May 19, 2025 • 16 mins
Just when you thought it was safe to buy an old running watch, knowing that every running metric has been invented, Garmin throws this curveball. Running Economy...that's even more important than VO2max...right? A: Yes. Here's why
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Source Written Article by the5krunner: “https://the5krunner.com/2025/05/19/garmin-running-economy-all-you-need-to-know/”
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—Credits:Content in this episode was generated using AI tools (NotebookLM) based on original content from @the5krunner, and other sources as cited.
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
(00:00):
Welcome to the deep dive. If you're anything like, say,
the 5K runner, always looking for ways to get faster, shave
off seconds, then, you know, just log in.
Miles isn't the whole picture. So today we're diving into
running efficiency. How understanding it can you
know give you that? Edge exactly.
For any runner chasing a PB, whether it's a 5K or even longer
(00:21):
stuff, it's not just about raw power, it's how efficiently you
use that power, especially at those race paces.
Speaking of efficiency, Garmin'sjust put out a new metric.
It's on their 4 Runner 970 called Running Economy Right?
Designed to give you a look at the energy you're using now.
You do need their HRM 600 chest strap for this one, it's quite
specific. Precisely.
(00:43):
So that's our goal for this deepdive, really get under the hood
of Garmin's running economy. What is it?
How do they calculate it? What effects it?
And we'll definitely look at this step.
Speed loss concept seems important.
Very important and also critically how this all differs
from things we already know likeVO2 Max and VVO 2 Max.
Got to keep those straight. OK, let's start there then.
(01:04):
Step speed loss or SSL sounds pretty technical.
What, in simple terms, is it telling us?
OK, think of it like this. Every single time your foot hits
the ground, you slow down just atiny, tiny bit.
It's unavoidable. Low braking effect.
Exactly. SSL, which Garmin rolled out May
(01:25):
2025, measures that difference. It looks at your forward speed
the instant your foot lands, andthen your minimum forward speed
while that foot is still on the ground.
It's measured in centimetres persecond.
It's going to be just per. 2nd And as the folks at the Five
runner.com point out, and they're right, lower is better.
You want that number small, lessbraking.
Like you're gliding more smoothly.
Terrifically put less loss of momentum with each step.
(01:47):
So how does the watch the Forerunner 970 actually, you
know, capture this and where do I see it?
Well, the key is that HRM 600 chest strap.
It's got the fancy sensors, the accelerometers needed to pick up
these really subtle changes in movement.
OK, not just the watch itself. No meets the strap.
That data then gets sent to the watch, currently the 970.
(02:08):
You can see it live during your run, like on a gauge, or you can
look at the averages after your run for the whole thing, or even
lap by lap, and you'll see SSL incentives but also SSL percent.
The SSL percent you mentioned, that's particularly useful.
Why should someone like the 5K runner focus on the percentage?
Good question. Because your raw SSL, the
(02:29):
cinemas value, well it naturallytends to go up as you run
faster. Makes sense right?
More force involved. So SSL percent, the SSL percent,
it kind of normalises that it takes the speed effect out of
the equation. Levels the playing field.
Exactly. So if you're trying to see if
tweaking your form is actually making you more efficient over
time across different speeds, SSL percent is the metric to
(02:49):
watch. Lower is always the goal.
So if the 5K runner sees his SSLspiking, what are the usual
suspects? Is it form hills to speed?
It's often a mix form is definitely a big one.
Like if your cadence is too low or you're over striding,
reaching out too. Far landing, way out in front.
Right, that's like hitting the brakes harder with every step,
(03:10):
so higher SSL. Makes sense?
Terrain matters too. Garmin uses the watches
barometer to adjust for hills, so uphill you'll usually see
lower SSL gravity help slow you down a bit, Downhill typically
higher SSL. But remember, these hill
adjustments don't work on treadmills, and SSL isn't really
for walking, it's a running metric.
(03:30):
Gotcha, now thinking about breaking forces.
