## Intensity factor

A light bike doesn't replace good fitness.

Moderator: Moderator Team

the jackel
Posts: 73
Joined: Wed Aug 22, 2007 7:44 pm
Location: London
This may be a dumb question, sorry if it is.

I understand the principle of IF but was wondering how to apply it beyond the 1hr mark. For example, I rode for 1.5 hrs the other day at an IF of 0.97. I appreciate this means I rode quite hard but what is the max that is realistic for that time frame, or for 2 hours or 3hours? Is there a simple guide that you shouldn't be able to achieve an IF greater than 0.xx for a given time period ( unless your FTP is incorrect obviously)?

TobinHatesYou
Posts: 6699
Joined: Mon Jul 24, 2017 12:02 pm
the jackel wrote:
Fri Jul 31, 2020 9:57 pm
This may be a dumb question, sorry if it is.

I understand the principle of IF but was wondering how to apply it beyond the 1hr mark. For example, I rode for 1.5 hrs the other day at an IF of 0.97. I appreciate this means I rode quite hard but what is the max that is realistic for that time frame, or for 2 hours or 3hours? Is there a simple guide that you shouldn't be able to achieve an IF greater than 0.xx for a given time period ( unless your FTP is incorrect obviously)?

It depends entirely on the type of efforts you are doing. Like, you can certainly achieve greater than 1.00 IF for 60min or longer if you do a lot of short bursty/sprint efforts. For a steady effort where normalized power ~ average power, then .97 seems about the practical max for a 90min stretch.

the jackel
Posts: 73
Joined: Wed Aug 22, 2007 7:44 pm
Location: London
Thanks for taking the time to reply

I appreciate this is subjective to an individual but is there a benchmark or guide for a 2 and or 3hr ride? What might the maximum achievable IF be, on the assumption its a hard effort target than loads of sprints?

petromyzon
Posts: 560
Joined: Mon Apr 05, 2010 4:14 pm
Here is a good summary of Critical Power models that have been used to address this for evenly-paced efforts.

https://www.gssiweb.org/sports-science- ... erformance

Clearly it's a model, it is not perfect and there will be individual variability. A criticism of this strategy is that it is very sensitive to the quality of the data over the short intervals used to fit the model. E.g. if there are even small inaccuracies in measurement of power over the shorter intervals this can result in 10's of Watts of error at the asymptote.

Further, individual motivation and practical issues such as terrain and interruptions can add so much variability that there is almost no point predicting the results. You just need to get out there and do what you can do.

You would also expect the answer to be very different depending upon the type of athlete - I bet Ironman athletes would be up in the high 90's like your number but a road racer with very developed anaerobic/glycolytic capacity like Sagan or Gilbert might not be able to get anywhere near 0.97.

Finally, as Tobin alludes to, there are issues with the Normalized Power calculation. In an ideal world your NP allows the assessment of the physiological stress of a variable effort >30mins by giving you a consistent average power to which it is equivalent. If you can generate a 60 minute NP greater than your FTP on a consistent basis then either your FTP needs increasing (good) or the calculation doesn't work for your physiology (annoying). This is a so-called "NP-buster". I've never been able to do it but plenty of people can.

Why do you want to know a guide for IF out to several hours? If it is because you are worried about having your FTP set too low then I would suggest you concentrate on getting a more robust FTP estimate. If it is to guide performance in longer events then you've just got to get out there, do the events and let experience be the best guide.

c60rider
Posts: 662
Joined: Mon Feb 27, 2017 11:12 pm
TobinHatesYou wrote:
Sat Aug 01, 2020 5:12 am
the jackel wrote:
Fri Jul 31, 2020 9:57 pm
This may be a dumb question, sorry if it is.

I understand the principle of IF but was wondering how to apply it beyond the 1hr mark. For example, I rode for 1.5 hrs the other day at an IF of 0.97. I appreciate this means I rode quite hard but what is the max that is realistic for that time frame, or for 2 hours or 3hours? Is there a simple guide that you shouldn't be able to achieve an IF greater than 0.xx for a given time period ( unless your FTP is incorrect obviously)?

