Barbara S. McClanahan

Validity and reliability of activity measures in African-American girls for GEMS.

PURPOSE To determine the reliability and validity of physical activity monitors and self-report instruments suitable for young African-American girls. METHODS A validation study was conducted by the Girls health Enrichment Multi-site Studies (GEMS) research team to compare an accelerometer with a pedometer and two self-report instruments for assessing physical activity in African-American girls, age 8-9 yr. Girls (N= 68) attended two clinic visits spaced 4 d apart. Each girl wore a MTI/CSA accelerometer (used as the criterion standard for validity) and a pedometer simultaneously for four consecutive days. Girls completed on two occasions a 24-h physical activity checklist of yesterday and usual activities, including sedentary activities (GEMS Activity Questionnaire, GAQ), and a 3-d computerized self-report instrument (Activitygram). RESULTS Girls were (mean +/- SD) 9.0 +/- 0.6 yr old and had a body mass index of 19.4 kg x m. Reliability measured by intraclass correlations (ICC) and Pearson correlation coefficients (r) were calculated for the MTI/CSA (ICC = 0.37, P< 0.0001), pedometer (ICC = 0.08, = 0.094), Activitygram (ICC = 0.24) (P = 0.005), and GAQ for physical (r = 0.80, P< 0.0001) and sedentary (r = 0.3-0.5, P< 0.005) activities. Significant Pearson correlations between the MTI/CSA and the other instruments, as a measure of validity, were observed for the 4-d average pedometer score (r = 0.47, P< 0.0001), 3-d average Activitygram score (r = 0.37, P= 0.002), and the average of the two yesterday and two usual GAQ activity scores for a subset of 18 physical activities questions (r = 0.27, = 0.03; and r = 0.29,P = 0.02, respectively). The MTI/CSA was uncorrelated with single day scores from the three other instruments. CONCLUSION The reliability of the instruments tested was acceptable, except the pedometer. Validity correlations were significant when more than one day was used. Self-report instruments need further development for improved reliability and validity.

Relationships among smoking status, ethnicity, socioeconomic indicators, and lifestyle variables in a biracial sample of women

BACKGROUND Smoking prevalence rates remain high among women and smoking initiation has increased for young adults. Little is known about the unique patterns of smoking, risk factors, and correlates of quitting in Black versus White women of child-bearing age. METHOD This study examined the relationships among smoking, ethnicity, socioeconomic status (SES), and lifestyle variables among 715 women (43.6% Blacks and 56.4% Whites). Stringent inclusion criteria were used for ethnicity, which allows for distinct comparisons but may reduce generalizability of results. RESULTS Black current smokers smoked fewer cigarettes per day and reported initiating smoking at a later age than Whites. Current versus never smoking was associated with income, education, and caffeine intake. There was a significant ethnicity by alcohol interaction (at lower levels of alcohol intake Whites were more likely to smoke but at higher levels of alcohol there were no ethnic differences). Former smoking versus current smoking was associated with alcohol intake, education, and pack years of smoking. CONCLUSIONS The results of the study suggest several ethnic differences in smoking patterns as well as several correlates of smoking status. These results have implications for the tailoring of interventions and illustrate the association of other health risk factors with smoking status.

Development and cross-validation of a prediction equation for estimating resting energy expenditure in healthy African-American and European-American women.

Objective: To develop, validate, and cross-validate a formula for predicting resting energy expenditure (REE) in African-American and European-American women.Design: A cross-sectional study of REE in women. Participants were randomly assigned to one of two groups. One group served to develop and validate a new equation for predicting REE while the second was used to cross-validate the prediction equation. The accuracy of the equation was compared to several existing formulae.Setting: University metabolic laboratory, Memphis, TN, USA.Subjects: Healthy, premenopausal African-American and European-American women between 18 and 39 y of age. The validation sample included 239 women (age: 28.4 y, wt: 70.7 kg, body mass index (BMI): 25.2 kg/m2, REE: 5840 kJ/day), while the cross-validation sample consisted of 232 women (age: 27.5 y, wt: 70.7 kg, BMI: 25.2 kg/m2, REE: 5784 kJ/day).Results: The prediction equation derived from the current sample, which included adjustments for ethnicity, was the only formula that demonstrated a high level of accuracy for predicting REE in both African-American and European-American women. The mean difference between REE predicted from the new formula and measured REE was 28 kJ/day (s.d.=668) for European-American women and 142 kJ/day (s.d.=584) for African-American women.Conclusions: Previous equations for predicting energy needs may not be appropriate for both African-American and European-American women due to ethnic differences in REE. A new equation that makes adjustments in predicted REE based on ethnicity is recommended for determining energy needs in these groups (Predicted REE (kJ/day)=616.93−14.9 (AGE (y))+35.12 (WT (kg))+19.83 (HT (cm))−271.88 (ETHNICITY: 1=African American; 0=European American)).Sponsorship: Support for this study was provided by Grant #HL53261 from the National Heart, Lung, and Blood Institute.

