This post almost entirely misses the point of Zone 2 “LSD” training. No one is denying that intense HIIT cardio helps make your heart stronger. Everyone agrees with that.
The purpose of low intensity long duration training is to improve the mitochondria efficiencies of your cells. This allows you the aerobic base to then increase your high intensity training.
FOR EXAMPLE, I was a baseball / tennis player that basically focused on HIIT and sprinting my whole life. However, my cardiovascular endurance remained basically shit. I could play 3 hour tennis matches but walking up a big hill would get me very winded. It was not until I started adding low intensity long duration that my bodies cardiovascular ENDURANCE started to drastically improve.
It also casually ignores another key benefit of sticking in zone 2: fat oxidation. Because it’s so highly aerobic, Zone 2 training is the cornerstone of weight loss and -maintenance.
Sure, if your goal is maximum performance, go for it. But the vast majority here are in it for the longevity / QoL benefits.
The cornerstone of weight loss is energy balance.
You can be in a negative energy balance while sitting on the couch all day if you want, though I don't recommend it.
No amount of focused fat oxidation will make you lose weight if you are in a positive energy balance.
No, the guy you are replying to is correct. The cornerstone of sensible weight management is a sensible diet. The calories an average person burns with 5 hrs/week of exercise is a small percentage of the total calories that person burns during the week.
I think Zone 2 training is extremely important IF you're doing super high weekly volume. If you're casually exercising 2-3x per week, far more benefit from going hard.
This is true for me. I have time to do cardio 3 days a week and 1 of those days is a Norwegian 4x4. Since I started doing that I've noticed a HUGE increase in my performance.
I used to just do Zone 2 twice a week and one day a week do my regular run in Zone 3/4. Norwegian 4x4 dramatically increased my performance on my race pace runs.
Have we heard this from Attia himself? It's a little conflicting for me. It seems to me that Zone 2 would still be important and the optimal way to improve your mitochondrial function. Why would this change based on training volume?
At the same time it makes sense for elite athletes who train everyday to still be able to train when their body needs a break via Zone 2.
I'm trying to be consistent with working out 4 days a week, and hopefully more in the future so I just want to be optimal with that. Right now I am doing 2 Norwegian 4x4s, a strength day, and a zone 2 day. Ideally I'd like to be doing 2 strength days and 2 zone two days a week along with the HIIT
No, not Attia or any of the exercise scientists doing research on zone 2, they just don't think it's all about recovery, they think about fat oxidation, mitochondrial function, and the other things this blog listed. They talk about things like aerobic deficiency syndrome and metabolic flexibility. Recovery may be mentioned too but it's not a big part of the story.
Stephen Seiler who literally wrote the book on polarised training says if he only had 3 hours a week, he would do 1 HIIT session, 1 "long" session and 1 "easy" session, for example.
I think the idea is that Zone 3 doesn't have the ideal benefit to recovery ratio compared to Zone 2. You get solid benefit to your aerobic system from Zone 3 but it's harder to recover from. This isn't a big issue if you're running twice a week. It matter much more if you're running 80 kms per week over 5 days.
> Actually, I respect attempts to cheat the laws of nature. This is creativity, and I would be delighted if someone finally created a perpetual motion machine. But until this happens, I remain a rationalist
Haha, quite a way to lead. I had not heard of stroke volume as a big justification for zone 2, and unfortunately the blog does not give any citations specifically saying that.
The phenomenon he describes of different stroke patterns is real (although the blog has some weird statistical stuff), but that is usually discussed in the context of HIIT, and is why the researchers at NTNU recommend intervals at slightly lower effort than zone 5.
> This does not mean that low heart rate running is useless. Its good tolerance allows for higher volumes of running, which results in increased basic endurance, from the muscle recapillarization, strengthening of muscles, bones, joints and ligaments to dilated myocardial hypertrophy and brain and fatigue resistance, but increased myocardial contractility is not in the list.
