Heart or Legs?
I attribute my level of fitness to having to commute by bike. My short cycle on the Brompton at least four times a week is the equivalent of interval training.
Racing between traffic lights, I push myself as hard as possible until either my legs or my heart rate scream at me to stop and only when I reach a red traffic light do I give myself time to recover.
Early in the week, after an endurance pedal on the Sunday, my legs are normally the first to scream loudest. But by the end of the week my legs tend to have recovered and I then find I reach my maximum heart rate, like bouncing off a rev limiter in a car.
This week, my legs are grumbling more than usual even though I only rode 70+ miles on Sunday. I suspect that when they begin to recover I will hit a different limit - over heating!
The English temperature has fallen and my merino wool jumper now adds another layer beneath my high-viz, (no longer) waterproof jacket. If it gets colder I have a BaaBaa merino beenie and full finger gloves but at the moment the jumper is proving fine for the mornings and a tad hot in the evenings.
Changing the subject - I stopped behind a wide vehicle whilst recovering (from hitting my periphal physiological limit) at a set of traffic lights and photographed the haulage operator's attempts to mitigate the risk of cyclists undertaking at junctions...