In a prior post I expressed a keen interesting in doing some heart rate variability (HRV) analysis to see if I could learn how my HRV could give me insights into hidden stress affecting my training and more broadly to understand if HRV could be a valuable biomarker for understanding more about how my body is reacting to different stressors.  So for about a month I took daily readings using two different HRV tools and followed my scheduled training plan, I was hoping that the HRV readings would help me understand which days I could potentially work harder and which days I should either take it easy or take a rest / recovery day altogether.

This analysis will be broken up into three blog posts:

Part 1.  Process and Measurement we’ll cover the devices I used for data collection

Part 2.  Data Analysis we’ll compare the data points with my activities

Part 3.  Expanded HRV Analysis over a 24 hour period

Let’s cover the process and measurement details.

I chose to use three different products to measure HRV which purport to give you better insight into your training performance (two of which for point readings and one for some extended testing):

– BioForce HRV

– SweetWater SweetBeat

– Zephyr Technologies BioHarness

BioForce and SweetWater require a heart rate monitor that is accurate enough to measure HRV and they both support a wide variety of HR monitors, BioForce and SweetWater are point-in-time sampling apps – meaning that you put on the HR monitor and take a 3 min test to calculate HRV.  I chose to use the Polar H7 Bluetooth HR monitor with both products.  BioHarness is a an advanced monitor measuring all sorts of bio markers and has the capability to be worn continuously for up to 24 hours, I’ll cover BioHarness a little later in this post.

First up, BioForce HRV

The BioForce product is marketed toward fitness enthusiasts and athletes.  The Pro package I bought came with a iPhone or Android app (I used the iPhone version), a Polar Heart Rate monitor, a wireless HRV receiver that plugs into the audio jack on the phone, access to a website to track your measurements, and a manual.  The only difference between packages is what type of heart rate monitor you want.  I ended up not needing the Pro package because I already had the Polar H7.

The BioForce HRV web site is actually quite sparse on HRV details and how the BioForce product works.  It is also spendy at $197 for Standard and $297 for Pro so I was concerned that if I wasn’t seeing the value from the product that I could return.  The site indicates a 3 month no questions asked money back guarantee and the owner (Joel Jameson) confirmed that policy via email so I thought since it was a training focused product it would be valuable to throw into the mix.

The manual “The Ultimate Guide to HRV Training” is good, lots of good information about HRV training and how the author Joel Jameson leverages HRV for his training programs.  It would be great if Joel would sell just the manual in addition to the full package.

Second up, SweetWater Health Sweetbeat

SweetBeat is a software only product purchased from the iTunes App Store for $4.99.  You are required to get your own heart rate monitor that the software supports, fortunately SweetBeat and BioForce both support the Polar H7 so I was able to use the same heart rate monitor for both products.

SweetWater markets HRV monitoring (they have a fair amount of reading material about HRV on their site) as a valuable tool not just for training but for stress reduction, identifying food sensitivities, etc.  So unlike BioForce that is designed for training in mind, the SweetBeat app is a little more general purpose but does contain a “training” setting.  It is this training setting I used for my measurements.

SweetWater also has a web based portal to track and record your readings but it not very full featured.

Third, Zephyr Technologies BioHarness 3

The BioHarness is completely different from SweetBeat and BioForce.  Where SweetBeat and BioForce are software only products, the BioHarness is hardware only (you can purchase analysis software separate from Zephyr).   It is a advanced performance monitoring device with internal memory capable of  the following (from their user manual):

  • Heart Rate 0 – 240 BPM (±1 BPM)
  • Breathing Rate 0 – 120 BPM (±1BPM)
  • Device Temperature 10 – 60°C (±2°C)
  • Position/posture ± 180°(Laying, standing)
  • Activity in VMU (Stationary, walk, run)
  • 3 axis Acceleration to 16g
  • Red / Orange / Green subject status indication
  • Transmit and/or Logging Modes
  • 250Hz ECG Transmission & Logging
  • 100Hz Accelerometer Logging
  • USB connectivity for data download & charging
  • Up to 500+ hours data storage
  • Internal algorithms for
  • Estimated core temperature
  • Jump Test
  • Dash Test
  • Fall detection
  • Heart Rate Variability
  • Human Real Data

The Process

I decided to take an HRV reading every morning before eating or drinking in order help ensure my physical state was similar for reading consistency.  Both SweetBeat and BioForce products sample your HRV over a period of 2-3 minutes of monitoring then give you a HRV score, the higher the score the more chances your parasympathetic system is in control – the lower the score the more chances your sympathetic system is in control.  In other words, if you have a low score your body might be under some stress (illness, recovery from training, stress, etc) and it may be worthwhile to allow your body to recover before pushing a hard training session.  Whereas, if you have a high score your body should be under relatively low stress and you can plan a harder training session.  Here is some further reading on Heart Rate Variability.

I would take a reading on SweetBeat then take a reading on BioForce, altering days of which product I use first.  I took this reading everyday for 30 days to see if it would give me some insight to how I should be modifying my training according to what my autonomic nervous system is telling me.  I didn’t used the BioHarness for this every morning sampling, but rather used the BioHarness in a more extended 24 hour test.

Here is 30 days represented on the BioForce HRV portal.  Green is supposed to indicate good to go for training, orange to red is supposed to tell you to take a recovery day.

Screen Shot 2013-10-07 at 8.34.01 PM

Here is 30 days represented on the Sweetbeat App.  Sweetbeat doesn’t have the best online portal or capabilities for tracking / trending, but they do allow for a data download so you can do your own analysis.  And honestly I wasn’t expecting too much from a $4.99 app either.



With regards to the BioHarness, again I didn’t do point in time sampling with the BioHarness.  I leveraged the BioHarness to collect data over multiple 24 hour periods to do some deeper HRV analysis and compare to point in time sampling.

So, that’s the setup.  In Part 2 I’ll dive into the numbers and my training decisions compared to the HRV readings, so stay tuned for the results!