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Garmin Stamina and Stamina Potential – A Native Feature Gauging Fatigue

Garmin Stamina and Stamina Potential May Just Be the Enlightenment Tool for Cyclists and Triathletes!

Garmin Stamina and Stamina Potential Cover Graphic
Garmin Stamina is a new, Native feature that shows, in realtime as well as in post-ride analysis, how much you’ve got “Left in the Tank”, as well as the POTENTIAL for what’s “Left in the tank”! Let’s learn some more.

With the release of the ’40 Series of Garmins (the 540, 840 and 1040), as well as a host of watches, Garmin has included the Garmin Stamina and Potential feature. This native Field looks at energy use, intensity, heart rate and other elements to gauge ‘Just how much is left in the tank’ when a cyclist or runner is exercising. It’s one more tool that a cyclist, runner, or triathlete might be able to use for training, breakthroughs, or in an event.

What Is Garmin Stamina?

Garmin Stamina and Stamina Potential Screen Garmin 1040
Ride ‘Blue’, and Garmin Stamina and Stamina Potential will still decline. Fatigue happens, no matter what.

Garmin Stamina is defined as a visible metric that reveals just how much a cyclist has left, in terms of residual energy, power and work, at any capacity, over time. When a cyclist rides harder, Stamina drops faster. When the cyclist recovers, Stamina rebounds. Garmin Stamina is measured in %. If a cyclist is fresh and recovered, Stamina will start at 100%. If this is their second workout of the day, or they haven’t adequately recovered from a previous effort, it may start at <100%.

What is Garmin Stamina Potential?

Garmin Stamina and Stamina Potential Early In an Interval Set
Garmin Stamina is using a pretty complex, really proprietary, algorithm to measure fatigue and work capacity. I think it’s looking at that gool ol’ Wattage, Heart Rate (Variability), Temperature and Cadence combination. It’s pretty cool.

Garmin Stamina Potential shows just how much fatigue is affecting a cyclist’s ability to generate power. I remember Dr. Allen Lim, in 2004, telling me about requiring his athletes to use at least 600 KiloJoules of energy prior to performing intervals, because “500 watts after 600 KiloJoules is a LOT HARDER than 500 watts after just 200 KiloJoules!” And he’s right.

Garmin Stamina begins on a scale of 100-0%, and it declines with Garmin Potential as a ride progresses.

The Garmin Stamina Page On Your Garmin Head Unit

If you have a new ’40 Series, turn on the Garmin Stamina Page by following these steps:

  1. On the main screen, tap on the ‘Sandwich’ Square.
  2. Tap on ‘Activity Profiles’.
  3. Pick a Profile (I have ‘Road’, ‘Indoor’, and ‘Mountain’).
  4. Tap on ‘Data Screens’.
  5. Scroll up and down and look to see if ‘Stamina’ is shown as a page or not. If not, press ‘Add New’.
  6. You should find ‘Stamina’ in the options, and add it.
  7. The Garmin head unit will then offer you ways to slide the ‘Stamina’ page around in order, until it’s where you want it. As a Lefty, I tend to swipe Left-to-Right, so mine is Second-from-Last.
Garmin Stamina Page Procedure
I call the ‘Settings’ button the ‘Sandwich’ button because it looks like two slices of bread with a thin slice of ham in between!

 

Garmin Stamina Settings Page 2
Once you’ve clicked on the Sandwich button, you’ll see this page. Tap the ‘Activity Profiles’ button.

 

Garmin Stamina Page 3
Go to the Profile where you want to add a Stamina Screen.

 

Garmin Stamina Click on 'Data Screens'
Click on ‘Data Screens’

 

'Stamina' Will be near the bottom of the list.
‘Stamina’ Will be near the bottom of the list.

 

Garmin Stamina Reorder Option
Slide the Stamina Page around in order so you can swipe to it or in the case of the 540, you can use the buttons to slide the pages around.

Back-Arrow out until you get to the main screen, and then tap on the Profile itself. Swipe until the screen shows up.

Garmin Stamina and Stamina Potential Page
What you end up with is a page that looks like this.

There are 3 Fields, including a Stamina Bar with Stamina and Stamina Potential in numbers, followed by a Wattage Graph, and finally, a traditional Heart Rate Graph. Above the Stamina Bar is an ‘Estimated Distance’ value, and it makes me wonder if that might not be useful for an Ultra-Cycling event. Hmmm.

How to Use Garmin Stamina and Stamina Potential

Garmin Stamina Stamina Potential 60-60s
I’m purposely avoiding revealing the wattage and heart rate values on this chart, because I honestly believe I couldn’t go any harder, or get Stamina down below 0%. These were Billat 60-60’s, and you can see that I drove the Garmin Stamina Potential down significantly as well.

