Originally Posted by
ColinL
'hammering' and 'cruising' are just adjectives... instead let's talk about the duration you can be at these HR zones regardless of whether you feel great, crappy, or in between.
if you can ride zone 5 for an hour you have good cardio, muscle endurance fitness and the ability to withstand pain. if you can ride zone 5 for 2 or more hours, your HR max is probably wrong as I noted above... or you're destined for greatness.
If you can ride in Zone 5 for an hour you're defining your zones wrong and if it wasn't physically painful they're way off.
Functional Threshold Power is the maximum power you can average over one hour and occurs approximately where your body is making lactate faster than it can get rid of it.
With the most accepted zone definitions (from Friel) zone 5 is at least 100% of that.
Basing zones off maximum heart rate is useless because assuming you know your actual maximum heart rate the fraction of it at which you reach your lactate threshold varies both with individuals and training.
Unless you've done a formal test (started pedaling at a comfortable 200W and added 20W/minute until your power is increasing but your heart rate isn't) you don't even know what your maximum is.
The 220-age formula is even more worthless useful since it's an average with a standard deviation of 12. 34% of 20 year olds would have a maximum between 200 and 212 and another 34% 188-200. 14% of 20 year olds would have a maximum of 212 - 224 and 14% 176-188. A few would be in the range 224-236 or 164-176. Zone definitions built around the average could have you not working at all on your hard days or in a permanent state of overtraining.
The right thing to do is get warmed up and ride as hard as you can for half an hour. Your average heart rate over the last 20 minutes is a good approximation for your lactate threshold provided that you remain motivated enough.
Chris Carmichael has zone definitions built around your heart rate in the second of two all-out eight minute efforts with a prescribed warm-up. That's easier to accommodate both psychologically and logistically.