Tag Archives: quantified bob

Visualizing HR, HRV, and GSR While Watching ‘Interstellar’ by Bob Troia

This blog repost is from one of our more “connected” users, Bob Troia, also known as Quantified Bob.  Bob enjoys tracking and analyzing his metrics based on the effects of many factors such as, his Bulletproof Diet, his glucose reading, even his personality type. To see exactly what Bob is tracking and read into his prior experiments go to his blog.


In this case, Quantified Bob took something as simple as watching the movie, Interstellar, and turned it into a Quantified Self experiment. He used a Polar H7 to capture 3-hours of biometrics, specifically RR-Intervals. The SweetBeatLife app then uses clinical grade algorithms to analyze the data. Anyone with one of our applications and a heart rate monitor chest strap (BTLE) can do the same. Bob exported his heart rate and heart rate variability data from SweetBeatLife, and his Galvanic Skin Response from a Basis B1. Read below to see his heart rate and heart rate variability response.

Heart Rate

“Interestingly, my heart rate trend (on the left, below) looks very similar to the original Reddit user (on the right)! Both of us are using data from our wrist-worn Basis devices – in my case, the older B1 model, and for the Reddit user the newer Basis Peak. Although the Peak is capable of capturing more samples, the data returned from Basis is always an average value for each minute.

Interstellar HR comparison

However, SweetBeatLife is recording data at a resolution of 1 sample per second via the Polar H7. The per-second pulse data is a little bit jumpy and hard to follow (in gray), so I’ll also include a 60-second moving average as well (in blue):

Interstellar Heart Rate Polar H7

It looks very similar to the data recorded by my Basis. Good!

Heart Rate Variability (HRV)

Heart Rate Variability uses a technique in which the spaces between heart beats are measured, and is a good way to measure stress via an individual’s “flight or fight” response (the higher one’s HRV, the better). There are a number of ways HRV can be calculated, and in this case we are using what’s known as rMSSD (root mean square of successive differences). You can check out Wikipedia for a pretty good overview of HRV.

Interstellar Heart Rate Variability

Not only can Bob see when the movie had him in sympathetic versus parasympathetic but he can point out when he was having deep thoughts of gravity and space. Bob was also able to determine that there is, “an inverse relationship between heart rate and HRV, which makes sense – if your heart starts beating faster, you are most likely encountering more stress, which increases your sympathetic response and thus lowers HRV.”

Read more about his Galvanic Skin Response and how Bob interpreted this data, read the original article here. If you want to better understand HRV and the many benefits of tracking it, I recommend browsing around the SweetWater Health Library.