EP31 - June 28, 2025 - Deep Dive chat on Sports Tech and training of the week (ft. AI Insights)
Lots of things to discuss this week mainly because it's two very busy weeks' worth of interesting sports tech and related stories for endurance athletes - training, nutrition, tips and physiology...oh, and a bit of tech as usual ;-)
- https://the5krunner.com/2025/06/17/garmin-edge-mtb-opinion-specs-first-look-review/
- https://the5krunner.com/2025/06/16/whoop-4-0-vs-whoop-5-0-sensor-architecture-changes-detailed-technical-content/
- https://the5krunner.com/2025/06/17/polar-announces-whoop-competitor/
- https://the5krunner.com/2025/06/17/why-more-fasting-doesnt-always-mean-more-fat-burn/
- https://the5krunner.com/2025/06/18/garmin-index-sleep-monitor-first-thoughts-review-opinion-specifications/
- https://the5krunner.com/2025/06/20/garmin-to-add-health-connect-support-to-apple/
- https://the5krunner.com/2025/06/20/garmin-enduro-4-inbound-speculation/
- https://the5krunner.com/2025/06/25/garmin-fenix-8-significant-new-features-coming/
- https://the5krunner.com/2025/06/25/garmin-tacx-alpine-all-you-need-to-know/
- https://the5krunner.com/2025/06/25/garmin-quatix-8-specifications-review-opinion/
- https://the5krunner.com/2025/06/26/stages-cycling-re-starts-trading/
- https://the5krunner.com/2025/06/26/garmin-edge-to-add-new-features-to-540-840-1040-1050/
- https://the5krunner.com/2025/06/28/core-2-body-temperature-sensor-review-easy-vo2max-boosts-for-endurance-athletes-greenteg/
Resources & Links:
- Main Channel: https://the5krunner.com
- My other channels: https://linktr.ee/the5krunner
—Credits: Content in this episode was generated using AI tools (NotebookLM) based on original content
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
(00:00):
Welcome to the Deep dive. This week we're cutting through
the noise and diving deep into astack of insights from a
fantastic source, the 5K runner.That's right, you know then that
triathlete, runner and gym enthusiast with a really sharp
eye for sleep, Wellness, health,span and, well, getting faster.
(00:20):
Absolutely. And our mission today really is
to distil the latest and most impactful takeaways from their
recent dispatches. We'll be exploring everything
from, you know, cutting edge sports tech and new health
monitoring solutions to some genuinely surprising findings
about practises like fasting. So if you're looking for that
(00:40):
kind of practical shortcut to understanding the tools and
knowledge that can really elevate your training in daily
life, well, you've come to the right place.
OK, let's get into it then. We have a lot of ground to
cover, starting with some prettyinnovative tech designed to help
you beat the heat. First up, let's talk about
staying cool when your body starts to, you know, really heat
up. We're looking at the Green Tag
(01:01):
Core 2 body temperature sensor. It came out late March 2025 and
it promises to help serious athletes, runners, triathletes,
cyclists optimise performance. What's truly intriguing here, I
think, is how this noninvasive device monitors your real time
core body temperature, not just skin temp.
(01:22):
OK, that gives you much deeper insight into your physiological
state. The 5K runners review really
highlights how precise this monitoring is supposed to be.
How precise are we talking? They claim medical grade
accuracy of 0.21°C. Wow.
Which you know that level of precision means you can
hopefully trust the data to finetune your heat training zones.
(01:43):
So how does it actually work? What does it tell you?
Well, the Core 2 tracks that core body temperature and skin
temperature too, and then it crunches those numbers into
metrics like the Heat Strain index or HSI.
HSI, right? Which basically indicates how
much physiological stress your body is under due to heat.
It also defines heat zones and calculates your heat training
load HTL. And all that feeds into
(02:04):
something called hash. Exactly your heat adaptation
score or hey dis OK. So this raises the question, why
bother with heat training anyway?
Is it just for competing in hot conditions?
That's a great question. The review underscores these
really well documented physiological benefits.
Things like boosting haemoglobinmass, increasing VO2 Max,
(02:27):
improving lactate threshold, enhancing power output and even
expanding blood plasma volume. So quite a lot then.
Yeah, essentially these adaptations lead to improved
performance in any temperature condition, not just hot ones.
Interesting. So it's not just about surviving
the heat. Not at all.
And the sweet spot for effectiveheat training according to Core
2 is heat zone 3. That's an HSI between 3 point O
(02:50):
and 6.9 and. How long do you need to stay in
that zone? Ideally about 45 to 60 minutes
per session. Right now, here's where the 5K
runners personal experience gets.
Really interesting they used it right.
They did, yeah. And despite putting in lots of
outdoor cycling hours during a hot UK summer, their heat
adaptation score didn't significantly increase.
Really, why not? It suggests cycling, maybe
(03:13):
because of the cooling airflow, might not be as effective for
accumulating that heat stress asyou'd think.
Running outdoors, on the other hand, proved much more
productive for heat adaptation in their experience.
OK, that makes sense. Less airflow.
Exactly. And surprisingly, maybe
uncomfortably, indoor heat training with thick clothing
actually worked. Right, like old school methods.
(03:36):
Yeah, and passive heat training too.
Like in a sauna. You have to log that manually in
the app. The device itself won't work in
there, but the principal stands.So it's a good example of how
these easy gangs they talk aboutstill require, you know,
deliberate effort and the right kind of effort.
Absolutely commitment and the right approach.
The reviewer did see their Garmin VO2 Max go up by two
(03:57):
points, but they couldn't definitively say it was just the
heat training given their overall training.
Sure, always hard to isolate 1 variable.
Exactly, but for anyone considering it improving your
hashes, that score takes about 10 to 14 sessions, usually over
2 to 12. Weeks aiming for that 4580
minutes in zone 3 each time. Right.
