The Beginner's Guide to Stravistix or How I Learned to Stop Worrying and Love the TRIMP

[kleph]

@kleph is right in that since it passed the 6 week (42 day threshold) the "Fitness" average is now the correct value. The "Fatigue" value averages over 14 days so that means your "Form" value should be an accurate representation of your training load. Looks as if you're squarely in the "optimal" zone, per their defined areas. So the training load would seem appropriate using this tool for where you are in your current training cycle.

And, at the same time, it's worth noting that since your "Fitness" score was not properly populated until recently, it was artificially depressed. Since the "Form" measure is the difference of "Fatigue" and "Fitness" it has been as well. Ergo, you almost certainly weren't training on the borderline of Overload during the end of June/early July.

 

[BuckeyeBama]

I got permission to load Chrome on my work laptop, so trying this now. The trends in fatigue and form align with my own notes. Thanks for the heads-up.

 

[kleph]

I got permission to load Chrome on my work laptop, so trying this now. The trends in fatigue and form align with my own notes. Thanks for the heads-up.

excellent.

i know from my running history, full-on marathon training puts me pretty close to my injury threshold. this has proven to be a handy tool to track things a little better as i start piling on the miles.

 

[kbenson13]

No. It merely means that I do more training then you. It doesn't mean that I'm any more fit then you. For example:

-Two runners complete the same duration workouts in a training plan.
-The effort of those duration workouts is the same when evaluating relative HR.

The faster runner does 150 min at LR pace.
The slower runner does 150 min at LR pace.

The faster runner does 20 miles.
The slower runner does 12 miles.

The faster runner is a 3:00 marathoner.
The slower runner is a 6:00 marathoner.

But if the conditions above are met (same duration and same relative HR), then they should have the same "Fitness". So fitness is not a measure of speed, abilities, or progress. It's simply a measure of training load. So my number being higher just means I have a larger training load.

Now in a lot of cases, the more training load you have the faster you will individually improve. But the intricacies of the training plan matter for that to be true.

It took me a while to internalize this, but now that I think I have, I found this post very helpful in understanding what StravistiX is and isn't. I really, really wanted "fitness" to somehow be a measure of how "fit" I'm becoming but based on what you're saying and what I've been reading, that's not the case. I guess theoretically you should be getting more "fit" the greater your training load but it may not be as linear as the "fitness" trend in StavistiX. It still appears to be a helpful tool in terms of understanding over training and under training. I will be watching my trends closely to see if I get into "overload" form during my current training cycle. It may be very possible based on the increasing length and intensity levels of my workouts over the coming weeks...

I'll have to read more to understand why training load declines slower than fatigue. I see why it happens mathematically based on the formulas. But I'm still not wholly clear on why the formulas are set up the way that they are. What's the research and thinking behind that...

 

[DopeyBadger]

I really, really wanted "fitness" to somehow be a measure of how "fit" I'm becoming

Use Garmin's VO2max estimation. I view the relationship between HR and Pace to be the gold standard for evaluating "improving fitness". Now, obviously your HRvPace will become worse in non-ideal conditions (like high heat), but that doesn't mean it's wrong. And it doesn't necessarily mean you're getting worse. Merely means that in those conditions on that day, that's where your estimated VO2max is, and thus in high heat you aren't as fast as when in ideal conditions. Now the race predictor isn't real accurate and I've covered that a few times previously why. But I believe that is the best "assessment of fitness".

I'll have to read more to understand why training load declines slower than fatigue. I see why it happens mathematically based on the formulas. But I'm still not wholly clear on why the formulas are set up the way that they are. What's the research and thinking behind that...

