A New Calculation Uses Heart Rate Variability to Better Tune DFAA-1

I’ve been a big fan of Dr. Bruce Rogers, since 2017. He is a trained MD, but publishes his work in credentialed journals. As a Masters’ level road cyclist, he knows how important heart health is. He is also fully aware of the cardiac risks to endurance athletes. This is why I am impressed with his latest work.

Dr. Rogers began to convince me that DFAA-1 had merit as a non-invasive way to calculate HRV equivalents to Ventilatory Threshold 1 (VT1) and Ventilatory Threshold 2 (VT2), around 2021, when Covid-19 was affecting afflicted athletes. As a Coach, it’s my duty to help my cyclists improve their health and fitness, but in a Holistic way.

Some of you may know that in 2016, a client and I had to perform CPR on another client (he lived). In 2023, a client of mine suffered a heart attack just after a remote class. He also lived, but both are events I never want to see repeated.

In fact, I have changed most of my protocols to include heart-healthy workouts. DFAA-1 is a new way to help everyone ride what I’ll call “Smart” aerobic base. At more intense levels of work, DFAA-1 can help identify ‘Threshold’ on a metabolic, Physiological level, instead of power. Power (watts) is just too immutable, and does not account for myriad other factors that lead to less accuracy in assessing proper intensity.

The ‘Limit’ for DFAA-1 At VT1

Now, remember – the calculation behind this technology is still nascent, but the application is fast-evolving. In 2021, research showed that a DFAA-1 of around 0.75 was fairly close to Ventilatory Threshold 1, or, the point of intensity at which our bodies begin to generate lactate at a higher rate, and thus, use more carbs in in our fuel mix. The original paradigm also set VT2, or the point of intensity at which our bodies begin to create more lactate than can be sustainably processed while staying aerobic, was around 0.5.

Well, the latest research paper from Dr. Rogers shows that there might be a better calculation for DFAA-1 at VT1.

The New Calculation for VT1 via DFAA-1

The goal of this study was to come up with a more accurate way to synchronize heart rate variability, and Ventilatory Threshold 1. What the researchers ended up doing was the following:

1. They looked at the HIGHEST recorded DFAA-1, usually during warmup or recovery, but it could also be done at rest.
2. Take this HIGHEST value (in my case, it’s about 1.8), and then ADD the more-traditional value of DFAA-1 at Ventilatory Threshold #2, which is 0.5. The result, in my case, is 2.3.
3. Use this new Value (2.3), and divide it by 2. The result, again, in my case, would be 1.15.
4. Use this last value, again, in my case, 1.15, and use THAT as the ‘more accurate’ value for VT1.

When a cyclist or a runner stays ABOVE the new value, they’re working aerobically. Thus, the majority of the gains would be synonymous with the now-ubiquitous ‘Zone 2’ or ‘Base’. Heck, I knew it as ‘LSD’, or Long, Steady Distance, from my days under the tutelage of Sally Edwards and Dr. Ken Cooper (at different times).

Testing the Metabolics of HRVT1

My clients at my VQ Velocity Virtual Studio are now heavily invested in training with DFAA-1. We have mostly installed the Garmin Connect IQ Field known as “AlphaHRV“, which takes Heart Rate Variability, and calculates DFAA-1. It is accessible within the Garmin Connect ecosystem, displays in real-time, and gets saved in .fit files for post-ride analysis.

I accessed the settings for AlphaHRV within Connect IQ, set VT1 at 1.15, set VT2 at 0.5, saved the settings, and then began my ride with my clients. For 20 minutes, I rode with my Vo2Master mask and Moxy Monitor on my body, while HRV was transmitted by a Polar H10.

Here are the results:

Honestly, I am MIGHTILY impressed.

• At 170 watts of power, DFAA-1 averaged 1.34. This is above the 1.15 value I calculated for myself. Ergo, this 20 minute time span was SAFELY within the AEROBIC level of intensity.
• SmO2 on the Left Lateralis averaged 39%. This dovetails into over 10 years of data collection for myself and clients. For me, 40% is a known ‘Safe’ value for VT1.
• Vo2 was measured at 38.56ml/kg/min. In the previous two posts, I measured my Vo2Max at 62 or 63ml/kg/min. This value, at 62% of Vo2max, is, Safely within my Aerobic Training Zone.
• Traditional Heart Rate averaged 136 beats per minute. Earlier this year, I performed a traditional Vo2max test, and the assessment from Vo2Master’s in-house software, showed my VT1 heart rate at roughly 140 beats per minute. Again – 136 bpm is Safely within my Aerobic Training Value.
• The last two metrics, AlphaHRV’s Respiratory Rate, and Vo2Master’s Respiratory Rate, are values that I included so that I could effectively determine whether the AlphaHRV ‘RR’ calculation was accurate. As you can see – it’s spot-on.

A Note About AlphaHRV On Garmin Connect:

Just a quick note: AlphaHRV includes an option for the RESPIRATORY RATE of VT1 and VT2. Now that I know I can breathe at 26 breaths per minute and stay at or below the intensity for VT1, I’ll set it at, say, 27 or 28 breaths per minute, as another Affirming Metric for ‘Base’ training.

Conclusion

DFAA-1 Continues to reveal more about the human heart and new methods by which measuring HRV can lead to a more scientific approach to cardiac health and fitness. My clients and I are employing AlphaHRV to ever greater effect as we settle into several months of mostly “Base/Zone 2/LSD” training, to give our hearts and bodies a rest, and prepare ourselves for another season of Tempo, Threshold, and Vo2 intervals in 2025. This should result in more fitness capacity over greater ranges and durations, which I hope will lead to more adventures on two wheels, for everyone under my umbrella at Online Bike Coach.

Thanks for Reading, and

ENJOY THE RIDE!