It depends entirely on the type of efforts you are doing. Like, you can certainly achieve greater than 1.00 IF for 60min or longer if you do a lot of short bursty/sprint efforts. For a steady effort where normalized power ~ average power, then .97 seems about the practical max for a 90min stretch.
If you can score more than 1.00 on IF for a 60 minute continuous period then basically your FTP is too low and it needs remeasuring and any training with a power meter is not giving you any useful comparable data. 0.97 over 90 minutes sounds like it wouldn't just be a quite hard ride but pretty close to maximal the entire time ie riding at 97% of your FTP power output. That takes a huge amount of focus and intensity if it's even possible for most. You should only be able to ride at 100% of your FTP for 60 minutes (Intensity Factor of 1.00). Testing it every 6 to 8 weeks will mean you are training in the correct intensities. Whether that be in an off-season period where you've lost a bit of fitness and need to reduce the figures (never feels good psychologically but it's how it is) or if you're building fitness and need to increase the power numbers to maintain the same zones (Greg Lemond's quote "it never gets easier it just gets faster"). It also enables you to become familiar with how it feels to do a true maximal test as sometimes you don't quite feel quite as good so do a slightly poorer test. The sessions that you do can give you an idea if your fitness is improving. For example you may be pushing towards the top end of your range on zone 4 intervals whereas a month ago they were in the middle range for the same perceived exertion.

TobinHatesYou
Posts: 6699
Joined: Mon Jul 24, 2017 12:02 pm
c60rider wrote:
Wed Aug 12, 2020 11:36 am
TobinHatesYou wrote:
Sat Aug 01, 2020 5:12 am
the jackel wrote:
Fri Jul 31, 2020 9:57 pm
This may be a dumb question, sorry if it is.

I understand the principle of IF but was wondering how to apply it beyond the 1hr mark. For example, I rode for 1.5 hrs the other day at an IF of 0.97. I appreciate this means I rode quite hard but what is the max that is realistic for that time frame, or for 2 hours or 3hours? Is there a simple guide that you shouldn't be able to achieve an IF greater than 0.xx for a given time period ( unless your FTP is incorrect obviously)?

It depends entirely on the type of efforts you are doing. Like, you can certainly achieve greater than 1.00 IF for 60min or longer if you do a lot of short bursty/sprint efforts. For a steady effort where normalized power ~ average power, then .97 seems about the practical max for a 90min stretch.
If you can score more than 1.00 on IF for a 60 minute continuous period then basically your FTP is too low and it needs remeasuring and any training with a power meter is not giving you any useful comparable data. 0.97 over 90 minutes sounds like it wouldn't just be a quite hard ride but pretty close to maximal the entire time ie riding at 97% of your FTP power output. That takes a huge amount of focus and intensity if it's even possible for most. You should only be able to ride at 100% of your FTP for 60 minutes (Intensity Factor of 1.00). Testing it every 6 to 8 weeks will mean you are training in the correct intensities. Whether that be in an off-season period where you've lost a bit of fitness and need to reduce the figures (never feels good psychologically but it's how it is) or if you're building fitness and need to increase the power numbers to maintain the same zones (Greg Lemond's quote "it never gets easier it just gets faster"). It also enables you to become familiar with how it feels to do a true maximal test as sometimes you don't quite feel quite as good so do a slightly poorer test. The sessions that you do can give you an idea if your fitness is improving. For example you may be pushing towards the top end of your range on zone 4 intervals whereas a month ago they were in the middle range for the same perceived exertion.

As petromyzon confirms, plenty of people can ride at >1.0 IF over a contiguous 60min because normalized power shoots way up with repeated high intensity efforts and minimum recovery. Honestly, I would bet most amateur/elite racers can do it, especially those who focus their training on anaerobic/neuro efforts. A kind of race that would be and IF/NP buster is a criterium with a steep, short hill.

And yes, I literally wrote that .97 over 90min is probably the practical max, though again, there are some freaks who can gut out .95 over 120min.
Last edited by TobinHatesYou on Wed Aug 12, 2020 1:39 pm, edited 2 times in total.

c60rider
Posts: 662
Joined: Mon Feb 27, 2017 11:12 pm
TobinHatesYou wrote:
Wed Aug 12, 2020 12:47 pm
c60rider wrote:
Wed Aug 12, 2020 11:36 am
TobinHatesYou wrote:
Sat Aug 01, 2020 5:12 am
the jackel wrote:
Fri Jul 31, 2020 9:57 pm
This may be a dumb question, sorry if it is.

