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Applying the Numbers Part 3: Training Stress Balance

BY Joe Friel

In the final installment of Applying the Numbers, Joe Friel explains how you can use the Performance Management Chart to manage your Fitness, Fatigue, and Form.

Training Stress Balance (TSB), the yellow line on the Performance Management Chart, is merely a way of describing what we call “Form.” What is Form? In a single phrase, it is race readiness.

So how is Form determined? It’s the result of subtracting today’s Fatigue (Acute Training Load, or ATL) from today’s Fitness (Chronic Training Load, or CTL). Both Fatigue and Fitness are expressed as Training Stress Score, or TSS per day (TSS/d). Once the software has done the math, the remainder is your Form (by the way, the resulting Form value is for tomorrow—not for today.) It can be either a negative or a positive number depending on which is greater- Fitness or Fatigue. If Form is negative you are likely to be tired and probably not race ready. If Form is positive then you are probably rested and perhaps on form— if it doesn’t get too high.

So what do the Form numbers mean and how can you use them to be race ready? Let’s dig a little deeper using exact Form numbers as guidelines.

The Right Numbers for Race Day

When I’m tapering and peaking athletes for A-priority races I like to have their Form at around plus 15 to plus 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 Form is just barely positive, around plus 5 to plus 10. I don’t know if this is physiological or psychological. It’s just the way it is for some. As mentioned above, Form is closely related to your readiness to race. When it’s below negative 10 you’re probably too tired to race well. You’re not “on form.” That may be OK for a C priority race. For a B race you will probably want your Form trending positive and between negative 10 and 0.

Transitional Phase

The range between negative 10 and plus 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 TSS is decreasing and 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 Form is falling).

If you spend much time in this negative 10 to plus 10 Form 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.

Productive Training

For most athletes I’ve found keeping Form in the negative 10 to negative 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.

Digging Too Deep

Pushing your Form below negative 30 greatly increases your risk of injury or illness. 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 a recovery day may mean a zero- a day off. For others it’s a session with a low TSS.

Losing Fitness

If you wander north of plus 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 TSS is simply too low for some reason.

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 Fitness, Fatigue, and especially 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 Form.

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About Joe Friel

Joe Friel is the author of The Triathlete’s Training Bible, Your Best Triathlon and other books on training. For more information visit his website at You can also view and purchase Joe’s training plans on TrainingPeaks.

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