The Load and Performance chart offers a snapshot of a rider's training using three metrics referred to as CTL, ATL, and TSB. These individual metrics are calculated using the T-score from your training rides and can be used as indicators of a riders fitness level, fatigue, and form over time.
CTL: Chronic Training Load. Your CTL is a long term daily average of your T-score and closely represents your fitness level as an indicator of the amount of training your body has physical adapted to. A prescribed training plan may, for example, plan to ramp up a rider's CTL by 15 points over an 8 week duration in order to build up fitness.
- The number of days is set to a default of 42 days, but can also be adjusted as needed under My Account > Power > CTL days.
ATL: Acute Training Load. Your ATL is a short term daily average of your T-score. This total represents the sum of your recent workouts from which you are likely still suffering residual fatigue.
- The number of days is set to a default of 7 days, but can be adjusted in the settings as needed under My Account > Power > CTL days.
TSB: Training Stress Balance. TSB is a simple subtraction of your ATL value from your CTL value. This means if your training for the last week comprised of much higher average T-scores than your training over the last several weeks, your TSB will be negative, indicating that a rider's form may be suffering.
These values help determine when rest days are needed, as well as being important for seasonal planning in order to adequately build up fitness or taper down in order to be fresh for an event. Additionally, the Load and Performance chart can be used to evaluate past seasons and pinpoint peak performances. By toggling on other metrics such as peak w/kg or peak heart rate, you can evaluate at what point in your training cycle you were able to achieve your best values and use them to plan your future training.