Heart Rate Sensor Frequency

[Shehbaz16]

Hi, 

What is the maximum frequency that the fitbit heart rate sensor can track your BPM?

From my understanding people who have created websites such as the one shown below can track your heart rate every 5 seconds. On this site when you click seconds for your intraday data you only get your heart rate for every 5 seconds when you download the csv file. However, in his code shown in github it should technically be showing the data for every second.

I need to know if fitbit only allows the sensor to track the heart rate for a max limit of every 5 seconds or can I make it have smaller intervals such as 1 second or 0.5 seconds?

https://iccir919.github.io/pulseWatch/public/index.html

https://github.com/iccir919/pulseWatch

[Gondwana]

In Exercise mode, Fitbits typically report HR every 1 to 3 seconds. Otherwise, it's typically 5 to 15 seconds. You can't increase these rates by sampling the data more frequently.

[Shehbaz16]

Why is it not possible to increase these rates while not in exercise mode?