Yep, it makes me think of other metrics like S drive, RYD has
legs bring stiffness and impact loading rate, and there's 4th
frontiers body shock too. Are these all just different
names for the same thing? They're definitely related
because they all look at ground contact, but they measure
different things. SSL is laser focused on that
(03:51):
horizontal breaking the change in forward speed while your
foot. 'S down OK horizontal focus.
Yeah, pester already is leg spring stiffness LSS.
That's more about the vertical bounds.
How springy your leg is, impact loading rate, ILR.
That's how quickly the vertical force ramps up when you land the
initial shock. Right, the jolt.
Kind of and 4th frontiers body shock BS that uses ECG data to
(04:12):
see how your body physiologically reacts to those
impacts. So related concepts but distinct
measurements. SSL is about forward momentum
loss. OK, that clarifies things.
And the five runner.com mentioned SSL is a key input for
Garmin's other new metric running economy.
How do they link up? Precisely.
Garmin's Running Economy or RE is their attempt to measure how
(04:34):
efficiently you use energy whilerunning aerobically.
So getting the most speed for the least effort basically.
You got it. They measure it in millilitres
of oxygen per kilogramme of bodyweight per kilometre, MLKGKLMA.
And just like SSL, lower is better, more efficient, like a
car with better fuel economy. So this is a big deal, right?
Moving away from needing a lab, a mask, a treadmill, bringing re
(04:56):
measurement to everyday runs. It's a significant shift, yeah.
Traditionally, like the science literature shows, you'd measure
RE in a lab looking at oxygen uptake MLK G men at a steady
pace on a treadmill right the. Classic setup.
Gurman is trying to give you similar insights, but from your
regular outdoor runs or track runs.
They do exclude indoor treadmillruns, trail runs, and runs where
you're carrying extra weight. OK.
(05:18):
And how many runs do you need for it to calculate?
Garmin says you need data from at least four or five runs, and
each needs to be over 30 minuteslong.
It needs a decent amount of datato establish your baseline RE.
And what data points is it actually using from those runs?
It's pulling together quite a few things.
Your heart rate, obviously your speed, and then those running
dynamics, stride length, ground contact time, vertical
(05:39):
oscillation, and crucially, stepspeed loss.
SSL. So that's the direct link.
The breaking metric feeds the economy metric.
Exactly. Garmin's logic is that breaking
which SSL measures costs energy.Every time you decelerate even
slightly, your body has to work harder to get back up to speed.
So higher SSL means higher energy cost, which means poor
(06:02):
running economy. That makes total sense.
If you keep tapping the brakes you burn more gas pretty much.
So if the 5K runner works on smoothing out his stride,
reducing that braking, his Garmin RE score should
theoretically improve get lower.That's the idea, yes.
Minimise the braking, reduce theenergy waste and you should see
(06:23):
that reflected in a better lowerRE score from Garmin.
Does Garma give any tips on how to actually train for better RE.
They do offer some general guidance, things like gradually
increasing your weekly mileage, adding strength training to your
routine, and doing some Sprint workouts.
These all align pretty well withwhat the broader science
suggests helps improve running efficiency overtime.
(06:44):
OK, it sounds like a potentiallypowerful tool, but are there
any, you know, caveats, limitations we should keep in
mind? Oh definitely.
It's important to be realistic. First off, this is Garmin's own
algorithm. We don't have independent peer
reviewed studies yet comparing Garmin's RE directly to lab
based oxygen consumption measurements.
So no third party validation. Yet not that we've seen.
(07:04):
Second, Garmin themselves say the SSL data isn't captured
absolutely continuously. There might be tiny gaps where
that key input is missing. And finally, while seeing the
number is interesting, we're still figuring out what specific
RE values mean in practise. Like what's a good score?
How much does a change of X points actually translate to
(07:24):
faster race times? The actionability is still
developing. Right.
It's a new window, but we're still learning how to interpret
the landscape outside. OK, let's zoom out a bit.
What does the established science say about running
economy in general? This isn't a new concept,
obviously. Absolutely not.
