The following post originally appeared on the TrainingPeaks blog and will be useful to you if you use TrainingPeaks or WKO software, a tool that can be used to analyze and plan training. It’s perhaps the most useful tool currently available to endurance athletes regardless of sport.
Chronic Training Load (CTL)
A TrainingPeaks subscriber recently said he uses the Performance Management Chart (PMC) and has a basic understanding of Chronic Training Load (CTL), Training Stress Score (TSS), Training Stress Balance (TSB), and the other markers of performance. He posed a basic question, which has probably crossed many a user’s mind—so what? In other words, why should you be interested in the numbers represented by all of the lines on the chart? Of what value are they? What should your goals be for them?
Let’s make sure you have a basic understanding before getting into the “so what” of CTL. That blue line on your PMC is a rolling 42-day (or whatever you may set the number of days to be) rolling average of your daily TSS. While it primarily indicates how much training load you are currently managing, it also serves as a good proxy for your fitness. If the blue line rises, you are capable of handling a higher training load and are therefore more fit. And you may also assume the opposite.
“So, what should my CTL be?” the subscriber asked. I’m afraid I can’t answer that question with a one-size-fits-all answer, as there are simply too many “it depends.” It depends, first of all, on what your sport is. For example, triathletes tend to have lower CTLs per sport than do single-sport athletes. That’s obvious because a cyclist, for example, devotes nearly all of his or her training time to the bike while a triathlete spreads the total training load between three sports. The next biggest “it depends” has to do with the individual athlete—how much training load are you capable of handling? Life isn’t fair. Some people can easily manage a very high CTL, such as, say, a 150 TSS/day average. Others would quickly wind up overtrained from attempting to do that. I won’t get into the other “it depends,” such as how much time one has available to train, as there are lots of them.
The best advice I can give you when it comes to what is an appropriate CTL for you is to use your historical data as a starting point. Simply do what you seem to be capable of doing. You shouldn’t become so focused on CTL that you try to take it very quickly to record highs. That’s a sure way to wind up overtrained. If you are in a serious period of training, such as the last 12 weeks before an A-priority race, you should see the line generally rising, however. In my blog post “The CTL Ramp Rate,” I suggested that during such periods of very focused training you may want to see your CTL rise by 5 to 8 points per week, excluding Rest & Recovery weeks spaced every third or fourth week. During R&R weeks, your CTL should be allowed to decline.
I hope that gets at the first “so what” question. I wish I could be more specific about the actual CTL number, but as explained above, I can’t. It just depends. However, I can tell you how to use that number on any given day to get an idea of how hard your workout might be. This is not pure science. It’s more ballpark than precise. It may give you something to hang your hat on when it comes to scheduling workouts.