Contribution of Light Physical Activity to Total Daily Physical Activity in Adolescent Girls

Abstract

Investigations examining physical activity (PA) in children/youth focus on increasing moderate-to-vigorous physical activity (MVPA) and/or achievement of activity recommendations. However, there is increasing evidence that light intensity physical activity (LPA) may play a role in obesity prevention. Little is known about the contribution of LPA to total activity (TPA). PURPOSE: The purposes of this investigation were to determine the contribution of LPA to TPA and to describe the characteristics of LPA in adolescent girls. METHODS: The Trial of Activity for Adolescent Girls (TAAG) was a multi-center grouprandomized trial designed to test an intervention to reduce the usual decline in MVPA in middle-school girls. Data represent a cross-sectional examination of 3443 8th grade girls (46% White, 22% African American, 21% Hispanic, 11% Other) at the follow-up measurement in spring 2005. PA was measured by accelerometry (ActiGraph 7164), with readings between 51-1499 counts·30 sec-1 considered LPA and those 1500-2600 as MVPA. Percent of time spent in LPA was calculated two ways: proportion of LPA per TPA (LPA+ MVPA) and proportion of LPA per time spent in non-sleep activity (sedentary + LPA+ MVPA). Participants also completed the 3-Day PA Recall (3DPAR) to provide context regarding PA. Data analysis consisted of 3-way ANOVAs (race x weight status x free/ reduced lunch), controlling for age, with site and school as random effects. RESULTS: Girls spent 93% of activity time in LPA and 36% of non-sleep activity time in LPA. African American girls spent more time in TPA (328 min/day) and LPA (307 min/day) than other racial groups (p<0.05). White girls spent the least amount of TPA in LPA (93%; p<0.001), and almost all race groups were different from each other in time spent in LPA per time spent in non-sleep activity. Overweight girls spent the highest percentage of activity time in LPA. There were no differences by free/reduced lunch. The most common light activities reported were travel by walking, chores, PE class, walking for exercise, dancing, and working. CONCLUSION: Adolescent girls spend a large proportion of time in LPA. These light activities could be potential intervention targets. Supported by NIH grants U01HL66858, U01HL66857, U01HL66845, U01HL66856, U01HL66855, U01HL66853, U01HL66852