Here at Progressive Endurance, I am all about measuring fitness gains and adjusting training zones accordingly for each athlete to get the most out of each individual.  If you were to read any number of fitness articles on testing zones, they will say to retest every 6 to 8 weeks.  I typically do 8 week cycles because it allows for two 4 week cycles of 3 weeks of building and 1 recovery week.  However, there are times when I would retest an athlete sooner than 8 week cycle based on some key numbers that every athlete should monitor if they use Training Peaks as the workout journal/data base.

Before you trust any numbers that auto populate in Training Peaks after a workout, you must be sure to have your threshold pace, HR, or power set correctly.  To do so, go to your settings and put the correct numbers in the box

The 2 numbers/terms that you need to monitor when looking at when your zones need to be changed for the run and the bike are you TSS and IF.

TSS – Training Stress Score.  This directly related your threshold that you have set in Training Peaks.  This number tells you how difficult a workout was on your body.  If your threshold is set correctly, it is impossible to score over 100 TSS in one hour.  Riding or running at threshold for one hour is 100 TSS.  Riding or running at 90% of threshold for one hour comes out to 80 TSS.  80% of threshold for one hour give 64 TSS.  50% of threshold for one hour only gives you 25 TSS.  As you can see, the percentage of threshold and the amount of TSS is not linear, its exponential either.

IF – Intensity factor.  This is essentially the percentage of threshold that you held for all, or part of the workout depending on how much of the workout you are looking at.

So now that we got the basic understanding of TSS and IF out of the way, I want to use a workout of an athlete I’m coaching this year, Kira Williams.  This was a run test that was prescribed 8 weeks after the last test.  But, for the sake of the discussion, let’s pretend that this was just a normal track workout with no static rest.

So the first thing I want you to see is the bottom middle of the picture.  Kira ran the entire workout (warm up, main set, and cool down) at 102% of threshold.  That alone doesn’t mean anything since the length of the workout is under an hour.  I suppose someone could manage to go 2% over threshold for almost 52 minutes… but I bet it would be close to impossible.  At this point, an eye brow has risen and more digging is needed to determine if her pace zones need adjusting.

The most obvious thing is the right above the IF (also located in big font at the top center of the picture) is the TSS.  Remember how i said someone can not score more than 100 TSS in an hour if the threshold is set up correctly.  Well, it is also impossible to score 100 TSS in less than an hour if your threshold is set up correctly.  Kira managed to hit 100 TSS in just 52 minutes.  I would bet if she continued to keep running, even at a comfortable pace for 8 more minutes, that number would be between 110 and 115 TSS.

At this point, as a coach, I know this athlete has made fitness gains and if we are only 3 to 4 weeks into the 8 week cycle, I would consider retesting early.  I don’t do this often, because most of the time zones don’t change that quickly.  However, I have done it before.

**Swim TSS is a little trickier to recognize increased fitness because of how Training Peaks measures time in the pool swimming.  In short, it doesn’t count the time resting on the wall in your total swim time.  So you could 60 minutes of swimming with lots of rest after each distance you swam over threshold and it would populate as 60 minutes of workout time in TrainingPeaks instead of the 90 minutes (or however long it took you) to get that 60 minutes of actual swimming.

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