Same reason fitness increases slower than fatigue. Fitness is the macro and fatigue the micro. Fatigue comes from damage to the muscles (myriad of things go into that). The fitness gains comes from the repair of that damage and making the muscles stronger (and mitochondria density/volume). So the fitness comes in small gains each time you have a repair, but the fatigue from an individual episode of damage is healed after hours, or days. I think these articles aren't direct answers, but they've got some great information in them.

http://www.cyclist.co.uk/in-depth/1618/detraining-do-you-lose-fitness-faster-than-you-gain-it

https://www.trainingpeaks.com/blog/how-much-down-time-is-too-much-the-concept-of-detr/

https://www.trainingpeaks.com/blog/why-am-i-so-tired/

https://runnersconnect.net/coach-corner/how-to-manage-fatigue-and-why-it-is-necessary/

https://runnersconnect.net/coach-corner/how-long-before-you-benefit-from-a-workout/

 

[BuckeyeBama]

The problem with the Garmin VO2 Max calculation is that it completely ignores run conditions. Run a hilly course or in extreme heat/humidity and the run is treated the same as a dead flat course in 40 degree weather. I ignore my summer scores. They are garbage. As soon as the weather cools down my score jumps up by 5 or more points. But if you take that into account you can track fitness progress. Just don't feel bad if your numbers drop after a few weeks running in bad conditions. You didn't lose fitness. The calculation just can't handle that situation .

 

[DopeyBadger]

The problem with the Garmin VO2 Max calculation is that it completely ignores run conditions. Run a hilly course or in extreme heat/humidity and the run is treated the same as a dead flat course in 40 degree weather. I ignore my summer scores. They are garbage. As soon as the weather cools down my score jumps up by 5 or more points. But if you take that into account you can track fitness progress. Just don't feel bad if your numbers drop after a few weeks running in bad conditions. You didn't lose fitness. The calculation just can't handle that situation .

I guess though that you can use as a current assessment of fitness. Yes if the heat is high I will be slower. The Garmin VO2max number drops in the same response. I'm capable of a 3:14 marathon in cold conditions. But I am not capable of a 3:14 marathon in 90F with 80% humidity. My VO2max score would be higher in colder temps because I'm actually capable of running faster in it. When the temp drops the relationship between your HRvPace improves and thus it believes you are capable of faster speeds. So if you view it as a current assessment of capabilities, then it's doing it right based on the current conditions. Now if I trained in TX and then suddenly raced in cold WI race, then the VO2max achieved in that race may not be immediately responsive because of how it takes samples from runs. But as you say, the hilly course can not be accounted for.

Now if you view it over the long term, then agreed it makes it difficult to assess gains across changing seasons. But within a season, I can see the merit in the tracking of the measurement. When the value drops after a few bad weeks, it merely means you aren't capable under the conditions you have been currently running in to be able to achieve similar results to prior to the few bad weeks.

 

[BuckeyeBama]

I guess though that you can use as a current assessment of fitness. Yes if the heat is high I will be slower. The Garmin VO2max number drops in the same response. I'm capable of a 3:14 marathon in cold conditions. But I am not capable of a 3:14 marathon in 90F with 80% humidity. My VO2max score would be higher in colder temps because I'm actually capable of running faster in it. When the temp drops the relationship between your HRvPace improves and thus it believes you are capable of faster speeds. So if you view it as a current assessment of capabilities, then it's doing it right based on the current conditions. Now if I trained in TX and then suddenly raced in cold WI race, then the VO2max achieved in that race may not be immediately responsive because of how it takes samples from runs. But as you say, the hilly course can not be accounted for.

Now if you view it over the long term, then agreed it makes it difficult to assess gains across changing seasons. But within a season, I can see the merit in the tracking of the measurement. When the value drops after a few bad weeks, it merely means you aren't capable under the conditions you have been currently running in to be able to achieve similar results to prior to the few bad weeks.

You know this, but the VO2 Max has nothing to do with your ability to run well in heat vs cold. It is about how efficiently your body uses O2. That does not change because your body cannot drop heat in hot/humid conditions. As long as you continue to exercise with the same intensity, your VO2 Max will remain the same or possibly improve, even though your run pace drops off. But the Garmin calculation shows it dropping. That is bogus.

