The following post originally appeared on the TrainingPeaks blog. It’s the last of a three-part series on the Performance Management Chart (PMC) with the other parts discussing Chronic Training Load (CTL) and Training Stress Score (TSS). The PMC is a powerful tool for serious athletes and coaches once they learn how to use it.
Training Stress Balance (TSB)
So how is TSB determined? It’s the result of subtracting your Acute Training Load (ATL), also known as “fatigue” or the red line on your chart, from your Chronic Training Load (CTL), also known as “fitness” or the blue line. Both ATL and CTL are expressed as TSS per day (TSS/d). Once the software has done the math, the remainder is your TSB. (By the way, the resulting TSB value is for tomorrow—not for today.) It can be either a negative or positive number depending on which is greater—CTL or ATL. If TSB is negative, you are likely to be tired and probably not race ready. If TSB is positive, then you are probably rested and perhaps on form—if it doesn’t get too high.
So what? What do the TSB numbers mean and how can you use them to be race ready? Let’s dig a little deeper using exact TSB numbers as guidelines.
When I’m tapering and peaking athletes for A-priority races, I like to have their TSB/Form at around +15 to +25 on race day. I’ve found that usually produces the best results. But not always. For some unknown reason, there are athletes who perform best when their TSB/Form is just barely positive, around +5 to +10. I don’t know if this is physiological or psychological. It’s just the way it is for some.
The range between -10 and +10 is generally a transitional phase. Time in this range should be rather brief. There are two common reasons to be in this range. The first is that you are moving through it toward being on form for a race (daily workout TSS is decreasing and TSB/Form is rising). The other common reason is that you are returning to focused training after a few days’ break and moving toward greater fatigue (daily TSS is increasing and TSB is falling).
If you spend much time in this -10 to +10 TSB range, your training is stagnant. Not much is happening. Other than peaking for a race or when in a rest and recovery break lasting a handful of days, this range is best avoided. Staying there for a long time, such as two weeks or more, is seldom a good thing. Try to pass through it in only a few days.
As mentioned above, TSB/Form is closely related to your readiness to race. When it’s below -10, you’re probably too tired to race well. You’re not “on form.” That may be okay for a C-priority race. For a B race you will probably want your TSB trending positive and somewhat above -10. Perhaps even at zero to +10. And, as mentioned, an A-priority race should probably be greater than +10 for most athletes.
If you wander north of +25, your training is much too easy. You’re losing a lot of fitness. This sad situation could be the result of injury, illness, lifestyle-based training interruption, or anything else that drastically reduces your training load. Your recent workout TSS is simply too low for some reason.
The other side of the coin is driving your TSB too low. For most athletes I’ve found keeping TSB in the -10 to -30 range when the training is hard and focused is a very productive and healthy range. This could be, for example, in the serious training weeks of the Base and Build periods. In this range, the likelihood of a breakdown is kept in check. But going south of -30 greatly increases your risk. Managing this part of the training period is done by making sure every recovery day TSS is appropriately low and that there are adequate recovery days each week. For some athletes a recovery day may mean a zero—a day off. For others it’s a session with a lower than usual TSS.
Franz Stampfl, Roger Bannister’s coach back in the 1950s, said, “Training is principally an act of faith.” By that he meant that you can’t predict exactly what will happen in a race regardless of how you may train. The Performance Management Chart with its CTL/Fitness, ATL/Fatigue, and especially TSB/Form, is a way of reducing the wishing and hoping that happens shortly before a race. But it by no means eliminates the individuality of training. You still must pay close attention to determine how your performance responds to varying degrees of TSB/Form.