Like anyone with an illness I’d like an easy answer, followed ideally by a simple cure.
The simplistic medical answer seems to be that the flow of blood to my brain was interrupted so I fainted but why?
My heart rate was high, but falling. It wasn’t unusually high, it had been 5% higher 10 days previously when sprinting up a hill at the end of an 88 mile sportive. It was probably high for a longer time than usual, which may be important. My Garmin was showing a lower speed than I was actually travelling so this may have made me not realise how hard I was pushing until it was too late. (I have since looked at the setting for wheel size on my Garmin, which I had set at automatic but was turning out a lot smaller than on my other bikes, despite them all being 700c. This seems to have resulted in a speed of 22mph being displayed as 18.4mph).
It was easy to discount some of the obvious factors that people suggested. I had breakfasted, hydrated and breakfast included a banana so some of the obvious boxes were ticked. On the other hand, I probably hadn’t had enough sleep and was a bit stressed.
I probably didn’t reduce my HR quickly enough, maybe partly because of the speed under-recording I’ve mentioned. While I use an HRM I haven’t used it in a scientific way so far. British Cycling suggest reducing intensity to Z1-Z2. I don’t really know my zones but Strava reckons that would be 96-136 bpm which suggests I should have cut back a lot more than I did.
So far, I think the conclusion is eat, drink, sleep, listen to my body more than my Garmin, and back off more radically. However, I don’t think that’s enough. It’s not as if I missed a PB or ended walking up a hill. I actually fainted and fell off my bike while riding it and broke a bone. The consequences could have been far worse and I don’t want a repeat.
So , tomorrow I will see a GP with a view to getting a referral to a Cardiologist. I’ve been helpfully advised to try to get a cardiac echo, a 24-hr ECG and perhaps even a treadmill test to be on the safe side for future training. Apparently I don’t want this to have been an exercise induced arrhythmia… he says desperately pasting into google.
I did have the all clear on an ECG and CT brain scan in A&E but I think was more to ensure I wasn’t about to drop dead rather than the diagnostic I want.