This piece originally appeared in the TrainingPeaks newsletter.
Chronic Training Load (CTL) on the PMC
If you use the Performance Management Chart (PMC) on TrainingPeaks.com, the mobile app, or WKO, you are probably familiar with Chronic Training Load (CTL). It’s a rolling, daily average of how much training load (measured in daily workout Training Stress Scores—TSS) an athlete is managing. The more stress you can handle, the greater your fitness is likely to be. If CTL is rising, then fitness is likely rising too. So CTL is a good proxy for “fitness” in the PMC model.
How Rapidly Should CTL Rise?
A common question I’m asked is how rapidly the CTL should rise over time. In other words, what should the ramp rate be? Obviously, if it doesn’t rise at all—it’s flat-lined—then fitness is probably stagnant. If you reduce your training load, CTL will drop, indicating a loss of fitness—negative ramping. A lot of zeroes back to back (meaning missed workouts) quickly lowers your CTL, indicating, without a doubt, a loss of fitness.
But most athletes want to know just the opposite: How rapidly can CTL be increased without producing a negative consequence such as overtraining, illness, or burnout? A key point to understand about these sad consequences of training too much is that they each take time to produce, usually many, many days, if not weeks. They don’t happen overnight, or even in a couple of days. Most require a few weeks of training beyond what you are capable of handling before the signs of overtraining matter—depending on many factors such as typical training loads, age, experience in the sport, fitness level, and more.
Some unique athletes are able to manage a very high ramp rate, such as greater than 10 CTL points per week, for a fairly long period of time before breaking down in some way. Such athletes are often elites. While it’s not a good idea to try to find your limits, what you can manage without breaking down is generally determined by trial and error. This may result from participating in a high training load camp with other highly motivated athletes. While it’s a little harder to drive yourself to the same extent without training partners, you could also do high-load training solo.
Regardless of how you do it, it’s wise to keep such a high ramp rate to a week or less before backing off to rest and recover. I call such a short period at a high ramp rate a “crash” period. It’s controlled overtraining. You’re wobbling on the edge. The crash period is described in my Training Bible books (see The Triathlete’s Training Bible and The Cyclist’s Training Bible). Such training typically results in a greatly increased level of fitness after a few days of post-crash R&R. Go much beyond a week at 10 or more weekly CTL ramp rate and the outcomes aren’t likely to be as beneficial. That’s one of the things that make the Grand Tours in cycling such challenging events.
What’s a Reasonable Ramp Rate?
So what’s a reasonable ramp rate—one that you maintain for a few weeks before taking an R&R break for a few days without becoming overtrained? While it depends to a great extent on who the athlete is, I’ve found that an increase in CTL of about 5–8 points per week is about right for most. Less than that and you’re probably not very focused on your training. More and you’re starting to get into the crash training load range.
When you do finally take an R&R break for a few days, your CTL will drop a bit since the training load is quite light as indicated by low TSS workouts relative to your “normal” training. But don’t let the falling CTL scare you away from recovery periods. They’re necessary if you are to reap the benefits of the recent training.
Of course, there are other things, such as lifestyle matters, that may add to the stress of training and reduce your capacity for even a moderately high CTL ramp rate. Some of the greatest lifestyle stressors are divorce, moving, financial difficulties, and changing jobs. These are the big ones, and one of these is a lot all by itself—but having a lot of lesser ones in your life can be just as challenging. Any of these scenarios can reduce your capacity for training, meaning that your ramp rate must be adjusted downward to maintain your health and well-being. If this is the case, then training must be reduced regardless of what your weekly rate of CTL ramping may be.
[Related: For more on CTL, read “Chronic Training Load—So What?“]