Why Zone 2 Matters for Mitochondria: The training intensity that improves cellular health | Be Well Moments

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Why is zone two training so important for mitochondrial health? It’s linked with improvements in fat oxidation and lactate clearance, which are used as surrogates of mitochondrial function in sports science.

This clip explores how different exercise intensities drive distinct metabolic responses, why athletes are useful models for understanding cellular energy, and how laboratory testing with metabolic carts and lactate measurements led to practical training zones from easy efforts to sprints.

I’m exploring with my guest how zone two work consistently improved fat oxidation and lactate clearance in testing, while higher intensities remain essential for performance and VO2, since competitions are decided at the top end.

Here, I’m discussing the balance between building a metabolically efficient engine at the mitochondrial level with zone two, and training the “turbo” at zones four and five plus sprint work for race demands, all in clear, everyday language you can apply.

As a nutritionist and health communicator, my aim is to translate these lab insights into practical training decisions that respect both mitochondrial function and cardiorespiratory adaptations.

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Episode Transcript

(00:00):
Welcome to Live Well Be Well, a show to help high performers
improve their health and well-being.
Why is Zone 2 training so important for our mitochondrial
health? Well, I mean, everything starts
with professional athletes. They have taught us a lot,

(00:21):
right? I always say we cannot
understand imperfection. It wouldn't understand
perfection in the first place. Those are the, the, the Formula
One cars, right? Those are the gold standard of
what a human should be, right? Metabolically speaking, right.
And This is why I've been fortunate for almost 30 years
to, to be able to work with thiskind of humans and being able to

(00:43):
understand them very well. So they have taught us a lot in
order to understand other concepts in, in different
pathologies characterized by these functions at the metabolic
cellular level, right? So performance on one hand,
right, it's about, as I mentioned, about producing ATP
fast, producing energy fast and,and, and, and lasting as long as

(01:05):
you can. Competition is that being as
fast as you can for as long as you can, right?
That's whether whether we're talking about swimming or rowing
or cycling or football, basketball, you need to be fast
and you need to sustain that effort, right?
So for that, you need to produceATP at very high levels and have

(01:26):
a very metabolically efficient engine, right?
Which is what happens at the cell and that furnace, that
powerhouse, that central part ofthat engine, the cell is
mitochondria, right? So what do we need to do with
athletes? Improve their mitochondria
function? So for that, back in the days,

(01:48):
I, I developed this methodologies to try to
understand how we can translate what we were learning about
cellular metabolism into training.
So we know that different exercise intensities elicit
different metabolic results. It's not the same result when
you go for like an easy spin on the bike, for example.

(02:09):
Then if you do a, a 32nd Sprint,you're mobilizing different
energy systems, right? So that's what I, I saw in the
laboratory with these methodologies with a metabolic
heart, with the lactate and I start to define different
training zones because there were different metabolic events.
If you do a maximal, I mean an incremental exercise intensity,

(02:32):
you see this beautifully. And anybody who has done this
test or performed this test as an, as, as an operator, you can
see these events happening in front of your eyes, right?
And therefore, we're talking about from very low intensity
all the way to maximum sprinting, right?
So if you, if you put together the dot, the dots, you're going

(02:54):
to see these metabolic events. That being said, that's why I, I
created different training zonesbecause I couldn't tell an
athlete, hey, you're in a, in a high glycolytic intensity or
you're in 100% oxidative phosphorylation state.
That's what you have to train, right?
You cannot speak that language, right?

(03:15):
So I, I had to do something thatwas very easy to understand and
that's what I decided in zone one through zone 6, right?
Then I started by trial and error.
OK, now let's try the next step.OK, what is the intensity that
elicits the best effect? That's just for mitochondria,
but for other intensities, right?

(03:35):
Because we, we always have to remember that when it comes to
for athletic performance, you always win competitions at the
high intensities. I have never heard about any
athlete or seen any athlete winning a, a competition that in
the zone 2 or low intensities never happens.
So, but unfortunately, people are taking to the, to the
extremes now and all of a suddenhigh intensity is gone.

(03:56):
It's worthless. Well, it depends.
If you're an athlete, you must train high intensity.
And my athletes train very high intensities.
In fact, you know, like about 50% of all the best times the
PRS happened during training that competition, right?
So it's very high intensity because you need to stimulate
that. So anyways, that's why you set

(04:17):
up all these training zones. And that's why I started to see
people in the responses back in the laboratory where you can
study that metabolic response very closely and see which
trainings have improved the most.
So what I saw is that, that's Zone 2.
That was the one that improved the most, 2 parameters that I
mentioned earlier, fat oxidationand lactate cleanse capacity,

(04:41):
which both are surrogates of monochondral function.
I was seeing this over 25 years ago.
And and then obviously, working with athletes, you saw that also
in the competition. That's where you saw that the
action, right? And so that's why this one too
came along. But of course, you have higher
intensities from 4, some 5, which are, you know, that that

(05:02):
turbo, you, you need to improve that, that turbo, right?
The important thing is that you also have to train the turbo,
which are like the high intensities, the zone 5, zone 4,
because you need to stimulate the tour because that's where
you're going to improve the competition as well.
But then you need to stimulate also the Sprint 'cause sometimes
you need to Sprint, you know. But anyways, boy, when it comes

(05:23):
to mitochondrial function, that's important.
But when it comes to VO2, right,which is the cardio respiratory
adaptations, training high intensity is very efficient.
That's probably more efficient, if if not more efficient than
training at zone 2. But as I said from the
beginning, that's, that's the how you express your cardio

(05:43):
respiratory adaptations to exercise, right?
And and but another thing is like how well matter kind of
function works. Thanks so much for listening to
hear the full episode. There's a link in the
description.