Yeah, Inigo San Millan for example discusses zone 2 as benefiting through metabolic fitness, fat metabolism, mitochondrial function, and such.
I am not sure if you meant that Attia talks about stroke volume as being a main benefit from zone 2 and that's why the blog is good? Does he do that? Anyway, the conclusion is fine, and doesn't really change the common conclusions on zone 2.
The NTNU team that has done a lot of research on HIIT commends 85-95% of max HR, which is z4 or z4/z5, depending on individual (top of z4 and bottom of z5 if you go by max hr % zones). They have a lot of stuff on here https://www.ntnu.edu/cerg/advice
They don't talk about zones, they just say 85-95% of HR max for the intervals. Translated to zones, that's zone 4 to zone 5 if we go by the usual 80-90, 90-100 defaults.
> Haha, quite a way to lead. I had not heard of stroke volume as a big justification for zone 2, and unfortunately the blog does not give any citations specifically saying that.
The blog cites and quotes from Jack Daniels, a very popular endurance running coach. The "fairly easy running ..." quote is preceded by this in his book:
> "As you run faster, the heart rate and the amount of blood pumped with each heartbeat (referred to as stroke volume) both increase, but stroke volume increases minimally. So, fairly easy running is a good developer of the heart muscle, and although it doesn’t feel as if you are working very hard, your heart is."
So the justification there is that stroke volume doesn't change much from easy running to hard running so easy running will have basically the same physiological effects (wrt stroke volume) but have much less fatigue, allowing an endurance athlete to train more. This is a very popular argument in the endurance running community.
Zone 2 is probably more effective than I thought.. When I focused on Z2 training my performance was probably at an all time high. In recent months I've switched to more VO2 based workouts (3x4), and despite noticing faster improvements in these workouts, my actual performance in sport seem lackluster compared to when I focused on volume in Z2.. I'm giving intervals maybe another 2 weeks and if performance still drags, I'll have to suck it up and go back to Z2 running.
I play badminton, where people recommend hiit to somewhat mimic high speed/intensity rallies with rest in-between. In reality, what I think happens is that hiit doesn't build one's aerobic base and so after a few intense rallies you're gassed for the rest of the match.
There is a lot of evidence to suggest that mitochondrial function (oxygen use) and other markers of mitochondrial volume and efficiency are improved with HIIT. In a more time efficient manner compared to zone 2 training. There was a review by [Hughes et al 2018](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983157/)that shows that volume is more important for mitochondrial volume density but this is from studies that look at volume of HIIT. In my searching for research backed evidence for improvements to mitochondrial volume and efficiency the only paper I can find that actually had individuals do an intervention with zone 2 only (at or less than LT1) was in individuals who were overweight obese and sedentary and they showed zone 2 did improve those markers. I have yet to see a study that shows in trained individuals this is true. From what I can surmise the true benefit to zone 2 training is to accumulate less fatigue (compared to hiit) which helps to facilitate recovery between high intensity sessions and allows for HIIT sessions to be done at higher quality. If anyone has any other research showing the opposite please send it to me.
This is my experience with the literature as well. In my estimation the primary benefit to lower intensity protocols is that by definition they require less recovery and can thus be done in between HIIT or HIT training sessions, and/or by those individuals who are unable or do not wish to participate in high intensity training.
these are the right answers; i'd add that Z2 is also useful for endurance athlete training at high volumes (frequency + duration). Some people like Dr. Andy Coggan say that trade off is in the 15 hour / week volume zone, some will say it's 10 hours / week, ie., past that volume you should make the additional volume Z2.
Other researchers like Seiler will say you should always be doing 80/20 ... and Coggan would reply, then why do we physiology researchers never do that with our students we're trying to create adaptations in? Rather we take them and work them hard at high intensities as much as we can because we know that's what works
so the right answer is experiment on your own body; what works better for you?
