EFFECTS OF A BEHAVIORAL INTERVENTION ON AN OBJECTIVE ASSESSMENT OF PHYSICAL ACTIVITY: PROJECT GRAD

544 Project GRAD is a randomized, controlled trial to determine the efficacy of a cognitive/behavioral intervention to increase or maintain physical activity among young adults. 338 undergraduate seniors were randomly assigned to either a behavioral intervention or to a control group. An objective measure of physical activity, the Tritrac Accelerometer was worn by a subsample of students (n=32 control, n=38 intervention; 57% female, 40% ethnic minority) approximately one year following the intervention. The accelerometer is a motion sensor that assesses movement in three planes, (vertical, horizontal, and side to side). Participants wore the tritrac for at least 8 hours/day for 7 consecutive days. The purpose of this study is to examine the intervention effects on this objective measure of physical activity, specifically minutes spent in light, moderate, and vigorous physical activity per week. The number of 10 and 20 minute boats of moderate and vigorous physical activity were calculated. The cutoffs used to define intensity were derived in another study. Groups were compared using independent t-tests separately by sex. Men in the intervention group completed more bouts of moderate physical activity(both 10 and 20 minute) than men in the control group (2.8 vs 0.8, p<.03 and 1.7 vs 0.3, p<.04 bouts, respectively). There were no significant differences for vigorous physical activity and no differences for women. There were no significant differences between intervention and control groups for the number of minutes spent in physical activity of any intensity. For women, the average min/wk spent in moderate and vigorous physical activity was 128.2 (87.7) and 18.5 (39.0), respectively, for control and 146.4 (67.3) and 31.3 (82.5), respectively, for intervention groups. For men, the average minutes spent in moderate or vigorous activity was 171.2 (93.0) and 23.4 (34.6), respectively, for control and 211.0 (88.7) and 22.2 (31.2), respectively, for intervention groups. The intervention appeared to increase continuous bouts of PA in men, but the total minutes of physical activity in all groups assessed by an objective measure, were much lower than expected.