Effects of physical activity on exercise tests and respiratory function.

BACKGROUND: Exercise is an important component of pulmonary rehabilitation for patients with chronic lung disease. OBJECTIVE: To explore the role of physical activity in maintaining cardiac and respiratory function in healthy people. METHODS: Cardiorespiratory fitness was measured by a maximal treadmill test (MTT), and respiratory function was tested by spirometry. The cross sectional study included data from 24 536 healthy persons who were examined at the Cooper Clinic between 1971 and 1995; the longitudinal study included data from 5707 healthy persons who had an initial visit between 1971 and 1995 and a subsequent visit during the next five years. All participants were aged 25-55 years and completed a cardiorespiratory test and a medical questionnaire. RESULTS: In the cross sectional study, after controlling for covariates, being active and not being a recent smoker were associated with better cardiorespiratory fitness and respiratory function in both men and women. In the follow up study, persons who remained or became active had better MTT than persons who remained or became sedentary. Men who remained active had higher forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC) than the other groups. Smoking was related to lower cardiorespiratory fitness and respiratory function. CONCLUSIONS: Physical activity and non-smoking or smoking cessation is associated with maintenance of cardiorespiratory fitness. Change in physical activity habits is associated with change in cardiorespiratory fitness, but respiratory function contributed little to this association during a five year follow up.

Factors influencing intent to get pregnant in HIV-infected women living in the southern USA.

This descriptive study sought to identify factors that influence HIV-infected women's intent to get pregnant. Interviews were conducted with a convenience sample of n = 322 HIV-infected women at risk for pregnancy. Participants were predominantly African-American (84.4%), single (57.9%), and ranged in age from 17 to 48 years. Forty per cent (n = 128) of the women had been pregnant since becoming HIV-positive. Potential factors influencing intent to get pregnant that were examined included demographic characteristics, HIV-related factors and personal beliefs and attitudes. In simple logistic regression models, younger age, increased motivation for child bearing, decreased perceived threat of HIV, decreased HIV symptomatology, higher traditional gender role orientation, and greater avoidance coping were all associated with greater intent to get pregnant. Following a model selection procedure, motivation for child bearing (OR = 16.05, 95% CI 7.95, 30.41) and traditional sex roles (OR = 4.49, 95% CI 1.44, 13.55) were significantly associated with greater intent to get pregnant. Traditional gender role orientation and motivation for childbearing are significant factors in predicting intent to get pregnant among HIV-infected women. These factors, as well as other non HIV-related factors, need to be routinely assessed by health care providers in developing plans of care for HIV-infected women.

Omission of active commuting to school and the prevalence of children's health-related physical activity levels: the Russian Longitudinal Monitoring Study.

BACKGROUND: Active commuting to school by walking or bicycle is a potential source of continuous moderate activity for children that has been largely ignored in surveys of physical activity. The purpose of this study was to evaluate the analytical impact of omitting active commuting to school (walking or bicycling) on conclusions about children's physical activity levels. METHODS: The Russian Longitudinal Monitoring Study (RLMS) is the first nationally representative household survey in the Russian Federation. More than 6400 households from all regions of Russia were surveyed eight times between 1992 and 1998. Analysis was conducted using physical activity data (school physical education classes, out-of-school active pursuits and active commuting to school) obtained by parent-proxy on 1094 (572 boys, 522 girls) school-aged Russian children (mean age 10.2 +/- 1.9 years) participating in the November 1998 round of the RLMS. Data were examined according to prevalence of achievement of health-related physical activity guidelines, active commuting to school behaviours included then omitted. RESULTS: Omitting active commuting to school resulted in a statistically significant decrease in the prevalence of achievement of health-related guidelines from 12% to 20%, similar for both genders. Likewise, the prevalence of sedentarism (defined as not meeting any of the guidelines) was increased by 17-22%. CONCLUSIONS: The present findings suggest that, in order to avoid misclassification bias of children's physical activity levels, it is necessary to include questions about mode of commuting to school. The findings also carry practice implications: the commonplace need to get to and from school may be a missed opportunity for children's health-related physical activity in motorized societies.

The relationship between pedometer-determined ambulatory activity and body composition variables.

