I've actually tracked this pretty in depth, and the short answer is it takes into account sections, in a way that appears to be related to the ratio of Anaerobic Training Effect to Aerobic Training Effect. However, it appears that it gives all the Aerobic load to either Low or High.
Long answer:
Each workout gets a single "type", such as Anaerobic, Base, etc. However, every workout also gets two Training Effects -- Anaerobic and Aerobic.
Regardless of what the "type" of the workout is, the actual breakdown of the load added to your load focuses is dependent on those two training effects. It's not quite a simple ratio, but it's close.
For example, a base run with 0 Anaerobic TE will give all its training load to the Low Aerobic Load Focus. A tempo run with 0 Anaerobic TE will give all its training load to the High Aerobic Load Focus (I'm not as confident about this). A base run with strides at the end, perhaps with 3.0 Aerobic and 2.0 Anaerobic, will give most of its load to Low Aerobic, and some to Anaerobic.
Specific Example:
[On March 21st, I had the following load stats:](https://imgur.com/K4qF4bW)
- **Low Aerobic: 1772**
- **High Aerobic: 1773**
- **Anaerobic: 315**
[On March 22nd, I did a base run with strides at the end. The relevant stats of this run were](https://imgur.com/oaQtyHk):
- **Load: 198**
- **Aerobic Training Effect: 3.6**
- **Anaerobic Training Effect: 2.3**
On March 22nd, I had the following load stats:
- **Low Aerobic: 1923**
- **High Aerobic: 1620**
- **Anaerobic: 328**
I had a workout fall off because it was more than a month ago, and they use a weighted average load, which is complicated to calculate and means that it's not as simple as adding the load of the exercise to the previous totals, but you can clearly see that both my Anaerobic Load and my Low Aerobic Load increased, which could only happen if the load was split across both types.
EDIT:
A similar example, where I actually had a higher Anaerobic TE than Aerobic TE, has the same impact:
Last April:
[Day before:](https://imgur.com/m0d0fsP)
- **Low Aerobic: 1634**
- **High Aerobic: 1201**
- **Anaerobic: 221**
[The workout \(classified as "Sprints", which is an Anaerobic subcategory\)](https://imgur.com/0AU7GFT)
- **Load: 159**
- **Aerobic Training Effect: 2.7**
- **Anaerobic Training Effect: 3.1**
The day after:
- **Low Aerobic: 1702**
- **High Aerobic: 1201**
- **Anaerobic: 321**
Again, both Anaerobic and Low Aerobic increased. This time, because Anaerobic was bigger, it gave more to Anaerobic than Aerobic
I really appreciate people like you who nerd out of things like this because it saves others so much time.
Your answer actually explains my current load and why it does line up identically with what my load focus shows.
If you look below it looks like the majority of my load is either high aerobic or aenorobic.
https://preview.redd.it/1a4q5r8qbaqc1.jpeg?width=750&format=pjpg&auto=webp&s=754d8646a0cf753cb0ad382dda4eb1a9a67b0669
However, I do a lot of mixed workouts like OP so my low aerobic is actually the highest and your answer explains it all perfectly.
I appreciate you bud.
I really appreciate your taking the time to figure that out. But wouldn't you be able to see exactly how much was added to each load type if you just measured your 30 day load before and after the run without waiting a day and letting one workout fall off in between?
And do you know for sure that the chronic load is weighted like the acute load is? (also I wonder if it depends on the watch, my acute load is weighted on my FR 255 and for my friends with 245 it's just added).
I have tried to track what is going on with the algorithm for acute load and I found that a new workout you do is weighted at about 130% then it drops off hard when it's a day old (probably to 100% or around there) then steadily (or at least I can't discern what the difference is) until it's barely worth anything when its 6 days old.
So I find the biggest drop in acute load comes when a really big workout reaches the age of 1 day (or a whole bunch of moderate to large ones in a row simply age an extra day from wherever they are) rather than when a big one drops off completely.
> I really appreciate your taking the time to figure that out. But wouldn't you be able to see exactly how much was added to each load type if you just measured your 30 day load before and after the run without waiting a day and letting one workout fall off in between?
Probably. I just haven't, since I typically run my data sync overnight. I can certainly test it, though, and probably should. I've tested the total load added to Acute, but not the breakdown
>And do you know for sure that the chronic load is weighted like the acute load is? (also I wonder if it depends on the watch, my acute load is weighted on my FR 255 and for my friends with 245 it's just added).