And once you're adapted, you need maintenance, maybe one to
(04:19):
three sessions a week, otherwiseyour HS can start to drop off
within two or three weeks. OK, good to know persistence
pays off. All right, shifting gears now,
quite literally, let's talk mountain biking.
Garmin's unveiled a new Edge MTB.
Yes, this is a surprisingly focused move from Garmin, and
probably a welcome one for mountain bikers.
(04:41):
What makes it so focused? Well, the headline features are
genuinely new for a Garmin device.
We're talking 5 Hertz GPS recording and dedicated timing
gates. 5 Hertz recording. What does that mean?
Five GPS points per second, but only when you're descending in
the enduro or downhill profiles.So super detailed tracking on
the way down. Exactly.
Gives you incredibly precise data on the lines you took, pick
(05:03):
speeds, that kind of thing. And timing gates.
That's also novel. You can manually set up to 10
gates on a course. Like virtual checkpoints?
Pretty much to track your split times and overall lap time.
It gives you real time feedback.Are you ahead or behind your?
Target. That sounds really useful for
practise runs. Definitely, and the 5K Runner
speculates these features, whileaimed at downhill MTB now, could
(05:24):
eventually trickle down to otheredge units, maybe even watches
for skiing or triathlon. Interesting potential.
What else is new about the unit itself?
Well, it's built tough, rugged rubberized shell, Gorilla Glass
and importantly it's buttons only.
Good for muddy gloves. Exactly.
No fiddling with touch screens. It also has new mounting options
(05:45):
like a top tube mount, and it still includes the usual MTB
dynamics, jump count distance, hang time, plus grit and flow
for trail difficulty and smoothness.
OK, it sounds pretty comprehensive for MTP.
What's the catch? Is it pricey?
Well, the 5K runner notes it's not exactly cheap for what's
positioned as a smaller edge unit.
It's $399, and Garmin deliberately left out some
(06:07):
features from other edges. Things like Power Guide,
training status, even Wi-Fi workout uploads.
Why would? They do that.
The thinking, according to the review, is that this laser focus
makes it a truly dedicated tool.By stripping away features are
relevant to core, downhill and dura writing, they make it
simpler and more effective for that specific purpose.
Right. Less clutter, more focus makes
(06:28):
sense for a dedicated device. Yeah, so while the emissions
might seem odd at first, it actually reinforces its role as
a specific tool for serious MTB writers.
OK, so Speaking of Garmin Edge, there's also news about updates
for existing models. Yes, hot on the heels of the
Edge MTB announcement, Garmin isalso pushing out significant
firmware updates. These are for the popular Edge
(06:50):
540-840-1040 and probably the 10:50 models too.
Great news for current owners then keeps their devices is
fresh. Exactly.
It shows Garmin's commitment to supporting their existing
lineup, which is always good to see.
So what's included in these updates?
Anything major? Well, they're adding those
forkside enhancements from the Edge MTD that gives you more
data about upcoming trail options at junctions.
(07:12):
Better navigation on the trails.Precisely.
Plus, something many users have apparently asked for the ability
to finally toggle the virtual partner off when following a
course. Oh, I could see why people
wanted that. Sometimes you just want to ride
the course without the ghost. Exactly, and from a multi sport
perspective, there's a crucial addition.
Support for viewing adaptive training plans for triathlons.
(07:35):
Meaning meaning the workouts generated by those specific
triathlon plans can now be executed directly on your Edge
device. Much smoother integration for
cyclists doing structured training.
That's a big plus for triathletes using Garmin.
Definitely. And then there are performance
boosts. Faster satellite lock, improved
connectivity, plus a bunch of bug fixes for things like radar
(07:57):
display issues, workout data fields, route recalculation
problems, the usual cleanup. So a pretty solid update all
around. Seems like it.
Now sticking with Garmin, the 5Krunner also dipped into some
speculation. Is a Garmin in Dural 4 on the
horizon? Yeah, this is interesting.
It's speculation, but it's basedon Garmin rolling out new
(08:17):
features specifically for ultra running and.
The thinking is new features often mean a new watch is
coming. Historically, yes.
New software capabilities often debut alongside new hardware.
Right. And the Enduro line, that's
always been about massive battery life, hasn't it?
Exactly. Uber battery life, usually with
the MIP display, solar charging,and typically in a super large
case. The Enduro 2 was based on the
(08:39):
Phoenix 7X, the Enduro 3 on the Phoenix 8.
So what's the speculation this time?
Just an Enduro 4 based on a Phoenix 9.
Well, that's part of it, but theinteresting angle the 5K runner
raises is the potential for Garmin to expand the enduro
range, maybe with smaller sizes.Because not everyone wants a
huge watch, even if they want long battery life.
(08:59):
Precisely the speculation is that these new ultra running
features combined with that userdesire for smaller long battery
watches could hint at maybe a smaller Enduro 3 variant, or
perhaps even something like a 4 runner 975 but with the MIP
display for that battery boost. So Garmin might be rethinking
the Uber battery means massive watch equation.
(09:20):
Possibly. It's not confirmed, of course,
just reading the tea leaves, butit suggests they might be
looking to offer more diverse options for the ultra insurance
crowd. OK, interesting to keep an eye
on. Now let's talk about features
that are coming specifically forthe Phoenix eight generation
major beta update. Yes, a big one.
This affects the Phoenix 8, Phoenix E Tactics 8, and Enduro
(09:41):
3. It's described as a significant
quarterly update. And it includes some genuinely
new features, not just tweaks. Definitely.
There are some things highlighted that aren't even in
the beta yet but are expected soon.
A suite of ultra running features for instance.