It's been studied for decades. In scientific terms, running
(07:45):
economy is usually defined as that oxygen cost of running at a
specific submaximal speed. Submaximal.
Not flat out. Exactly.
Usually expressed as MLK G min or MLK GTO.
And a really key take away from all the research is just how
much it varies between individuals.
What works for one runner might not work for another.
So personalization is key. Totally.
(08:06):
You need to figure out what works for your body and your
mechanics. And why is RE so important,
especially for runners doing longer stuff like the 5K runner
tackles various distances? It becomes absolutely crucial
for endurance. Even small gains in efficiency
add up massively over, say, 1/2 marathon or marathon.
(08:26):
You save a little bit of energy with every single step.
So it accumulates. Hugely.
It can mean less fatigue later in the race, maybe a faster
overall time. In fact, for well trained
runners, RE is often a better predictor of performance than
even their VO2 Max. Wow, better than VO2 Max?
That's saying something. So what factors does the science
point to as influencing RE? It's a whole collection of
(08:49):
things. Your basic metabolism them in
cardio, respiratory fitness, matter of course how well your
body generates energy and delivers oxygen.
The engine basics. Right.
Then there's bio mechanics, yourrunning form, how you move.
That's huge neuromuscular factors to how your brain and
muscles talk to each other and coordinate everything.
Plus your training history, the shoes you wear.
Think about the carbon plate debate.
(09:10):
Oh yeah, definitely. And even things like heat, wind,
altitude all play a role. You mentioned the shoes.
How do those fancy carbon platedshoes supposedly help with RE
according to the research? Well, the study suggests the
stiff plate changes how your foot and ankle work during
ground contact. It seems to reduce energy loss
in the mid sole and maybe returna bit more energy, acting like a
(09:31):
spring or a lever. Less energy wasted.
Essentially, it alters the mechanics, especially around the
calf muscles, leading to small but potentially meaningful
metabolic savings. Better economy, but it's more
about the shoes mechanics than making your body fundamentally
more efficient. That makes sense.
Yeah, it's an equipment assist. Yeah.
OK. So just to hammer this home
running economy is efficiency below your maximum effort.
(09:55):
How's that different again from VO2 Max VA 2 Max?
Right, Critical distinction. VO2 Max.
That's your maximal oxygen uptake, the absolute highest
rate your body can consume oxygen during really intense
exercise. Think of it as the maximum size
of your aerobic engine. Peak capacity.
Peak capacity, then VVO 2 Max velocity at VO2 Max.
That's the slowest speed at whatyou actually hit that peak VO2
(10:16):
Max running economy is different.
It's about how much oxygen you use at sub maximal speeds.
Those paces you actually hold for distance races you could
have a massive VO2 Max. Huge engine.
But be really uneconomical, burning way more fuel than
someone else with the same engine size running at the same
steady pace. RE is about fuel efficiency, not
(10:36):
engine size. That's a great analogy.
So the Wikipedia source mentioned lab measurements on
treadmills. How do they typically do that?
In the lab, they'll usually havea runner run at one or maybe
several constant steady speeds on a treadmill, maybe for 5-10
minutes at each speed. While wearing the mask I assume.
Yep, wearing the mask to measureoxygen intake and carbon dioxide
(10:59):
output. They calculate the oxygen cost
at those speeds. Often they'll standardise it,
maybe estimate the cost at say 16 kilometres per hour, so they
can compare different people. And express it as MLKG men or
MLKGKO. Exactly, though it's worth
remembering treadmill running isn't identical to running
outside. No air resistance, the built
moves under you. Muscle activation can be
(11:21):
slightly different. Good point.
Does the science give us any like benchmark numbers for RE?
What's typical? There are some published ranges.
For example, studies might show recreational runners around,
say, 47 millikumen at 14 kilometres, whereas elites might
be down closer to 40 millikum atthat same speed.
So lowers is better, more efficient.
(11:42):
Correct, but these are just averages.
There's a lot of individual variation, even among elites.
Your own VO2 Max influences it too.
It really highlights the economyis quite personal.