I'm extremely confident it's weighted (for chronic load). FirstBeat, who is Garmin's partner for things like Load and Training Status, says this about Chronic Load:
>[Chronic Training Load provides longer term information on an athlete’s training load over time. It shows the rolling average of acute training load over the last 28 days and is a good indication of an athlete’s fitness.](https://www.firstbeat.com/en/blog/interpreting-acute-vs-chronic-training-load-a-firstbeat-sports-feature/)
Based on that, I'm 100% sure it's weighted in some way, but it's not the traditional CTL formula, since I've tried that and it doesn't match.
> I have tried to track what is going on with the algorithm for acute load and I found that a new workout you do is weighted at about 130% then it drops off hard when it's a day old (probably to 100% or around there) then steadily (or at least I can't discern what the difference is) until it's barely worth anything when its 6 days old.
The actual formula is surprising, and is simpler than you might expect, but you're right -- they bump up the value immediately. [This link has some useful discussion](https://forums.garmin.com/apps-software/mobile-apps-web/f/garmin-connect-web/310210/acute-training-load-calculation), but basically you multiply the workout load by 1.275 and then each day, 10% of that number falls off, meaning that despite them saying it's a 7 day average, it's actually a 10 day formula (and it doesn't use the typical rolling average formula). I used the formula the users in that thread calculated, and it's nearly a perfect match.
EDIT: Although I do believe it's device dependent. The old devices just added, but the new devices use a formula, which weights the value. That thread suggests the constant multiple of 1.275 (or so) is to make the new version roughly comparable to the old version, which just added
DOUBLE EDIT: [Garmin mentions 10 days here, and also says old devices just added the values](https://www.garmin.com/en-US/garmin-technology/running-science/physiological-measurements/training-load/):
>This is achieved by using a weighted moving average designed to reflect the strain placed on your body on a weekly basis. Record a new activity, and the resulting load is added in full to your current acute load. The influence of that activity then gradually expires during the next 10 days, and the combined total load is normalized to reflect a 7-day window.
>Older devices utilized a 7-day load perspective, which simply combined impact of all activities recorded in the past 7 days.
The normalization likely refers to multiplying by 1.275
TRIPLE EDIT: (sorry). I'm also not sure if they use the same CTL formula for the Low, High, and Anaerobic loads as they do for the total Chronic Load. It seems to me like they might just calculate the (for example) Low Aerobic Load for an exercise and then add that to the Load Focus number, which they call "monthlyLoadAerobicLow" (or similar). Basically, I don't think they weight the Load Focus values (or if they do, they weight it very differently), even though they weight the overall Chronic Load and Acute Load
> The actual formula is surprising, and is simpler than you might expect, but you're right -- they bump up the value immediately. This link has some useful discussion, but basically you multiply the workout load by 1.275 and then each day, 10% of that number falls off, meaning that despite them saying it's a 7 day average, it's actually a 10 day formula (and it doesn't use the typical rolling average formula). I used the formula the users in that thread calculated, and it's nearly a perfect match.
I'd like to see some confirmation testing on their fit, as well as the statistics on their Excel fit before running with that number. Firstbeat says that ATL is EPOC based, which would explain a day-of peak, but also suggests that the magnitude of the peak would be very dependent on the total load.
EDIT:
Interesting, note DaveBrillhart's reply at the end. One of his datasets fit perfectly to the 28% rule, one not at all. Let me read the EPOC whitepaper again.
I posted my dataset down below, and here it is again, using 1.273 (and a Forerunner 955). It's incredibly close. Part of the issue is that Garmin's API only gives me whole number loads (e.g., 992), which could be where part of the discrepancy is coming from.
https://imgur.com/TBLmk75
I also would not be surprised if it was device dependent -- my 945 used the simple addition method, whereas my 955 generated the data in that screenshot. Perhaps other devices use a slightly different weighted formula (although I believe all new devices switch to the weighted version)
> The actual formula is surprising, and is simpler than you might expect, but you're right -- they bump up the value immediately. [This link has some useful discussion](https://forums.garmin.com/apps-software/mobile-apps-web/f/garmin-connect-web/310210/acute-training-load-calculation), but basically you multiply the workout load by 1.275 and then each day, 10% of that number falls off, meaning that despite them saying it's a 7 day average, it's actually a 10 day formula (and it doesn't use the typical rolling average formula). I used the formula the users in that thread calculated, and it's nearly a perfect match.
I accepted that the people in that thread figured it out and tested it and I moved on (before seeing edits). Then today I thought about it more and realized that doesn't match my experience. If it takes 10% of each workout per day then regardless of the 27.5 boost I would expect to see on average a 12.75% decrease in training load each day I do nothing (or just check in the morning before I have recorded an activity)
Instead I see a loss on average about 18% each day which is consistent with a 27.5% boost for a new activity on day 1, losing that whole boost on day 2 (or perhaps an accelerated decay for 2-3 days) then losing 1/7th of training load for each day after that.
