Measuring LTHR

http://www.joefrielsblog.com/2011/04/determining-your-lthr.html

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19646528#p19646528]Essex Man[/url] wrote:

I have seen it stated that you should perform your effort to get your LTHR or FTP, and then multiply by 0.95. I can see this applies to power, which can drop off, but surely this is not the case for heart rate?

Is there any general consensus by those on here with experience as 5% difference is quite a lot!

Personally, I would like to assess my LTHR from 10 mile time trial efforts.

Thanks.

What is it that you're actually trying to achieve? Are you trying to ascertain the average HR you should ride a 25-mile TT at?

I ask, because,

1) HR is dependent upon a variety of factors, which include, but aren't limited to
a) the power you're riding at
b) the cadence you've chosen
c) the ambient temperature
d) altitude
e) the position you're in (e.g. it may change between a road bike and a TT bike)
f) the food you've eaten
g) any anxiety or stress you're facing
h) etc

2) There is no such thing as 'LTHR' - or at least any scientific definition, because
a) HR is a dependent variable
b) Lactate threshold is the power output (in cycling, in running it'd be measured in say m/s) that is elicited by a 1mmol/L increase in blood lactate (i.e., a lactate reading of 2.Xmmol/L) or the power that elicits a fixed rate of 2.5 mmol/L and is the intensity that could be maximally sustained for 3to4 hours in well trained or elite athletes.
c) Lactate threshold is significantly below the effort that can be sustained maximally for say a 25mile TT or 1 hr effort

3) HR can also vary significantly due to fatigue and changes in blood volume. For e.g., the last time i rode a 25mile TT i did one on the saturday and one on the sunday. HR difference between the 2 events was 10 or 12 b/min different (lower on the sunday) yet my power output was only different by 1 or 2 W. In other words attempting to pace by HR would lead to all sorts of mistakes. It's much better to use perceived exertion

Ric

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19650460#p19650460]Essex Man[/url] wrote:

Hi Ric,
Thanks for taking the time to post in such detail.
I'd like to improve my TT times. In recent weeks they have got worse after steady improvements.
I won't be buying a power meter any time soon, but I wanted to reassess my training intensity.
It's all just for fun though, I won't be getting jabbed for blood samples in the lab any time soon.
Thanks.

If you want to use HR as some sort of way of determining your training intensity (technically it's a surrogate for such), then there's likely a multitude of ways for a variety of different measures (e.g., HR could be done via HRmax or HR at FTP, power can be done via MAP or FTP, RPE could be done with a 10 or 20 point Borg scale).

The important thing is the training that you do and the consistency of doing it.

If you use HR for your training 'intensity' (and i do this with some of the people i coach who don't have power meters) then you're better off targeting a range (e.g. 170 - 175 b/min) rather than an absolute number (e.g. 172 b/min). This is because HR can alter for a given intensity (power output) under a variety of conditions and that additionally, you don't need to be smacking things out at 100% of your maximum for that duration to get a training effect. This also applies to using power as well.

So, for e.g., if say i was asking someone to do some 20-min efforts at TT power, i may give them a range to work off (power or HR), but i'd also expect that they should use perceived effort as well. If i said ride at say 270 - 300 W but this felt easy this could suggest that their power meter needs calibrating if it had previously been difficult or that their fitness had improved. So, i'd be looking at an effort that was hurting, but could be sustained for longer than 20-mins (some of this comes down to experience as well, and thus some numbers can help dial in perceived exertion quicker)

ric