how to measure CTL

Miscreant

Hi, i'm a pretty big newbie when it comes to training and terms. I know CTL has to do with your training load, right? Do you need one of the cycling programs to figure it out? Or is there some way i can do some math and figure it out? Also, what is the main benefit of knowing it, just so you can either stay consistent or increase training without just adding time/intensity but switching the workouts up?

daveryanwyoming

Yep
CyclingPeaks WKO+ sure makes it a heck of a lot easier. But you can hand calculate everything or use a spreadsheet. Here's what you need to calculate:

- Normalized Power using 30 second smoothing and pwr^4 averaging
- Intensity Factor = NP/FTP
- TSS = IF^2*hours*100
- CTL = CTL(d-1) + [TSS-CTL(d-1)]*[1 - exp^(-1/42)]
- ATL = ATL(d-1) + [TSS-ATL(d-1)]*[1 - exp^(-1/7)]
- TSB = CTL-ATL

All of that is easy to drop into a spreadsheet but it's much easier to just use WKO+. A spreadsheet version can still be useful for forward looking CTL, ATL and TSB estimates for instance when planning a race taper.
The main benefit is to monitor your training load and have a measure of how deep your training base is. Also the benefit of being able to predict when you'll peak for events as opposed to hitting those peaks randomly. A lot of folks have also found their weekly CTL ramp rate during builds helps them predict overtraining and illness. So it's a good way to make sure you don't overdo things and get yourself sick during heavy training. It helps you figure out when you need additional rest or when you can afford to press a bit harder and lets you quantify the overall stress created by any individual workout and lets you compare that to the short and long term stresses your body has already adapted to.

In short, it's another training metric. Just as valuable or usesless as any others depending on how much time you take to understand it and how you apply the results. Check out this piece on the PMC: http://www.cyclingpeakssoftware.com...ancemanager.asp

Good luck,
Dave

Miscreant

thanks as always to you dave for the super informative reply!

Porkyboy

Hi

A long time ago Dave Ryan said:


I get all my data off a CompuTrainer or PowerTap and I'm finding that my TSB on the PMC does not always conform to the TSB=CTL-ATL formula, any ideas why that might be? Sure beats me! It will be spot on for a couple of days and then be a bit different, for example my TSB on 01.06.2006 was -21.9 with a CTL of 65.1 and an ATL of 91.4 so in theory my TSB should have been -26.3. Just trying to understand.

Hmm.. Think I've worked it out, the CTL is the figure for the NEXT day? What an idiot

Thanks.

PBUK

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frenchyge

Sounds like you figured it out, but to be more clear: TSB is the predictor of how you will feel on today's ride based your training load through yesterday.

Today's TSB equals yesterday's CTL minus yesterday's ATL.

daveryanwyoming

yep, like frenchyge said, but my apologies I should have written that as:

TSB(d) = CTL(d-1) - ATL(d-1)

-Dave

ctgt

Dave, what value/cell reference/operator should I be using when you indicate "exp" in this formula? (I'm trying to set this up in Excel)

daveryanwyoming

Actually, that is Excel notation for e^x (sorry can't write decent formulas in straight text) or "e" taken to the "x" power.

So for instance CTL based on CTL from the previous day, TSS, and using a 42 day time constant can be entered into Excel as:

"=ROUND(G2+(D3-G2)*(1-EXP(-1/42)),1)"

That adds a 1 decimal place rounding and in the case of the spreadsheet I pulled it from G2 represents previous day CTL, D3 represents current day TSS and this formula was pulled from cell G3 so copying the formula down(ctrl-d) the G column calculates running CTL over many days or weeks. You seed the sequence by putting your starting CTL into cell G2 in this example.

-Dave

bing181

If you get there, would you mind sharing it? I'm an Excel klutz, and the Training Peaks software is only PC. I've tried to find an Excel spreasheet, but no luck so far.

Not to mention, I only have hand-copied Power data from my Tacx trainer, not anything I can upload from a Powertap or SRM.

B

ctgt

Dave's 11:10 post solved it perfectly. Right now I'm just experimenting with how much info I want to include, but I could send you a working copy as I think I've got it working.

daveryanwyoming

Sounds good. You can also download a very nice PMC spreadsheet from:
http://groups.google.com/group/wattage/topics
You've gotta join the wattage group which is free but full of good information. Once you join, go to the files page and look for:
PMC Template_Modified.xls

It's a very nice PMC tool that supports forward looking load planning.

-Dave

rmur17

one shorthand way of calculating this (and avoiding the EXP bits), is to simply replace:

*(1-EXP(-1/42)) with /(tc+0.5) where tc=42 for CTL, tc=7 for ATL

try it .

Should be quite close unless you drop tc very low and that's not pertinent for pseudo-PMC purposes.

IMHO I don't believe it's appropriate to carry a decimal point for any TSS, CTL, ATL or TSB factor. With the inherent degree of inaccuracy present firstly in the PM readings and secondly in how we all establish FTP, I think it's unjustified.

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rmur

daveryanwyoming

Yeah, can't argue with that. I did it to check my predictions against WKO+ that carries a single decimal point. But you're right, you'd be hard pressed to notice the difference between a CTL of 90 and 90.1

-Dave

ctgt

Wow. That's cool. Now I want to figure it out.