The Grey Zone

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You are traveling through another dimension, a dimension not only of sight and sound but of mind. A journey into a wondrous land of imagination. Next stop, the Twilight Zone…

There is a twighlight zone for training that is called “the grey zone”. I have heard of this off and on that past few years, but never really got a good handle it. Until Now.

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I recently posted a rant on my lack of progress in running, titled “What’s the Freakin’ Point?“. A pro triathlete named Gabriela Baranová commented “Be careful not to train the gray zone”. I emailed her asking what she meant by that.

Here is the conversation, printed with her permission. I am so thankful she took the time to share her wisdom on this topic. This is long, but you really must read all of it! I believe that it explains why my hard efforts at running have not resulted in much improvement.


Here is more about Gray Zone: Some people (and very many of them, including myself) get caught doing all their workouts at the same pace or close to same pace – what is know as a Gray Zone. This GZ is generally a pace that is too fast for the recovery and too slow for the key run (such as intervals, tempo run or a short fast brick run). People generally settle on a pace because they feel it gives them a “good workout”. If they fall into this zone on most of their runs they will not reap the benefits of a structured run training program and it will lead to a performance stagnation.

I have never really paid much attention to this, even though I knew there was a lot of truth about it. Me and some of my friends had this discussion 10-12 years ago and since than I knew it was there, but like I said, sometimes we think “good workout has to be one where you can run fast and long”. That is not true.I have experienced it very well last year and I will write you all about it later plus how to avoid it. I will be in touch tonight.


After reading your comment “Beware of the grey zone”, I googled “grey zone” and found a little bit of information, but nothing real solid, like HR zones. I’ve been trying to make my long runs easier and my short runs harder. I’ve kind of come to the conclusion that Zone 1 and 3 are the grey zones to be avoided during training. Zone 1 is for recovery, Zone 3 is for long endurance racing. Zone 2 should be for long workouts, and Zone 4+ for hard interval workouts. That’s what I’ve been focusing on for the last few weeks. I find it hard not to run in Zone 3, as that’s what I’m used to.

The way you explain it makes a lot of sense, and it’s exactly what I’ve been doing: trying to have “good workouts”.


Here is my perception of Heart Rate zones:

Zone 1: Recovery
Intensity: Very Low
% Lactate Threshold: 65%-84%
% Max Heart Rate: 60%-70%
RPE Scale: 1 (RPE is rate of perceived
extortion, in another words it’s how hard it should feel, I use scale
1-5 but some books and coaches use scales as much as 1-20 for more
accurate perception of the effort given during the workout)
This is not a gray zone.

These are the easiest workouts, used to promote recovery after harder
workouts or after a race (not necessarily a triathlon or not only after
a triathlon, it can be used after a running race to help the body
process the lactate quicker. It is also generally the intensity level
used during the recovery period of interval work.

You could use this zone to recover after a running race. Right
after the race or you can use it the next day after the triathlon race
or your hard brick workout. Many coaches believe and I do too, that we
should take a recovery day after a race day, but it should be day where
we do something, so this is it.
Zone 2: Endurance
Intensity: Moderate
% Lactate Threshold: 85%-91%
% Max Heart Rate: 71%-75%
RPE Scale: 2
Used for: Used for long, endurance workouts and easy speed workout;
builds and maintains aerobic endurance.

This is the zone we should be running our long, or moderately long
workout in. This is not a gray zone.

Zone 3: Tempo
Intensity: Intensive
% Lactate Threshold: 92%-95%
% Max Heart Rate: 76%-80%
RPE Scale: 3-5
This is a gray zone.

This is the one. And yes, most people will probably have a question
“why?” This zone is to be used in base training only substituting for
a interval workouts. During off season or in base phase where we are
training our endurance, this only should be used here. Most people as I
have said, including me tend to run in this zone during the season too
while performing their longer or recovery runs. It’s not beneficial for
the recovery nor it’s beneficial for the interval workout.

Zone 4: Lactate threshold
Also known as: Anaerobic Threshold, Race/Pace
Intensity: Race/Pace
% Lactate Threshold: 96%-100%
% Max Heart Rate: 81%-90%
RPE Scale: 4
This is a gray zone too (if you run your
long runs in it)

This zone should be only used during : intervals, hill work, and
fartlek. Training at or slightly below your Lactate Threshold (a.k.a.
Anaerobic Threshold) helps your body lean to “recycle” the lactic acid
during high intensity work.

This zone is very beneficial. Very good work out here can be an
interval workout based on threshold level. Let’s say you go to the
track. You warm up for 20 min, than you start running and bring your
pace to your threshold level. When you do that try to hold it there for
as long as you can and than proceed with a recovery. You can walk or
run in very slow pace till your heart rate reaches 70% and repeat again
till the end (depending on the length of your workout)
Again, this can be a gray zone if someone is not running
intervals but simply just running a long endurance run (40 minutes or
more). In this scenario, this not beneficial.
Zone 5a: Threshold Endurance
% Lactate Threshold: 100%-102%
% Max Heart Rate: 91%-93%
RPE Scale: 5

Used for: Intervals, hill work, and tempo work; typically used after
some Zone 4 time has already been done. Zone 5 workouts are very short
because it is difficult to maintain this level for any length of time.

Zones 5 are not gray zones. Effort in these zones are sustainable for
short periods of times and therefore if one was to run in this zone
for an hour it would be very uncomfortable .

Zone 5b: Anaerobic Endurance
Also known as: Speed Endurance
% Lactate Threshold: 103%-105%
% Max Heart Rate: 94%-98%
RPE Scale: 5 +

Used for: Intervals and hill work to improve anaerobic endurance.
Intervals in this zone generally have work-to-rest ratio of 1:1, for
example, a 20 second sprint followed by 20 seconds of easy recovery
(Zone 1).