I understand the principle of IF but was wondering how to apply it beyond the 1hr mark. For example, I rode for 1.5 hrs the other day at an IF of 0.97. I appreciate this means I rode quite hard but what is the max that is realistic for that time frame, or for 2 hours or 3hours? Is there a simple guide that you shouldn't be able to achieve an IF greater than 0.xx for a given time period ( unless your FTP is incorrect obviously)?

It depends entirely on the type of efforts you are doing. Like, you can certainly achieve greater than 1.00 IF for 60min or longer if you do a lot of short bursty/sprint efforts. For a steady effort where normalized power ~ average power, then .97 seems about the practical max for a 90min stretch.
If you can score more than 1.00 on IF for a 60 minute continuous period then basically your FTP is too low and it needs remeasuring and any training with a power meter is not giving you any useful comparable data. 0.97 over 90 minutes sounds like it wouldn't just be a quite hard ride but pretty close to maximal the entire time ie riding at 97% of your FTP power output. That takes a huge amount of focus and intensity if it's even possible for most. You should only be able to ride at 100% of your FTP for 60 minutes (Intensity Factor of 1.00). Testing it every 6 to 8 weeks will mean you are training in the correct intensities. Whether that be in an off-season period where you've lost a bit of fitness and need to reduce the figures (never feels good psychologically but it's how it is) or if you're building fitness and need to increase the power numbers to maintain the same zones (Greg Lemond's quote "it never gets easier it just gets faster"). It also enables you to become familiar with how it feels to do a true maximal test as sometimes you don't quite feel quite as good so do a slightly poorer test. The sessions that you do can give you an idea if your fitness is improving. For example you may be pushing towards the top end of your range on zone 4 intervals whereas a month ago they were in the middle range for the same perceived exertion.

As petromyzon confirms, plenty of people can ride at >1.0 IF over a contiguous 60min because normalized power shoots way up with repeated high intensity efforts and minimum recovery. Honestly, I would bet most amateur/elite racers can do it, especially those who focus their training on anaerobic/neuro efforts. A kind of race that would be and IF/NP buster is a criterium with a steep, short hill.

And yes, I literally wrote that .97 over 90min is probably the practical max, though again, there are some freaks who can gut out .95 over 120min.
Written by Andrew Coggan who actually created the Intensity Factor metric

https://www.trainingpeaks.com/blog/norm ... ing-stress/

TobinHatesYou
Posts: 6699
Joined: Mon Jul 24, 2017 12:02 pm
c60rider wrote:
Wed Aug 12, 2020 1:28 pm

Written by Andrew Coggan who actually created the Intensity Factor metric

https://www.trainingpeaks.com/blog/norm ... ing-stress/

Nothing there disputes what I said. Do you not understand how much NP and avg power can differ?

Imagine a rider with a 375W FT. Now imagine he races a crit with a hill. 2min laps broken down by 30s at 600W followed by 90s at 275W. His average power for 60min would be 356W, but his NP would be well over 375W, resulting in an IF >1.00.

Hell, I recently did a 255W avg 60min effort where my NP was 296W. The laps were 11min long with 45s of 550W and the rest at 233W. I can tell you right now that my FT has never been 296W.

JMeinholdt
Posts: 384
Joined: Wed Feb 26, 2020 10:31 pm
Location: Topeka, KS
TobinHatesYou wrote:
Wed Aug 12, 2020 1:46 pm
Nothing there disputes what I said. Do you not understand how much NP and avg power can differ?
This. I routinely have efforts >60 minutes over 1.00 IF. The reason being is that my terrain is a lot of short rolling hills. It doesn't even take a TON of effort to go over 1.00 IF for me because all I have to do is power up the hills at 2-300% FTP for 30 seconds to a minute and coast down the other side and do it all over again.
Wilier Cento10AIR Rim Brake - SRAM Force AXS
3T Exploro 105 - Gravel/Commuter/Trainer

c60rider
Posts: 662
Joined: Mon Feb 27, 2017 11:12 pm
I can only quote what Andrew Coggan says and that is....

"Note that one particularly useful application of IF is to check for changes in threshold power – specifically, an IF of more than 1.05 for a race that is approximately 1 hour in duration is often a sign that the rider’s threshold power is actually greater than that presently entered into the program"

So if over a 1hr period whether it's a race or a training hour that you consider to be flat out then the above applies. If you disagree with that then take it up with him seeing as he created it.

