Ok, there are so many different terms when you use Training Peaks and they have lots of different help buried everywhere. Here’s a simple decoder ring:

- It all starts with your FTP, that is your functional threshold power. This is the amount of wattage that you can generate for an hour. For the average person it is 200 watts, for athletes, 250-300 watts is amazing fyi. We are basically not that much more than two light bulbs of power ðŸ™‚ Or to put it another way, you generate 200Wh of total energy.
- Normalized Power. It is actually hard to figure out what power you are generating because on a millisecond. basis your output varies, so Training Peaks tries to estimate the power you would use if you were pedaling constantly for an hour during your ride. It’s complicated, but basically that’s what your effort was during your ride.
- IF or intensity factor. This is just the ratio of your NP to your FTP. So if you did your FTP right, then in an hour ride, your NP/FTP should also be less or equal to 1.0.
- TSS or Training Peaks Stress Score. This is the basic unit of measure and it is pretty simple a TSS of 100 means that your normalized power over an hour ride was equal to your FTP. So you can think of it as 100%. The idea here is that you can two hours at say half power and this is equivalent to one hour at full power because 2hrs * 100 watts = 1 hour * 200 watts. In the old training days, you would say let’s go out for two hours, but it is very different if you are going out on a recovery ride vs. all out. This normalizes that. As another example if you go say for four hours at full power, you just did (4 hours * NP=200 watts)/(FTP = 200 watts * 1 hour) * 100 = 400 TSS.
- TSSd or TSS per day. This measure how hard you are working. It turns out that if you go on a rapid ramp, say from 50 TSSd to 100 TSSd to 200 TSSd, you will basically bonk, so one thing to watch for is how you ramp up.
- weekly TSS, this is basically the sum of all your TSS’s over a week of training. Turns out that for different athletic levels, you can see what the average person needs to do to compete so a beginner category 5 racer needs a Weekly TSS of 192 to 385 put another way, you should train the equivalent of 2 hours at your full FTP each week to be in shape (and see below, but you need a CTL of 70 that is you should be able to do 70% of your FTP on most of your workouts).
- Chronic Training Level or Fitness. This is a measure that is basically a rolling average of your last 45 days. it is exponentially weighted and shows you basically how much you’ve been training. For instance, if you have a CTL of 25, this means that over the last 45 days, you’ve been training at 25 TSS/day, that is about Â¼ or potential. The chronic term threw me off, but perhaps a better term is your long term TSS.
- Acute Training Level or Fatigue. This is the short term 7 day measure of your TSSd. That is, how hard you are working right now. Basically if you gradually ramp your training, your CTL will rise with a 45 day average and your ATL will rise with a 7 day average. You can see that if you quickly jump and do a hard week, then the CTL will lag and be lower than your ATL. Put another way, while your Fitness will rise somewhat, your Fatigue will go up a lot. This is pretty intuitive. It means that most of the time, you want to gradually increase your Fitness and then your Fatigue will be relatively close. If you ramp too fast, while you will get more fit, you will get tired more quickly.
- Training Stress Balance or Form. This is basically your Fatigue minus your Fitness, the way to look at this is that if you train gradually and then taper before a big race what will happen is that your Fitness will stay relatively the same (it is a 45 day average, so slacking off, you will stay fit), but your Fatigue will drop really fast (it is 7 day average), so you will be relatively well rested but be a high level. In this case your Form will be high. That means you are ready for the race. Obviously, if the day of the race, you will go crazy, so your Fatigue level will rise dramatically and you won’t be able to do much the day after, so your Form will drop. In essence these scores are an analytic way to look at what is intuitive,
- You can see the key measure here is your real FTP. If the FTP is too low, there will be many days where you will be able to jam rally high TSS. To take it to the extreme, if you think your FTP (that is wattage generated in an hour ride at your hardest) is 10 watts and every day, you are running at 500 watts per hour, then your TSS will be (500 watts * 1 hour) /( 10 watts * 1 hour) * 100 = TSS of 5000. That is going to make you feel like a god, Â but it doesn’t make sense, in the end if your FTP is correct, it means that after an hour at that wattage, you will want to fall over and die. That’s the definition of FTP, it needs to be your absolute maximum with nothing left over after an hour.
- hrTSS, rTSS, sTSS. If you don’t have a power meter, then you can estimate this through your heart rate (hrTSS). It also turns out your maximum power when you are running (rTSS) or swimming (sTSS) are different from biking. So depending on your sport, you need to use different TSS values.