Like what? Things like cut off times,
dedicated rest breaks, tracking within an activity and course
(10:03):
point notes all aimed at better managing those long complex
events. Tools for the ultra crowd again
makes sense with the enduro speculation.
Right. And for the broader user base,
Garmin seems to be pushing for deeper links with both Apple
Health and Google Health Connect.
Better data sharing. Potentially, yeah.
And also maybe integration with Google Maps, which could finally
(10:23):
bring proper point of interest support into the Garmin
ecosystem natively. Handy.
What about the features actuallyin the beta now?
Some cool stuff there too. A new calculator app, believe it
or not, with a tip splitter function.
OK, random but potentially useful.
Custom focus modes too, letting you control settings like screen
brightness and satellite accuracy more easily for
(10:44):
different situations, plus enhanced morning and evening
reports. And for athletes?
The new triathlon adaptive training plan support we
mentioned for the Edge is also coming to these watches.
Big deal for multi sport folks. And for runners specifically,
this sounds like a big update for them.
Huge There are new running dynamics metrics coming, Impact
Load, which quantifies the effects of downhill running.
(11:06):
OK, that sounds useful for injury prevention possibly.
Then there's Running Tolerance, which models that load and
suggest safe ranges and running economy.
Running economy? I thought that was hard to
measure accurately. It requires the newer HRM 600
chest strap apparently, but someconsider running economy even
more critical for performance than VO2 Max.
(11:27):
It's about how efficiently you use oxygen at a given pace.
Wow, OK, so Garmin is really pushing the data analysis side.
Continuously providing really rich data-driven insights,
however. There's always a however with
Garmin features, isn't there? Well, the 5K runner does point
out Garmin Garmin's typical tactics.
These shiny new features are primarily rolling out to the
(11:49):
newest generation watches. Encouraging upgrades from older
models like the Finnix 7. That certainly seems to be the
strategy. Keeps the upgrade cycle moving
right? So we've covered a lot on
performance tracking, but what about the other side of the
coin? Recovery.
Garmin's got something new theretoo, right?
The index sleep monitor. Yes, exactly.
Moving from intense training to crucial recovery, Garmin has
(12:13):
just launched this new device inthe Wellness space.
And what is it exactly? A watch replacement for sleep.
It's a lightweight smart band designed to be worn on the upper
arm. And yes, it fills A definite gap
in Garmin's product range. A gap for people who don't like
wearing watches to bed. Exactly that, or for people who
maybe primarily use a Garmin by computer like an Edge and don't
(12:33):
wear a watch daily so they miss out on sleep metrics.
Makes sense. So what's new here?
What does it track? Its main goal is a comprehensive
view of sleep, fitness and recovery.
It gives you a sleep score, tracks sleep stages, continuous
heart rate. Standard stuff.
But also, crucially, heart rate variability, HRV, which as you
know is a key indicator of recovery and stress.
(12:56):
Right, HRV is huge now what else?
Breathing variations, blood oxygen saturation, spell of two,
and interestingly, skin temperature changes.
Skin temp, What can that tell you?
It can offer insights into recent activity, your sleep
environment, potential illness coming on, and even cycles for
woman's health. Okay, quite a lot packed into an
(13:16):
arm band. Is it comfortable?
It's designed for comfort, apparently made from a
breathable fabric band that's machine washable.
Washable is good battery life. Up to seven nights, even with
CO2 tracking enabled. Pretty decent and it syncs with
Garmin Connect obviously. Critically, yes, it seamlessly
syncs data to the app. And importantly, it updates
those key advanced metrics like training, readiness, recovery
(13:38):
time, and your overall HRV status.
So it feeds into the whole Garmin ecosystem.
What's interesting though is howthey're positioning it.
It overlaps with Woop on sleep features, but Garmin isn't
calling it a sports tracker, right?
Exactly. The 5K runner points this out.
Garmin has explicitly chosen notto position the Index sleep as a
sports HR tracker during workouts.
(13:59):
It's purely A dedicated sleep and recovery device.
Which is interesting timing because Polar just announced.
Their own direct whoop competitor.
Yes, the timing is notable. The 204 seven wearable landscape
is definitely heating up. So Polar's jumping into the
screen free wearable game. They are.
They announced it will launch onSeptember 3rd.
A direct woo competitor. And what's the duck news here?
(14:20):
How will it differ? Here's the kicker.
According to the 5K Runner, unlike Woo, Oler's new screen
free wrist wearable will not be subscription based.
Wow that's huge a one time purchase.
That seems to be the plan. It's designed as a passive data
collector. Sleep, activity, health,
fitness, with no notifications, just tracking.
(14:41):
And it's likely to feature Polar's new Elixir sensor tech.
Bolar has a strong background inHR monitoring, don't they?
A very deep legacy in sport science and heart rate accuracy.
Their existing app Polar Flow isalready really robust.
What does Flow offer now that might compete with Whoop?
Comprehensive activity tracking,their Training load Pro feature
(15:01):
for assessing strain, and advanced sleep and recovery
insights via Sleep Plus stages and nightly recharge.
So they have the science. Where does Woop maybe have an
edge? Woop arguably excels in the app
aesthetics, the slickness of theinterface and maybe that AI
driven coaching aspect. Polar, on the other hand,
traditionally offers more robustworkout support within flow over
(15:23):
100 sport modes, adaptive training plans, etcetera.
So this new polar device, no screen, no subscription.
Who's it for? Well, this is Polar's first
screen free wrist wearable and that non subscription model is a
massive differentiator. The 5K runner speculates that
WOOP might keep its hold on the higher end, maybe more lifestyle
(15:43):
focused market, but Polar could grab a significant chunk of the
more price sensitive market, especially in Europe where Polar
has a really strong existing customer base.
It really connects to that bigger picture of information
overload, doesn't it? Absolutely.