OK, let's dig into those biomechanical factors again.
What does research say about body size and shape?
Well, body mass matters a bit. Heavier runners tend to be
(12:03):
slightly less economical, generally speaking, but where
you carry the mass matters more.Weight on your feet or lower
legs cost more energy than weight around your hips.
Distal weight is worse. Seems to be yeah.
Limb length is more complicated.The research isn't totally clear
on its impact. What about running style?
Stride length? Foot strike.
This is interesting. Most research suggests that the
(12:23):
stride length you naturally choose is probably the most
economical for you. Trying to force a longer or
shorter stride often makes you less efficient.
Don't mess with what feels natural.
Generally, yeah, vertical oscillation, how much you bounce
up and down. It's complex, but excessive
bouncing likely wastes energy. As for foot strike, the idea
that 4 foot striking is always better for economy hasn't really
(12:46):
held up consistently in studies.Oh really?
Yeah, it seems your habitual pattern, what your body is used
to, is often the most efficient for you.
However, one thing that does seem linked to better economy is
shorter ground contact time. Less time spent on the ground
per step. OK.
And lastly, those neuromuscular factors, brain and muscles
working together. Super important practise makes
(13:08):
perfect, right? As you run more, your brain gets
better at sending signals, activating muscles efficiently,
reducing wasted effort like muscles fighting each other or.
Coordinated. Exactly.
Muscle power matters too. Faster runners often show more
muscle pre activation just before landing and shorter
contact times. And lower leg stiffness helps.
Think tendons acting like springthe.
(13:28):
Stretch shortening cycle. Precisely using that elastic
energy return efficiently is keyfor propulsion without costing
extra metabolic energy. OK, bring it all back to Garmin.
Their RE uses SSL, that breakingmetric.
So if the 5K runner experiments,maybe tries a smoother stride,
maybe plays with foot strike like he mentioned on his site
trying to lower his SSL, right? What should he expect to see on
(13:52):
his Garmin RE score? Logically, if he successfully
reduces his SSL indicating less braking.
Less wasted energy. And his Garmin RE score should
improve. It should trend lower,
indicating better economy. The basic physics supports it.
Less breaking equals more efficient forward motion.
While Garmin's exact algorithm is secret, the science says
(14:12):
minimising deceleration should help economy, so it.
Aligns with the underlying principles.
OK, final recap. Make sure everyone's clear,
especially if the 5K runner is listening closely for his next
run analysis. Let's do it.
VO2 Max size of your aerobic engine potential.
Yep. Maximum capacity.
VO2 Max how fast you're going when you hit that maximum engine
output. The speed of VO2 Max right?
(14:33):
And running economy, including Garmin's version using SSL.
That's about how efficiently youuse your fuel, your oxygen, at
those steady submaximal paces you actually race at.
Exactly, you can have that Ferrari engine high VO2 Max, but
if your RE is poor it's like driving with the handbrake
slightly on, you're wasting fuel.
Great analogy. Improving RE means taking that
(14:56):
handbrake off. Precisely.
A runner with amazing VO2 Max but poor Aria will burn more
energy at a given pace than someone with maybe a slightly
lower VO2 Max but fantastic economy.
That efficiency is often the real key to unlocking endurance
performance. This has been really
illuminating. Diving into Garmin's new
metrics, step speed, loss and running economy, and seeing how
(15:17):
they connect to and differ from the established science is
fascinating. It really is.
Understanding SSL is a measure of breaking and seeing how
Garmin incorporates it into their RE metric on the 4 runner
970 gives runners a new lens. A new way to think about
efficiency. Yeah, and by understanding all
these factors, bio mechanics, neuromuscular stuff, training,
(15:37):
hopefully runners like yourself and the 5K runner can get deeper
insights, maybe find ways to tweak things for better
performance. So here's something to chew on
for your next run. Now that you've got this deeper
understanding of step speed, loss breaking and running
economy, what's one small thing you could experiment with?