 

[DopeyBadger]

You know this, but the VO2 Max has nothing to do with your ability to run well in heat vs cold. It is about how efficiently your body uses O2. That does not change because your body cannot drop heat in hot/humid conditions. As long as you continue to exercise with the same intensity, your VO2 Max will remain the same or possibly improve, even though your run pace drops off. But the Garmin calculation shows it dropping. That is bogus.

I guess I didn't think about it, but why couldn't how efficiently your body using oxygen decrease in higher temps/humid conditions? It seems there are a few research articles suggesting just that. Ambient temperature can influence the oxygen consumption. It's a bit of a mixed bag (as many things can be in research), but this is what I could find with a quick look.

https://www.jstage.jst.go.jp/article/jhe1972/7/2/7_2_127/_pdf

3.1. Effect of environmental temperature on oxygen uptake
Both absolute oxygen uptake (L/min) and relative oxygen uptake (mL/kg/min) at 35 ± 1 °C during rest were significantly higher compared with those at 22 ± 1 °C (p < 0.05; Fig. 2). However, there was no significant difference at rest between 10 ± 1 °C and 22 ± 1 °C in terms of oxygen uptake, even though a high trend was shown at 10 ± 1 °C compared with 22 ± 1 °C. Similarly, oxygen uptake was higher at 35 ± 1 °C compared with 22 ± 1 °C at 5, 10, and 15 minutes during submaximal exercise. However, both absolute and relative maximal oxygen uptake (VO2max) were significantly higher at 22 ± 1 °C compared with 10 ± 1 °C or 35 ± 1 °C (p < 0.01).

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5390419/

https://www.livestrong.com/article/356549-factors-affecting-vo2-max/

Temperature
The outside air temperature can affect VO2 max, as you consume more oxygen more easily at warmer temperatures.

https://journals.lww.com/acsm-msse/...mbient_temperature_on_the_capacity_to.18.aspx

 

[kleph]

It still appears to be a helpful tool in terms of understanding over training and under training. I will be watching my trends closely to see if I get into "overload" form during my current training cycle. It may be very possible based on the increasing length and intensity levels of my workouts over the coming weeks...

This is almost exactly how I am using it in my training. It's a good yardstick to understand my general progress - particularly when I'm trying to determine if my workload is overly ambitious - but I make it a point to try not and follow it day by day.

 

[BuckeyeBama]

I guess I didn't think about it, but why couldn't how efficiently your body using oxygen decrease in higher temps/humid conditions? It seems there are a few research articles suggesting just that. Ambient temperature can influence the oxygen consumption. It's a bit of a mixed bag (as many things can be in research), but this is what I could find with a quick look.

https://www.jstage.jst.go.jp/article/jhe1972/7/2/7_2_127/_pdf

3.1. Effect of environmental temperature on oxygen uptake
Both absolute oxygen uptake (L/min) and relative oxygen uptake (mL/kg/min) at 35 ± 1 °C during rest were significantly higher compared with those at 22 ± 1 °C (p < 0.05; Fig. 2). However, there was no significant difference at rest between 10 ± 1 °C and 22 ± 1 °C in terms of oxygen uptake, even though a high trend was shown at 10 ± 1 °C compared with 22 ± 1 °C. Similarly, oxygen uptake was higher at 35 ± 1 °C compared with 22 ± 1 °C at 5, 10, and 15 minutes during submaximal exercise. However, both absolute and relative maximal oxygen uptake (VO2max) were significantly higher at 22 ± 1 °C compared with 10 ± 1 °C or 35 ± 1 °C (p < 0.01).

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5390419/

https://www.livestrong.com/article/356549-factors-affecting-vo2-max/

Temperature
The outside air temperature can affect VO2 max, as you consume more oxygen more easily at warmer temperatures.

https://journals.lww.com/acsm-msse/...mbient_temperature_on_the_capacity_to.18.aspx

View attachment 339570

You are giving Garmin way too much credit. Their calculation does not take that into account, and your VO2 Max is not effected in the way that the Garmin scores it.

