Accuracy of Heart Rate Measurement by the Fitbit Charge 2 During Wheelchair Activities in People With Spinal Cord Injury: Instrument Validation Study

The objective of this study is to investigate the heart rate (HR) accuracy measured at the wrist with the photoplethysmography (PPG) technique with a Fitbit Charge 2 (Fitbit Inc) in wheelchair users with spinal cord injury, how the activity intensity affects the HR accuracy, and whether this HR accuracy is affected by lesion level.