A tiny adjustment in your form, maybe how you think about your
(15:58):
cadence or foot landing, just tosee if you can nudge that
efficiency needle. Yeah.
Become your own. Exeriment.
Exactly. Check out resources like the 5K
Runner site for more ideas and think about how this applies to
your running. Thanks for joining us for this
Dee dive.
Welcome to the deep dive. If you're anything like, say,
the 5K runner, always looking for ways to get faster, shave
off seconds, then, you know, just log in.
Miles isn't the whole picture. So today we're diving into
running efficiency. How understanding it can you
know give you that? Edge exactly.
For any runner chasing a PB, whether it's a 5K or even longer
(00:21):
stuff, it's not just about raw power, it's how efficiently you
use that power, especially at those race paces.
Speaking of efficiency, Garmin'sjust put out a new metric.
It's on their 4 Runner 970 called Running Economy Right?
Designed to give you a look at the energy you're using now.
You do need their HRM 600 chest strap for this one, it's quite
specific. Precisely.
(00:43):
So that's our goal for this deepdive, really get under the hood
of Garmin's running economy. What is it?
How do they calculate it? What effects it?
And we'll definitely look at this step.
Speed loss concept seems important.
Very important and also critically how this all differs
from things we already know likeVO2 Max and VVO 2 Max.
Got to keep those straight. OK, let's start there then.
(01:04):
Step speed loss or SSL sounds pretty technical.
What, in simple terms, is it telling us?
OK, think of it like this. Every single time your foot hits
the ground, you slow down just atiny, tiny bit.
It's unavoidable. Low braking effect.
Exactly. SSL, which Garmin rolled out May
(01:25):
2025, measures that difference. It looks at your forward speed
the instant your foot lands, andthen your minimum forward speed
while that foot is still on the ground.
It's measured in centimetres persecond.
It's going to be just per. 2nd And as the folks at the Five
runner.com point out, and they're right, lower is better.
You want that number small, lessbraking.
Like you're gliding more smoothly.
Terrifically put less loss of momentum with each step.
(01:47):
So how does the watch the Forerunner 970 actually, you
know, capture this and where do I see it?
Well, the key is that HRM 600 chest strap.
It's got the fancy sensors, the accelerometers needed to pick up
these really subtle changes in movement.
OK, not just the watch itself. No meets the strap.
That data then gets sent to the watch, currently the 970.
(02:08):
You can see it live during your run, like on a gauge, or you can
look at the averages after your run for the whole thing, or even
lap by lap, and you'll see SSL incentives but also SSL percent.
The SSL percent you mentioned, that's particularly useful.
Why should someone like the 5K runner focus on the percentage?
Good question. Because your raw SSL, the
(02:29):
cinemas value, well it naturallytends to go up as you run
faster. Makes sense right?
More force involved. So SSL percent, the SSL percent,
it kind of normalises that it takes the speed effect out of
the equation. Levels the playing field.
Exactly. So if you're trying to see if
tweaking your form is actually making you more efficient over
time across different speeds, SSL percent is the metric to
(02:49):
watch. Lower is always the goal.
So if the 5K runner sees his SSLspiking, what are the usual
suspects? Is it form hills to speed?
It's often a mix form is definitely a big one.
Like if your cadence is too low or you're over striding,
reaching out too. Far landing, way out in front.
Right, that's like hitting the brakes harder with every step,
(03:10):
so higher SSL. Makes sense?
Terrain matters too. Garmin uses the watches
barometer to adjust for hills, so uphill you'll usually see
lower SSL gravity help slow you down a bit, Downhill typically
higher SSL. But remember, these hill
adjustments don't work on treadmills, and SSL isn't really
for walking, it's a running metric.
(03:30):
Gotcha, now thinking about breaking forces.
Yep, it makes me think of other metrics like S drive, RYD has
legs bring stiffness and impact loading rate, and there's 4th
frontiers body shock too. Are these all just different
names for the same thing? They're definitely related
because they all look at ground contact, but they measure
different things. SSL is laser focused on that
(03:51):
horizontal breaking the change in forward speed while your
foot. 'S down OK horizontal focus.
