I wonder if I’ve misunderstood something about the HR zones that are most commonly used. The basic concept, to my understanding, please correct me, is that the two lactate thresholds define the zones.
So you can either have 3 zones, with z1 under the first threshold, and z3 over the second. Or you can divide the lower ones into two parts, so you have a 5 zone model, with z1+z2 under the first threshold, z3+z4 under the second, and z5 above the second. So that means that z5 is anaerobic.
But now I’ve seen many graphs (mainly on instagram etc), where they use a 5 zone model, but where LT2 is situated under z4, so that both z4 and z5 are above the threshold.
What’s the benefit this way of dividing the zones? I know that all zones are really a human construct and that the limits are not really as sharp as we sometimes want to think they are.
“I wonder if I’ve misunderstood something about the HR zones that are most commonly used. The basic concept, to my understanding, please correct me, is that the two lactate thresholds define the zones.”
correct
Not sure about instagram but never saw a z4 starting above lt2. But keep in mind those zones are just a way of guide and simplification for easier planning (just as you said). So most importantly you want to know the number and ranges of zones your coach or the creator of your workouts use.
5 zone system is the most common one with some small variations and one of the variations is around the z4 and lt2. Mainly some people use lt2 as top of z4 and some are using it as middle of z4. And consequently if they use top of z4, it often comes with a z6 from 105% and z5 100-105% where with lt2 in the middle of z4 gives you z5 from 105% and z5 is anarobic.
In cycling the z4 being 90-105% is more common bc of Coggan and his zones and much higher value of using power. When riding by power it makes sense to put lt2 in the middle of the zone and hr zones are following for simplicity.
The most important thing to remember is that if a coach says intervals shoudl be slightly below LT2, you can decode that accordingly: it should be top of your z4 or it should be bottom half of z4. In reality you cycle by power and check with hr not the other way around.
LT2 as top of z4 comes from Joe Friel who was much more focused on running. And makes sense bc you often run just below LT2 and workouts above LT2 are sprints where zones are not that important.
It really depends how important for you is the work around lt2. For running and cycling you should know your exact lt2 anyways so decoding of the workout is up to you.
ps. it can have an impact when using watches with some load calculation. I would use standard hr ranges from garmin etc. bc if you change the ranges it can calculate the Load completly wrong, like 20m of z4 is not the same as 20min of z5 from extertion perspective.
“So that means that z5 is anaerobic.”
agree, but the reason why some people are using z6 or z5 from 105% is jsut to have clear indicator that the work is anaerobic bc 101% of hr can be easily considered an aerobic on a bad day. Or in other words most of the time you are not planning a workout where you target 101% or so bc if you train your anaerobic engine mosto of the time you want to go short and hard 105%+
ps. consider diffrent zone systems just as diffrent languages. There are many languages but thought we have the same or very similar. To understnd other people correctly you need to translate from one lnaguage into another. “The basic concept, to my understanding, please correct me, is that the two lactate thresholds define the zones.” thats the most important thing to remmeber.
But that guy also posted an incorrect chart, more specifically a chart where the lactate threshold is below zone 4. It is not, at least not if you define zone 4 to be below threshold. Well, that’s kind of circular logic, but the point is that the lactate threashold/VT2/RCP is what draws a line between aerobic and anaerobic work.
It’s not only lactate which defines this point, there are also other ventilatory parameters, e.g. the end-tidal carbon dioxide pressure (PETCO2) drops here, see for example
Of course you can label each zone whatever you wish, I mean zone5 can be z5-z7 or z5a-z5c, but you cannot post things like this chart:
I think a reason for that (you usually see that zone model in the Norwegian system) is that it comes from very high level athletes, who have a very high first threshold and a narrow heavy intensity domain (the zone between thresholds). In those cases it may not be that practical to split the heavy domain in 2, but just one, and then have Z4 and Z5 both above threshold, one for just hard work, and one for very, very hard work.
Thanks. I’m not a very high level athlete, but I do have very narrow zones anyway: 168 at the first threshold and 180 at the second. I always wondered what sense it makes to split up those zones. Each zone becomes like 6 bpm wide.
Exactly, you would be a good example. It doesn’t make much sense to have 6-bom wide zones, therefore you start by splitting the moderate domain into zones 1 and 2, you have z3 for between thresholds, and then zone 4 falls above the 2nd threshold.
That doesn’t fit so well with the intervals model, which splits each domain into 2 zones by default. What I tend to do in that case is simply be a bit extra conservative with the first threshold, in your case I’d maybe set it up with zone 2 up to 160, then z3 161-70, Z4 171-180, or something like that. (Depending on what type of athlete you are and your goals, though).