OBJECTIVE: To examine the relationship between pedometer-determined ambulatory activity (steps/day) and body composition variables body mass index (BMI) and percentage body fat). DESIGN: : Secondary analysis of a cross-sectional objective activity monitoring study for up to 21 consecutive days. SUBJECTS: A total of 109 apparently healthy adults (eight African American males, 23 African-American females, 33 Caucasian males, 45 Caucasian females), age 44.9+/-15.8 y, BMI=26.9+/-5.1 kg/m2. MEASUREMENTS: Pedometer-assessed ambulatory activity (steps/day), height and weight, and percentage body fat by bioelectrical impedance. RESULTS: Analyzed as both a continuous and a categorical variable (determined using 25th and 75th percentiles for distribution for steps/day), ambulatory activity was consistently related to body composition variables. Steps/day was inversely correlated with BMI and percentage body fat (r=-0.30, and r=-0.27, respectively, both P<0.01). The consistency of the relationship was also evident when examined using accepted BMI cut-off points for normal-weight, overweight, and obese categories. CONCLUSIONS: Individuals in this small sample with values greater than approximately 9000 steps/day are more frequently classified as normal weight for height. Individuals with values less than approximately 5000 steps/day are more frequently classified as obese. These findings require further corroborative investigation but provide preliminary cutoff points for identifying individuals at risk who may benefit from appropriate physical activity intervention.

Prevalence of attention-deficit/hyperactivity disorder in a community sample of older adolescents.

OBJECTIVE: To study the prevalence and correlates of attention-deficit/hyperactivity disorder (ADHD) in a community sample of older adolescents. METHOD: From 1986 to 1988, 3,419 seventh, eighth, and ninth graders were screened with the Center for Epidemiologic Studies-Depression Scale. The top decile scorers and a random sample of the remainder were interviewed with the Schedule for Affective Disorders and Schizophrenia for School-Age Children. These data are from the second wave of interviews (N = 490, mean age = 18.65). RESULTS: The weighted prevalence of DSM-III-R ADHD was 1.51% (males: 2.62%, females: 0.54%). Significant associations (p < .05) were found for gender (male), comorbid affective disorders, baseline undesirable life events, and fewer than two biological parents at baseline. Family cohesion (p = .058) is inversely associated with ADHD. For subjects not meeting the age-at-onset criterion, 1.94% met the eight symptom criteria, and females (3.2%) were more prevalent than males (0.3%). CONCLUSIONS: ADHD remains a problem in this sample of older adolescents and is often comorbid with affective disorders. A significant number report eight ADHD symptoms but do not meet the age-at-onset criterion. This group deserves research attention.

Racial/ethnic health disparities in South Carolina and the role of rural locality and educational attainment.

BACKGROUND: The prevalence of selected health indicators were compared among the Catawba Indians, African Americans, and whites in South Carolina, considering the possible role of rural locality and education. METHODS: Catawba members were respondents of a 1998 survey (N = 808). Other South Carolina residents were respondents of the 1995-1997 Behavioral Risk Factor Survey (4,150 whites and 1,413 African Americans). Prevalence of cardiovascular disease, diabetes, hypertension, overweight, poor health, smoking, physical inactivity, and poor diet were compared among the racial/ethnic groups. Logistic regression analyses were conducted within strata of urban/rural locality and education to determine whether these factors were associated with the adverse health indicators. RESULTS: Both Catawba and African Americans had higher prevalence of diabetes, hypertension, overweight, poor health, physical inactivity, and poor diet than whites. In addition, prevalence of diabetes, poor health, smoking, and poor diet were higher among the Catawba than among African Americans. Restricting the analyses to comparisons within urban/rural locality had little effect, whereas restricting the analyses to comparisons by education level eliminated many of the disparities among those with low education. CONCLUSIONS: Prevalence of chronic disease and adverse health behavior are higher among the Catawba than among other residents of South Carolina, especially compared with white residents.

Association among physical activity level, cardiorespiratory fitness, and risk of musculoskeletal injury.