As more players enter the space,the real value isn't just
collecting data, it's how that data is interpreted and
presented back to you in a way that helps you make actual
(16:06):
decisions without getting buriedin numbers.
Making the data actionable, not just interesting.
Precisely. OK, let's switch gears again.
Back to cycling, but more the business side stages cycling.
They went bankrupt, but they're back.
Yeah, this is a sort of resilience story with a
strategic twist. Stages, Cycling's parent
company, filed for bankruptcy back in June 2024.
(16:29):
I. Remember that a lot of their
debt was owed to Giant. The bike manufacturer wasn't.
It exactly and Giant subsequently acquired Stages
assets, their power metres, indoor bikes, bike computers,
the whole lot. So Giant bought them out of
bankruptcy. What's the latest update?
Just two days ago, June 24th, 2025, Giant officially
relaunched the Stages cycling brand.
(16:49):
They're back in business. What are they selling initially?
Their initial focus seems to be squarely on the crank arm based
power metre lineup. They're updating them for
compatibility with modern Shimano crank sets.
Good news for cyclists who likedstages, power metres.
Definitely, and the interesting strategic angle here, as the 5K
runner suggests, is what Giant might do next.
(17:11):
Like what put Stages power metres on giant bikes from the
factory. That's the strong suggestion.
Integrate stages tech into theirown bikes offering pre installed
accessories. That increases the value for the
bike buyer and simplifies things.
Makes sense for Giant, but what about the other stuff Giant
acquired? The Stages bike computers, for
example. That's the big question.
(17:32):
Giant owns them now, but there'szero confirmation on whether
they'll restart production. The article suggests those
computers would need a quote complete overhaul to really
compete with Garmin and Wahoo today.
Yeah, that market moves fast. Still, the stages brand is
strong, isn't it? Used in the propelloton and all
that. It definitely has brand
recognition and credibility, so its return, even if it's
(17:53):
initially just the power metres,is a notable development for
cyclists. Now for the real tech heads, the
5K runner also do a deep dive into the sensor tech inside WHO
bands, comparing the 4.0 and 5.0.
Getting into the nitty gritty, what do they find?
Are they different under the hood?
They look the same from the outside.
(18:13):
That's the key point. They look identical on the
underside where the sensors are,but the internal electronics
actually different. Really.
So the 5.0 isn't just a softwareupdate on the same hardware.
Apparently not entirely. The WHUOP 5 Point O features an
enhanced PPG sensor. That's the optical heart rate
sensor. Enhanced how?
It boasts an increased sampling rate around 26 Hertz compared to
(18:37):
lower rates previously. Meaning it's taking readings
more frequently. Exactly.
More snapshots of your blood flow per second.
This allows for more precise tracking of physiological
metrics and, crucially, improvedsignal clarity.
The review strongly suggests this points to upgraded
hardware, or at least firmware enabled bling that higher
frequency tracking. OK, so a genuine internal
(18:59):
upgrade. What about the WHEOPMG?
The one with ECG? Internally, it's described as
essentially identical to the five point O, except for the
addition of a specific circuit board just for that ECG feature.
Got it. So subtle but significant
hardware evolution happening even when the outside looks the
same. Speaks to how this tech is
(19:19):
constantly improving. Constantly.
Yeah. Often in ways you can't
immediately see. Alright, to wrap U our deep dive
into the latest from the 5K runner, let's switch focus one
last time to something a lot of people are curious about,
intermittent fasting and fat burn.
Yes, and this article tackles a common assumption head on, the
(19:40):
idea that when fasting, longer is always better for burning
fat. Right, that seems to be the
general advice often like push for 1618 even 24 hours.
But this piece raises an important question.
What's the optimal fasting duration for you?
It introduces the concept of a metabolic sweet spot for fat
burning. A sweet spot, meaning there's a
point of diminishing returns or even negative effects.
(20:01):
Exactly a point where your body is most efficiently using fat
for fuel. And crucially, this sweet spot
isn't fixed. It can change daily based on
your diet, your sleep, stress levels, lots of factors.
And fasting beyond that sweet spot.
Especially past 24 hours withoutgetting enough protein could
actually lead to muscle loss, which most people want to avoid.
OK, so how do you find this sweet spot?
(20:23):
What did the 5K runner learn? They drew insights from Lumen,
that health tech company, with the Breathalyser device.
Right, the one that measures if you're burning carbs or fat.
Yeah, Lumens data suggests most people reach their peak fat
burns somewhere between 12 and 18 hours into a fast. 12 to 18
hours, what's the average? The average seems to be around
13 hours, and this aligns prettywell with broader scientific
(20:46):
studies too. Interesting.
So not necessarily 16 or 18 hours for everyone.
Not necessarily. The data also showed some
individual differences. People with a healthy BMI might
hit peak fat burn a bit sooner, and men tend to have slightly
higher fat oxidation rates than women on average.
So this really challenges those rigid protocols like always
doing 16.8 or 18.6 fasting. It does.
(21:08):
It suggests a more personalised approach might be better.
Tools like Lumen, by analysing the Q euro in your breath, aim
to help with that personalization.
How? By telling you when you've hit
peak that burn. Essentially, yes, by showing you
when your body shifts away from primarily burning fat and starts
relying more on carbs again, that shift could be your signal.
(21:30):
A signal that it might be time to break the fast.
Exactly, especially if your goalis maximising fat use while
preserving muscle. It's about knowing when
extending the fast might become less beneficial or even
detrimental to muscle mass. So the key takeaway is
personalization is key fast, smarter, not just longer.
That's the clear message. Focus on metabolic health, find
(21:53):
your optimal window and prioritise preserving muscle.
It's about using data, if possible, to listen to your body
rather than just sticking to an arbitrary time schedule.