Self-perception and Body Image Associations with Body Mass Index among 8–10-year-old African American Girls

OBJECTIVES The purpose of this study was to examine relationships among body mass index (BMI), self-perceptions, and body image discrepancy in African American (AA) girls. METHODS Baseline self-perception and BMI data were collected by trained staff from 303 preadolescent AA girls participating in the girls health enrichment multi-site studies. Correlations and multivariable logistic regression analyses were performed to identify relationships of BMI with self-perception factors. RESULTS Girls with a BMI at or above the 85th percentile were more likely to have greater body image discrepancy and participate in weight control behaviors than girls with a BMI below the 85th percentile. Body image discrepancy was not related to self-esteem, but was positively correlated with physical activity self-concept and self-efficacy, and diet self-efficacy. CONCLUSION Girls with higher BMI had greater body image discrepancy and were less confident in abilities to be active and eat healthy. Findings may inform the development of obesity interventions for preadolescents.

Bone mineral density in triathletes over a competitive season

There is evidence from previous cross-sectional studies that high volumes of certain sports, including running, swimming and cycling, may have a negative impact on bone mineral density. The aim of the present study was to evaluate prospectively the effects of high athletic training in individuals who engage in high volumes of all three of these activities (triathletes). Bone mineral density for the total body, arms and legs was determined by dual-energy X-ray absorptiometry in 21 competitive triathletes (9 men, 12 women) at the beginning of the training season and 24 weeks later. Age, body mass index, calcium intake and training volume were also recorded to examine potential mediators of bone mineral density change. Men had greater bone mineral density at all sites than women. No significant changes were observed over the 24 weeks for either total body or leg bone mineral density. Bone mineral density in both arms increased by approximately 2% in men ( P ≪ 0.03), but no change was observed for women. Change in bone mineral density at all sites was unrelated to age, body mass index, calcium intake and training volume. The results suggest that adverse changes in bone mineral density do not occur over the course of 6 months of training in competitive triathletes.

Measurement of body composition in 8-10-year-old African-American girls: a comparison of dual-energy X-ray absorptiometry and foot-to-foot bioimpedance methods.

OBJECTIVE The purpose of this study was to evaluate body composition outcomes of foot-to-foot (FF) bioelectrical impedance (BIA) and dual-energy x-ray (DEXA) in 8 to 10-year-old African-American girls and, if different, to develop and cross-validate specific BIA prediction equations for this at-risk group. METHODS DEXA and FF-BIA body composition outcomes were analyzed in 183, 8-10-year-old African-American girls from the Memphis site of the Girls health Enrichment Multi-site Study (GEMS). RESULTS Mean body composition outcomes by FF-BIA and DEXA were significantly different (p<0.0001); therefore, population-specific equations were developed and cross-validated using split-sample, cross-validation methods. When equations were used, BIA and DEXA outcomes were significantly correlated (percent body fat [r=0.931], fat mass [r=0.985], and fat-free mass [r=0.944]). Mean predicted BIA measurements for body fat, fat mass, and fat-free mass were essentially equal to their counterpart DEXA measurements (t[182]=- 0.013, p = 0.897, t[182]=- 0.06, p=0.956, and t[182]=- 0.26, p=0.792, respectively). The Bland-Altman analysis revealed a significant slope for percent fat (p=0.009) and slopes approaching significance for fat mass (p=0.07) and fat-free mass (p=0.06). CONCLUSION Although FF-BIA and DEXA are not directly interchangeable in young African-American girls, these equations accurately estimated average percent fat, fat mass, and fat-free mass of the cross-validation sample of African-American girls. However, the application of this equation may result in potential underestimation or overestimation of fat with respect to DEXA measures in some populations.