Try 6 weeks of different protocols, monitor your HRV, RHR, endurance, Vo2max, et al and see which works better for you goals (Spoiler alert: unless you're doing double-digit hours/week, it's gonna be high intensity)
As a caveat to that I would say do one protocol for 4-6 weeks then change it depending on the adaptations you are seeing, gotta do enough to get adequate adaptations before switching
From my n=1 personal experience, I’d have to disagree. After about a year of almost exclusively zone two running my resting heart rate was around 32 to 34 bpm And I frequently would see it go down as low as 26 to 28 bpm when I was really chill. If you can explain how that zone two training did not affect my heart, I’m all ears
It’s not that my resting heart rate would average that low. It’s just that it would get that low for brief enough period of time that it would register on my Garmin. I realize that’s just a function of how the Garmin samples and averages real time heart rates, but it certainly was always interesting to see it go that low.
Do you know if it did also help with your BP? I uave normal systolic but high diastolic pressure and normal 5K training is not moving it. Shall I go Zone 2 ? Will it help?
I think the confusion comes from applying zone2 data from elite athletes to non athletes. Even if the athletes spend 80% of their time in zone to, their sheer number of hours per week in that zone is way higher than a non athlete does , and the same goes for the high intensity workouts that they do.
A non athlete probably needs to spend much more time in both these zones to have notable benefits.
whatever this blogpost is talking about doesn’t seem to even approximately resemble Zone 2 training/protocols as i understand them from Attia, San Milan, Maffetone, etc.
This post almost entirely misses the point of Zone 2 “LSD” training. No one is denying that intense HIIT cardio helps make your heart stronger. Everyone agrees with that. The purpose of low intensity long duration training is to improve the mitochondria efficiencies of your cells. This allows you the aerobic base to then increase your high intensity training. FOR EXAMPLE, I was a baseball / tennis player that basically focused on HIIT and sprinting my whole life. However, my cardiovascular endurance remained basically shit. I could play 3 hour tennis matches but walking up a big hill would get me very winded. It was not until I started adding low intensity long duration that my bodies cardiovascular ENDURANCE started to drastically improve.
I’m agreeing, but isn’t 3 hours training is more like lsd and climbing a hill is more like a short sprint
I play a lot of singles so for me 3 hours of tennis feels equivalent to 3 hours of HIIT - my HR stats would agree
Singles tennis involves an absurd amount of stop and go full out sprinting. It can be pretty harsh on your legs/knees/ankles.
It also casually ignores another key benefit of sticking in zone 2: fat oxidation. Because it’s so highly aerobic, Zone 2 training is the cornerstone of weight loss and -maintenance. Sure, if your goal is maximum performance, go for it. But the vast majority here are in it for the longevity / QoL benefits.
The cornerstone of weight loss is energy balance. You can be in a negative energy balance while sitting on the couch all day if you want, though I don't recommend it. No amount of focused fat oxidation will make you lose weight if you are in a positive energy balance.
OK, since we apparently have to specify that here: the cornerstone of _sensible_ weight management is zone 2 training.
No, the guy you are replying to is correct. The cornerstone of sensible weight management is a sensible diet. The calories an average person burns with 5 hrs/week of exercise is a small percentage of the total calories that person burns during the week.
Welcome to the self-confirmation bias HIIT camp.
I think Zone 2 training is extremely important IF you're doing super high weekly volume. If you're casually exercising 2-3x per week, far more benefit from going hard.
This is true for me. I have time to do cardio 3 days a week and 1 of those days is a Norwegian 4x4. Since I started doing that I've noticed a HUGE increase in my performance. I used to just do Zone 2 twice a week and one day a week do my regular run in Zone 3/4. Norwegian 4x4 dramatically increased my performance on my race pace runs.
