I've never heard of zone 5 before....sounds like you do fine regardless!

What was your time? What was your HR? DO you run all your runs at that rate?
Zone 5 for you would be around 185bpm. That is high if you can maintain that for 1.5 hours.

Generally zone 5 is an anaerobic zone which will end up burning muscle before fat for fuel once your carbs are gone. Zone 5 training generally is for intervals and sprints followed by resting periods or recovery jogs.

More power to you though if you can maintain it for a half mary.

Here are zones from Gale Bernhardt's Training Plans for Multisport Athletes. I think these are more realistic. A great book even if you read just the section on hr zones and training.
Here's an example of how the zones breakdown in her book.

Assuming running lactate threshold of 180

z1: 119-153
z2: 154-163
z3: 164-172
z4: 173-179
z5a: 180-183 LT
z5b: 184-190 Anaerobic endurance
z5c: 191-199 power

Hi Toni,

How did you test your zones? No athlete could possibly maintain zone 5 for that duration, so you need to develop another method. Each zone is optimal for stimulating certain adaptations nd we need to blend them to make all the changes that will enble us to bring everything together on race day. Ken Fitness-Concepts.com

Like Ken says guys, I have to agree with him. You have to establish your HR max and then your anerobic threshold (or vise versa). Sounds like you have a higher HR max than you thought and likewise your anerobic threshold is higher as well. There is no way you could have done that distance in a zone 5. You should conduct the proper tests and find out what your levels are. Its an individual thing based on your aerobic ability. Look at the article on the trifuel web page:

http://www.trifuel.com/triathlon/heart-rate-training/index.php

Read it and try some tests on yourself.

Libor

PoC, I agree! Personally I've never seen anthing close to a 190 bpm and certainly cannot stay at anything over 180-183 very long at all. I realize that everyone's HR and LTRH vary, but as Chris mentioned the HR monitor may have been off.

I'd try using the HR more to determine if it's accurate.

Thanks for sharing the HRs about when we exercise but it doesn't make much sense to any of us unless we know your HRmax. A 24 yr olds HRmax 'theoretically' is 196 where as a 40 year olds (like me) 'theoretically' is 180. We all (should have) higher HRmaxs though. My point is while catwoods 180bpm (if she is 18yrs old) would be 90%. Mine at age 40 would be a slower 162. BIG DIFFERENCE! Speaking in % HRmax would be more understandable for two reasons 1) we all should have higher that the theoretical HRmaxs and 2) we all are different ages. Am I wrong in this thinking?

Everyone is different ... the 220 minus age formula is accurate for the average of a population, but a single standard deviation is +/- 12 bpm. Athletes with lower HRs have larger left ventricals with thin walls. They can pump a lot of blood per beat, but cannot empty the chamber quickly. Those with high HRs have smaller chambers, but thicker muscular walls which empty quickly, but with a lower stroke volume.

Cardiac output is HR x stroke volume. What helps us go fast is the total amount of blood we pump, whether it is through a lot of beats per minute or a lot of blood per beat. We've had great champions with extremely low HRs, moderate HRs, and extremely high HRs. HR levels are a very individual thing, but miles per hour and minutes per mile win races, not beats per minute.

Toni, you need to test your own thresholds and not assume that 180+ is zone 5 for you. If you have a performance lab in your area, having metbolic testing is incredibly useful. I know of labs in Washington DC http://www.fitness-concepts.com/voxmax.htm and Chicago http://www.multisportmadness.com/PT/index.html This is the most precise way to adjust training to your unique physiology. Good luck, Ken

I was using a HRM and used the standard formula. 220 minus my age( 37) I was going into zone 5 quite a bit. I was going at a good pace but I held back.

After a physical I had to go get some additional test done because my resting heart rate was too low. After all the testing was done I went to a cardiologist, who also ran marathons. He reviewed everything and gave me a clean bill of health. I spoke to him about the HRM and he advised that the standard formula is for someone starting out. If you have been training to go with 220 minus HALF my age.

Now my zone 5 is about 180-200 compared to the 163-183 it used to be.
He also was a proponent of perceived effort to guide you.

I now use the HRM but not as my only guide to my pacing.

Hi Toni,

Forget every formula. No formula takes individual differences into account. I have personally performed or supervised my staff performing over 6,700 VO2 max and lactate threshold tests and individual differences are enormous. Write me off list at and i'll send you an exerpt from my book, The Triathletes Guide to Run Training, which will help you determine your zones. Ken