Is there a difference in student physical activity between a field school and a traditional classroom setting?

OBJECTIVES: We compared the physical activity of nine students participating in an anthropological field school to their activity expenditures in traditional classrooms. We predicted that the students would exhibit higher physical activity during the field school due to the substantial physical requirements associated with the program compared to traditional classroom environments which are frequently more sedentary. METHODS: Participants (n = 9) wore wrist accelerometers for ~23 h each day for 6 days during an anthropological field school and also in a traditional classroom environment. Accelerometers were programed with participant height, weight, age, and sex. Each accelerometer recorded total energy expenditure in kilocalories (kcal), step counts, and time in four physical activity levels (vigorous, moderate, easy, and very easy) between the field school and traditional classroom settings. RESULTS: During the field school portion of the study, participants burned more calories (p < .01), took more steps (p < .0001), and engaged in more moderate and easy exercise (p < .0001). CONCLUSIONS: This study provides insights into the physical benefits of study abroad programs and field schools. Our multi-day accelerometer data revealed significant differences in even relatively low intensities of physical activity. This is particularly pertinent in the United States where sedentary lifestyles are increasing among college students. Taken together, the results underscore the importance of study abroad programs, field schools, and other applied learning opportunities beyond the educational, professional, and social benefits.

Shift in body fat distribution from lower body to upper body among urban Colombian women, 1988-1989 to 2007-2008.

OBJECTIVE: Body fat distribution may be a stronger predictor of metabolic risk than BMI. Yet, few studies have investigated secular changes in body fat distribution in middle-income countries or how those changes vary by socioeconomic status (SES). This study evaluated changes in body fat distribution by SES in Colombia, a middle-income country where BMI is increasing rapidly. DESIGN: We applied factor analysis to previously published data to assess secular changes in adiposity and body fat distribution in cross-sectional samples of urban Colombian women. Anthropometry was used to assess weight, height and skinfolds (biceps, triceps, subscapular, suprailiac, thigh, calf). SETTING: Cali, Colombia. PARTICIPANTS: Women (18-44 years) in 1988-1989 (n 1533) and 2007-2009 (n 577) from three SES groups. RESULTS: We identified an overall adiposity factor, which increased between 1988-1989 and 2007-2008 in all SES groups, particularly in the middle SES group. We also identified arm, leg and trunk adiposity factors. In all SES groups, leg adiposity decreased, while trunk and arm adiposity increased. CONCLUSIONS: Factor analysis highlighted three trends that were not readily visible in BMI data and variable-by-variable analysis of skinfolds: (i) overall adiposity increased between time periods in all SES groups; (ii) the adiposity increase was driven by a shift from lower body to upper body; (iii) the adiposity increase was greatest in the middle SES group. Factor analysis provided novel insights into secular changes and socioeconomic variation in body fat distribution during a period of rapid economic development in a middle-income country.

No change in energy efficiency in lactation: Insights from a longitudinal study.

OBJECTIVES: Lactation is the most energy-demanding phase of reproduction for human females, but it is still unclear how women in different environments are able to meet this additional energy demand. Previous studies have investigated whether changes in metabolism could have an energy-sparing effect in lactation, with conflicting results. Here, we asked whether increased energy efficiency in physical activity serves as an energy-sparing mechanism in lactation. METHODS: We used a longitudinal design with a control group. Participants were 33 well-nourished, exclusively breastfeeding women and 29 non-pregnant, non-lactating (NPNL) controls aged 32 ± 4 years. Lactating women were measured at peak- and post-lactation. NPNL controls completed a baseline measurement and a follow-up visit. Energy efficiency in physical activity was assessed using a graded submaximal exercise test and calculated as delta efficiency (change in work accomplished over change in energy expended) and gross efficiency (work accomplished over energy expended). RESULTS: There was no significant change in either delta efficiency or gross efficiency from peak to post lactation in lactating women, and no significant difference in delta efficiency between lactating women and NPNL controls at any time period. However, lactating women showed greater between-visit variation in delta efficiency than the NPNL controls. Additionally, 79% of lactating participants lost weight between visits (mean weight loss -3.6 ± 2.3kg), consistent with a mobilization of body tissues to support lactation. CONCLUSION: We found no support for the idea that lactating women undergo an increase in energy efficiency to support the energy costs of lactation.

Local trends in diet in urban Colombia, 1990-1995 to 2008: little evidence of a nutrition transition among low-income women.