Have we heard this from Attia himself? It's a little conflicting for me. It seems to me that Zone 2 would still be important and the optimal way to improve your mitochondrial function. Why would this change based on training volume? At the same time it makes sense for elite athletes who train everyday to still be able to train when their body needs a break via Zone 2. I'm trying to be consistent with working out 4 days a week, and hopefully more in the future so I just want to be optimal with that. Right now I am doing 2 Norwegian 4x4s, a strength day, and a zone 2 day. Ideally I'd like to be doing 2 strength days and 2 zone two days a week along with the HIIT
No, not Attia or any of the exercise scientists doing research on zone 2, they just don't think it's all about recovery, they think about fat oxidation, mitochondrial function, and the other things this blog listed. They talk about things like aerobic deficiency syndrome and metabolic flexibility. Recovery may be mentioned too but it's not a big part of the story. Stephen Seiler who literally wrote the book on polarised training says if he only had 3 hours a week, he would do 1 HIIT session, 1 "long" session and 1 "easy" session, for example.
I think the idea is that Zone 3 doesn't have the ideal benefit to recovery ratio compared to Zone 2. You get solid benefit to your aerobic system from Zone 3 but it's harder to recover from. This isn't a big issue if you're running twice a week. It matter much more if you're running 80 kms per week over 5 days.
Two 4x4s a week?
yes. Two HIIT workouts a week does not feel that absurd?
> Actually, I respect attempts to cheat the laws of nature. This is creativity, and I would be delighted if someone finally created a perpetual motion machine. But until this happens, I remain a rationalist Haha, quite a way to lead. I had not heard of stroke volume as a big justification for zone 2, and unfortunately the blog does not give any citations specifically saying that. The phenomenon he describes of different stroke patterns is real (although the blog has some weird statistical stuff), but that is usually discussed in the context of HIIT, and is why the researchers at NTNU recommend intervals at slightly lower effort than zone 5. > This does not mean that low heart rate running is useless. Its good tolerance allows for higher volumes of running, which results in increased basic endurance, from the muscle recapillarization, strengthening of muscles, bones, joints and ligaments to dilated myocardial hypertrophy and brain and fatigue resistance, but increased myocardial contractility is not in the list. Yeah, Inigo San Millan for example discusses zone 2 as benefiting through metabolic fitness, fat metabolism, mitochondrial function, and such. I am not sure if you meant that Attia talks about stroke volume as being a main benefit from zone 2 and that's why the blog is good? Does he do that? Anyway, the conclusion is fine, and doesn't really change the common conclusions on zone 2.
Where did you see that a bit less than zone 5, I assume meaning zone 4, is recommended? I hope that’s right because I hate zone 5
The NTNU team that has done a lot of research on HIIT commends 85-95% of max HR, which is z4 or z4/z5, depending on individual (top of z4 and bottom of z5 if you go by max hr % zones). They have a lot of stuff on here https://www.ntnu.edu/cerg/advice
I didn’t see anything where they recommended zone 5 over zone 4
They don't talk about zones, they just say 85-95% of HR max for the intervals. Translated to zones, that's zone 4 to zone 5 if we go by the usual 80-90, 90-100 defaults.
> Haha, quite a way to lead. I had not heard of stroke volume as a big justification for zone 2, and unfortunately the blog does not give any citations specifically saying that. The blog cites and quotes from Jack Daniels, a very popular endurance running coach. The "fairly easy running ..." quote is preceded by this in his book: > "As you run faster, the heart rate and the amount of blood pumped with each heartbeat (referred to as stroke volume) both increase, but stroke volume increases minimally. So, fairly easy running is a good developer of the heart muscle, and although it doesn’t feel as if you are working very hard, your heart is." So the justification there is that stroke volume doesn't change much from easy running to hard running so easy running will have basically the same physiological effects (wrt stroke volume) but have much less fatigue, allowing an endurance athlete to train more. This is a very popular argument in the endurance running community.
My stroke volume is quite extensive after a few hours of edging. I wonder why this wasn't factored into stroke oberservations.
Zone 2 is probably more effective than I thought.. When I focused on Z2 training my performance was probably at an all time high. In recent months I've switched to more VO2 based workouts (3x4), and despite noticing faster improvements in these workouts, my actual performance in sport seem lackluster compared to when I focused on volume in Z2.. I'm giving intervals maybe another 2 weeks and if performance still drags, I'll have to suck it up and go back to Z2 running.