What an incredibly insightful deep dive covering everything
from, you know, core temperaturesensors to the nitty gritty of
fasting metabolism. These stories from the 5K Runner
really do give us that shortcut to being well informed.
(22:15):
It's fascinating, isn't it? If you connect these dots, you
see this clear trend. Our ability to gather and
actually interpret highly personalised data about our own
bodies is just exploding. Moving beyond generic advice.
Exactly, it empowers us to crafttruly customised strategies for
training, for recovery, for overall well-being, based on our
(22:36):
own individual Physiology. Absolutely.
And it really leaves you with a provocative thought, doesn't it?
As these technologies get even more accessible, more integrated
into our lives, how is our relationship with our own bodies
and all this data they produce going to keep evolving?
What new insights are just around the corner?
What will we unlock next that completely changes how we think
(22:57):
about performance or health? We'll definitely be here to
unpack it all for you when it happens.
Thanks for diving deep with us today.
Until next time, stay curious.
Welcome to the Deep dive. This week we're cutting through
the noise and diving deep into astack of insights from a
fantastic source, the 5K runner.That's right, you know then that
triathlete, runner and gym enthusiast with a really sharp
eye for sleep, Wellness, health,span and, well, getting faster.
(00:20):
Absolutely. And our mission today really is
to distil the latest and most impactful takeaways from their
recent dispatches. We'll be exploring everything
from, you know, cutting edge sports tech and new health
monitoring solutions to some genuinely surprising findings
about practises like fasting. So if you're looking for that
(00:40):
kind of practical shortcut to understanding the tools and
knowledge that can really elevate your training in daily
life, well, you've come to the right place.
OK, let's get into it then. We have a lot of ground to
cover, starting with some prettyinnovative tech designed to help
you beat the heat. First up, let's talk about
staying cool when your body starts to, you know, really heat
up. We're looking at the Green Tag
(01:01):
Core 2 body temperature sensor. It came out late March 2025 and
it promises to help serious athletes, runners, triathletes,
cyclists optimise performance. What's truly intriguing here, I
think, is how this noninvasive device monitors your real time
core body temperature, not just skin temp.
(01:22):
OK, that gives you much deeper insight into your physiological
state. The 5K runners review really
highlights how precise this monitoring is supposed to be.
How precise are we talking? They claim medical grade
accuracy of 0.21°C. Wow.
Which you know that level of precision means you can
hopefully trust the data to finetune your heat training zones.
(01:43):
So how does it actually work? What does it tell you?
Well, the Core 2 tracks that core body temperature and skin
temperature too, and then it crunches those numbers into
metrics like the Heat Strain index or HSI.
HSI, right? Which basically indicates how
much physiological stress your body is under due to heat.
It also defines heat zones and calculates your heat training
load HTL. And all that feeds into
(02:04):
something called hash. Exactly your heat adaptation
score or hey dis OK. So this raises the question, why
bother with heat training anyway?
Is it just for competing in hot conditions?
That's a great question. The review underscores these
really well documented physiological benefits.
Things like boosting haemoglobinmass, increasing VO2 Max,
(02:27):
improving lactate threshold, enhancing power output and even
expanding blood plasma volume. So quite a lot then.
Yeah, essentially these adaptations lead to improved
performance in any temperature condition, not just hot ones.
Interesting. So it's not just about surviving
the heat. Not at all.
And the sweet spot for effectiveheat training according to Core
2 is heat zone 3. That's an HSI between 3 point O
(02:50):
and 6.9 and. How long do you need to stay in
that zone? Ideally about 45 to 60 minutes
per session. Right now, here's where the 5K
runners personal experience gets.
Really interesting they used it right.
They did, yeah. And despite putting in lots of
outdoor cycling hours during a hot UK summer, their heat
adaptation score didn't significantly increase.
Really, why not? It suggests cycling, maybe
(03:13):
because of the cooling airflow, might not be as effective for
accumulating that heat stress asyou'd think.
Running outdoors, on the other hand, proved much more
productive for heat adaptation in their experience.
OK, that makes sense. Less airflow.
Exactly. And surprisingly, maybe
uncomfortably, indoor heat training with thick clothing
actually worked. Right, like old school methods.
(03:36):
Yeah, and passive heat training too.
Like in a sauna. You have to log that manually in
the app. The device itself won't work in
there, but the principal stands.So it's a good example of how
these easy gangs they talk aboutstill require, you know,
deliberate effort and the right kind of effort.
Absolutely commitment and the right approach.
The reviewer did see their Garmin VO2 Max go up by two
(03:57):
points, but they couldn't definitively say it was just the
heat training given their overall training.
Sure, always hard to isolate 1 variable.
Exactly, but for anyone considering it improving your
hashes, that score takes about 10 to 14 sessions, usually over
2 to 12. Weeks aiming for that 4580
minutes in zone 3 each time. Right.
And once you're adapted, you need maintenance, maybe one to
(04:19):
three sessions a week, otherwiseyour HS can start to drop off
within two or three weeks. OK, good to know persistence
pays off. All right, shifting gears now,
quite literally, let's talk mountain biking.
Garmin's unveiled a new Edge MTB.
Yes, this is a surprisingly focused move from Garmin, and
probably a welcome one for mountain bikers.
(04:41):
What makes it so focused? Well, the headline features are
genuinely new for a Garmin device.
We're talking 5 Hertz GPS recording and dedicated timing
gates. 5 Hertz recording. What does that mean?
Five GPS points per second, but only when you're descending in
the enduro or downhill profiles.So super detailed tracking on
the way down. Exactly.
Gives you incredibly precise data on the lines you took, pick
(05:03):
speeds, that kind of thing. And timing gates.
That's also novel. You can manually set up to 10
gates on a course. Like virtual checkpoints?
