Related Experiment Video
Updated: May 29, 2026
Assessment of Physical Activity Intensity with Accelerometers and Oxygen Consumption
Published on: June 20, 2025
Development of the physical activity index as a measure of total activity load and total kilocalorie expenditure
Kimberly A Smith1, Michael Gallagher, Anne E Hays
1Department of Exercise and Rehabilitative Sciences, Slippery Rock University, Slippery Rock, PA, USA.
Background:
Pedometers are most accurate at measuring steps, less accurate at estimating distance, and even less accurate at estimating kilocalorie expenditure. The purpose of this investigation was to create a Physical Activity Index (PAI) using pedometer step counts and rating of perceived exertion (RPE) to enhance the ability to estimate kilocalorie expenditure during walking exercise.
Methods:
Thirty-two females performed 3 counterbalanced walking bouts. During each bout, oxygen consumption, RPE, and step counts were measured. The PAI was calculated as the product of RPE and step count for each of the bouts.
Results:
Concurrent validation of the PAI was established using VO2 as the criterion variable. A multiple regression analysis revealed a strong, positive relation between PAI score and VO2 (r=.91). Data were then used to develop a statistical model to estimate kcal expenditure using the PAI score as the predictor variable.
Conclusion:
The PAI was found to be an accurate method of estimating kcal expenditure and is a simple, unobtrusive and inexpensive tool which may be used in public health settings.