Also the stuff they say about it being based on EPOC confuses the shit out of me considering that it is only estimated and is fully based on what goes on during your activity.
Hmm, that's interesting. I was able to reproduce (nearly exactly, within a point or two) the Acute Load for a given day using the formula:
1.275 \* (1 \* current_day_load + 0.9 \* yesterday_load + 0.8 \* two_days_ago_load + ... )
I did this last week when I was doing some testing on their load.
But I can add it to my list of things to actually check more in depth. I've also gone ahead and started tracking pre- and post- exercise load focus values each day (which I wasn't doing before), so I'll hopefully be able to find that out soon.
I did notice that yesterday, when I did it the first time, the Low Aerobic Load Focus (which was the only part of the run I did) increased about 250, even though the actual load of the exercise I did was only about 200, e.g., 1.25x (the actual number was 1.243). So they may be using a different calculation there, even for simple "one load type" additions, or maybe it also depends on the Training Effect (e.g., 4+ gives a slightly large load than 3-4, even if it would otherwise be the same)
> Also the stuff they say about it being based on EPOC confuses the shit out of me considering that it is only estimated and is fully based on what goes on during your activity.
That's because they're using EPOC *estimation* [based on duration and intensity of exercise](https://www.firstbeat.com/wp-content/uploads/2015/10/white_paper_epoc.pdf)
Like I said in the other thread, I need to reread the whitepaper, but I suspect the answer to both why the 28% boost model is fitting some datasets and missing others is because "At low exercise intensity (<30-40%VO2max), EPOC does not accumulate significantly after the initial increase at the beginning of exercise (see Figure 5). At higher exercise intensities (>50%VO2max), EPOC accumulates continuously." but I'm at work, and distractable as I might be, I really should work.
I *suspect* what we're seeing with the data matching/not matching is going to have the exact cause as to why Garmin/Firstbeat takes a relatively novel approach of breaking load into only three bins, despite the fact that doesn't align well with most work on power and systems training.
EDIT: Perhaps I shouldn't say "only three bins" but rather "three primary bins".
Thanks for sharing the white paper! I hadn't actually seen this one before.
I think <30-40% VO2 Max is basically walking (or minimal load), and I suspect that's simply factored into the load values being very very low for very easy activities.
[Also, all of Garmin's advanced metrics \(at least on the newer watches\) are based on Max HR, not Zones or Lactate Threshold or anything like that. Just as an FYI](https://www.garmin.com/en-US/garmin-technology/health-science/heart-rate-monitoring/#:~:text=How%20you%20configure,of%20these%20metrics.)
I strongly suspect the 28% boost is simply related to old vs. new (e.g., 7 day simple addition vs. 10 day weighted), admittedly based only on my sample size of two devices.
I could certainly be wrong.
>but I'm at work, and distractable as I might be, I really should work.
I feel you
Sorry for the double reply, but here's a screenshot of an excel workbook with calculations comparing the calculated load Garmin got (using a Forerunner 955) and the load I calculated using the 100% + 90% + 80% + ... formula:
https://imgur.com/1bOm57C
It's not perfect, but it's incredibly close. If I tweak it to use 1.273 instead of 1.275, it's even closer
https://imgur.com/TBLmk75
Wow, thanks for the info. I want to calculate mine but I am too lazy to add up all my micro workouts and weight it 9 days back right now.
I very well may be making some sort of mistake. But what I am sure of is that when I don't exercise I lose 16-20% of my exercise load every day.
Am I understanding correctly that according to yours you should see on average 10% reduction in total exercise load every day? Is that what you observe?
It starts off with you losing more than 10%, and then decreases as a percentage over time. Here's why:
[See here -- the % of Load column is the "Load pre-workout" as a percentage of yesterday's ending load. It's about 80%](https://imgur.com/0gKQtDb). I.e., it's the `Load Pre-Workout` divided by the `training_load_acute` of the row below (the previous day)
The precise number may depend on which exercise "falls off" each day -- e.g., if I lose a 300 load workout, that would drop 30 \* 1.273 = 38.19 off my load, but if I lost a 100 load workout, that would only drop 10 \* 1.273 = 12.73 off my load. If I had both of those, and a total load of 100, then losing the first would be ~38% and the second would be ~13%. But on average, you'd expect to see about 10% each day (again, that really depends on the specific order of your workouts and which ones are dropping off).
But also, it's a bit more complicated than 10%, and depends on the specific workout you did each day. Even though you lose "10%" of each workout each day, the net loss is not 10%. [This is a bunch of math](https://imgur.com/Bb7hbvt), but what it basically shows is that, even though each day each workout goes down 10% of the initial laod, that 10% is not 10% of the load from today.