To help public health practitioners promote physical activities with a low risk of injury, this study determined the relation among type and duration of physical activity, cardiorespiratory fitness, and musculoskeletal injury in a sample of adults enrolled in the Aerobics Center Longitudinal Study. Subjects included 4,034 men and 967 women who underwent a baseline physical examination between 1970 and 1985 and who returned a mailed follow-up survey in 1986. At baseline, a treadmill graded exercise test was used to measure cardiorespiratory fitness. At follow-up, subjects reported injuries and type and duration of physical activity in the preceding 12 months. Polytomous logistic regression was used to estimate the association among physical activity type and duration, cardiorespiratory fitness, and injury. The risk of sustaining an activity-related injury increased with higher duration of physical activity per week and cardiorespiratory fitness levels. Results suggest that cardiorespiratory fitness may be a surrogate for unmeasured components of physical activity, such as exercise intensity. Among walkers, increasing duration of activity per week was not associated with an increased risk of injury. Results suggest that, for most adults, walking is a safe form of physical activity associated with a lower risk of injury than running or sport participation.

Behavioral and demographic correlates of diabetes, hypertension and overweight among the Catawba Indian Nation.

OBJECTIVE: In 1998, the Catawba Diabetes and Health Survey (CDHS) was conducted among adult members of the Catawba Indian Nation living in the Carolinas to determine the prevalence of diabetes and other health conditions, and to assess the population's health-related behaviors. DESIGN: A population-based sample of adult members of the Catawba Indian Nation (N = 633) were surveyed by telephone or in person regarding health status and health-related behaviors. Logistic regression was used to determine demographic and behavioral correlates of diabetes, hypertension, and overweight among the Catawba. RESULTS: Age-adjusted prevalence rates of self-reported diabetes, hypertension and overweight were 12.3%, 29.1%, and 63.8%, respectively. Older age was related to diabetes, hypertension, and overweight (P<.0001 each), and heavier weight status was related to diabetes (P = .026) and hypertension (P<.0001). Nearly 40% of the Catawba are physically inactive (29.5% men, 46.5% women). Physical inactivity was related to diabetes and hypertension among men only, and related to overweight among women only (P<.05 each). Current smoking was inversely related to overweight among men and women (P = .002). Dietary behavior was not associated with the health outcomes. CONCLUSION: Given the high rates of overweight and physical inactivity, reducing the rates of both may be very important for the health of the Catawba, considering their association with diabetes and hypertension.

Environmental influences, physical activity, and weight status in 8- to 16-year-olds.

OBJECTIVE: To assess the association between vigorous physical activity, participation on sport teams and in exercise programs, television watching, family environment, and weight status in youth. DESIGN: Cross-sectional data from the Third National Health and Nutrition Examination Survey. PARTICIPANTS: A group of 2791 youth between the ages of 8 and 16 years who were enrolled in the Third National Health and Nutrition Examination Survey. MAIN OUTCOME MEASURES: Overweight was defined using age- and sex-specific 85th percentile of body mass index using Center for Disease Control and Prevention growth charts. RESULTS: Both males and females who had an overweight mother and or father were more likely to be overweight compared with youth who did not have an overweight parent. Females who watched 4 or more hours of television were more likely to be overweight than those who watched less than 4 hours. Males and 14- to 16-year-old females who participated in sport team and exercise programs were less likely to be overweight than their counterparts who did not participate. Also, females with larger families and males from families with higher family incomes were less likely to be overweight. CONCLUSIONS: These results suggest that family environment is associated with overweight in youth and that sport and exercise program participants are less like to be overweight and that, for females, increased television watching is related to overweight.

Insulin resistance precedes weight loss in adults without diabetes : the Rancho Bernardo Study.

Insulin resistance is closely associated with both aging and overweight; yet in old age, weight loss is common, although insulin resistance increases. To study this paradox, the authors evaluated the role of insulin resistance in weight change among older adults from the Rancho Bernardo Study cohort. Participants were 725 nondiabetic men and women who were aged 50-89 years when weight and insulin were measured at baseline (1984-1987). The participants were evaluated again in 1992-1996, at which time weight was remeasured. Fasting insulin and homeostasis model assessment (HOMA) measurements were evaluated in separate but parallel statistical models as surrogates for insulin resistance. Insulin resistance, when defined as the top quartile of fasting insulin level or HOMA value, was significantly associated with weight loss before and after adjustment for baseline weight and age (fasting insulin: beta = -1.30 kg, p = 0.01; HOMA: beta = -1.18 kg, p = 0.01). Results were the same for men versus women, for the overweight (body mass index (weight (kg)/height (m)(2)) > 26.6) [corrected] versus the normal weight (body mass index < or = 26.6) [corrected], and for younger persons (age <70 years) versus older persons (age > or = 70 years). Insulin-resistant individuals had a threefold increased likelihood of losing 10 or more kg compared with those without insulin resistance. The authors conclude that hyperinsulinemia, independently of age and baseline weight, may have a catabolic effect in the elderly.

