There are many explanations on the web of the acronyms that TrainingPeaks uses on their platform, but none that I’ve seen that tell the athlete how to interpret these, or how their coach does this.
I’ve tried to that here. Hope this is useful.
Please note that the chart you see below, the Performance Management Chart, is only available on the Premium version of TPeaks. If you only have the basic one, you can still see the values of IF, TSS etc on the Workout Quick View.
TSS / RED DOTS: This is is a composite number that takes into account the duration and intensity of a workout to arrive at a single estimate of the overall training load and physiological stress created by that training session. These are the red dots. Hard rides are shown by dots higher on the chart, easy rides are lower on the chart.
NOTE: When looking at an athlete’s chart, if the red TSS dots are all grouped closely, this shows that the athlete is not varying the intensity of their training to allow for growth. For growth, we should see some red dots higher, then lower, then higher etc. This means the rider is stressing his/her system enough to encourage adaptation, then resting well enough to allow that adaptation to become permanent (‘permanent’ as long as the athlete keeps working, does not get ill, etc).
INTENSITY FACTOR (IF) / BLUE DOTS: For any workout or part of a workout, the ratio of the Normalized Power to the rider’s functional threshold power, which gives the user a relative intensity in relation to their threshold power. IF is used to calculate TSS. These are shown by light blue dots.
NOTE: These are very similar to the red TSS dots in effect. Too many closely bunched, mid-range or lower ranged blue dots means the rider is not stressing the system enough. Therefore changes in form will be very slow and incremental, if coming at all. If the IF blue dots are all bunched but higher on the chart, this means that the rider is over-stressing their system, and not allowing for adequate rest – ie recovery. At first, an athlete training this will get stronger but the gains will crumble sooner rather then later as the athlete enters an over-training phase.
NOTE: Normalised Power: Average power is simply an average of the watts produced during a workout—including zeros. The only downside with this metric is that all power values have the same weight, so periods of lower output like coasting, drafting, or stopping can dramatically reduce the average. That’s where normalized power comes in. Normalized power is an estimate of the power you could have maintained for the same work load at a steady effort. It de-emphasizes periods of lower power output and places greater weight on harder efforts.
FITNESS (CTL): Dark Blue ‘mountain line’. The most important of them all. Chronic Training Load (Fitness) combines duration and intensity to provide a value of how much an athlete has trained historically. TrainingPeaks calculates CTL, by default, as the exponentially weighted average of daily TSS for the past 42 days (7 weeks). Note that, in effect, CTL represents the training an athlete has done in the past 3 months given the nature of exponentially weighted averages.
Why is this number so important? It represents a real (within the TPeaks system) indicator of where the rider is ‘at’, ie their form. It should be noted that the TrainingPeaks system in my experience rewards more ‘points’ for longer rides than for short but very intense rides. Still, within the TPeaks system or algorithm, this is relative and an indicator of overall rider fitness.
Within a tapering period this number will likely drop slightly, which does not mean that the athlete is getting weaker. True form takes time to begin to drop off. Within a tapering period a rider rests more than within a traditional periodisation block to be as strong as possible and yet adequately rested for race / event day.
FATIGUE (ATL) / PINK LINE: Acute Training Load (Fatigue) combines duration and intensity to provide a value of how much an athlete has recently trained. TrainingPeaks calculates ATL, by default, as the exponentially weighted average of daily TSS for the past 7 days. Note that, in effect, ATL represents the training an athlete has done in the past two weeks given the nature of exponentially weighted averages.
On the chart, a steady ATL line shows that a rider again is not stressing the system enough to encourage adaptations. In a week of training with say 2-3 intense interval workouts and 2-3 very easy recovery rides this number will fluctuate a lot.
FORM (TSB) / YELLOW LINE: Training Stress Balance (Form) represents the difference in the balance of training stress. TSB provides a measure of how much an athlete trained recently (ATL), compared with how much an athlete trained historically (CTL). TrainingPeaks calculates TSB by subtracting yesterday’s Fatigue from yesterday’s Fitness. Form (TSB) = Yesterday’s Fitness (CTL) – Yesterday’s Fatigue (ATL). TSB is not as a predictor of performance but as a measure of how adapted an athlete is to their training load.
NOTE: ‘FORM’ is not an ideal name for TSB in my opinion, as as stated it is ‘not as a predictor of performance but as a measure of how adapted an athlete is to their training load.’ When a coach looks at the TSB numbers from a week of riding, if say they rider is in Week 1, 2 or 3 of a three week training block, the numbers should be from -10 to -28. Minus numbers shows that there rider is adequately stressing the body. Single digit numbers, up to zero and above, show the rider is not stressing the system, and this is whey we see these kinds of numbers in recovery or off weeks. So, in a sense, where TSB is concerned, negative is a positive.