OBJECTIVES: To quantify changes in the diets of low-income women in Cali, Colombia between 1990-1995 and 2008, a period of increases in body size, and to situate these changes within national-level trends in food availability, as well as to compare these changes with those expected in countries undergoing a nutrition transition. METHODS: Individual dietary intake was assessed via 24-hour recalls in both 1990-1995 (n = 85) and 2008 (n = 88). Dietary data were analyzed for intake of energy, macronutrients, and specific food items. National-level trends in food availability were evaluated using data from the Food and Agriculture Organization. RESULTS: Total energy and protein intake did not change over time, but in 2008 women consumed proportionally more fat (23.0 vs. 19.1% of calories; P = 0.002) and less carbohydrate (66.5 vs. 71.0% of calories; P < 0.001) than in 1990-1995. The increased fat consumption is attributable to vegetable oils. This increase in vegetable oil consumption, and a decrease in starchy vegetable consumption, fit with both national-level trends in food supply, and the expectations of a nutrition transition. On the other hand, the increased consumption of non-starchy vegetables, and the stability in consumption of added sugars and animal-source proteins was contrary to the expectations of a nutrition transition. CONCLUSIONS: The changes in diet among low-income women in Cali, Colombia between 1990-1995 and 2008 partially match national-level trends in food supply and the theoretical expectations of a nutrition transition, but are nonetheless a localized phenomenon. They do not help explain concurrent changes in body size.

Stable isotopes (carbon, nitrogen, sulfur), diet, and anthropometry in urban Colombian women: investigating socioeconomic differences.

OBJECTIVES: We conducted stable isotope and dietary analyses of women from higher and lower socioeconomic status (SES) groups in Cali, Colombia. The objectives were to test between-group differences in stable isotope, dietary, and anthropometric characteristics, and to evaluate relationships between diet and stable isotope values. METHODS: Hair samples from 38 women (mean age 33.4) from higher and lower SES groups were analyzed for δ(13) C, δ(15) N, and δ(34) S values. Dietary intake was assessed via 24-h recalls. Anthropometric variables measured were body mass index, five body circumferences, and six skinfold thicknesses. RESULTS: Mean δ(13) C and δ(15) N values of the higher SES group (-16.4 and 10.3‰) were significantly greater than those of the lower SES group (-17.2 and 9.6‰; P < 0.01), but mean δ(34) S values did not differ significantly between groups (higher SES: 4.6‰; lower SES: 5.1‰). The higher SES group consumed a greater percentage of protein than the lower SES group (14% vs. 12% of energy; P = 0.03), but the groups did not differ in other dietary characteristics or in anthropometric characteristics. δ(13) C, δ(15) N, and δ(34) S values were not correlated with intake of the dietary items predicted (sugars, animal-source protein, and marine foods, respectively). The lower SES group was more variable in all three stable isotope values (P < 0.05), mirroring a trend toward greater dietary variability in this group. CONCLUSIONS: Stable isotope values revealed a difference between SES groups that was not explained by the dietary data. The relationship between diet and stable isotope composition is complex.

Socioeconomic status, stature, and obesity in women: 20-year trends in urban Colombia.

OBJECTIVES: Ongoing social and economic changes in developing countries are associated with increases in body size, and most notably increases in the prevalence of obesity. The social patterning of these changes in terms of socioeconomic status (SES) is not well documented. The aim of this study was to assess the changes in stature, body mass index (BMI) and fatness in adult women in urban Cali, Colombia between 1988-1989 and 2007-2008. METHODS: We compared the results of anthropometric surveys completed in 1988-1989 and 2007-2008 of nonpregnant, nonlactating women, 18-44 years of age. Samples in both studies were stratified by SES. We calculated age-standardized prevalence rates to assess time trends in obesity. Body fatness was assessed by skinfold thicknesses. RESULTS: Stature increased in all SES groups and remained positively associated with SES. BMI increased only in the lower SES group, from 24.4 to 25.9 kg/m(2) and remained negatively associated with SES. The age-standardized prevalence of obesity increased from 7.9 to 17.0% in the lower SES group, but only from 4.5 to 8.2% in the middle SES group, and was unchanged in the upper SES group. Body fatness increased in all SES groups, but only in the upper body. CONCLUSION: The increased stature in all SES groups is indicative of general improvements in socioeconomic conditions. The increased prevalence of obesity in the lower SES groups is in keeping with the findings in other middle-income developing countries.