Identification of facilitators and barriers to participation in weight gain prevention research by African American girls.

OBJECTIVE The purpose of the current study is to describe the development, implementation, and success of recruitment and adherence strategies of 303 African American preadolescent girls and their primary caregiver in the Girls health Enrichment Multi-site Studies (GEMS) program. METHODS A socio-ecologic model was used to guide selection and implementation of recruitment and retention strategies which were continuously monitored and revised in response. Strategy mode and frequency associated with program enrollment, engagement, and retention were analyzed. RESULTS Successful recruitment approaches included radio messages (23.1%), school fliers (20.1%), and friend referral (15%). Initially 463 potential participants responded, 320 girls were screened, and 303 enrolled. Significant increases in participant accrual were observed between Wave 4 (n=28) and Wave 5 (n=91) after using a team recruitment approach. Implementing case management strategies and providing make-up sessions also served to keep participants current and engaged in the program. In year 2, community field trips replaced the more structured sessions providing participants with experiential learning opportunities. Overall intervention attendance rates ranged from 79.7% to 90.5% among waves. Further, 75.9% and 80.2%, respectively, of participants attended 1-year and 2-year follow-ups. CONCLUSION Multiple recruitment strategies and flexible, responsive approaches to recruitment and retention guided by the socio-ecologic model facilitated optimal implementation of an intervention for preadolescent girls. Through the application of the socio-ecologic model researchers and program leaders will be able to identify strategies to enhance the probability of successful outcomes.

Community-based physical activity as adjunctive smoking cessation treatment: Rationale, design, and baseline data for the Lifestyle Enhancement Program (LEAP) randomized controlled trial

Despite advances in behavioral and pharmacological treatment for tobacco use and dependence, quit rates remain suboptimal. Increasing physical activity has shown some promise as a strategy for improving cessation outcomes. However, initial efficacy studies focused on intensive, highly structured exercise programs that may not be applicable to the general population of smokers. We describe the rationale and study design and report baseline participant characteristics from the Lifestyle Enhancement Program (LEAP), a two-group, randomized controlled trial. Adult smokers who engaged in low levels of leisure time physical activity were randomly assigned to treatment conditions consisting of an individualized physical activity intervention delivered by health fitness instructors in community-based exercise facilities or an equal contact wellness control. All participants received standard cognitive behavioral smoking cessation counseling combined with nicotine replacement therapy. The primary outcomes are seven-day point prevalence abstinence at seven weeks, six- and 12 months. Secondary outcomes include self-reported physical activity, dietary intake, body mass index, waist circumference, percent body fat, and nicotine withdrawal symptoms. Participants consist of 392 sedentary smokers (mean [standard deviation] age = 44.6 [10.2] = years; 62% female; 31% African American). Results reported here provide information regarding experiences recruiting smokers willing to change multiple health behaviors including smoking and physical activity.

Comparison of nutritional intake in US adolescent swimmers and non-athletes

Swimming is a very popular sport among adolescents in the US. Little is known about the diet of competitive adolescent swimmers in the US but data from other countries indicate several inadequacies, including excessive intake of fat and lower than recommended intake of carbohydrate and several micronutrients that may affect athletic performance and bone accrual. We assessed usual diet, using a food frequency questionnaire and calcium checklist, among 191 adolescent males and females [91 swimmers (mean 13.7, s = 2.5 years) and 100 non-athletes (mean 14.4, s = 2.8 years)]. For both males and females, swimmers and non-athletes generally had similar average intakes of macro- and micro-nutrients, including higher than recommended amounts of total fat (36%) and saturated fat (12%), and inadequate amounts of calcium, vitamin D, and daily servings of fruits, vegetables, grains, and dairy products. This first study of nutritional intake among adolescent swimmers in the US suggests that dietary habits of adolescents who swim competitively may jeopardize optimal athletic performance and place them at risk for future chronic diseases, including osteoporosis.