# Functional Threshold HR (FTHR)



## Bridgey (Mar 26, 2003)

I am 40yrs old and my Max HR is 184. Based a past race I worked my FTHR out to be 165 (20mins at about 174bpm avg x .95). However today I entered a club race that went for 57mins 30sec. The first 14mins of race my AVG HR was abt 160 (I was feeling good still). However for the rest of the race (43mins) the AVG was about 172 to 174. (I was in a 2man break away).

For the 57mins 30sec my AVG HR was 170 (92% of my max). This is all based on my Garmin report (with a premium HR strap which I believe to be accurate). 

Does this mean my Functional Threshold HR or Lactate Threshold (The HR I can hold for a 1hr Timetrial) is abt 170. (92% of max). I admit I went way into the red for this race and probably couldn't reproduce the effort every week. I also came into the race relatively fresh.

I don't own a Power Meter yet, but I notice in the 2nd half my Power was starting to lag (abt 1km'h to 2km'h slower than 1st half). I was riding at the limit from 14min mark on. Even though my AVG HR stayed consistent my Power didn't. Given that I couldn't sustain the power, does this basically make this data (ie. basing intevals on my FTHR) useless.

I'm not really up to date with the scientific approach to my data, but is this basically in line with most other competitive cyclist ie. having a FTHR at about 92% of max (assuming I got my figures right).


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## dot (Mar 4, 2004)

It was not a TT race, effort was never constant.
When I race short XC races (<=1 hr) my Avg HR might be in 90-94% of my MHR, once it even hit 96% when I lacked endurance. Invensity varies too much to take this value into consideration.

Short anaerobic power bursts keep HR too high and blur the whole picture.


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## Bridgey (Mar 26, 2003)

So should I take a 20min period from the race where I was in the 2man break and my avg speed was consistent and then work it out that way to get something accurate?


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## dot (Mar 4, 2004)

Bridgey said:


> So should I take a 20min period from the race where I was in the 2man break and my avg speed was consistent and then work it out that way to get something accurate?


Even in the break you worked in shifts.


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## iliveonnitro (Feb 19, 2006)

20min HR * 0.95 is not the way to calculate what you call "FTHR"


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## Bridgey (Mar 26, 2003)

iliveonnitro said:


> 20min HR * 0.95 is not the way to calculate what you call "FTHR"


?? Okay there are some intervals, etc that you do prior to this all out 20min effort test. Then you take 5% off to arrive at your FTHR. Isn't this what the books are saying? Pretty hard to go for an hr timetrial.

In my race the guy I was with was stronger than I was. So using an exertion scale, I was using much the same effort behind him to what I was out in front. I was basically just hanging on for how ever long I could. After he dropped me with about 10mins to go, I still kept up the same exertion. My AVG HR for those laps didn't change to when I was with him. He just rode away that's all. I guess my Power output was changing though. 

But it appears I can't determine my FTHR from this data. Which is a bummer. I guess I'm going to have to invest in a power meter and just base my intervals on an exertion scale til then.


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## dot (Mar 4, 2004)

Bridgey said:


> But it appears I can't determine my FTHR from this data. Which is a bummer. I guess I'm going to have to invest in a power meter and just base my intervals on an exertion scale til then.


I wouldn't bother. You can do Carmichael Field Test, 2x8 min (quick and simple) and then calculate your LTHR from this test, highest Av HR * .95 = LTHR. Don't be too precise, HR is very unstable, 2-3 beats lower or higher won't make a difference but will save your fifteen hundred  at least for now.

It's possible to set zones in half a dozen ways (VO2max based Karvonen, MHR based Edwards, LTHR based Friel, Carmichael, FTP-based Coggan and a weird scale from Peter Keen, LTHR-based scale form Stephen Seiler pages and so on) but all of them end up being no more than 5 beats different from each other.

my HR zones, based on different formulas:


```
Friel   coggan      MHR     Edwards  Karvonen
         <=113      <=114   96-114    
109-136  114-138   115-124  115-124 
137-148  139-      125-143  125-134   129-145
149-156     -157   144-157  134-152   145-160
157-168  158-      158-     153-      160-
169-171     -174      -169     -172      -176
172-176            170-179   
177<=      176<=    180=<     173<=    176 <
```


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## Bridgey (Mar 26, 2003)

Thanks for the resources. I must look into them. Ultimately though I think I probably need to take a less scientific approach to my training til I get a power meter (hurry up Garmin Vector!!). Maybe estimate my exertion with intervals, etc. HR appears not to be a reliable tool of measurement. Already started reading 'Training and Racing with Power'. 

Thanks for the replies.


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## dot (Mar 4, 2004)

Bridgey said:


> HR appears not to be a reliable tool of measurement


that's not a correct notion. Other sports can't use powermeters so they have to rely on HR and speed and skiers are ahead in terms of VO2max (I keep reiterating this to nausea)


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## hrumpole (Jun 17, 2008)

Good estimate is 30 minute TT, and take the AHR for the last 20.

HR is a really good way to train, and it is reliable. You just have to pay attention--cardiac drift, etc, and have to pay attention to PE. Day to day results might vary, but over time you will know what you're doing. People have trained that way for years, and there are folks on this board who are blazing fast that use nothing but.

The difference with power is that you know exactly how much work you're doing, and for how long. You see the numbers go up, and it's like putting another plate on the barbell. It is more efficient. But to call HR-based training ineffective or a waste of time just seems silly.


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## SKIBUMM (Feb 26, 2010)

HR train as mentioned is very valuable. Also mentioned it is like trying contol untagle string. There are a lot of methods out there and I see so amny people come in with "their zones" and I can watch them and tell they are not anywhere close to knowing their zones. Many go by the old 22- your age for max and as an example I am 46 and my AT is 178 so I am above my "max HR" in high zone 3. Do as described above for testing or go and have a true max HR test done at a local university or testing facility. You can do a submaximal test too but not quite as accurate. Now for the kicker. You should have it re done about once every 6 months and some will argue once every three months if you are trainig hard. I had mine done every 6 months but have gotten to know how it feels when I am at AT and can do a pretty close estimate but mine has been pretty stable over the last couple of years. Also just and FYI you will have different AT numbers for biking, running and swimming if that is what you are traing at. They will not vary by much but will be different


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## Alex_Simmons/RST (Jan 12, 2008)

dot said:


> Bridgey said:
> 
> 
> > HR appears not to be a reliable tool of measurement.
> ...


Well it is a correct notion depending on what one is referring to.

HR is only an indicator of intensity of effort. It isn't however a measure of fitness.


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