Garmin to add Training Load Ratio and Chronic Load
The Garmin Forerunner 965 Review is now live
The Garmin Forerunner 965 will debut the new Load Ratio metric upon its release on Tuesday, 14 March. Development is seemingly complete, as users with supported devices can now view Chronic Load alongside Acute Load in the Garmin Connect app.
First Up – What’s New
While Acute Load and Chronic Load have been part of Garmin algorithms for some time, Chronic Load is now visible in the app for the first time. These established metrics are widely used across various athletic platforms to monitor training progression.
What Is Chronic Load (CTL)?
Chronic Load (CTL) represents the long-term impact of your training. Ideally, this should increase at a rate your body can tolerate. It serves as a measure of fitness and “fitness fatigue,” which can be influenced by short-term activities. The impact of these short-term efforts is measured by your Acute Training Load (ATL).
The calculation is typically based on time spent in heart rate zones using HR TRIMP, although Garmin uses an EPOC-based method:
- Acute Training Load (ATL) is a 7-day or 15-day moving average of HR TRIMP/EPOC.
- Chronic Training Load (CTL) is often a 42-day moving average of HR TRIMP/EPOC.
These timeframes align with sports science principles dating back to the 1970s. Typically, subtracting one from the other determines “form”; a positive result suggests the athlete is in a prime state to perform.
What is Garmin’s New Load Ratio?
Garmin’s Load Ratio (LR) is based on Firstbeat’s Acute:Chronic Workload Ratio (ACWR). This metric uses a traffic light system to indicate training safety and effectiveness.
The Acute vs. Chronic Training Load ratio is colour-coded:
- Green (Optimal): Ratio of 0.8–1.3. This is the “sweet spot” where injury risk is minimised.
- Yellow (Moderate): Increasing load.
- Red (High Risk): A ratio >1.5 is the danger zone, while >1.8 indicates significant injury risk.
Load ratio compares your short-term (acute) and long-term (chronic) training load. Train with your watch for two weeks to see your ratio. Training load is a measurement of effort calculated from recent exercise load scores, accounting for duration and intensity. [Garmin]
Take Out & Thoughts
This is a valuable addition for athletes to consider alongside HRV data and perceived exertion. While not a new concept in sports science, Garmin is likely launching it now to coincide with the AMOLED screens of the Forerunner 965 and 265.
Garmin will also introduce wrist-based running dynamics metrics simultaneously. If your device currently supports Acute Load, it is highly probable you will receive Chronic Load and the Load Ratio/ACWR update.
Last Updated on 5 March 2026 by the5krunner
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tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors.
Seems interesting
Tuesday 14th March (should actually be Thursday) or Tuesday 14th February for the 965?
im hoping he meant February 14th!
nope, sy
I’ve got it visible in my connect app now. A bit of a cramped window
At this point Garmin will have almost every paid Strava feature.
I think they are only missing auto-detect pace trend on matching activities.
Easy to implement if they want
Yes, got it right now on my Instinct 2, but I’m running a beta, not sure if it makes a difference. It’s a toggle on the acute load screen.
From what I can see it seem to be the lower end of the “optimal load” band.
So this is basically Training Load that Polar had for years?
yeah
same old , same old
The acute:chronic ratio isn’t anything new, and certainly not something developed by firstbeat. See https://runalyze.com/glossary/ac-ratio
yes,
as above “It’s nothing particularly special or new”
it predates Runalyze (founded 2011) probably by decades too !
Is it possible to have these features for FR255?
Thanks.
you might have to ask Garmin 😉
yes, i hope FR255 gets these too. it should do but maybe not straight away
Thank you for your reply.
I have found where it is in Connect App.
I truly believe Garmin should add more indicators like this to complete its daily monitor system. Currently, I think it is still far from enough.
what is shown depends on your watch
Correct me if I am wrong but the acute Vs chronic metrics should be available in the Garmin App calculated for activities coming from any watch that record activities with heart rate. Why is it limited to certains watches? This does not feel honest way to do things.
it can be calculated for any watch that has hr zones
some watches may not make that calculation
yes all watches that already show acute chronic load will almost certainly also calculate chronic
they then SHOULD show chronic
and SHOULD be able to display the ratio
but…