Accuracy of the wearable activity tracker Garmin Forerunner 235 for the assessment of heart rate during rest and activity.

Accurate measures of heart rate (HR) during rehabilitation and sporting activities are important for precise exercise prescription to maintain or increase capacity. Wrist-worn activity monitors utilizing photoplethysmography technology (PPG) to configure HR show discrepant findings regarding validity depending on the type and intensity of exercises measured, and no previous study has yet investigated the accuracy during running at speeds exceeding 9.6 km/h.