The Relations Between Simple Response Measures Of Physical Activity And Cardiorespiratory Fitness

Abstract

The relations among physical activity (PA), cardiorespiratory fitness (CRF), and the risks of all-cause mortality have been well documented. Feasible and valid assessments of PA are necessary for continued research. PURPOSE To determine the relations between simple response assessments of PA and CRF. METHODS 687 participants, including males (n=504) and females (n=1 83), responded to four recall questions about PA behavior. The questions were “Over the past 3 months (or 18 months), what percentage of the weeks would you say that you were regularly physically active at a moderate (or vigorous) intensity?” Thus, participants answered four questions (moderate and vigorous × 3 and 18 months). Simple definitions of regular PA and moderate or vigorous intensity were provided with the questions. The response to each question was a selection from 0% to 100% subdivided in 10% increments. On the same day, all participants completed a maximal treadmill test using a modified Balke protocol and a more detailed survey of PA that allows the estimate of total MET-hrs/week of PA. The treadmill time was converted to an estimate of aerobic power. Participants were classified as “fit” for health purposes with aerobic power values above or equal to 9 METS for females and 10 METS for males with subjects below those values as “unfit”. The classification scheme was based on past research identifying aerobic power levels consistent with a reduced risk of all-cause mortality. RESULTS Partial correlations (r) between treadmill time and reported percent of time, controlling for age and gender indicated significant (p < .001) relations with rs ranging from a low of .38 (r2= .14) for moderate PA for 18 months to a high of .51 (r2= .26) for vigorous PA for 3 months. Multivariate ANCOVA controlling for age and gender indicated higher (p < .001) PA for four questions and total MET-hrs/week for “fit” participants. CONCLUSIONS The simple response assessments of PA demonstrated moderate relations with CRF assessments that have been consistently related to reduced risks for all-cause mortality. These simple questions for PA assessment have implications for large scale monitoring and tracking of PA in epidemiologic research. Supported in part by NIH grant AG06945