Objective: Measuring physical activity is a key part of studying its health effects. Questionnaires and pedometers each have weaknesses but are the cheapest and easiest to use measurement methods for large-scale studies. We examined their capacity to detect expected associations between physical activity and a range of surrogate health measures. Design: Cross-sectional analysis of 669 community-dwelling participants (mean age 63.3 (7.7) years) who completed the Physical Activity Scale for the Elderly (PASE) questionnaire and who, within 2 weeks, wore a pedometer for 7 days. Results: PASE score and step count were only poorly correlated (r=0.37 in women, r=0.30 in men). Of 12 expected associations examined between activity and surrogate markers of health, 10 were detected as statistically significant by step counts but only 3 by PASE scores. Significant associations in the expected direction were found between step counts and high-density lipoprotein, body mass index, waist circumference, waist-to- hip ratio, blood glucose level, white cell count and fibrinogen. There was no association with either systolic or diastolic blood pressure. The association between PASE score and these markers was detected as significant only for body mass index and waist circumference in women and waist-to-hip ratio in both sexes. Associations were stronger for steps multiplied by stride length than for raw step count. Conclusions: Pedometer-derived step counts are a more valid measurement of overall physical activity in this sample than PASE score. Researchers should use objective measures of physical activity whenever possible.
British Journal of Sports Medicine Vol. 44, Issue 10, p. 756-761