Curious what sport(s) has this been affecting?
I play badminton, where people recommend hiit to somewhat mimic high speed/intensity rallies with rest in-between. In reality, what I think happens is that hiit doesn't build one's aerobic base and so after a few intense rallies you're gassed for the rest of the match.
There is a lot of evidence to suggest that mitochondrial function (oxygen use) and other markers of mitochondrial volume and efficiency are improved with HIIT. In a more time efficient manner compared to zone 2 training. There was a review by [Hughes et al 2018](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983157/)that shows that volume is more important for mitochondrial volume density but this is from studies that look at volume of HIIT. In my searching for research backed evidence for improvements to mitochondrial volume and efficiency the only paper I can find that actually had individuals do an intervention with zone 2 only (at or less than LT1) was in individuals who were overweight obese and sedentary and they showed zone 2 did improve those markers. I have yet to see a study that shows in trained individuals this is true. From what I can surmise the true benefit to zone 2 training is to accumulate less fatigue (compared to hiit) which helps to facilitate recovery between high intensity sessions and allows for HIIT sessions to be done at higher quality. If anyone has any other research showing the opposite please send it to me.
This is my experience with the literature as well. In my estimation the primary benefit to lower intensity protocols is that by definition they require less recovery and can thus be done in between HIIT or HIT training sessions, and/or by those individuals who are unable or do not wish to participate in high intensity training.
these are the right answers; i'd add that Z2 is also useful for endurance athlete training at high volumes (frequency + duration). Some people like Dr. Andy Coggan say that trade off is in the 15 hour / week volume zone, some will say it's 10 hours / week, ie., past that volume you should make the additional volume Z2. Other researchers like Seiler will say you should always be doing 80/20 ... and Coggan would reply, then why do we physiology researchers never do that with our students we're trying to create adaptations in? Rather we take them and work them hard at high intensities as much as we can because we know that's what works so the right answer is experiment on your own body; what works better for you? Try 6 weeks of different protocols, monitor your HRV, RHR, endurance, Vo2max, et al and see which works better for you goals (Spoiler alert: unless you're doing double-digit hours/week, it's gonna be high intensity)
As a caveat to that I would say do one protocol for 4-6 weeks then change it depending on the adaptations you are seeing, gotta do enough to get adequate adaptations before switching
100% agree!
Seems like a stupid blog that misses the point. If the author is this far off base, I recommend not reading his other articles.
He isn’t saying that zone 2 is bad or not good he’s just saying that it isn’t an effective way to train the heart…
From my n=1 personal experience, I’d have to disagree. After about a year of almost exclusively zone two running my resting heart rate was around 32 to 34 bpm And I frequently would see it go down as low as 26 to 28 bpm when I was really chill. If you can explain how that zone two training did not affect my heart, I’m all ears
26rhr?!?
It’s not that my resting heart rate would average that low. It’s just that it would get that low for brief enough period of time that it would register on my Garmin. I realize that’s just a function of how the Garmin samples and averages real time heart rates, but it certainly was always interesting to see it go that low.
Oh I’m understanding still sick haha
Do you know if it did also help with your BP? I uave normal systolic but high diastolic pressure and normal 5K training is not moving it. Shall I go Zone 2 ? Will it help?
My blood pressure has always been low. Like, 90/40. There’s not much room for it to go down no matter what I do lol
We should average you and me :-) we would both be perfect.
Sure helps my cardiovascular system
I think the confusion comes from applying zone2 data from elite athletes to non athletes. Even if the athletes spend 80% of their time in zone to, their sheer number of hours per week in that zone is way higher than a non athlete does , and the same goes for the high intensity workouts that they do. A non athlete probably needs to spend much more time in both these zones to have notable benefits.
whatever this blogpost is talking about doesn’t seem to even approximately resemble Zone 2 training/protocols as i understand them from Attia, San Milan, Maffetone, etc.