Zone 5c: Anaerobic Capacity
Power workout
% Lactate Threshold: 106%+
% Max Heart Rate: 98%-100%
RPE Scale: 5++

Used for: Short-term Sprinting. Intervals in this zone have a work to
rest ratio of 1:2 or more.

Carol, I hope this explains it little better. As I have said I experienced this myself last year. During the off season I ran mostly on the treadmill. The pace was 10-12 minutes well in the 1 or 2. zone. Once a week or when I got bored, I would do a tempo run on a treadmill, something like fartlek and when I came closer to March I also did some intervals but just very few on the treadmill.

My first triathlon of the season I was able to hold 6 min pace for the whole runs (not longer than Olympic, that’s as far as I go for now). Later on in the season I didn’t use a treadmill anymore and ran solely outside. My run times got worse although I put in more training. Most of it, now when I look at it at a gray zone. So went from 6 to 7 min a mile. Amazing, isn’t it?

After the experience I know it’s working, but like you said it’s very hard not to run in that 3. zone it’s just feels right.

So the conclusion would be instead of trying harder sometimes, we should focus more on tasks at hand and use our brains to guide our hearts. Not only on displays of heart rate monitors but also in our inner mind during the work out.


When doing easy/long runs, should I not worry about high cadence (footstrkes/min)? I ran today, can’t seem to stay out of Zone 3 AND keep a high cadence. In order to stay in Zone 2 or below, I have to “slog” at 150 or less footstrikes/min, which just feels wrong. I ended up
experimenting with trying to keep my cadence up, but get my heart rate down in other ways (i.e., relax muscles not used, shorter stride length, change posture, etc.). Not much success with that!


I wouldn’t worry about cadence on your long runs. Regards to other methods you mentioned, like changing a stride length – I wouldn’t do that you might be offsetting the body’s balance on the
run and creating injury and this goes as well for the posture assuming that your posture is fine now. That being said it’s just natural that when your run your interval workouts your posture is going to be slightly different than posture while running long easy run. During intense speeds runners push out their chest more, but maybe not so much during the long easier runs.
Plus the leg turnover or cadence is much faster at higher speeds than slower speeds.

I know that there are many theories out there that stand for high turnover during running, but from my standpoint of view, you should save this high cadence for RACING, INTERVALS, TEMPO RUNS & SHORT BRICK RUNS where you simulate the actual race day conditions. UNLIKE on the bike, while running there are no gears. So on the bike we can change the gear to keep a high cadence and to ride easier so our heart rate goes down. But on the run, we can not shift the pavement, so the slower pace has to come down to slowing the stride repetitions per minute. Shortening of the stride will occur but it will be minimal and unnoticeable, you should not try to force change in your stride.

You can also try softer surfaces that you are running on now. This will soften the landing and also soften the foot strike. This will help you feel like you were running faster but in reality you are not. What is actually happening is that some softer surfaces are absorbing your power
therefore you stride length may become smaller but you will be able to keep faster turnover if you feel that it is really important to your training. Treadmill is excellent for this. * Please remember that sand is the worst surface to run on. (by soft I mean top soil, treadmill board)

Carol, definitely try to keep yourself in zone 2 on longer runs without worrying about repetitions. I am pretty sure you will see improvements. Sometimes less is more. And don’t forget to stretch and get enough sleep. Those are very important. Once I had a coach tell me, when you don’t have time to stretch before your workout than don’t do anything, and if you do, it’s not going to give you much.


Gabi, Thank you so much again for this detailed explanation. You don’t know how helpful you have been!

Reminder to all my blog readers: Please visit Gabi’s new online store!

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4 comments on “The Grey Zone
  1. Crumbs says:

    Excellent post! I wish the Polar watch company had explained it this well when I bought my watch/HRM. I look forward to adjusting my workouts.

  2. Jenni G says:

    This is great stuff, Carol! I’ve been hearing more and more about HR training lately. Gabi explains the different zones well and I like how she combines all the methods together, pace, HR, RPE, etc. What I’ve seen is either one or the other and your left to try to figure out the overlap! The one method with 20 different zones just made me close the book! Too complicated! It seems I’ve been running in the grey zone alot but find it very difficult to slow down. I think this is the hardest part about HR training, especially for those who love speed.

  3. Jonathan says:

    Great post Carol, a few years ago, our club coach gave a presentation and the main point was that most people do easy stuff too easy and hard stuff not hard enough. Meaning that if you go out with say a running club, most people will poddle along chatting away and not really doing any good. They are in the “social zone”.

    For this reason, I do 85% of my training alone…

  4. Chary Weilert says:

    Hey! Long time, no talkie! Thanks for the insightful blog entry…and congrats on winning a bike! I’ve been wanting to tell you that I placed third in my age group last month! My first AG finish worth mentioning. Granted, it’s all relative to who shows up that day (or who doesn’t), but I improved my time by five minutes from last year, so I would’ve been happy regardless of whether or not I brought home a medal. I celebrated by buying a (used) tri bike. It’s a Quintana Roo Caliente, and it’s NICE! I’m still getting accustomed to the aerobars (my arms/shoulders feel sore), and trying to get some insight as to how to get a professional fit by watching YouTube videos to avoid spending more bucks. I adjust it a little every day, so I hopefully we’ll get used to each other soon. I totally understand what you mean about ‘cheating’ on your bike with a new one. In fact, I know how much you adore your bike, so I was wondering how the switch-over would go! Are you keeping both bikes? I hope your lucky year continues! And thanks again for your blog entries!

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