Pretty much to track your split times and overall lap time.
It gives you real time feedback.Are you ahead or behind your?
Target. That sounds really useful for
practise runs. Definitely, and the 5K Runner
speculates these features, whileaimed at downhill MTB now, could
(05:24):
eventually trickle down to otheredge units, maybe even watches
for skiing or triathlon. Interesting potential.
What else is new about the unit itself?
Well, it's built tough, rugged rubberized shell, Gorilla Glass
and importantly it's buttons only.
Good for muddy gloves. Exactly.
No fiddling with touch screens. It also has new mounting options
(05:45):
like a top tube mount, and it still includes the usual MTB
dynamics, jump count distance, hang time, plus grit and flow
for trail difficulty and smoothness.
OK, it sounds pretty comprehensive for MTP.
What's the catch? Is it pricey?
Well, the 5K runner notes it's not exactly cheap for what's
positioned as a smaller edge unit.
It's $399, and Garmin deliberately left out some
(06:07):
features from other edges. Things like Power Guide,
training status, even Wi-Fi workout uploads.
Why would? They do that.
The thinking, according to the review, is that this laser focus
makes it a truly dedicated tool.By stripping away features are
relevant to core, downhill and dura writing, they make it
simpler and more effective for that specific purpose.
Right. Less clutter, more focus makes
(06:28):
sense for a dedicated device. Yeah, so while the emissions
might seem odd at first, it actually reinforces its role as
a specific tool for serious MTB writers.
OK, so Speaking of Garmin Edge, there's also news about updates
for existing models. Yes, hot on the heels of the
Edge MTB announcement, Garmin isalso pushing out significant
firmware updates. These are for the popular Edge
(06:50):
540-840-1040 and probably the 10:50 models too.
Great news for current owners then keeps their devices is
fresh. Exactly.
It shows Garmin's commitment to supporting their existing
lineup, which is always good to see.
So what's included in these updates?
Anything major? Well, they're adding those
forkside enhancements from the Edge MTD that gives you more
data about upcoming trail options at junctions.
(07:12):
Better navigation on the trails.Precisely.
Plus, something many users have apparently asked for the ability
to finally toggle the virtual partner off when following a
course. Oh, I could see why people
wanted that. Sometimes you just want to ride
the course without the ghost. Exactly, and from a multi sport
perspective, there's a crucial addition.
Support for viewing adaptive training plans for triathlons.
(07:35):
Meaning meaning the workouts generated by those specific
triathlon plans can now be executed directly on your Edge
device. Much smoother integration for
cyclists doing structured training.
That's a big plus for triathletes using Garmin.
Definitely. And then there are performance
boosts. Faster satellite lock, improved
connectivity, plus a bunch of bug fixes for things like radar
(07:57):
display issues, workout data fields, route recalculation
problems, the usual cleanup. So a pretty solid update all
around. Seems like it.
Now sticking with Garmin, the 5Krunner also dipped into some
speculation. Is a Garmin in Dural 4 on the
horizon? Yeah, this is interesting.
It's speculation, but it's basedon Garmin rolling out new
(08:17):
features specifically for ultra running and.
The thinking is new features often mean a new watch is
coming. Historically, yes.
New software capabilities often debut alongside new hardware.
Right. And the Enduro line, that's
always been about massive battery life, hasn't it?
Exactly. Uber battery life, usually with
the MIP display, solar charging,and typically in a super large
case. The Enduro 2 was based on the
(08:39):
Phoenix 7X, the Enduro 3 on the Phoenix 8.
So what's the speculation this time?
Just an Enduro 4 based on a Phoenix 9.
Well, that's part of it, but theinteresting angle the 5K runner
raises is the potential for Garmin to expand the enduro
range, maybe with smaller sizes.Because not everyone wants a
huge watch, even if they want long battery life.
(08:59):
Precisely the speculation is that these new ultra running
features combined with that userdesire for smaller long battery
watches could hint at maybe a smaller Enduro 3 variant, or
perhaps even something like a 4 runner 975 but with the MIP
display for that battery boost. So Garmin might be rethinking
the Uber battery means massive watch equation.
(09:20):
Possibly. It's not confirmed, of course,
just reading the tea leaves, butit suggests they might be
looking to offer more diverse options for the ultra insurance
crowd. OK, interesting to keep an eye
on. Now let's talk about features
that are coming specifically forthe Phoenix eight generation
major beta update. Yes, a big one.
This affects the Phoenix 8, Phoenix E Tactics 8, and Enduro
(09:41):
3. It's described as a significant
quarterly update. And it includes some genuinely
new features, not just tweaks. Definitely.
There are some things highlighted that aren't even in
the beta yet but are expected soon.
A suite of ultra running features for instance.
Like what? Things like cut off times,
dedicated rest breaks, tracking within an activity and course
(10:03):
point notes all aimed at better managing those long complex
events. Tools for the ultra crowd again
makes sense with the enduro speculation.
Right. And for the broader user base,
Garmin seems to be pushing for deeper links with both Apple
Health and Google Health Connect.
Better data sharing. Potentially, yeah.
And also maybe integration with Google Maps, which could finally
(10:23):
bring proper point of interest support into the Garmin
ecosystem natively. Handy.
What about the features actuallyin the beta now?
Some cool stuff there too. A new calculator app, believe it
or not, with a tip splitter function.
OK, random but potentially useful.
Custom focus modes too, letting you control settings like screen
brightness and satellite accuracy more easily for
(10:44):
different situations, plus enhanced morning and evening
reports. And for athletes?
The new triathlon adaptive training plan support we
mentioned for the Edge is also coming to these watches.
Big deal for multi sport folks. And for runners specifically,
this sounds like a big update for them.