Yeah, pester already is leg spring stiffness LSS.
That's more about the vertical bounds.
How springy your leg is, impact loading rate, ILR.
That's how quickly the vertical force ramps up when you land the
initial shock. Right, the jolt.
Kind of and 4th frontiers body shock BS that uses ECG data to
(04:12):
see how your body physiologically reacts to those
impacts. So related concepts but distinct
measurements. SSL is about forward momentum
loss. OK, that clarifies things.
And the five runner.com mentioned SSL is a key input for
Garmin's other new metric running economy.
How do they link up? Precisely.
Garmin's Running Economy or RE is their attempt to measure how
(04:34):
efficiently you use energy whilerunning aerobically.
So getting the most speed for the least effort basically.
You got it. They measure it in millilitres
of oxygen per kilogramme of bodyweight per kilometre, MLKGKLMA.
And just like SSL, lower is better, more efficient, like a
car with better fuel economy. So this is a big deal, right?
Moving away from needing a lab, a mask, a treadmill, bringing re
(04:56):
measurement to everyday runs. It's a significant shift, yeah.
Traditionally, like the science literature shows, you'd measure
RE in a lab looking at oxygen uptake MLK G men at a steady
pace on a treadmill right the. Classic setup.
Gurman is trying to give you similar insights, but from your
regular outdoor runs or track runs.
They do exclude indoor treadmillruns, trail runs, and runs where
you're carrying extra weight. OK.
(05:18):
And how many runs do you need for it to calculate?
Garmin says you need data from at least four or five runs, and
each needs to be over 30 minuteslong.
It needs a decent amount of datato establish your baseline RE.
And what data points is it actually using from those runs?
It's pulling together quite a few things.
Your heart rate, obviously your speed, and then those running
dynamics, stride length, ground contact time, vertical
(05:39):
oscillation, and crucially, stepspeed loss.
SSL. So that's the direct link.
The breaking metric feeds the economy metric.
Exactly. Garmin's logic is that breaking
which SSL measures costs energy.Every time you decelerate even
slightly, your body has to work harder to get back up to speed.
So higher SSL means higher energy cost, which means poor
(06:02):
running economy. That makes total sense.
If you keep tapping the brakes you burn more gas pretty much.
So if the 5K runner works on smoothing out his stride,
reducing that braking, his Garmin RE score should
theoretically improve get lower.That's the idea, yes.
Minimise the braking, reduce theenergy waste and you should see
(06:23):
that reflected in a better lowerRE score from Garmin.
Does Garma give any tips on how to actually train for better RE.
They do offer some general guidance, things like gradually
increasing your weekly mileage, adding strength training to your
routine, and doing some Sprint workouts.
These all align pretty well withwhat the broader science
suggests helps improve running efficiency overtime.
(06:44):
OK, it sounds like a potentiallypowerful tool, but are there
any, you know, caveats, limitations we should keep in
mind? Oh definitely.
It's important to be realistic. First off, this is Garmin's own
algorithm. We don't have independent peer
reviewed studies yet comparing Garmin's RE directly to lab
based oxygen consumption measurements.
So no third party validation. Yet not that we've seen.
(07:04):
Second, Garmin themselves say the SSL data isn't captured
absolutely continuously. There might be tiny gaps where
that key input is missing. And finally, while seeing the
number is interesting, we're still figuring out what specific
RE values mean in practise. Like what's a good score?
How much does a change of X points actually translate to
(07:24):
faster race times? The actionability is still
developing. Right.
It's a new window, but we're still learning how to interpret
the landscape outside. OK, let's zoom out a bit.
What does the established science say about running
economy in general? This isn't a new concept,
obviously. Absolutely not.
It's been studied for decades. In scientific terms, running
(07:45):
economy is usually defined as that oxygen cost of running at a
specific submaximal speed. Submaximal.
Not flat out. Exactly.
Usually expressed as MLK G min or MLK GTO.
And a really key take away from all the research is just how
much it varies between individuals.
