AINSWORTH, B. E., D. R. BASSETT, JR., S. J. STRATH, A. M. SWARTZ, W. L. O’BRIEN, R. W. THOMPSON, D. A. JONES, C. A. MACERA, and C. D. KIMSEY. Comparison of three methods for measuring time spent in physical activity. Med. Sci. Sports Exerc., Vol. 32, No. 9, Suppl., pp. S457–S464, 2000.
Purpose: Three methods for measuring time spent in daily physical activity (PA) were compared during a 21-d period among 83 adults (38 men and 45 women).
Methods: Each day, participants wore a Computer Science and Applications, Inc. (CSA) monitor and completed a 1-page, 48-item PA log that reflected time spent in household, occupational, transportation, sport, conditioning, and leisure activities. Once a week, participants also completed a telephone survey to identify the number of minutes spent each week in nonoccupational walking and in moderate intensity and hard/very hard-intensity PA. Data were analyzed using descriptive statistics and Spearman rank-order correlations. Three equations developed to compute CSA cut points for moderate and hard/very hard PA were also compared with the PA logs and PA survey.
Results: There was modest to good agreement for the time spent in different PA intensity categories between the three CSA cut point methods (r = 0.43–0.94, P < 0.001). Correlations between the CSA and PA logs ranged from r = 0.22 to r = 0.36, depending on the comparisons. Correlations between the survey items and PA logs were r = 0.26–0.54 (P < 0.01) for moderate and walking activities and r < 0.09 (P > 0.05) for hard/very hard activities. Correlations between the survey items and the CSA min per day varied according to the method used to compute the CSA intensity cut points.
Conclusions: The results were consistent with findings from other PA validation studies that show motion sensors, PA logs, and surveys reflect PA; however, these methods do not always provide similar estimates of the time spent in resting/light, moderate, or hard/very hard PA.