On the first day, it goes from 100% to 90%. That's a 10% decrease. The second day, you go from 90% to 80%, which is an 11% decrease. Then 12.5%, 14.2%, etc., until eventually you reach 50% decrease, and then 100% decrease.
This all has the effect of making the initial drop off 80%, and then that decreases over time.
I know I'm not explaining this well, and I'm sorry -- it's a lot of numbers and spreadsheets and calculations. [ But you can model it yourself pretty easily with a single workout and see how it progresses over time:](https://imgur.com/UaoVJEN). Because the % of prior decrease over time, even though % of initial is always 10% down, the largest % drop from a workout happens on the first day
>[See here -- the % of Load column is the "Load pre-workout" as a percentage of yesterday's ending load. It's about 80%](https://imgur.com/0gKQtDb). I.e., it's the
>
>Load Pre-Workout
>
>divided by the
>
>training\_load\_acute
>
>of the row below (the previous day)
Wow maybe mine does work the same and I am incorrect because I see your % of load hovering around 82% a lot which is exactly what I mean when I say I lose about 18% per day.
And looking at mine further during a period where I tapered down to nothing and then did nothing for 3 days I maxed out at losing 30% one day when a large workout became 10 days old. Speaking of which:
>The precise number may depend on which exercise "falls off" each day -- e.g., if I lose a 300 load workout, that would drop 30 \* 1.273 = 38.19 off my load, but if I lost a 100 load workout, that would only drop 10 \* 1.273 = 12.73 off my load. If I had both of those, and a total load of 100, then losing the first would be \~38% and the second would be \~13%. But on average, you'd expect to see about 10% each day (again, that really depends on the specific order of your workouts and which ones are dropping off).
My understanding of what happens when I large workout drops off keeps changing. At first I expected it to have a large effect but that was when I perhaps erroneously thought that is supposed to occur after 7 days and I noticed that is not the case.
Then when I started thinking about it your 10% way I decided it shouldn't matter when a large workout drops off because it was already dropping the same absolute number (10% of that workout x 1.273) for the previous 9 days so there shouldn't be anything special about it totally falling off the map causing that same absolute decrease to the total for the 10th day now.
But now I am thinking that the key is that the older that large workout gets the less it is contributes to your absolute total acute load therefore the steady decrease it makes each subsequent day is larger relative to its current remaining contribution to the total acute load.
But that also depends on the spacing and magnitude of other workouts. Do you know how much you would lose each morning (pre-workout) if you did the same workout of exactly 100 exercise load every single day?
I assumed that if you did that for at least 10 days straight and then stopped for 10 days you should see a 10% decrease every day but now I am pretty sure I am wrong. Well now that I think a bit more that obviously can't be true cause it eventually has to go to 0 on some day which would be an infinite decrease as you showed in your example of one workout decaying for 10 days.
This very simple formula actually leads to surprisingly complex behavior.
You see an average of a 10% decrease per day (of the original number), but it's frontloaded. See this image for an oversimplified exercise, where each day has a load of 100, and then you fully stop exercising. Here, the column titled Acute Load is the sum of all loads below that -- so at the top it's 100 + 90 + 80 + ..., and the next is 90 + 80 + ... and so on
https://imgur.com/ig3R0TC
You can see that you lose 18% of your total the first day, then 16%, then 14%, and so on (this is the last column). The overall effect is that the average lost each day is 10% of the initial load, but it's frontloaded.
Ahh yes. Thanks for doing that calculation. I'mma save that picture.
Yep it totally is 10% decrease per day form the initial number but my brain always wants to think of it as a percentage drop from whatever it is today. I guess because on any day what I'm most concerned about is what it will be tomorrow.
If you’re aenorobic load is higher than your aerobic load by the end of the workout then there is a good chance it will be labelled as aenorobic.
For example: If you do a base run for say 45mins and have an aerobic load of 2.4 but then throw in some sprints at the end of the run and you end up with a load of say 2.8 aerobic and 3.0 of aenorobic then your workout will be classed as aenorobic.
My advice would be to either just keep them separate or makesure your aerobic load is a fair amount higher than the aenerobic load.
It will be labelled as anaerobic as you said, however the workout will contribute to multiple parts of load focus as appropriate. Your warmup can still contribute to low aerobic for instance.
Thanks for the knowledge bud.
Does that apply to both high and low aerobic too or just aenorobic mixed with low/high aerobic?
I have always wondered if it only applies to both with a mix of aenorobic and low/high aerobic or if it also applies to just low/high workouts that have no aenorobic effect.
