Originally Posted by
Symtex
I am unable to train at any other zone but 4 or 5. When I jump on a bike, I have to spin. My cadence is around 70-80 and that take my HR to at least Zone 4. I'm 41 years old so that means around 145-160 bpm. I want to train to do longer distance but I am uncertain how I will achieved that. I would have to reduce my cadence in the low 50's to get low enough and that would reduce my speed to below 20km/h.
I'm 43 with an aerobic threshold around 140 bpm and lactate threshold heart rate of 168 which would make Friel Z4 158-168 BPM.
Ride as hard as you can for half an hour at a steady pace. At the end you should have nothing left. Try a few times until you get that right. Your lactate threshold heart rate is the average over the last 20 minutes (it takes a while to catch up to your output)
Friel starts Z2 at 81% of that, Z3 at 90%, Z4 at 94%, and Z5a at 100%; although you'd be better off using your aerobic threshold AeT (where conversation doesn't flow, breathing becomes rhythmic, and lactate starts to accumulate. It's about what you can manage for a 5 hour steady-state effort with an even split) as the limit for endurance training.
Perhaps not coincidentally, AeT heart rates are close to what Phil Maffetone's formula spits out.