Here’s a quick, very basic review of John Stark's workout from last night. I want to use the review to introduce the idea of Training Stress Score (TSS) -- a basic concept that many of you are already familiar with -- as well as discuss what went well (and didn't) in John's workout. In his review of Rebecca's workout, Tim discussed the idea of stress. TSS is an algorithm we can use to quantify stress.
Before defining TSS, lets define two other important terms: Normalized Power (NP) and Intensity Factor (IF). Normalized Power is an estimate of the power that you could have maintained for the same physiological "cost" if your power had been perfectly constant, such as on an ergometer, instead of a variable power output. We can very loosely think of it as how hard the effort felt. Intensity Factor is simply Normalized Power relative to FTP. If a rider completes a ride with a Normalized Power of 200 watts and his FTP is 300 watts, the IF for the ride is .66.
Training Stress Score (TSS) is a composite number that takes into account the duration and intensity of a workout to arrive at a single estimate of the overall training load and physiological stress created by that training session. We don't need to dive into the exact formula, but the two inputs are Normalized Power:FTP (again, also called Intensity Factor) and Time. In cycling, TSS is calculated on power. If a power meter is not present, it can be estimated from heart rate, as well (although power is a more reliable metric).
Take a look at the screenshot below from John's workout.
Here we can see the planned and completed metrics for the workout. We can see that things are almost exactly as prescribed. Any workout that has the blue graph above the description can be completed in ERG mode on a trainer, and TrainingPeaks will calculate certain planned values -- in this case time, TSS, and IF.
Great job, John!