (Vo2, Ve, HR, R, and work time) were determined prior to and following swim training during treadmill running and tethered swimming Vo2max tests. Identical measures were made on 15 control subjects who did not participate in any form of training. As a result of training, the experimental subjects significantly increased (all P is less than 0.01) their swimming Vo2max (380 ml/min) max Ve (14.9 l/min,btps) and max swim time (4.0 min), and significantly decreased (P is less than 0.05) their max HR (3.5 beats/min). However, there was no significant improvement in Vo2max when the same subjects were evaluated by the treadmill running test. Differences in Vo2max and associated measures during running and swimming tests remained essentially unchanged for control subjects. The results of the present study clearly demonstrate the specificity of the cardiorespiratory adaptation to swim training in male recreational swimmers.