Garmin Forerunner 245

Good Stuff:

Reduced to £200
Relatively large screen compared to body (30mm)
Export GPX files (from web interface or USB)
Customisable Watchfaces and Data Screens
Garmin Linux SDK Available

Bad Stuff:

Grey strap - grooves collect dirt
Charge cable not magnetic
Body not as rugged as Casio Protrek or GShock
Garmin Web and App software is inconsistent
Lots of training metrics and stats fairly useless

Garmin v Casio

Casio make some big chunky watches, the only problem is that the actual display realestate is small compared to the size of the watch.

Casio Protrek PRW-3510 - Diameter = 22mm = 0.86inches
Garmin 245 - Display Diameter = 30mm = 1.2inches

The Casio GShock GSquad line up have even smaller screens.

Ideally what I would like is a Garmin Instinct case with a ForeRunner 245 or 255 screen.

Heart Rate Zone Nonsense

All fitness watches make a big deal about heart rate zones and their effect on training. Garmin defines the Heart Rate Zones as:

Zone 1 (Warm Up) - Relaxed, easy pace, rhythmic breathing.
Zone 2 (Easy) - Comfortable pace, slightly deeper breathing, conversation possible.
Zone 3 (Aerobic) - Moderate pace, more difficult to hold conversation.
Zone 4 (Threshold) - Fast pace and a bit uncomfortable, breathing forceful.
Zone 5 (Maximum) - Sprinting pace, unsustainable for long period of time, labored breathing.

Here are two test activities, a 10km run and a 10km walk.

A 10km walk in 1 Hour 25 Minutes 23 Seconds = approx 7km/h or 8:30 per km. Max HR = 124bpm.
I felt most of this walk was in Zone 3 (Areobic) with a bit in Zone 2 (Easy). I would struggle to walk much faster.

A 10km run in 56 Minutes 56 Seconds = approx 10.5km/h or 5:40 per km. Max HR = 178bpm
I felt most of this run was in Zone 4 (Threshold) with a bit in Zone 5 (Maximum).

Garmin Heart Rate Zones

Lets see how these activities stack up against the Garmin Heart Rate Zones:


A 10km walk at 7km/h or 8:30 per km	10km run at 10.5km/h or 5:40 per km

The Heart Rate Zones for a brisk 10km walk is a bit under where I felt. But the Heart Rate Zones for a 10km run is all wrong. Sustained Zone 5 for nearly an hour is not possible. Max HR 178 which is higher than Garmins calculated HR for me. So much for smart Algorithms and AIs.

Karvonen Heart Rate Zones

Lets see how these activities stack up against the Karvonen Formula Heart Rate Zones (with Resting HR 55 and Max HR 185):


A 10km walk at 7km/h or 8:30 per km	10km run at 10.5km/h or 5:40 per km

The Heart Rate Zones for a brisk 10km walk is wrong. A brisk walk is in the same zone as sitting on the couch! Heart Rate Zones for a 10km run is better but still too high.

Steve Heart Rate Zones

Max HR 192

Lets see how these activities stack up against my custom Heart Rate Zones (Max HR 192):


A 10km walk at 7km/h or 8:30 per km	10km run at 10.5km/h or 5:40 per km

The Heart Rate Zones for a brisk 10km walk is okayish, a bit low. Heart Rate Zones for a 10km run is about right.

Max HR 185

Lets see how these activities stack up against my custom Heart Rate Zones (Max HR 185):


A 10km walk at 7km/h or 8:30 per km	10km run at 10.5km/h or 5:40 per km

The Heart Rate Zones for a brisk 10km walk is okayish, a bit low. Heart Rate Zones for a 10km run is a bit high.

Cycling

Now lets look at a HIIT Cycling activity.

A 24minute HIIT session on a stationary bike, with 30sec intensive intervals followed by 60seconds recovery. Max HR = 154bpm.
I felt the 30second intensive intervals were all out, and I would struggle to do more, yet my Max HR was only 154bpm, nowhere near as high as running.