My personal example, and this happens every summer with me - my VO2 Max drops by about 5 points when I slow down to compensate for the heat. My effort level remains the same, but my times are slower, so Garmin drops my VO2 Max. But if I take a business trip in the summer to someplace cooler and run a few days at the pace that the cooler weather allows (at the same effort), my VO2 Max jumps back up to where it was before it dropped - sometimes higher. Then I return home, slow back down because of the heat, and watch the VO2 Max drop again.

This happens in days. My VO2 Max might go up 5 or 6 points in 4 days. That is simply not possible. And it drops just as fast when I return - also not possible.

I am not saying that it is useless. You just have to take these things into account and not allow yourself to get frustrated.

 

[DopeyBadger]

My personal example, and this happens every summer with me - my VO2 Max drops by about 5 points when I slow down to compensate for the heat. My effort level remains the same, but my times are slower, so Garmin drops my VO2 Max. But if I take a business trip in the summer to someplace cooler and run a few days at the pace that the cooler weather allows (at the same effort), my VO2 Max jumps back up to where it was before it dropped - sometimes higher. Then I return home, slow back down because of the heat, and watch the VO2 Max drop again.

Agreed. And that's because Garmin's VO2max is a HRvPace look-up table. It simply uses your %HR and a "known" value for different associated %HRs to determine the relationship to pace. For instance it says marathon %VO2max is around 82%. Based on the relationship between HR and %VO2max, wherever your recent runs have you at a 82% VO2max is going to spit out a piece of data for the Garmin to draw a line. Then, it'll use those paces at those set %VO2max values for 5k, 10k, LT, HM, M, LR, Easy type paces to determine a VO2max estimation. This is similar to what I do for myself:

This is real data. I tracked the relationship of my HR vs Pace over time during a Spring season. When one is able to run at a faster pace at a set HR, then the ability to race faster goes up. In lock-step when I saw increases in my ability to race faster, the Garmin VO2max increased. When the end of the spring season came, my HRvsPace relationship started to reverse direction. This was because under those new hotter temperature conditions I was no longer able to race as fast. The Garmin VO2max declined. So under the conditions I was in, I was less capable of running the same speed then when it was cooler. The Garmin VO2max reflected that. I wasn't losing fitness per se, but I was not capable of running the same speeds in the conditions under which I was now running.

In laboratory conditions, when the temperature of the room is manipulated, then it appears the oxygen consumption ability of the runner can be manipulated as well per the research I found.

So the Garmin VO2max is not measuring true VO2max as a measure of oxygen consumption. But, when temperature changes both the Garmin VO2max (HRvsPace relationship) and true VO2max (laboratory tested oxygen consumption) go up and down in a similar (but not necessarily the same) manner.

This happens in days. My VO2 Max might go up 5 or 6 points in 4 days. That is simply not possible. And it drops just as fast when I return - also not possible.

I'll use this chart as an example. The average runner's body weight was 72kg in the study. So a 3.2 L/min oxygen consumption at 4C at 45 min was a VO2max of 44.6.

Absolute VO2max (in Liters) = weight in kg X VDOT/100

But at 31C at 45 min the oxygen consumption was 2.6 L/min. For the same body weight, that equates to a VO2max of about 36.1.

So in this laboratory setting, when altering the temperature from 4C (39 F) to 31C (88F) the VO2max of the same runners was altered from 44.6 down to 36.1 (or a drop of about 8 points in a matter of a week or so dependent on the testing temperature). And this drop (8 points, or 19%) in VO2max simply couldn't be accounted for with detraining since Jack Daniels data suggests it takes about 72 days of inactivity with no leg aerobic exercise to reduce by that much. So yes, it would appear a significant drop in true VO2max (oxygen consumption) is possible in a very short period of time when accounting for changes in ambient temperature per the research I was able to find. Now that doesn't necessarily mean Garmin VO2max measurements drop at the same rate or in the same way as a true laboratory VO2max measurement, but it does appear that what you've experienced in your Garmin VO2max value is replicated in this particular laboratory setting for true VO2max oxygen consumption.