What works for one runner might not work for another.
So personalization is key. Totally.
(08:06):
You need to figure out what works for your body and your
mechanics. And why is RE so important,
especially for runners doing longer stuff like the 5K runner
tackles various distances? It becomes absolutely crucial
for endurance. Even small gains in efficiency
add up massively over, say, 1/2 marathon or marathon.
(08:26):
You save a little bit of energy with every single step.
So it accumulates. Hugely.
It can mean less fatigue later in the race, maybe a faster
overall time. In fact, for well trained
runners, RE is often a better predictor of performance than
even their VO2 Max. Wow, better than VO2 Max?
That's saying something. So what factors does the science
point to as influencing RE? It's a whole collection of
(08:49):
things. Your basic metabolism them in
cardio, respiratory fitness, matter of course how well your
body generates energy and delivers oxygen.
The engine basics. Right.
Then there's bio mechanics, yourrunning form, how you move.
That's huge neuromuscular factors to how your brain and
muscles talk to each other and coordinate everything.
Plus your training history, the shoes you wear.
Think about the carbon plate debate.
(09:10):
Oh yeah, definitely. And even things like heat, wind,
altitude all play a role. You mentioned the shoes.
How do those fancy carbon platedshoes supposedly help with RE
according to the research? Well, the study suggests the
stiff plate changes how your foot and ankle work during
ground contact. It seems to reduce energy loss
in the mid sole and maybe returna bit more energy, acting like a
(09:31):
spring or a lever. Less energy wasted.
Essentially, it alters the mechanics, especially around the
calf muscles, leading to small but potentially meaningful
metabolic savings. Better economy, but it's more
about the shoes mechanics than making your body fundamentally
more efficient. That makes sense.
Yeah, it's an equipment assist. Yeah.
OK. So just to hammer this home
running economy is efficiency below your maximum effort.
(09:55):
How's that different again from VO2 Max VA 2 Max?
Right, Critical distinction. VO2 Max.
That's your maximal oxygen uptake, the absolute highest
rate your body can consume oxygen during really intense
exercise. Think of it as the maximum size
of your aerobic engine. Peak capacity.
Peak capacity, then VVO 2 Max velocity at VO2 Max.
That's the slowest speed at whatyou actually hit that peak VO2
(10:16):
Max running economy is different.
It's about how much oxygen you use at sub maximal speeds.
Those paces you actually hold for distance races you could
have a massive VO2 Max. Huge engine.
But be really uneconomical, burning way more fuel than
someone else with the same engine size running at the same
steady pace. RE is about fuel efficiency, not
(10:36):
engine size. That's a great analogy.
So the Wikipedia source mentioned lab measurements on
treadmills. How do they typically do that?
In the lab, they'll usually havea runner run at one or maybe
several constant steady speeds on a treadmill, maybe for 5-10
minutes at each speed. While wearing the mask I assume.
Yep, wearing the mask to measureoxygen intake and carbon dioxide
(10:59):
output. They calculate the oxygen cost
at those speeds. Often they'll standardise it,
maybe estimate the cost at say 16 kilometres per hour, so they
can compare different people. And express it as MLKG men or
MLKGKO. Exactly, though it's worth
remembering treadmill running isn't identical to running
outside. No air resistance, the built
moves under you. Muscle activation can be
(11:21):
slightly different. Good point.
Does the science give us any like benchmark numbers for RE?
What's typical? There are some published ranges.
For example, studies might show recreational runners around,
say, 47 millikumen at 14 kilometres, whereas elites might
be down closer to 40 millikum atthat same speed.
So lowers is better, more efficient.
(11:42):
Correct, but these are just averages.
There's a lot of individual variation, even among elites.
Your own VO2 Max influences it too.
It really highlights the economyis quite personal.
OK, let's dig into those biomechanical factors again.
What does research say about body size and shape?
Well, body mass matters a bit. Heavier runners tend to be
(12:03):
slightly less economical, generally speaking, but where
you carry the mass matters more.Weight on your feet or lower
legs cost more energy than weight around your hips.