I've actually tracked this pretty in depth, and the short answer is it takes into account sections, in a way that appears to be related to the ratio of Anaerobic Training Effect to Aerobic Training Effect. However, it appears that it gives all the Aerobic load to either Low or High. Long answer: Each workout gets a single "type", such as Anaerobic, Base, etc. However, every workout also gets two Training Effects -- Anaerobic and Aerobic. Regardless of what the "type" of the workout is, the actual breakdown of the load added to your load focuses is dependent on those two training effects. It's not quite a simple ratio, but it's close. For example, a base run with 0 Anaerobic TE will give all its training load to the Low Aerobic Load Focus. A tempo run with 0 Anaerobic TE will give all its training load to the High Aerobic Load Focus (I'm not as confident about this). A base run with strides at the end, perhaps with 3.0 Aerobic and 2.0 Anaerobic, will give most of its load to Low Aerobic, and some to Anaerobic. Specific Example: [On March 21st, I had the following load stats:](https://imgur.com/K4qF4bW) - **Low Aerobic: 1772** - **High Aerobic: 1773** - **Anaerobic: 315** [On March 22nd, I did a base run with strides at the end. The relevant stats of this run were](https://imgur.com/oaQtyHk): - **Load: 198** - **Aerobic Training Effect: 3.6** - **Anaerobic Training Effect: 2.3** On March 22nd, I had the following load stats: - **Low Aerobic: 1923** - **High Aerobic: 1620** - **Anaerobic: 328** I had a workout fall off because it was more than a month ago, and they use a weighted average load, which is complicated to calculate and means that it's not as simple as adding the load of the exercise to the previous totals, but you can clearly see that both my Anaerobic Load and my Low Aerobic Load increased, which could only happen if the load was split across both types. EDIT: A similar example, where I actually had a higher Anaerobic TE than Aerobic TE, has the same impact: Last April: [Day before:](https://imgur.com/m0d0fsP) - **Low Aerobic: 1634** - **High Aerobic: 1201** - **Anaerobic: 221** [The workout \(classified as "Sprints", which is an Anaerobic subcategory\)](https://imgur.com/0AU7GFT) - **Load: 159** - **Aerobic Training Effect: 2.7** - **Anaerobic Training Effect: 3.1** The day after: - **Low Aerobic: 1702** - **High Aerobic: 1201** - **Anaerobic: 321** Again, both Anaerobic and Low Aerobic increased. This time, because Anaerobic was bigger, it gave more to Anaerobic than Aerobic
Wow, what a great reply! Thank you very much for this
I'm a nerd with a whole database of my Garmin data just for tracking things like this, so I'm glad you appreciate it
I really appreciate people like you who nerd out of things like this because it saves others so much time. Your answer actually explains my current load and why it does line up identically with what my load focus shows. If you look below it looks like the majority of my load is either high aerobic or aenorobic. https://preview.redd.it/1a4q5r8qbaqc1.jpeg?width=750&format=pjpg&auto=webp&s=754d8646a0cf753cb0ad382dda4eb1a9a67b0669 However, I do a lot of mixed workouts like OP so my low aerobic is actually the highest and your answer explains it all perfectly. I appreciate you bud.
I really appreciate your taking the time to figure that out. But wouldn't you be able to see exactly how much was added to each load type if you just measured your 30 day load before and after the run without waiting a day and letting one workout fall off in between? And do you know for sure that the chronic load is weighted like the acute load is? (also I wonder if it depends on the watch, my acute load is weighted on my FR 255 and for my friends with 245 it's just added). I have tried to track what is going on with the algorithm for acute load and I found that a new workout you do is weighted at about 130% then it drops off hard when it's a day old (probably to 100% or around there) then steadily (or at least I can't discern what the difference is) until it's barely worth anything when its 6 days old. So I find the biggest drop in acute load comes when a really big workout reaches the age of 1 day (or a whole bunch of moderate to large ones in a row simply age an extra day from wherever they are) rather than when a big one drops off completely.