TobinHatesYou
Posts: 6699
Joined: Mon Jul 24, 2017 12:02 pm
c60rider wrote:
Thu Aug 13, 2020 4:41 pm
I can only quote what Andrew Coggan says and that is....

"Note that one particularly useful application of IF is to check for changes in threshold power – specifically, an IF of more than 1.05 for a race that is approximately 1 hour in duration is often a sign that the rider’s threshold power is actually greater than that presently entered into the program"

So if over a 1hr period whether it's a race or a training hour that you consider to be flat out then the above applies. If you disagree with that then take it up with him seeing as he created it.

You really don’t understand IF, TSS, NP and average power and it’s no longer funny. Do you not see the word “often” in the passage you quoted? Why do you think he didn’t use the word “always?”

This is the final workout in a training plan I'm trying for fun. According to you it would be impossible.

bikeboy1tr
Posts: 720
Joined: Thu Mar 21, 2013 3:19 am
Location: Southern Ontario Canada
That final training session is it made up of a shitload of jumps with 3 full gas sprints followed by more jumps and another 3 full gas sprints? If that doesnt get you over the 1.0 factor dont know what will.
viewtopic.php?f=10&t=154188
2018 Colnago V2R Rim Brake
2014 Norco Threshold Disc Brake
2012 Time RXRS Ulteam Rim Brake
2008 Time VXR Rim Brake
2006 Ridley Crosswind Rim Brake

TobinHatesYou
Posts: 6699
Joined: Mon Jul 24, 2017 12:02 pm
bikeboy1tr wrote:
Fri Aug 14, 2020 2:01 am
That final training session is it made up of a shitload of jumps with 3 full gas sprints followed by more jumps and another 3 full gas sprints? If that doesnt get you over the 1.0 factor dont know what will.

It's a simulated 3 lap circuit race with 9 full gas jumps and a bunch of other surges. At 1.23 IF, I do expect to fail. 1.15 would be more "reasonable."

Cycomanic
Posts: 220
Joined: Tue Feb 04, 2020 11:10 pm
I think there's a couple of things to remember:
1. FTP is a convenient measure but it's unclear what (if) it corresponds to anything physiological. Moreover, how did you actually measure FTP hardly anyone ever does 60min TT efforts and everything else is just a way to estimate it.
2. Also if you actually do 60min TT efforts, unless you're very experienced pacing will have a big impact on your numbers.
3. There are efforts that allow you to exceed 1.0 IF in 60min, the so-called NP busters
4. Considering the mentioned uncertainties in FTP measurements maybe your NP value is for thos 60min efforts is actually a better estimate of your FTP.

Coming back to the OP, NP busters are hard you really need to make an focused effort. So if your 0.97 IF 90min ride was "quite hard" it's much more likely that your FTP is too low, than you being a strong physiological outlier.

TheRich
Posts: 782
Joined: Tue Jan 01, 2019 1:36 am
Cycomanic wrote:
Sun Aug 16, 2020 2:54 pm
I think there's a couple of things to remember:
1. FTP is a convenient measure but it's unclear what (if) it corresponds to anything physiological. Moreover, how did you actually measure FTP hardly anyone ever does 60min TT efforts and everything else is just a way to estimate it.
2. Also if you actually do 60min TT efforts, unless you're very experienced pacing will have a big impact on your numbers.
3. There are efforts that allow you to exceed 1.0 IF in 60min, the so-called NP busters
4. Considering the mentioned uncertainties in FTP measurements maybe your NP value is for thos 60min efforts is actually a better estimate of your FTP.

Coming back to the OP, NP busters are hard you really need to make an focused effort. So if your 0.97 IF 90min ride was "quite hard" it's much more likely that your FTP is too low, than you being a strong physiological outlier.
Uh no. FTP typically has little to do with your hour power...which would be determined by your average, not normalized, power. The vast majority of people lack the endurance to do an hour of FTP, and if they used their hour of power number, it would be too easy for almost all FTP-based workouts. I'd make a WAG that if you can do an hour at FTP, either your FTP is too low or you've gone overboard and become too much of a diesel.

FTP and NP are just numbers, don't try to find the deeper truth because there isn't one.