Huge There are new running dynamics metrics coming, Impact
Load, which quantifies the effects of downhill running.
(11:06):
OK, that sounds useful for injury prevention possibly.
Then there's Running Tolerance, which models that load and
suggest safe ranges and running economy.
Running economy? I thought that was hard to
measure accurately. It requires the newer HRM 600
chest strap apparently, but someconsider running economy even
more critical for performance than VO2 Max.
(11:27):
It's about how efficiently you use oxygen at a given pace.
Wow, OK, so Garmin is really pushing the data analysis side.
Continuously providing really rich data-driven insights,
however. There's always a however with
Garmin features, isn't there? Well, the 5K runner does point
out Garmin Garmin's typical tactics.
These shiny new features are primarily rolling out to the
(11:49):
newest generation watches. Encouraging upgrades from older
models like the Finnix 7. That certainly seems to be the
strategy. Keeps the upgrade cycle moving
right? So we've covered a lot on
performance tracking, but what about the other side of the
coin? Recovery.
Garmin's got something new theretoo, right?
The index sleep monitor. Yes, exactly.
Moving from intense training to crucial recovery, Garmin has
(12:13):
just launched this new device inthe Wellness space.
And what is it exactly? A watch replacement for sleep.
It's a lightweight smart band designed to be worn on the upper
arm. And yes, it fills A definite gap
in Garmin's product range. A gap for people who don't like
wearing watches to bed. Exactly that, or for people who
maybe primarily use a Garmin by computer like an Edge and don't
(12:33):
wear a watch daily so they miss out on sleep metrics.
Makes sense. So what's new here?
What does it track? Its main goal is a comprehensive
view of sleep, fitness and recovery.
It gives you a sleep score, tracks sleep stages, continuous
heart rate. Standard stuff.
But also, crucially, heart rate variability, HRV, which as you
know is a key indicator of recovery and stress.
(12:56):
Right, HRV is huge now what else?
Breathing variations, blood oxygen saturation, spell of two,
and interestingly, skin temperature changes.
Skin temp, What can that tell you?
It can offer insights into recent activity, your sleep
environment, potential illness coming on, and even cycles for
woman's health. Okay, quite a lot packed into an
(13:16):
arm band. Is it comfortable?
It's designed for comfort, apparently made from a
breathable fabric band that's machine washable.
Washable is good battery life. Up to seven nights, even with
CO2 tracking enabled. Pretty decent and it syncs with
Garmin Connect obviously. Critically, yes, it seamlessly
syncs data to the app. And importantly, it updates
those key advanced metrics like training, readiness, recovery
(13:38):
time, and your overall HRV status.
So it feeds into the whole Garmin ecosystem.
What's interesting though is howthey're positioning it.
It overlaps with Woop on sleep features, but Garmin isn't
calling it a sports tracker, right?
Exactly. The 5K runner points this out.
Garmin has explicitly chosen notto position the Index sleep as a
sports HR tracker during workouts.
(13:59):
It's purely A dedicated sleep and recovery device.
Which is interesting timing because Polar just announced.
Their own direct whoop competitor.
Yes, the timing is notable. The 204 seven wearable landscape
is definitely heating up. So Polar's jumping into the
screen free wearable game. They are.
They announced it will launch onSeptember 3rd.
A direct woo competitor. And what's the duck news here?
(14:20):
How will it differ? Here's the kicker.
According to the 5K Runner, unlike Woo, Oler's new screen
free wrist wearable will not be subscription based.
Wow that's huge a one time purchase.
That seems to be the plan. It's designed as a passive data
collector. Sleep, activity, health,
fitness, with no notifications, just tracking.
(14:41):
And it's likely to feature Polar's new Elixir sensor tech.
Bolar has a strong background inHR monitoring, don't they?
A very deep legacy in sport science and heart rate accuracy.
Their existing app Polar Flow isalready really robust.
What does Flow offer now that might compete with Whoop?
Comprehensive activity tracking,their Training load Pro feature
(15:01):
for assessing strain, and advanced sleep and recovery
insights via Sleep Plus stages and nightly recharge.
So they have the science. Where does Woop maybe have an
edge? Woop arguably excels in the app
aesthetics, the slickness of theinterface and maybe that AI
driven coaching aspect. Polar, on the other hand,
traditionally offers more robustworkout support within flow over
(15:23):
100 sport modes, adaptive training plans, etcetera.
So this new polar device, no screen, no subscription.
Who's it for? Well, this is Polar's first
screen free wrist wearable and that non subscription model is a
massive differentiator. The 5K runner speculates that
WOOP might keep its hold on the higher end, maybe more lifestyle
(15:43):
focused market, but Polar could grab a significant chunk of the
more price sensitive market, especially in Europe where Polar
has a really strong existing customer base.
It really connects to that bigger picture of information
overload, doesn't it? Absolutely.
As more players enter the space,the real value isn't just
collecting data, it's how that data is interpreted and
presented back to you in a way that helps you make actual
(16:06):
decisions without getting buriedin numbers.
Making the data actionable, not just interesting.
Precisely. OK, let's switch gears again.
Back to cycling, but more the business side stages cycling.
They went bankrupt, but they're back.
Yeah, this is a sort of resilience story with a
strategic twist. Stages, Cycling's parent
company, filed for bankruptcy back in June 2024.
(16:29):
I. Remember that a lot of their
debt was owed to Giant. The bike manufacturer wasn't.
It exactly and Giant subsequently acquired Stages
assets, their power metres, indoor bikes, bike computers,
the whole lot. So Giant bought them out of
bankruptcy. What's the latest update?
Just two days ago, June 24th, 2025, Giant officially
relaunched the Stages cycling brand.
(16:49):
They're back in business. What are they selling initially?