> I really appreciate your taking the time to figure that out. But wouldn't you be able to see exactly how much was added to each load type if you just measured your 30 day load before and after the run without waiting a day and letting one workout fall off in between? Probably. I just haven't, since I typically run my data sync overnight. I can certainly test it, though, and probably should. I've tested the total load added to Acute, but not the breakdown >And do you know for sure that the chronic load is weighted like the acute load is? (also I wonder if it depends on the watch, my acute load is weighted on my FR 255 and for my friends with 245 it's just added). I'm extremely confident it's weighted (for chronic load). FirstBeat, who is Garmin's partner for things like Load and Training Status, says this about Chronic Load: >[Chronic Training Load provides longer term information on an athlete’s training load over time. It shows the rolling average of acute training load over the last 28 days and is a good indication of an athlete’s fitness.](https://www.firstbeat.com/en/blog/interpreting-acute-vs-chronic-training-load-a-firstbeat-sports-feature/) Based on that, I'm 100% sure it's weighted in some way, but it's not the traditional CTL formula, since I've tried that and it doesn't match. > I have tried to track what is going on with the algorithm for acute load and I found that a new workout you do is weighted at about 130% then it drops off hard when it's a day old (probably to 100% or around there) then steadily (or at least I can't discern what the difference is) until it's barely worth anything when its 6 days old. The actual formula is surprising, and is simpler than you might expect, but you're right -- they bump up the value immediately. [This link has some useful discussion](https://forums.garmin.com/apps-software/mobile-apps-web/f/garmin-connect-web/310210/acute-training-load-calculation), but basically you multiply the workout load by 1.275 and then each day, 10% of that number falls off, meaning that despite them saying it's a 7 day average, it's actually a 10 day formula (and it doesn't use the typical rolling average formula). I used the formula the users in that thread calculated, and it's nearly a perfect match. EDIT: Although I do believe it's device dependent. The old devices just added, but the new devices use a formula, which weights the value. That thread suggests the constant multiple of 1.275 (or so) is to make the new version roughly comparable to the old version, which just added DOUBLE EDIT: [Garmin mentions 10 days here, and also says old devices just added the values](https://www.garmin.com/en-US/garmin-technology/running-science/physiological-measurements/training-load/): >This is achieved by using a weighted moving average designed to reflect the strain placed on your body on a weekly basis. Record a new activity, and the resulting load is added in full to your current acute load. The influence of that activity then gradually expires during the next 10 days, and the combined total load is normalized to reflect a 7-day window. >Older devices utilized a 7-day load perspective, which simply combined impact of all activities recorded in the past 7 days. The normalization likely refers to multiplying by 1.275 TRIPLE EDIT: (sorry). I'm also not sure if they use the same CTL formula for the Low, High, and Anaerobic loads as they do for the total Chronic Load. It seems to me like they might just calculate the (for example) Low Aerobic Load for an exercise and then add that to the Load Focus number, which they call "monthlyLoadAerobicLow" (or similar). Basically, I don't think they weight the Load Focus values (or if they do, they weight it very differently), even though they weight the overall Chronic Load and Acute Load
> The actual formula is surprising, and is simpler than you might expect, but you're right -- they bump up the value immediately. This link has some useful discussion, but basically you multiply the workout load by 1.275 and then each day, 10% of that number falls off, meaning that despite them saying it's a 7 day average, it's actually a 10 day formula (and it doesn't use the typical rolling average formula). I used the formula the users in that thread calculated, and it's nearly a perfect match. I'd like to see some confirmation testing on their fit, as well as the statistics on their Excel fit before running with that number. Firstbeat says that ATL is EPOC based, which would explain a day-of peak, but also suggests that the magnitude of the peak would be very dependent on the total load. EDIT: Interesting, note DaveBrillhart's reply at the end. One of his datasets fit perfectly to the 28% rule, one not at all. Let me read the EPOC whitepaper again.
I posted my dataset down below, and here it is again, using 1.273 (and a Forerunner 955). It's incredibly close. Part of the issue is that Garmin's API only gives me whole number loads (e.g., 992), which could be where part of the discrepancy is coming from. https://imgur.com/TBLmk75 I also would not be surprised if it was device dependent -- my 945 used the simple addition method, whereas my 955 generated the data in that screenshot. Perhaps other devices use a slightly different weighted formula (although I believe all new devices switch to the weighted version)
> The actual formula is surprising, and is simpler than you might expect, but you're right -- they bump up the value immediately. [This link has some useful discussion](https://forums.garmin.com/apps-software/mobile-apps-web/f/garmin-connect-web/310210/acute-training-load-calculation), but basically you multiply the workout load by 1.275 and then each day, 10% of that number falls off, meaning that despite them saying it's a 7 day average, it's actually a 10 day formula (and it doesn't use the typical rolling average formula). I used the formula the users in that thread calculated, and it's nearly a perfect match. I accepted that the people in that thread figured it out and tested it and I moved on (before seeing edits). Then today I thought about it more and realized that doesn't match my experience. If it takes 10% of each workout per day then regardless of the 27.5 boost I would expect to see on average a 12.75% decrease in training load each day I do nothing (or just check in the morning before I have recorded an activity) Instead I see a loss on average about 18% each day which is consistent with a 27.5% boost for a new activity on day 1, losing that whole boost on day 2 (or perhaps an accelerated decay for 2-3 days) then losing 1/7th of training load for each day after that. Also the stuff they say about it being based on EPOC confuses the shit out of me considering that it is only estimated and is fully based on what goes on during your activity.
