The accuracy of heart rate and energy expenditure measurements using the Polar M430 watch

Abstract

This study was designed to assess the accuracy of the Polar M430 fitness watch to measure heart rate (HR) and energy expenditure (EE) during low, moderate, and high intensity treadmill exercise. Twenty subjects (12 males, 8 females) participated in one treadmill exercise session. The exercise session was broken up into three different 5-minute, self-selected rating of perceived exertion (RPE) workloads. The workloads used in this study were at RPE 11 (low intensity), RPE 13 (moderate intensity), and RPE 15 (high intensity), respectively. The watch was worn by subjects while they were also connected to an electrocardiogram (ECG) and a Parvo metabolic analyzer. It was found that in terms of HR, the watch was very accurate at the low and moderate intensities, but significantly underestimated HR at RPE 15 (3 bpm) Correlations between the watch and ECG measurements were strong and ranged from R=.96-.99. In terms of EE, there was no significant difference between the watch and the Parvo at RPE 11 or 13. However, at RPE 15 the watch significantly underestimated EE by having a mean absolute percentage error of 14.9% compared to directly measured values. Correlations ranged from R= .66-.89. Based on these results, it appears the Polar M430 fitness watch is an accurate tool to measure HR at all exercise intensities but is only an accurate tool to measure EE during low and moderate intensity exercise.