One topic we have not explored is the effect that ramp slope (rate of power/speed increase) could have on the HRVT (1 and 2). Ramp slope does not appear to have a major effect on gas exchange parameters such as the VT1 or VO2 max, but it does affect corresponding cycling power (and muscle O2 desat). The idea behind this issue is that there is a lag between what is going on in the muscle and the associated ventilatory metrics. However, since HR is usually a linear function of VO2 (up to the VT2 at least), HR at the VT1 appears to be an accurate measure. Does that apply to the HRVT as well? On one hand there may be a lag in autonomic balance, causing a delay in a1 drop with a quick ramp. In addition, we are looking at 2 minute window sampling in a1 computation, another potential area for lag in response. However, it would be nice to have a shorter test to obtain readings for many reasons. Therefore I decided to do a 30w/minute cycling ramp instead of my usual 5w/minute standard. In addition, the end ramp power was planned to be well above the MLSS (but not to exhaustion) to make sure the a1 drop was sufficient. As in previous tests, time of day, sleep, nutrition, temp, fan, cycling gear were all similar. The 5 w/min ramp was done from 130 to 230w (20min) and the 30w/min ramp from 100 to 340w (8min).
Standard 5w/min Ramp:
- Both ramps have near linear HR rise (and hence VO2 increase).
- The 5w/min ramp did not have the low nadir DFA a1 seen with the 30w/min ramp - as expected since the short ramp was done to MLSS+.
- Despite the huge difference in ramp slope, both HRVT and HRVT2 were very close in each case.
- The HRVT is usually what I see when fresh, without fatigue. The HRVT2 HR is a bit on the low side (should have been about 156 bpm). Recall from our study that the limits of agreement are wider at the HRVT2, but in line with those of other comparative methods of MLSS (muscle O2 desat and critical power).
- Although this is N=1 early data, it may be possible to get an accurate measurement of the HRVT HR with shorter ramps. For those of you comparing HRVT over ramp slopes, I would love to hear of your experiences.
- HRVT power should not be inferred with steep slope ramps, instead use the 5w/min or even constant power intervals for that.
Heart rate variability during dynamic exercise
- Firstbeat VO2 estimation - valid or voodoo?
- Heart rate variability during exercise - threshold testing
- Exercise in the heat and VO2 max estimation
- DFA alpha1, HRV complexity and polarized training
- HRV artifact avoidance vs correction, getting it right the first time
- VT1 correlation to HRV indexes - revisited
- DFA a1 and Zone 1 limits - the effect of Kubios artifact correction
- HRV artifact effects on DFA a1 using alternate software
- A just published article on DFA a1 and Zone 1 demarcation
- DFA a1 vs intensity metrics via ramp vs constant power intervals
- DFA a1 decline with intensity, effect of elevated skin temperature
- Fractal Correlation Properties of Heart Rate Variability (DFA a1): A New Biomarker for Intensity Distribution in Endurance Exercise
- Movesense Medical ECG V2.0 Firmware brief review
- Movesense Medical ECG - improving the waveform and HRV accuracy
- DFA a1 and the aerobic threshold, video conference presentation
- DFA a1 - running ramp and sample rate observations with the Movesense ECG
- DFA a1 calculation - Kubios vs Python mini validation
- Frontiers in Physiology - Validation of DFA a1 as a marker of VT1
- Real time Aerobic thresholds and polarized training with HRV Logger
- Active Recovery with HRV Logger
- DFA a1 and exercise intensity FAQ
- DFA a1 agreement using Polar H10, ECG, HRV logger
- DFA a1 post HIT, and as marker of fatigue
- DFA a1 stability over longer exercise times
- DFA a1, Sample rates and Device quirks
- DFA a1 and the HRVT2 - VT2/LT2
- Low DFA a1 while running - a possible fix?
- Runalyze vs Kubios DFA a1 agreement
- DFA a1 - Runalyze vs Kubios vs Logger results in a cyclist
- Best practices for Runalyze and DFA a1 thresholds
- ACSM - HRVT validation in a cardiac disease population
- FatMaxxer - a new app for real time a1
- Another look at indoor exercise without a fan
- ECG artifact strips from Fatmaxxer - a guide
- ECG arrhythmia and artifact visualization tips
- DFA a1 as a marker of endurance exercise fatigue
- To train hard or not, that's the question
- DFA a1 HRVT and Ramp slope