As I was writing this I realized I did not want it to be a “woe is me” story. I confess I do slip into that mindset occasionally. Who wouldn’t? Then I decided not to make it an advice piece about rising above adversity. There is already plenty of that out there. So, my focus here is more like plain, unembellished news. You can blame me if you fall asleep reading this.
Last spring, after I finally got a diagnosis for my heart arrhythmia, I picked up a Frontier X heart rate monitor. Frontier described it as a continuously monitoring EKG. (I prefer EKG over ECG and since they mean the same thing I will stick with EKG even though Frontier uses ECG.) I thought this would be an improvement over my Kardia EKG, as that one requires me to sense I have a problem, stop, fish out the device and get it synced to my phone. By the time I get a recording my heart rate has dropped to near normal.
There were times in the past when my HR would shoot sky high on a training run, but since 2019 it has been less volatile, and only turned up while racing. I did not bother to carry my Kardia for the 2022 Honolulu Marathon, which I abandoned after eight miles due to high HR and fatigue. Having learned my lesson, I carried it on a 10k and ran hard on purpose. Sure enough, I finally got a strip (a recording) that revealed Premature Atrial Contractions (PACs).
I started using the Frontier X hoping to find the conditions most likely to trigger PACs, so that I could avoid them. I soon realized that my heart is not so simple. Frontier does not recognize PACs per se, it only distinguishes between normal and abnormal heart rhythm. Every abnormal heartbeat is marked on the HR chart with an “O” for “Other.” Each recording is scored by percentage using three categories: Normal, Other, and Noise. Since we know that my arrhythmia is in the form of PACs, the Other value is a good measure of PAC activity. For most of my workouts the Other value runs 5%-10%, occasionally 25%. I don’t feel any difference, and my HR looks reasonable.
On my bike ride last Sunday, I had what got me to the cardiologist in the first place, a sudden increase in HR to a crazy high level. My cardiologist, Dr. John Cogan, called it supra-ventricular tachycardia (SVT) and had me start carrying a Kardia portable EKG. He also switched my calcium channel blocker meds to Diltiazem, which can help regulate SVT. Ever since then I have not seen sudden and extreme SVT. Not until last Sunday. Again, my HR was high for the marathon and the 10k, but not crazy high, and not suddenly high. Well, except for the marathon, it shot up when I started running at my goal pace, just past Nuuanu St. High, but not crazy high. And that time I felt it. Weak and dizzy.
The Frontier X has an alert feature. You can set two, for heart rate (how fast the heart is beating) or heart strain (how hard the heart is beating, based on the intensity of the trigger voltage). I have one set to go off when HR hits 151, because 150 would be a doable but very high run effort for me. When the alert is triggered the chest senor vibrates, and a red mark is saved on the recording. I also set one for strain, at 0.23 mV, but I have no idea if that is meaningful. It never triggers. I guess I could lower it until it does. A feature probably aimed at weightlifters, where heart strain is a thing.
Last Sunday was a low intensity three hour ride, starting from Waihee Park just past Kaneohe and going north for ninety minutes or so, which typically means turning around at Punalu’u Park. (“A three hour ride.” I sense a Netflix show based on that.) I like this route because it is relatively flat, with plenty of nice scenery. I just wish the road was better. I stopped roughly an hour in for a nature break at Swanzy Beach Park. Not too much farther up the road I felt my chest buzz. My Frontier had triggered an alert. Weird. I had some alerts on my long, hard climbs up Pineapple Hill, but I was riding those at high intensity. On Sunday’s ride I was just cruising along, 100 BPM, when all of a sudden, bzzz. 150? No way.
I checked my Garmin head to see what it showed. Zero. I was dead. No, the Bluetooth signal from the Frontier cheat strap had been lost. I decided I must have been hit by some powerful radio signal. RFI. It happens. It couldn’t be my heart, could it? Not at this pace. There are some massive antennas next to the Kaaawa 7-Elevin. Must be related. I just kept going to Punalu’u, where I stopped my Frontier X, started a new session, and resynched it to my Garmin. Worked fine.
Back on the road, headed back to Kaaawa, it happened again, only this time my Garmin did not give up. Instead, it displayed HR in upper zone five. It had been hovering around two all morning, where it was supposed to. I felt fine, so I kept going. HR back to normal. It happened again. I thought about stopping. A 54 bus passed me. I realized I would not be playing my bus pass card because the next bus would be a long time coming. I felt fine, so I kept going. Dr. Cogan had assured me I would not keel over. (Spoiler -- he was right.)
In order to see any details from a Frontier X session you must upload the recording, first from the chest strap sensor to the phone, and then from the phone to the cloud. The cloud-based app analyses it and prepares a report. The entire process can take as long as an hour. I ended up with one chart from the Garmin and two from Frontier, before and after Punalu’u. There is a portion of the Garmin chart with no HR data, but there is good HR data in the Frontier report. I do find it awkward to correlate one to the other.
The periods of high HR show a sudden increase, a sustained section, then a sudden decrease. The highs reach about 165 BPM. Exactly what was happening way back when this all began, when I thought I had a faulty chest strap or there was a problem with my singlet. I used to clean my chest with rubbing alcohol in hopes of getting a clean signal. It wasn’t the hardware. It was me.
Recall how Frontier computes the percentage of good, bad, and ugly? Normally I get 5%-10% Other. Sunday’s first report has a good/bad ratio of 34/66. That’s right, awesomely bad. And the HR chart is nearly solid with “O” marks. Never saw that before. The second report was slightly better, 50/50, but that is still terrible. So, significantly more PACs than usual, virtually continuous, and three periods of rapid HR. Very, very strange.
The above clip shows the end of the first hour of the ride, up to the point I stopped it in order to reconnect to the Garmin. The graph up to this point looks the same. HR was between 90 and 110, normal easy cruise for me. You can see where the heart rate line suddenly rises to 159 , just before and after it was 95. (In later spikes it went higher.) Also note the constant flood of "Other" flags. The EKG strip at the top of this page, from the same sample but stating in the rapid HR section, shows the abnormally sudden transition from high to low.
To summarize, Sunday's ride produced two new issues. A flood of irregular heart beats so continuous it begs the question, what is normal? That, and three episodes of sudden onset rapid heart rate. Not the first time seeing this, but unseen for several years and never before recorded.
Sorry if I am starting to sound like Josh Gates, or an episode of Ghost Hunters.
On Tuesday I did a short but high intensity workout as prep for a time trial test on Wednesday. Warm-up, then 2 x 1:30 in zone four with 3:00 recovery. Rhythm score was 76/24/0. The time trial followed my standard protocol, warm-up, 5 min all out, 10 min recovery, 20 min maximum effort. For that the score was 74/26/0. Virtually the same, and totally different from Sunday. High, but in still in my normal range.
As a result of all this I find myself in a continuous game of mindset ping-pong. I contemplate what races I want to do. Another marathon. Another Ironman. Then I realize that my heart might just put those ambitions beyond reach. As a coach I am conditioned to think that with proper training anyone can improve. I am currently in the middle of an FTP raising exercise. Will it improve? Or will my heart get in the way? For now I will keep going, and will know more in a couple of months.