Using GPS, accelerometry and heart rate to predict outdoor graded walking energy expenditure

J Sci Med Sport. 2018 Feb;21(2):166-172. doi: 10.1016/j.jsams.2017.10.004. Epub 2017 Oct 13.

Abstract

Objectives: To determine the best method and combination of methods among global positioning system (GPS), accelerometry, and heart rate (HR) for estimating energy expenditure (EE) during level and graded outdoor walking.

Design: Thirty adults completed 6-min outdoor walks at speeds of 2.0, 3.5, and 5.0kmh-1 during three randomized outdoor walking sessions: one level walking session and two graded (uphill and downhill) walking sessions on a 3.4% and a 10.4% grade. EE was measured using a portable metabolic system (K4b2). Participants wore a GlobalSat® DG100 GPS receiver, an ActiGraph™ wGT3X+ accelerometer, and a Polar® HR monitor. Linear mixed models (LMMs) were tested for EE predictions based on GPS speed and grade, accelerometer counts or HR-related parameters (alone and combined). Root-mean-square error (RMSE) was used to determine the accuracy of the models. Published speed/grade-, count-, and HR-based equations were also cross-validated.

Results: According to the LMMs, GPS was as accurate as accelerometry (RMSE=0.89-0.90kcalmin-1) and more accurate than HR (RMSE=1.20kcalmin-1) for estimating EE during level walking; GPS was the most accurate method for estimating EE during both level and uphill (RMSE=1.34kcalmin-1)/downhill (RMSE=0.84kcalmin-1) walking; combining methods did not increase the accuracy reached using GPS (or accelerometry for level walking). The cross-validation results were in accordance with the LMMs, except for downhill walking.

Conclusions: Our study provides useful information regarding the best method(s) for estimating EE with appropriate equations during level and graded outdoor walking.

Keywords: Accelerometer; Energy metabolism; Exercise; Global positioning system; Methods; Public health.

Publication types

  • Comparative Study

MeSH terms

  • Accelerometry / methods*
  • Adult
  • Cross-Sectional Studies
  • Energy Metabolism / physiology*
  • Female
  • Geographic Information Systems*
  • Heart Rate / physiology*
  • Humans
  • Linear Models
  • Male
  • Monitoring, Physiologic / methods
  • Walking / physiology*
  • Wearable Electronic Devices
  • Young Adult