Distal weight is worse. Seems to be yeah.
Limb length is more complicated.The research isn't totally clear
on its impact. What about running style?
Stride length? Foot strike.
This is interesting. Most research suggests that the
(12:23):
stride length you naturally choose is probably the most
economical for you. Trying to force a longer or
shorter stride often makes you less efficient.
Don't mess with what feels natural.
Generally, yeah, vertical oscillation, how much you bounce
up and down. It's complex, but excessive
bouncing likely wastes energy. As for foot strike, the idea
that 4 foot striking is always better for economy hasn't really
(12:46):
held up consistently in studies.Oh really?
Yeah, it seems your habitual pattern, what your body is used
to, is often the most efficient for you.
However, one thing that does seem linked to better economy is
shorter ground contact time. Less time spent on the ground
per step. OK.
And lastly, those neuromuscular factors, brain and muscles
working together. Super important practise makes
(13:08):
perfect, right? As you run more, your brain gets
better at sending signals, activating muscles efficiently,
reducing wasted effort like muscles fighting each other or.
Coordinated. Exactly.
Muscle power matters too. Faster runners often show more
muscle pre activation just before landing and shorter
contact times. And lower leg stiffness helps.
Think tendons acting like springthe.
(13:28):
Stretch shortening cycle. Precisely using that elastic
energy return efficiently is keyfor propulsion without costing
extra metabolic energy. OK, bring it all back to Garmin.
Their RE uses SSL, that breakingmetric.
So if the 5K runner experiments,maybe tries a smoother stride,
maybe plays with foot strike like he mentioned on his site
trying to lower his SSL, right? What should he expect to see on
(13:52):
his Garmin RE score? Logically, if he successfully
reduces his SSL indicating less braking.
Less wasted energy. And his Garmin RE score should
improve. It should trend lower,
indicating better economy. The basic physics supports it.
Less breaking equals more efficient forward motion.
While Garmin's exact algorithm is secret, the science says
(14:12):
minimising deceleration should help economy, so it.
Aligns with the underlying principles.
OK, final recap. Make sure everyone's clear,
especially if the 5K runner is listening closely for his next
run analysis. Let's do it.
VO2 Max size of your aerobic engine potential.
Yep. Maximum capacity.
VO2 Max how fast you're going when you hit that maximum engine
output. The speed of VO2 Max right?
(14:33):
And running economy, including Garmin's version using SSL.
That's about how efficiently youuse your fuel, your oxygen, at
those steady submaximal paces you actually race at.
Exactly, you can have that Ferrari engine high VO2 Max, but
if your RE is poor it's like driving with the handbrake
slightly on, you're wasting fuel.
Great analogy. Improving RE means taking that
(14:56):
handbrake off. Precisely.
A runner with amazing VO2 Max but poor Aria will burn more
energy at a given pace than someone with maybe a slightly
lower VO2 Max but fantastic economy.
That efficiency is often the real key to unlocking endurance
performance. This has been really
illuminating. Diving into Garmin's new
metrics, step speed, loss and running economy, and seeing how
(15:17):
they connect to and differ from the established science is
fascinating. It really is.
Understanding SSL is a measure of breaking and seeing how
Garmin incorporates it into their RE metric on the 4 runner
970 gives runners a new lens. A new way to think about
efficiency. Yeah, and by understanding all
these factors, bio mechanics, neuromuscular stuff, training,
(15:37):
hopefully runners like yourself and the 5K runner can get deeper
insights, maybe find ways to tweak things for better
performance. So here's something to chew on
for your next run. Now that you've got this deeper
understanding of step speed, loss breaking and running
economy, what's one small thing you could experiment with?
A tiny adjustment in your form, maybe how you think about your
(15:58):
cadence or foot landing, just tosee if you can nudge that
efficiency needle. Yeah.
Become your own. Exeriment.
Exactly. Check out resources like the 5K
Runner site for more ideas and think about how this applies to
your running. Thanks for joining us for this
Dee dive.
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