|| Checking for direct PDF access through Ovid
We conducted four studies to examine the reliability and validity of a 7- d re-call for estimating free-living physical activity in college students. High and reproducible correlations (r's=0.82 to 0.87) between the re-call and a concurrent 7-d diary were observed, and re-call effectively classified subjects into highly active (≥280 kcal·kg-1· wk-1) and inactive (<245 kcal·kg-1·wk-1) groups. Significant correlations between re-call and a psychometric predictor of physical activity (selfmotivation) were also robust across samples and consistent with those seen when direct measures of activity have been used. Increases in time and distance records for supervised running were accompanied by increases in total and vigorous re-call, but not in moderate re-call, supporting the re-call's sensitivity to measured changes in group activity levels. Re-call was not, however, highly correlated with supervised running, and this is consistent with its use as a measure of free-living activity. Re-call was also not spuriously contaminated by response distortion or attitudinal variables, and intra-class reliability for repeated assessments of total (P1=0.89) and vigorous (P1=0.90) re-call was high across 7 wk. Finally, re-call provided a better estimate of a 7-d diary than did practical bio-behavioral estimates of habitual activity (12-min run and skinfold thickness), and re-call was highly correlated with a concurrent physical activity questionnaire (r's=0.83 to 0.94) and O2max (ml·kg1 ·min1) (r=0.61). Our results are consistent with previous studies on community-based adult populations; they support that the 7-d re-call is reliable and valid for college students when compared with concurrent bio-behavioral and selfreport estimates of physical activity.