Author and graduation date: Laura M. GREENLEE, April, 1998

Committee members: Thomas L. McKenzie (Chair), James F. Sallis, Michael J. Buono

Thesis title: Physical Activity of Mexican and Anglo American Women: A Longitudinal Study

The purpose of this study was to investigate the longitudinal changes in work and leisure physical activity among Mexican-American and Anglo-American women. One hundred eighty-eight women of Mexican-American (n = 113, mean age 30.8) and Anglo-American (n = 75, mean age 31.2) ethnic backgrounds participated. Two Seven-Day Physical Activity Recall interviews were administered 6 months apart at baseline and two additional interviews were administered 6 months apart at follow-up 8 years later. Data from the two 7-Day PAR interviews each measurement period were averaged. Subjects' height, weight, BMI, and family health information were also obtained. No intervention was performed between data collection periods, although most subjects continued to participate in family interviews on physical activity and nutrition at 2-year intervals. Independent t-tests were used to compare group differences in physical activity at baseline and at follow-up. Partial t-tests were used to compare changes in physical activity between baseline and follow-up within each group. An alpha level of .004 was used for the t-tests as required by the Bonferroni correction. Pearson correlations ( adjusted for BMI and age) were used to assess tracking of physical activity over time within each group. An alpha level of .05 was used for the Pearson correlations.

Comparisons of group differences at baseline (p < .046) and follow-up (p <.022) revealed that Mexican- and Anglo-American women had similar levels of physical activity. Comparison of the change between Mexican-Americans' baseline and follow-up physical activity identified significant increases in all leisure (p <.001) and in average daily energy expenditure (p <.001). Fore Anglo-Americans, statistically significant increases were found in weekday vigorous (p <.003) and in average daily energy expenditure (p <.001). With Mexican-Americans, there was significant tracking of moderate work (r = .42, p <.001) physical activity. The tracking of average daily energy expenditure in Mexican-Americans (r = .35, p <.001) was significant; however, the tracking of average daily energy expenditure in Anglo-Americans (r = .32, p <.005) just missed being statistically significant.

It was concluded that physical activity tracks in Mexican- and Anglo-American women, and that tracking of physical activity is stronger in work than in leisure environments. The findings that both groups increased physical activity over time is contrary to the results of several other studies. This unexpected increase in physical activity could be attributed to the change in the women's roles as mothers from when their children were age 4 to age 12. Further study is needed to assess how the many roles of motherhood might influence physical activity.

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