Title: Objectively and Subjectively Measured Physical Activity and their Associations with Cardiometabolic Risk: An Observational Study of Physical Activity in Cardiometabolic Risk Factors in the UK Biobank (Preprint)

Abstract

The association between physical activity behavior and cardiometabolic risk factors in longitudinal cohort studies has depended largely on questionnaire-based reporting. While there are differences between self-reported activity levels and objectively measured accelerometer-based activity, how these differences manifest in disease risk is unknown. Here, we sought to evaluate these differences and to model the impact in their association with cardiometabolic factors.

We sought to evaluate the difference between objective physical activity measured by an accelerometer and self-report physical activity in their association with cardiometabolic factors.

We assessed physical activity (PA) using both wrist-word accelerometer data and self-reported questionnaires in 16K participants of the UK Biobank, focusing on walking, sleeping, sedentary, and moderate-to-vigorous physical activity (MVPA). We compared the concordance between self-reported and objective measures of PA. Next, we compared the association between objective measured or self-reported PA and future clinical biomarker levels (e.g., body mass index, pulse rate, glucose control, cholesterol).

Participants underestimated their weekly sedentary duration on average of 2.86 hours, and that the correlation between subjective and objective activity were respectively r=0.12 for sedentary time, r=0.16 for moderate to vigorous physical activity, r=0.18 for walking, and r=0.13 for sleeping. We found an inverse association between objectively measured moderate-to-vigorous physical activity and cardiometabolic biomarkers such as BMI and pulse rate but found no association for subjectively reported activity.

These findings provide evidence that the association of self-reported activity is likely underestimated and biased.

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