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  • Author: David R. Jacobs Jr x
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Barbara E. Ainsworth, Mark Richardson, David R. Jacobs Jr. and Arthur S. Leon

We examined gender differences in leisure-time physical activity (LTPA) in 50 women and 28 men using questionnaire data and identified how LTPA status may be misclassified based on physical activity questionnaire content. LTPA was determined using the Four Week Physical Activity History modification of the Minnesota LTPA questionnaire. LTPA was classified as total, light- (≤ 4.0 METS), moderate- (4.5-5.5 METS), and heavy-intensity (≥ 6.0 METs), and household LTPA. The questionnaire was administered 14 times (every 26 days). Scores were computed as kcal·day−1 and min·day−1 with the 14 visits averaged to yield one year LTPA scores. Skewed data were log-transformed and are presented as the geometric mean. There were no gender differences in kcal·day−1 for total- (385 vs 421), moderate- (28.2 vs 23.3), and light-intensity LTPA (72.2 vs 52.6, p > .05). Heavy-intensity LTPA was greater in men than in women (98.1 vs 50.5, p = 0.01), while household LTPA was greater in women than in men (238.2 vs 134.7, p < .0001). Omission of heavy-intensity LTPA from the questionnaire reduced total LTI’A by 25% in men and 12% in women. In contrast, omission of household LTPA reduced total LTPA by 35% in men and 57% in women. Thus LTPA may be underestimated and activity status misclassified if questionnaires fail to include activities with high gender-specific participation rates.

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Shujun Gao, Lisa Harnack, Kathryn Schmitz, Janet Fulton, Leslie Lytle, Pamela Van Coevering and David R. Jacobs Jr.

Background:

We assessed the validity and reliability of a modified Godin-Leisure-Time Exercise Questionnaire in youth in grades 6 through 8.

Methods:

The questionnaire was completed by 250 children twice at a 1 wk interval to assess reliability. After the second questionnaire administration the children wore an accelerometer for 7 d (criterion measure).

Results:

Pearson correlations between the first and second reports of frequency of participation in strenuous and moderate physical activity were 0.68 and 0.51, respectively. Self-reported participation in strenuous activity was weakly correlated with strenuous activity as measured by accelerometer (r = 0.23, P = 0.01). A weak non-significant correlation was found between reported versus measured engagement in moderate activity (r = 0.13, P = 0.07).

Conclusion:

Findings suggest the questionnaire evaluated in this study may be of very limited use for assessing children’s physical activity.

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Kelley Pettee Gabriel, Adriana Pérez, David R. Jacobs Jr, Joowon Lee, Harold W. Kohl III and Barbara Sternfeld

Background: Single-method assessment of physical activity (PA) has limitations. The utility and cross-validation of a composite PA score that includes reported and accelerometer-derived PA data has not been evaluated. Methods: Participants attending the Year 20 exam were randomly assigned to the derivation (two-thirds) or validation (one-third) data set. Principal components analysis was used to create a composite score reflecting Year 20 combined reported and accelerometer PA data. Generalized linear regression models were constructed to estimate the variability explained (R 2) by each PA assessment strategy (self-report only, accelerometer only, composite score, or self-report plus accelerometer) with cardiovascular health indicators. This process was repeated in the validation set to determine cross-validation. Results: At Year 20, 3549 participants (45.2 [3.6] y, 56.7% female, and 53.5% black) attended the clinic exam and 2540 agreed to wear the accelerometer. Higher R 2 values were obtained when combined assessment strategies were used; however, the approach yielding the highest R 2 value varied by cardiovascular health outcome. Findings from the cross-validation also supported internal study validity. Conclusions: Findings support continued refinement of methodological approaches to combine data from multiple sources to create a more robust estimate that reflects the complexities of PA behavior.