A longitudinal study of adolescent mental health service use.

This study examines longitudinal mental health service use patterns of a school-based sample of adolescents. Based on the Center for Epidemiologic Studies Depression Scale scores, a stratified sample of middle-school students was interviewed using the Schedule for Affective Disorders and Schizophrenia for School-Aged Children: cycle one (n = 579; mean age 12.83) and cycle two (n = 490; mean age 18.65). Service use also was assessed by mailed questionnaire: cycle three (n = 330; mean age 20.60). Service use decreased over time. Whites and males received significantly more treatment in the first cycle. In the second cycle, service use by race and gender was equal; in the third cycle, females received more treatment. Those with a psychiatric diagnosis (first cycle, 54%; second cycle, 33%) received treatment in the prior year. Under-treatment of youth with psychiatric diagnoses is a significant problem, with differences in service use by race and gender over time.

Physical activity, physical fitness, and Framingham 10-year risk score: the cross-cultural activity participation study.

PURPOSE: Although physical activity and physical fitness are inversely and causally associated with coronary heart disease (CHD) morbidity and mortality, available equations for estimating CHD risk do not include scores for activity or fitness. Therefore, this study evaluated the association of physical fitness and moderate-intensity physical activity with the 10-year Framingham CHD risk estimate. METHODS: Cross-sectional analyses were performed on data from 137 healthy middle-aged women (53.9 +/- 9.9 yr; 28.3 +/- 6.0 kg/m2). Health histories, body composition, blood pressure, and blood samples were obtained from a clinical examination. Levels of moderate (3-6 METS) intensity physical activity, expressed as MET-minutes/day of energy expenditure, were derived from multiple 24-hour physical activity records. Physical fitness was quantified as duration of a symptom-limited maximal treadmill exercise test. RESULTS: After adjustment for race, body mass index (BMI), and hormone replacement status, a graded reduction in the Framingham risk score was observed across low (5.8%), moderate (4.0%), and high (3.6%) fitness levels (P for trend = 0.009). Women in both the moderate and high fitness categories had a lower (P < 0.01) risk score compared with their low fit counterparts. Significant differences in risk were not seen among low (3.9%), moderate (4.9%), and high (4.4%) physical activity groups. The lack of association between the risk score by physical activity may have been due to the homogeneity of activity levels among participants. Our findings reinforce existing data that show enhanced levels of fitness are associated with lower risk for CHD.

Moderate-intensity physical activity and fasting insulin levels in women: the Cross-Cultural Activity Participation Study.

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.

Association of very low birth weight with exposures to environmental sulfur dioxide and total suspended particulates.

This paper presents results of a population-based case-control study of the association between maternal exposures to environmental sulfur dioxide and total suspended particulates (TSP) and risk for having a very low birth weight (VLBW) baby, i.e., one weighing less than 1,500 g at birth. The study, which took place between April 1, 1986 and March 30, 1988, comprised 143 mothers of VLBW babies and 202 mothers of babies weighing 2,500 g or more living in Georgia Health Care District 9. Environmental exposure estimates (microg/m3) were obtained through environmental transport modeling that allowed us to assign environmental sulfur dioxide and TSP exposure estimates at the birth home of each study subject. Exposures less than or equal to 9.94 microg/m3, the median of TSP and sulfur dioxide exposures for the controls, were considered as referent exposures. Exposures to atmospheric TSP and sulfur dioxide above the 95th percentile (56.75 microg/m3) yielded an adjusted odds ratio of 2.88 (95% confidence interval (CI): 1.16, 7.13), that from above the 75th to the 95th percentile (25.18-56.75 microg/m3) yielded an adjusted odds ratio of 1.27 (95% CI: 0.68, 2.37), and that from above the median (9.94 microg/m3) to the 75th percentile, an adjusted odds ratio of 0.99 (95% CI: 0.51, 1.72). The trend demonstrated in these adjusted estimates suggests an association between VLBW and maternal exposures to high levels of air pollution.

Moderate physical activity patterns of minority women: the Cross-Cultural Activity Participation Study.