Zones with Max HR 185	Zones with Max HR 192

No matter how hard I pedalled and how hard my heart was hammering I did not get into Zone 5 at all.

In my experience cycling has a lower Heart Rate than Running. This maybe because the only thing that you can carry directly from running to cycling is your aerobic fitness, and your heart is leaving your legs in the dust. Or is it because only half your body is active? So the big question here, is that if the heart is not working so hard is cycling an effective HIIT workout. Compared to running or elliptical?

But wait, there is more! The high heart rate peaks do not align with the 30 second intenisty periods. Instead peaks are seen in the 60 second recovery period. WTF?

Laps	Time	Cumulative Time	Avg HR	Max HR
1	5:00.0	5:00.0	99	108
2	0:30.0	5:30.0	105	109
3	1:00.0	6:30.0	116	132
4	0:30.0	7:00.0	112	122
5	1:00.0	8:00.0	99	120
6	0:30.0	8:30.0	118	121
7	1:00.0	9:30.0	131	143
8	0:30.0	10:00	123	129
9	1:00.0	11:00	127	137
10	0:30.0	11:30	132	142
11	1:00.0	12:30	144	149
12	0:30	13:00	133	141
13	1:00	14:00	145	149
14	0:30.0	14:30	133	138
15	1:00	15:30	142	152
16	0:30	16:00	137	140
17	1:00.0	17:00	142	152
18	0:30.0	17:30	133	144
19	1:00.0	18:30	148	152
20	0:30.0	19:00	135	140
21	1:00.0	20:00	146	154
22	4:00	24:00	114	136

It seems as if the Garmin is slow to react to changes in HR and also misses brief peaks.

Summary

The problem is that if I set Heart Rate zones based on a % of my estimated max Heart Rate then a run looks ok, but a brisk walk ends up being in the same zone as sitting on the couch eating donuts. Also time spent in HR Zones contributes to Garmin Intensity minutes. I get nothing for a brisk walk, but over 100 Intensity minutes for a run. Then with HIIT workouts the Garmin is slow to react to changes in HR, and missed peaks.I see similar for heavy duty weight training, meaning no anerobic activity is recorded.

I am not sure whats going on. Most websites parrot the HR (220 - Age) formula and recommend heart zone based training regardless of type of exercise. I have posted on a couple of forums asking about this but the reason I got was because a brisk walk is not really exercise! Odd because the WHO recommends brisk walking. And the other advice was to get a HR Chest Strap instead.

Garmin Heart Rate and Heart Rate Zones just do not work for me, and I have to rely on perceived exersion.

SDK Environment

And a bonus with the Garmin is that custom watch faces, and custom activity displays are available in the Garmin Connect IQ Store. If that is not enough there is a Garmin SDK to create your own.

Install Visual Code:
snap install --classic code


This:
https://forums.garmin.com/developer/connect-iq/i/bug-reports/connect-iq-sdk-download-not-working-with-firefox-on-linux

But with:
wget': wget http://archive.ubuntu.com/ubuntu/pool/universe/e/enchant/libenchant1c2a_1.6.0-11.3build1_amd64.deb -O libenchant1c2a_1.6.0-11.3build1_amd64.deb

sudo dpkg -i libenchant1c2a_1.6.0-11.3build1_amd64.deb


Then:
https://developer.garmin.com/connect-iq/sdk/

Create new project with Watch Template
https://developer.garmin.com/connect-iq/connect-iq-basics/your-first-app/#yourfirstconnectiqapp

Ok, I just tried it with VS code,  While it creates a project, there are no target devices.  Use "edit products" to add target devices, or Monkey C: Build for Device


Run then Run Without Debugging

Get Timeout so:
Need to sym plink .prg file from project bin dir to /tmp/GARMIN/APPS
ln -s /home/swatts/Garmin/Steve/Watch2/Watch2/bin/Watch2.prg .

Then we are up an running.

Time to create some Garmin Apps.