You may notice variations between the SimplyMe app and HealthKit (Apple Watch app) due to different data sets being included in resting heart rate calculations.

Our team of data scientists are currently in the midst of refining the algorithm we use to generate your heart rate data. In alignment with peer-reviewed scientific studies, we currently exclude outlier data points that may skew the analysis of your resting heart rate - such as when your heart rate drops during asleep periods.
This can result in a higher average resting heart rate and lower VO2 max than that displayed in your HealthKit app.