The goal with all training is to make you tired in specific ways, and then allow your body to recover and adapt. It’s very difficult to measure how tired your body gets, so instead what we usually measure is what we do to it. “Workload” is usually how we quantify what we do to the body.
It’s important to realize that workload and fatigue are often used to describe the same thing, but are different. Sometimes running a mile in 8 minutes might be really hard and make you really tired. Sometimes you feel pretty good from it. Over days and weeks, however, workload and fatigue should correlate pretty well.
In TrainingPeaks, workload is “measured” (estimated) by Training Stress Score (TSS). TSS estimates workload by comparing each second of exercise to your “threshold”, or what you could hold for one hour.
For example: If your threshold power on a bike is 300 watts (W), Training Peaks is going to analyze your power second by second comparing each reading to 300W. If that second is 200W, you’ll get something like 0.0125TSS per second. If a second reads 300W, you’ll get something like .028TSS per second. Then it tallies up all the seconds, and gives you something like 45TSS per hour (60m of 200W with a 300W threshold), or 100TSS (60m of 300W with a 300W threshold).
What does this matter to you?
You need to have a GOOD threshold value! If your threshold value isn’t correct, then your TSS is WRONG.
You need to have GOOD data! If you have a good threshold value, but you’re comparing it to crap data, then your TSS is WRONG!
There are MANY different ways that TrainingPeaks tries to estimate your TSS, most of them are crap:
rTSS: The small “r” denotes that this is Run TSS, which is calculated based off of your Threshold running pace. It’s fairly easy to define your threshold here, but unless you only run on flat non-technical ground, all paces during your workout are garbage. DON’T USE rTSS.
tTSS: When you don’t have anything else, Training Peaks will estimate TSS based simply on time. Really, this is just measuring volume, which we know isn’t great. ONLY PAY ATTENTION TO THIS AS A LAST RESORT
hrTSS: Heart Rate TSS. If you’re wearing a heart rate monitor and don’t have cycling power, always use this. USE THIS EVERY DAY
TSS: This is power based. If you’re on a bike, use this. If you’re running DON’T USE THIS. It’s an estimation that hasn’t been validated by any scientific data. It’s a gimmick. ONLY USE THIS IF YOU ARE ON A BIKE.
TSS*: This means manually added TSS. ONLY COACH USES THIS