Using data from 12 days of detailed physical activity records (PA records), we analyzed the physical activity patterns of 141 African American and Native American women, ages 40 and older, enrolled in the Cross-Cultural Activity Participation Study. PA records were completed every other month for three consecutive 4-day periods. The proportion of women who met the 1993 Centers for Disease Control and Prevention and the American College of Sports Medicine recommendation to accumulate at least 30 minutes of moderate intensity activity during most days of the week (at least 3 days of the 4-day periods) ranged from 63% to 70%. Nearly one third of women met the recommendation for more than one 4-day period. On days when subjects accumulated at least 30 minutes of moderate activity, time spent in moderate activity was 112 minutes/day. Most women performed household chores (95%, median = 24 minutes/day), walking for exercise (87%, median = 30 minutes/day), occupational (65%, median = 37 minutes/day), child care (53%, median = 32 minutes/day), and lawn and garden activities (51%, median = 43 minutes/day). Fewer than 25% reported conditioning and sports activities. In general, more Native Americans than African Americans were active in moderate activities. In conclusion, definitions used to characterize regular physical activity should be consistent among studies, and physical activity surveys among women should include occupation-related and home-related activities.

Estimating environmental exposures to sulfur dioxide from multiple industrial sources for a case-control study.

This paper first discusses how population exposures to environmental pollutants are estimated from environmental monitoring data and the problems that are encountered in estimating risk from pollutants on the basis of ecologic studies. We then present a technique of estimating individualized exposures to an atmospheric pollutant, sulfur dioxide (SO2), through atmospheric transport modeling for a case-control study. The transport model uses the quantities of SO2 released from 30 geographically identified industrial facilities and meteorological data (wind speed and direction) to predict the downwind ground-level concentrations of SO2 at geographically identified residences, receptors, of 797 study subjects. A distribution of facility SO2 emissions, uncertainties in effective stack height, and model uncertainty are incorporated to examine the uncertainty in the predicted versus ambient monitoring SO2 levels, and to generate an exposure uncertainty distribution for both the cases and controls. The transport model's accuracy is evaluated by comparing recorded ambient measurements of SO2 with the model's predicted SO2 estimates at geographically identified ambient monitoring stations.

Incidence and predictors of suicidal behaviors in a longitudinal sample of young adolescents.

OBJECTIVE: This analysis examines 1-year transition probabilities and baseline predictors for suicidal behaviors in young adolescents. METHOD: Adolescents from a two-stage, community-based longitudinal study were classified into suicidal behavior categories (attempt, plan, ideation, and none) for baseline and follow-up years. Transition probabilities for movement among categories were calculated, and polytomous logistic regression analysis was used to examine predictors of suicidal behaviors. RESULTS: Among those with no suicidal behaviors at baseline, 1-year incidence rates were 1.3% for attempts and 1.7% each for plans and ideation. Increasing family cohesion was protective for suicide attempts (odds ratio [OR] = 0.9). Female subjects were more likely than males to report plans (OR = 8.9) and ideation (OR = 4.1). Increasing impulsivity (OR = 2.3), prior suicidal behavior (OR = 10.6), and undesirable life events (OR = 1.1) were significant predictors of plans. CONCLUSIONS: While there are a number of predictors of suicidal behaviors, the false-positive rate is high. Focusing on proximal risk factors, particularly stressors in adolescent development, may overlook the fundamental role of underlying mental disorder and familial factors--both biological and environmental. Suicide and suicidal behaviors are the result of a constellation of adverse factors requiring a range of interventions for prevention.

Prevalence of PTSD in a community sample of older adolescents.

OBJECTIVE: To examine prevalence and correlates of trauma and posttraumatic stress disorder (PTSD) symptoms and diagnosis in older adolescents aged 16 through 22 years. METHOD: The second cycle of a longitudinal epidemiological study in the Southeast included a semistructured interview assessing PTSD symptomatology administered to 490 adolescents. RESULTS: Approximately 3% of female subjects and 1% of male subjects satisfied the DSM-IV criteria for PTSD. Females reported more traumatic events than males, and black subjects reported more events than white subjects. Being female (odds ratio = 12.32), experiencing rape or child sexual abuse (odds ratio = 49.37), and witnessing an accident or medical emergency (odds ratio = 85.02) were associated with increased risk of PTSD. CONCLUSIONS: While relatively few adolescents satisfy the criteria for PTSD, most subjects who experienced a traumatic event reported some PTSD symptoms. Specific types of traumatic events were associated with occurrence of PTSD.