Their initial focus seems to be squarely on the crank arm based
power metre lineup. They're updating them for
compatibility with modern Shimano crank sets.
Good news for cyclists who likedstages, power metres.
Definitely, and the interesting strategic angle here, as the 5K
runner suggests, is what Giant might do next.
(17:11):
Like what put Stages power metres on giant bikes from the
factory. That's the strong suggestion.
Integrate stages tech into theirown bikes offering pre installed
accessories. That increases the value for the
bike buyer and simplifies things.
Makes sense for Giant, but what about the other stuff Giant
acquired? The Stages bike computers, for
example. That's the big question.
(17:32):
Giant owns them now, but there'szero confirmation on whether
they'll restart production. The article suggests those
computers would need a quote complete overhaul to really
compete with Garmin and Wahoo today.
Yeah, that market moves fast. Still, the stages brand is
strong, isn't it? Used in the propelloton and all
that. It definitely has brand
recognition and credibility, so its return, even if it's
(17:53):
initially just the power metres,is a notable development for
cyclists. Now for the real tech heads, the
5K runner also do a deep dive into the sensor tech inside WHO
bands, comparing the 4.0 and 5.0.
Getting into the nitty gritty, what do they find?
Are they different under the hood?
They look the same from the outside.
(18:13):
That's the key point. They look identical on the
underside where the sensors are,but the internal electronics
actually different. Really.
So the 5.0 isn't just a softwareupdate on the same hardware.
Apparently not entirely. The WHUOP 5 Point O features an
enhanced PPG sensor. That's the optical heart rate
sensor. Enhanced how?
It boasts an increased sampling rate around 26 Hertz compared to
(18:37):
lower rates previously. Meaning it's taking readings
more frequently. Exactly.
More snapshots of your blood flow per second.
This allows for more precise tracking of physiological
metrics and, crucially, improvedsignal clarity.
The review strongly suggests this points to upgraded
hardware, or at least firmware enabled bling that higher
frequency tracking. OK, so a genuine internal
(18:59):
upgrade. What about the WHEOPMG?
The one with ECG? Internally, it's described as
essentially identical to the five point O, except for the
addition of a specific circuit board just for that ECG feature.
Got it. So subtle but significant
hardware evolution happening even when the outside looks the
same. Speaks to how this tech is
(19:19):
constantly improving. Constantly.
Yeah. Often in ways you can't
immediately see. Alright, to wrap U our deep dive
into the latest from the 5K runner, let's switch focus one
last time to something a lot of people are curious about,
intermittent fasting and fat burn.
Yes, and this article tackles a common assumption head on, the
(19:40):
idea that when fasting, longer is always better for burning
fat. Right, that seems to be the
general advice often like push for 1618 even 24 hours.
But this piece raises an important question.
What's the optimal fasting duration for you?
It introduces the concept of a metabolic sweet spot for fat
burning. A sweet spot, meaning there's a
point of diminishing returns or even negative effects.
(20:01):
Exactly a point where your body is most efficiently using fat
for fuel. And crucially, this sweet spot
isn't fixed. It can change daily based on
your diet, your sleep, stress levels, lots of factors.
And fasting beyond that sweet spot.
Especially past 24 hours withoutgetting enough protein could
actually lead to muscle loss, which most people want to avoid.
OK, so how do you find this sweet spot?
(20:23):
What did the 5K runner learn? They drew insights from Lumen,
that health tech company, with the Breathalyser device.
Right, the one that measures if you're burning carbs or fat.
Yeah, Lumens data suggests most people reach their peak fat
burns somewhere between 12 and 18 hours into a fast. 12 to 18
hours, what's the average? The average seems to be around
13 hours, and this aligns prettywell with broader scientific
(20:46):
studies too. Interesting.
So not necessarily 16 or 18 hours for everyone.
Not necessarily. The data also showed some
individual differences. People with a healthy BMI might
hit peak fat burn a bit sooner, and men tend to have slightly
higher fat oxidation rates than women on average.
So this really challenges those rigid protocols like always
doing 16.8 or 18.6 fasting. It does.
(21:08):
It suggests a more personalised approach might be better.
Tools like Lumen, by analysing the Q euro in your breath, aim
to help with that personalization.
How? By telling you when you've hit
peak that burn. Essentially, yes, by showing you
when your body shifts away from primarily burning fat and starts
relying more on carbs again, that shift could be your signal.
(21:30):
A signal that it might be time to break the fast.
Exactly, especially if your goalis maximising fat use while
preserving muscle. It's about knowing when
extending the fast might become less beneficial or even
detrimental to muscle mass. So the key takeaway is
personalization is key fast, smarter, not just longer.
That's the clear message. Focus on metabolic health, find
(21:53):
your optimal window and prioritise preserving muscle.
It's about using data, if possible, to listen to your body
rather than just sticking to an arbitrary time schedule.
What an incredibly insightful deep dive covering everything
from, you know, core temperaturesensors to the nitty gritty of
fasting metabolism. These stories from the 5K Runner
really do give us that shortcut to being well informed.
(22:15):
It's fascinating, isn't it? If you connect these dots, you
see this clear trend. Our ability to gather and
actually interpret highly personalised data about our own
bodies is just exploding. Moving beyond generic advice.
Exactly, it empowers us to crafttruly customised strategies for
training, for recovery, for overall well-being, based on our
(22:36):
own individual Physiology. Absolutely.
And it really leaves you with a provocative thought, doesn't it?
As these technologies get even more accessible, more integrated
into our lives, how is our relationship with our own bodies
and all this data they produce going to keep evolving?
What new insights are just around the corner?
What will we unlock next that completely changes how we think
(22:57):
about performance or health? We'll definitely be here to
unpack it all for you when it happens.
Thanks for diving deep with us today.
Until next time, stay curious.
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