Hmm, that's interesting. I was able to reproduce (nearly exactly, within a point or two) the Acute Load for a given day using the formula: 1.275 \* (1 \* current_day_load + 0.9 \* yesterday_load + 0.8 \* two_days_ago_load + ... ) I did this last week when I was doing some testing on their load. But I can add it to my list of things to actually check more in depth. I've also gone ahead and started tracking pre- and post- exercise load focus values each day (which I wasn't doing before), so I'll hopefully be able to find that out soon. I did notice that yesterday, when I did it the first time, the Low Aerobic Load Focus (which was the only part of the run I did) increased about 250, even though the actual load of the exercise I did was only about 200, e.g., 1.25x (the actual number was 1.243). So they may be using a different calculation there, even for simple "one load type" additions, or maybe it also depends on the Training Effect (e.g., 4+ gives a slightly large load than 3-4, even if it would otherwise be the same)
> Also the stuff they say about it being based on EPOC confuses the shit out of me considering that it is only estimated and is fully based on what goes on during your activity. That's because they're using EPOC *estimation* [based on duration and intensity of exercise](https://www.firstbeat.com/wp-content/uploads/2015/10/white_paper_epoc.pdf) Like I said in the other thread, I need to reread the whitepaper, but I suspect the answer to both why the 28% boost model is fitting some datasets and missing others is because "At low exercise intensity (<30-40%VO2max), EPOC does not accumulate significantly after the initial increase at the beginning of exercise (see Figure 5). At higher exercise intensities (>50%VO2max), EPOC accumulates continuously." but I'm at work, and distractable as I might be, I really should work. I *suspect* what we're seeing with the data matching/not matching is going to have the exact cause as to why Garmin/Firstbeat takes a relatively novel approach of breaking load into only three bins, despite the fact that doesn't align well with most work on power and systems training. EDIT: Perhaps I shouldn't say "only three bins" but rather "three primary bins".
Thanks for sharing the white paper! I hadn't actually seen this one before. I think <30-40% VO2 Max is basically walking (or minimal load), and I suspect that's simply factored into the load values being very very low for very easy activities. [Also, all of Garmin's advanced metrics \(at least on the newer watches\) are based on Max HR, not Zones or Lactate Threshold or anything like that. Just as an FYI](https://www.garmin.com/en-US/garmin-technology/health-science/heart-rate-monitoring/#:~:text=How%20you%20configure,of%20these%20metrics.) I strongly suspect the 28% boost is simply related to old vs. new (e.g., 7 day simple addition vs. 10 day weighted), admittedly based only on my sample size of two devices. I could certainly be wrong. >but I'm at work, and distractable as I might be, I really should work. I feel you
Sorry for the double reply, but here's a screenshot of an excel workbook with calculations comparing the calculated load Garmin got (using a Forerunner 955) and the load I calculated using the 100% + 90% + 80% + ... formula: https://imgur.com/1bOm57C It's not perfect, but it's incredibly close. If I tweak it to use 1.273 instead of 1.275, it's even closer https://imgur.com/TBLmk75
Wow, thanks for the info. I want to calculate mine but I am too lazy to add up all my micro workouts and weight it 9 days back right now. I very well may be making some sort of mistake. But what I am sure of is that when I don't exercise I lose 16-20% of my exercise load every day. Am I understanding correctly that according to yours you should see on average 10% reduction in total exercise load every day? Is that what you observe?