Now the reason this came up was a discussion about a measure of tracking fitness gains/losses over time. If I were to compare the 2017 summer to the 2018 summer's VO2max number, then we could get a pretty good general idea as to whether I've made training gains/losses. If I were to compare my beginning of Spring 2017 to end of Spring 2017 under similar weather conditions, then I could get a pretty good general idea as to whether gains/losses have been made. But I think we can both agree, that the data becomes harder to interpret when you compare different temperatures (or across different seasons/the whole year). But it is a reflective measurement of what you are capable of in that very moment in those specific conditions in which you just ran.

 

[BuckeyeBama]

Agreed. And that's because Garmin's VO2max is a HRvPace look-up table. It simply uses your %HR and a "known" value for different associated %HRs to determine the relationship to pace. For instance it says marathon %VO2max is around 82%. Based on the relationship between HR and %VO2max, wherever your recent runs have you at a 82% VO2max is going to spit out a piece of data for the Garmin to draw a line. Then, it'll use those paces at those set %VO2max values for 5k, 10k, LT, HM, M, LR, Easy type paces to determine a VO2max estimation. This is similar to what I do for myself:

This is real data. I tracked the relationship of my HR vs Pace over time during a Spring season. When one is able to run at a faster pace at a set HR, then the ability to race faster goes up. In lock-step when I saw increases in my ability to race faster, the Garmin VO2max increased. When the end of the spring season came, my HRvsPace relationship started to reverse direction. This was because under those new hotter temperature conditions I was no longer able to race as fast. The Garmin VO2max declined. So under the conditions I was in, I was less capable of running the same speed then when it was cooler. The Garmin VO2max reflected that. I wasn't losing fitness per se, but I was not capable of running the same speeds in the conditions under which I was now running.

In laboratory conditions, when the temperature of the room is manipulated, then it appears the oxygen consumption ability of the runner can be manipulated as well per the research I found.

So the Garmin VO2max is not measuring true VO2max as a measure of oxygen consumption. But, when temperature changes both the Garmin VO2max (HRvsPace relationship) and true VO2max (laboratory tested oxygen consumption) go up and down in a similar (but not necessarily the same) manner.

I'll use this chart as an example. The average runner's body weight was 72kg in the study. So a 3.2 L/min oxygen consumption at 4C at 45 min was a VO2max of 44.6.

Absolute VO2max (in Liters) = weight in kg X VDOT/100

But at 31C at 45 min the oxygen consumption was 2.6 L/min. For the same body weight, that equates to a VO2max of about 36.1.

So in this laboratory setting, when altering the temperature from 4C (39 F) to 31C (88F) the VO2max of the same runners was altered from 44.6 down to 36.1 (or a drop of about 8 points in a matter of a week or so dependent on the testing temperature). And this drop (8 points, or 19%) in VO2max simply couldn't be accounted for with detraining since Jack Daniels data suggests it takes about 72 days of inactivity with no leg aerobic exercise to reduce by that much. So yes, it would appear a significant drop in true VO2max (oxygen consumption) is possible in a very short period of time when accounting for changes in ambient temperature per the research I was able to find. Now that doesn't necessarily mean Garmin VO2max measurements drop at the same rate or in the same way as a true laboratory VO2max measurement, but it does appear that what you've experienced in your Garmin VO2max value is replicated in this particular laboratory setting for true VO2max oxygen consumption.

Now the reason this came up was a discussion about a measure of tracking fitness gains/losses over time. If I were to compare the 2017 summer to the 2018 summer's VO2max number, then we could get a pretty good general idea as to whether I've made training gains/losses. If I were to compare my beginning of Spring 2017 to end of Spring 2017 under similar weather conditions, then I could get a pretty good general idea as to whether gains/losses have been made. But I think we can both agree, that the data becomes harder to interpret when you compare different temperatures (or across different seasons/the whole year). But it is a reflective measurement of what you are capable of in that very moment in those specific conditions in which you just ran.

