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Testing For DFAa1 to Determine Lower Threshold Power

The DFAa1 Ramp Test Helped Me Set A More Accurate Lower Threshold Power

The DFAa1 Ramp Test is a protocol that shows cyclists where their bodies begin to change biologically when under strain. It uses Heart Rate Variability (HRV), and I have studied it since at least 2004, when I wrote a pocket book for Suunto for their T6 watch. The absolute distilled version of Heart Rate Variability says, “The heart is beating when it wants to, vs. beating when it has to.” In other words, no two beats are the same. A stochastic heart rate is a happy heart. A consistent heart rate is a strained heart.

When the Strain of heart rate contractions reaches a value of around .75, then it’s time to look at the actual heart rate itself, as well as the power being generated by the cyclist. With that value, we then have a much better idea of a cyclist’s Lower Threshold Power.

Why is an Accurate Lower Threshold Power So Important?

Lower Threshold Power is the KEY to POLARIZED TRAINING. When a cyclist is riding below their Lower Threshold Power, they’re teaching the body to become more economical. They’re teaching the body how to improve STAMINA. They’re teaching the body to BURN FAT. Over time, with regular testing and Progression, the DFAa1 test can reveal economy at higher heart rates, and higher wattages. If you believe in Polarized Training, then it should be 80-90% of your overall training volume. But ride too hard, and the gains are not as solid.

I’ve been using the Fitness Signature Values from Xert for years, which include a calculation for Lower Threshold Power. Lower Threshold Power can be found via a Lactate Test, a Vo2 test, and through the use of a Moxy Muscle Oxygen Monitor, but all of these are expensive, all of them have margins of error, and the Lactate Test is invasive.

Having a modern heart rate chest strap that can calculate HRV, and using a cheap app to reveal the data, provides everything we need to know, for less than $100usd.

What is the DFAa1 Test?

My friend and fellow coach, Richard Collier, of London, UK, was the first to really compel me to attempt this test. This is his protocol, based on conversations with Dr. Bruce Rogers, Marco Altini, a professor in Japan, and the developers of the www.runalyze.com website in Germany.

I have since named the workout after Richard, in my Xert Workout Library.

It’s a simple ramp test, from 55 to 105% of Threshold Power (NOT Lower Threshold Power), over 24 minutes and 30 seconds.

What do I need to test?

We begin by setting our Garmins up to record HRV via BLE.

To begin, go into your Garmin head unit settings, and press “System”.

Garmin 1030 System Page
Start by going into the “System” page on your modern Garmin.

Then press “Data Recording”.

Garmin 1030 Data Recording Page
Select “Data Recording”

Set ‘Recording Interval’ to ‘1 Sec’. At the bottom of the page, you’ll see “Log HRV”. Turn that feature ON.

Garmin 1030 Log HRV Page Setting
Set ‘Recording Interval’ to 1-sec (always do this), and set ‘Log HRV’ to ‘ON’.

Next, make sure you have one of the preferred BLE Channel Heart Rate Chest Straps.

Go back into “Settings”, and press “Sensors”. Then press “Search All”.

Garmin 1030 Search All Sensor Setting
Press “Search All”. – You MIGHT have to turn the Garmin off and then back on again to catch the BLE signal.

And just WAIT.

It SHOULD give you a “BLE” AlphaNumeric Identifier. Select that, save it, and you’re good to go on that part. Remember – you do NOT want the ANT+ version of the signal. You want the BLE.

Garmin 1030 BLE Chest Strap Discovery
This takes time, and it may require a Garmin reboot. Go with the Polar H10 HR strap, or the Garmin HRM Pro strap. I also love the 4III’s Viiiva strap.

Next, go ahead and download “HRV Logger”, from either iOS or Google Play on Android. It’s a good backup and it will visually help you ‘see’ where this 0.75 fraction exists.

DFAa1 HRV Logger by Marco Altini
The DFAa1 HRV Logger by Marco Altini and ASMA gives you a visual display of your DFAa1 Fraction, as well as providing a great backup data source. ALWAYS BACK UP YOUR DATA!

Finally, go ahead and buy a one-year subscription to www.runalyze.com. Believe me; if you can spend $10/mo on a training platform, $12 for an app on a phone, and NOT spend $$ on a coach, then the $30 you’ll spend on Runalyze, just for the DFAa1 interpretation, is well worth it.

OR, you can do the test and send me the data, which is what most of my clients do, and I’ll run it through everything for you.

The DFAa1 Test and Results (for me).

Thus far, I have performed three DFAa1 tests. Here are the results:

Richard Wharton Xert DFAa1 HRV Test
There’s not much to see here – just a standard ramp protocol with heart rate included. If I were using the old school method of trying to identify a deflection point for THRESHOLD, not LOWER THRESHOLD, I’d guess 172-175 bpm. But that’s NOT Lower Threshold. So let’s see what Runalyze shows.

This is one of the tests, performed in late May.

Here’s the HRV data from www.runalyze.com:

Richard Wharton Runalyze HRV DFAa1 Test Results
Some important notes here: 1) Set ‘window overlap’ to ‘115’. 2) Click to ‘Heart Rate’ and look for high validity and low artifacts. 3) Look at the Heart Rate first, and then think ‘When was the last time I rode a bike based on my Heart Rate?’

And here’s the Power…

Richard Wharton Runalyze HRV DFAa1 Test Results
Note: Lower Threshold Power = 172 watts. This was in late May of 2021, when I was first experimenting with DFAa1 testing.

Now – here’s the data that I just got from a test run on Sunday, June 27th, after two weeks of consistent 75 XSS training, and an emphasis on staying BELOW my Lower Threshold Heart Rate (and Power)…..

Richard Wharton DFAa1 Late June 2021 Heart Rate
HR for Lower Threshold went from 147 to 158, a 7% rise.

And here’s the Power…

Richard Wharton DFAa1 Power reading late June 2021
Note the ‘mounds’ of dots on the first half of the image. Remember the mantra from 2004: “It beats because it WANTS TO, vs. beating because IT HAS TO.” This is that value, visualized. Power at Lower Threshold rose from 172 to 205w, a 16% rise.

CONCLUSION: Use the DFAa1 Collier Ramp Test on a regular basis to help your POLARIZED Training.

In order to keep this short enough, I’m going to stop here. Next post, however, I’ll show you the Vo2master data from these rides. I’m riding for 75 XSS BELOW my DFAa1 HR, but my NORMALIZED WATTAGE keeps RISING!

It’s literally a ‘more watts per beat’ situation, and I am really loving it.

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Like what you see in these posts? Why not take the next step? Coach Wharton is currently accepting new clients for both Xert and PerfPro training methodologies. He is also available to discuss specific questions or equipment/training issues—just  schedule an online video consultation.