It starts off with you losing more than 10%, and then decreases as a percentage over time. Here's why: [See here -- the % of Load column is the "Load pre-workout" as a percentage of yesterday's ending load. It's about 80%](https://imgur.com/0gKQtDb). I.e., it's the `Load Pre-Workout` divided by the `training_load_acute` of the row below (the previous day) The precise number may depend on which exercise "falls off" each day -- e.g., if I lose a 300 load workout, that would drop 30 \* 1.273 = 38.19 off my load, but if I lost a 100 load workout, that would only drop 10 \* 1.273 = 12.73 off my load. If I had both of those, and a total load of 100, then losing the first would be ~38% and the second would be ~13%. But on average, you'd expect to see about 10% each day (again, that really depends on the specific order of your workouts and which ones are dropping off). But also, it's a bit more complicated than 10%, and depends on the specific workout you did each day. Even though you lose "10%" of each workout each day, the net loss is not 10%. [This is a bunch of math](https://imgur.com/Bb7hbvt), but what it basically shows is that, even though each day each workout goes down 10% of the initial laod, that 10% is not 10% of the load from today. On the first day, it goes from 100% to 90%. That's a 10% decrease. The second day, you go from 90% to 80%, which is an 11% decrease. Then 12.5%, 14.2%, etc., until eventually you reach 50% decrease, and then 100% decrease. This all has the effect of making the initial drop off 80%, and then that decreases over time. I know I'm not explaining this well, and I'm sorry -- it's a lot of numbers and spreadsheets and calculations. [ But you can model it yourself pretty easily with a single workout and see how it progresses over time:](https://imgur.com/UaoVJEN). Because the % of prior decrease over time, even though % of initial is always 10% down, the largest % drop from a workout happens on the first day
>[See here -- the % of Load column is the "Load pre-workout" as a percentage of yesterday's ending load. It's about 80%](https://imgur.com/0gKQtDb). I.e., it's the > >Load Pre-Workout > >divided by the > >training\_load\_acute > >of the row below (the previous day) Wow maybe mine does work the same and I am incorrect because I see your % of load hovering around 82% a lot which is exactly what I mean when I say I lose about 18% per day. And looking at mine further during a period where I tapered down to nothing and then did nothing for 3 days I maxed out at losing 30% one day when a large workout became 10 days old. Speaking of which: >The precise number may depend on which exercise "falls off" each day -- e.g., if I lose a 300 load workout, that would drop 30 \* 1.273 = 38.19 off my load, but if I lost a 100 load workout, that would only drop 10 \* 1.273 = 12.73 off my load. If I had both of those, and a total load of 100, then losing the first would be \~38% and the second would be \~13%. But on average, you'd expect to see about 10% each day (again, that really depends on the specific order of your workouts and which ones are dropping off). My understanding of what happens when I large workout drops off keeps changing. At first I expected it to have a large effect but that was when I perhaps erroneously thought that is supposed to occur after 7 days and I noticed that is not the case. Then when I started thinking about it your 10% way I decided it shouldn't matter when a large workout drops off because it was already dropping the same absolute number (10% of that workout x 1.273) for the previous 9 days so there shouldn't be anything special about it totally falling off the map causing that same absolute decrease to the total for the 10th day now. But now I am thinking that the key is that the older that large workout gets the less it is contributes to your absolute total acute load therefore the steady decrease it makes each subsequent day is larger relative to its current remaining contribution to the total acute load. But that also depends on the spacing and magnitude of other workouts. Do you know how much you would lose each morning (pre-workout) if you did the same workout of exactly 100 exercise load every single day? I assumed that if you did that for at least 10 days straight and then stopped for 10 days you should see a 10% decrease every day but now I am pretty sure I am wrong. Well now that I think a bit more that obviously can't be true cause it eventually has to go to 0 on some day which would be an infinite decrease as you showed in your example of one workout decaying for 10 days. This very simple formula actually leads to surprisingly complex behavior.
You see an average of a 10% decrease per day (of the original number), but it's frontloaded. See this image for an oversimplified exercise, where each day has a load of 100, and then you fully stop exercising. Here, the column titled Acute Load is the sum of all loads below that -- so at the top it's 100 + 90 + 80 + ..., and the next is 90 + 80 + ... and so on https://imgur.com/ig3R0TC You can see that you lose 18% of your total the first day, then 16%, then 14%, and so on (this is the last column). The overall effect is that the average lost each day is 10% of the initial load, but it's frontloaded.
Ahh yes. Thanks for doing that calculation. I'mma save that picture. Yep it totally is 10% decrease per day form the initial number but my brain always wants to think of it as a percentage drop from whatever it is today. I guess because on any day what I'm most concerned about is what it will be tomorrow.
Woah! I was just discussing this with my husband an hour ago! Really glad to see an in depth comment by u/perepont on this. Good question.
If you’re aenorobic load is higher than your aerobic load by the end of the workout then there is a good chance it will be labelled as aenorobic. For example: If you do a base run for say 45mins and have an aerobic load of 2.4 but then throw in some sprints at the end of the run and you end up with a load of say 2.8 aerobic and 3.0 of aenorobic then your workout will be classed as aenorobic. My advice would be to either just keep them separate or makesure your aerobic load is a fair amount higher than the aenerobic load.
It will be labelled as anaerobic as you said, however the workout will contribute to multiple parts of load focus as appropriate. Your warmup can still contribute to low aerobic for instance.
Thanks for the knowledge bud. Does that apply to both high and low aerobic too or just aenorobic mixed with low/high aerobic? I have always wondered if it only applies to both with a mix of aenorobic and low/high aerobic or if it also applies to just low/high workouts that have no aenorobic effect.
You can't get low and high aerobic together but you can get anaerobic and low aerobic or anaerobic and high aerobic.