I understand. I already use something like this from Garmin… Performance Condition. At this point I can guess my PC based on how I feel that day. Firstbeat technologies are good when you provide good data in my experience.
I recommend spending several weeks playing with Kubios free (or learn rhrv) and practice working with RR intervals if you haven’t. If you’ve been collecting hrv data during workouts and ramp tests, you already have a data set to work with.
Funny HRV story. I follow my HRV daily. I was off the bike last week for three days due a family trip out of town. Since I was rested, I thought I’d treat my Saturday group ride like it was a race meaning that I’d do openers and all that. On Wednesday I did some 2-3 minute threshold intervals. I put in 1.5 hours. The rest was easy Z1/2. Thursday I did a super easy 30 minutes on the trainer. Friday called for openers. I did 3x45 second intervals and one 17 second max interval because I was going for a KOM. I maybe have over done it by a touch here.
My HRV score had been trending up all week and my resting heartrate was going lower and lower indicated that I was well rested.
This morning (Saturday) I check my HRV and it has tanked after the openers and HRV4Training tells me to take it easy. 
I did the group ride anyway and rode well. I broke a bunch of power PRs. I can’t say that I was on fire or anything from those openers.
For me this means I am more tired and not more rested. When I am extremely tired my resting hr is tanking. My lowest resting hr is usually during vo2 max block
I always wonder why people tie so rigorously HRV and previous training sessions. Almost like there was vacuum in between their training session and the next HRV measurement, like those other 23 hours don’t impact their sympathetic/parasympathetic nervous system at all.
I mean no one has ever said HRV score is a proxy of a state of your leg muscles. Your muscles could be primed up yet your HRV low for many reasons not connected to just training.
The Tale of Two Readings. I compare my HRV using two different apps (using Wahoo Tickr.) Yesterday, after 4.5 hours of sleep, Elite HRV read my HRV at 73, while I’m normally around 50. It rated readiness at 3, due to elevated parasympathetic activity. Another app, Kubios, rated my readiness at 99% - a number I’ve never seen before. Both apps had similar RMSSD and SDNN, which are the only two data points I usually look at.
My TickR combined with my Garmin records HRV but I’ve got to manually locate, start it and stand up/still for 3minutes I can’t see its worthwhile to do often 
“Heavier” alcohol consumption (3 glasses wine/women, 4/men) can affect HRVFrom NY Times on the effect of alcohol on the heart:
The researchers found that when people drank moderate amounts of wine, their nighttime heart rates rose by 4 percent compared with when they did not drink alcohol. But their heart rates returned to normal in the morning hours. When people drank heavier amounts, however, their nighttime heart rates spiked 14 percent and remained elevated into the morning. The study also found that alcohol, especially when consumed in higher amounts, temporarily lowered the participants’ heart rate variability, a measure of the variation in time between heartbeats. A higher variability is generally a sign of better cardiovascular fitness.
Blockquote
In my experience, I get more like a 25% increase if I’ve drunk a lot.
I don’t know if it’s my body trying to burn it all off or something, but you can see it pretty obviously in my overnight (sleep) heart rate data.
No better than a mood ring.
HRV can be a worthwhile data point but not all apps are created equal. I recently had a really poor night’s sleep of 4.5 hours. EliteHRV recorded an HRV of 73, extremely high for me, but rated readiness as 3 (out of 10) due to parasympathetic reaction. Another HRV app rated my readiness at 99% - a level I’ve never seen before – based on the same day’s readings.
I have installed Elite HRV for Android and got a new Garmin HRM dual strap (my other two straps were in a very sorry state and ready to be retired).
I got my first HRV reading today in the morning, and I think I like the process and the insights it can give you if you feed it enough data. Too early to tell if it’s really useful…
Intervals.icu now imports the csv file that HRV4Training saves on Dropbox. Handy for people using HRV4Training and wanting to graph HRV along with load and other training metrics.
So use a strap that is known to not be that accurate at recording hrv and assume the calculations produced by it are good? (See the recommendations of which strap to use for DFA alpha 1)
I think that Tickr was approved by EliteHRV, which is app I’m using. I don’t understand DFA Alpha 1 but will go back and review. Thanks.
I have found multiple tickrs to be completely useless for measuring DFA Alpha 1, and purchased a Polar H10 which works nicely. The number of ‘artifacts removed’ in the HRV logger app with the Tickr makes the results totally useless.
What is a good watch/bracelet to tracking HRV? I like the smaller watches/bracelet because i have small wrists.
Unfortunately wrist based wearables aren’t much good for HRV. They aren’t accurate or sensitive enough for the metric. Apparently though the Oura ring is ok for taking measurements for general health etc. It can also link automatically into the HRV4 training app. If you want to use HRV for monitoring DFA/Alpha1 you are pretty much stuck with a Polar chest strap. Or an ECG machine 
Can second this. TICKR was awful for HRV, so I bought the Cor(e?)sense thing… which was better, but still not great.
Bought a H10 last week and the values have been rock solid. Don’t think I’ve seen a single artefact or strange reading.
I’m using Apple Watch 4 and morning readings (using Mindfulness app) to feed HRV4Training for daily readiness estimates. HRV4’s Marco Altini has a blog post on the accuracy (it is very good!), and the need for only 1 reading at the same time each day (when I wake up). During workouts my Garmin 530 and chest HRM provide real-time reporting of HRV relative to recent baseline.
What do you want from HRV?