Remember the ground rules:

  • Once you start a ride file, Stamina and Stamina Potential will begin to decay.
  • The rate of decay is dependent upon time spent at different intensities.
  • At low intensities, Garmin Stamina and Stamina Potential will decay at the same rate. If you ride at a higher intensity, the Garmin Stamina value will drop faster than the Garmin Stamina Potential value.
  • Garmin Stamina can rebound, but it will never be higher than Garmin Stamina Potential.
  • “500 watts after 600 KiloJoules is harder than 500 watt after 200 KiloJoules!”

A 20-Minute Effort With Stamina and Stamina Potential

I’ve been using Garmin Stamina and Stamina Potential for a couple of months now, especially in my Indoor Virtual Studio over at VQ Velocity. We recently rode some ubiquitous 2 x 20 minute efforts right at or just above Threshold. Here are the results of the first interval.

20 Minute Garmin Stamina and Stamina Potential Chart Interval 1
While I was not paying complete attention to this metric, I was watching it out of the corner of my eye.

 

I’ll crowd the chart a bit, to show some other physiological metrics, just so you can see how ‘hard’ this interval really was.

20 Minute Garmin Stamina and Stamina Potential Chart Interval 1 Chart 2 with SmO2
Garmin Stamina and Stamina Potential seem to be pulling from a combo of heart rate variability, wattage, and maybe respiratory rate. I added the SmO2 values from Moxy to show that I actually was at my physiological threshold, which was ABOVE the threshold value provided by Garmin (and other metric platforms, btw….). See my previous blog about SmO2 Tipping Points, and Borrowed Time.

On-Screen, the Page looked like this…

 

Garmin Stamina Stamina Potential 20 Minute Effort
Stamina will decrease faster than Stamina Potential when you’re riding over your Threshold. Stamina Potential is a little slower, but I’m finding that it definitely helps me gauge my effort on work, especially later in a ride.

Look carefully at the Red, Black, and Clear Line. You’ll see an ‘arrow’ where the red meets the black. This is the point where the Garmin Stamina is declining faster than the Garmin Potential Stamina. Red means decline. Green means recovery. Potential will NOT recover during a ride. It may plateau, but it won’t rebound.

For context, here’s the graph of the SECOND 20-minute interval……

Second 20-minute Interval Garmin Stamina Stamina Potential
Physiologically, I got some training effect out of this effort, but had I followed the physics and tried to hold the same power that I had held in the first interval, I would have blown up. Stamina at 3% is an indicator that you’re ON BORROWED TIME. When Stamina and Stamina Potential are BOTH pretty low, you’re cooked, and it’s time to go home.

Billat 60-60s With Stamina and Stamina Potential.

Garmin Stamina Stamina Potential 60-60s With Comments
The 60-second interval intensity for these efforts was roughly 350-375 watts. Watching Stamina and Potential, I was able to gauge just how much I had left in the tank, before exhaustion.

 

Above is the post-ride overview of a set of Billat 60-second intervals with 60-second recoveries. Notice how Garmin Stamina pulls Stamina Potential down over the course of the ride.

Here’s what the ride looked like on my Garmin 1040.

Garmin Stamina and Stamina Potential Early In an Interval Set
This was Interval #7. Stamina is now in the gutter, but I still have some Potential left, so let’s keep going. 

 

Garmin Stamina Billat 60-60s Interval 11
11 Intervals in, and Stamina hovered between 15 and 3%. Stamina Potential dropped about 2 points per 60-second effort.

 

Garmin and Garmin Potential Screen 60-60 Intervals Last Effort
This was my last interval before calling it a morning. The Stamina got down to about 2% in the interval before, but I was unable to perform it for the full 60-seconds, and Stamina rebounded artificially high. While this last interval was high quality at 374 watts, Stamina only came down to 8%, while Stamina Potential reached its’ lowest level, at 24%. I was definitely fatigued.

For context, here is a link to the ride itself on Garmin Connect…


And here is an image of what Garmin gave this ride, in terms of Aerobic TE, Anaerobic TE, EPOC, and Training Effect.

Garmin Stamina Stamina Potential Workout Summary With EPOC Aerobic Anaerobic TE Scores
While I’m ignoring the ‘Tempo’ summary, this was a highly effective Aerobic and Anaerobic Workout that took days from which to recover.

Pay Attention to Garmin Stamina and Stamina Potential

Garmin has been at this game of product development now for about two decades. They bought a company (FirstBeat) with even deeper roots and history. They’re an Aviation company, a sport metrics company, and a travel logistics company. But they’re really onto something here. These developments use a history of science, a slightly conservative approach, but one that is loading features into rugged devices, and then helping recreational athletes improve their fitness in a holistic way. That’s what’s so fascinating about the Garmin Ecosystem. Their motto is, “Beat Yesterday.” And as both a coach and an athlete, using features like Garmin Stamina and Stamina Potential, I am.

Functional Threshold Power Chart Garmin Stamina and Stamina Potential
Something must be working….. The tools are all here at OBC and Garmin Connect.

I’ll post later about the possibilities of BREAKING this fatigue model, and how the model later adapts, but it’s really rare.

Thanks for reading, and ENJOY THE RIDE!