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, within 2 weeks, wore a pedometer for seven 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, ten 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 (BMI), waist circumference (WC), waist hip ratio (WHR), 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 BMI and WC in women, and WHR 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.