I think that you are confusing two things - a person's O2 uptake on a specific run vs a person's ability to efficiently use O2. Your VO2 Max is the later. And your body does not lose or gain that efficiency in a short period of time (Lord knows that I wish it were possible). So you will not drop from 44.6 down to 36.1 simply because the conditions change. The score might drop, but that is meaningless because your body did not lose anything. That is what I am talking about.

 

[DopeyBadger]

I think that you are confusing two things - a person's O2 uptake on a specific run vs a person's ability to efficiently use O2. Your VO2 Max is the later. And your body does not lose or gain that efficiency in a short period of time (Lord knows that I wish it were possible). So you will not drop from 44.6 down to 36.1 simply because the conditions change. The score might drop, but that is meaningless because your body did not lose anything. That is what I am talking about.

I think I'm understanding your point better. There seems to be a contingent out there that would prefer it be called VO2max (the maximal uptake) and VO2peak (the highest uptake taken in an individual test under possible differing conditions). VO2max being a maximal will not sway wildly because it represents the maximal achieved or attainable value. VO2peak can vary wildly because it is based on the current conditions of the test and desired output to exhaustion (or effort of participant). But since people test for maximal uptake in a test, while it represents the VO2peak it may or may not represent the VO2max. So the study I showed earlier would say the tests done at 4C represent a possible VO2max and VO2peak for that particular test, the tests done at 31C represent only a VO2peak in those particular conditions (because the runner failed to reach the maximal attainable value for them based on what was previously achieved in a 4C). It does not represent "the oxygen intake during an exercise intensity at which actual oxygen intake reaches a maximum beyond which no increase in effort can raise it’’.

http://cpxinternational.com/wp-content/uploads/2014/05/028_BJW-Vo2-Peak-vs-Max-final-2.pdf

It would seem Garmin would need to change the phrase from "VO2max" to "VO2peak" to meet the idea of what it's actually estimating. Since it isn't a set value at the highest attained (or attainable) value, but rather is a reflection of current conditions. So more like the term VO2peak. Because as you say, it shouldn't decrease wildly if it's truly a maximal attained.

I think that makes more sense and seems to be the point you're trying to convey. Am I getting closer to the same page?

 

[BuckeyeBama]

I think that makes more sense and seems to be the point you're trying to convey. Am I getting closer to the same page?

You actually made me understand my train of thought better than I had before. I used to be a real training nut. I was doing VO2 Max workouts before we knew what they were just because I knew that they made me a faster runner over longer distances. The science gets better and better, and I now only use it to try and achieve simple goals. But improving my VO2max has been the single thing that has provided predictable results for me. That is why I get so annoyed with the Garmin score.

 

[DopeyBadger]

You actually made me understand my train of thought better than I had before. I used to be a real training nut. I was doing VO2 Max workouts before we knew what they were just because I knew that they made me a faster runner over longer distances. The science gets better and better, and I now only use it to try and achieve simple goals. But improving my VO2max has been the single thing that has provided predictable results for me. That is why I get so annoyed with the Garmin score.

I definitely think this thought experiment back and forth helped both of us better understand the concept and each other's POV.

 

[kbenson13]

This continues to be a great discussion and I'm glad I was there to spark it off again!

 

[kleph]

i am about six weeks into my marathon training and that's a good excuse to look at my stravistix report to see how i'm doing. since fitness is rolling average of the last 42 days, it should now correlate with the race training effort.

 

[BuckeyeBama]

My form figure has been in the mid-20s for a few weeks now. Pushing hard, but fitness score improving. Wondering if anyone has seen their form scores this high for a long period of time without getting dead legs. My legs feel fine - tired after my long run and speed work, but fine. Should I be concerned?

 

[kbenson13]

Looks like I generally hover between -10 to -20 on my form score, with occasional short stretches in the -20s... I thought I was going to bust through -30 but my well-designed training plan pulled back just in time!