The impact of training
On one side of the coin, the reason you’re training – improving your performance, your fitness, your speed, your ability to run further for longer.
On the other, the impact of your workouts – fatigue, muscle soreness, dehydration, injury risk … the list could go on.
How can a single Training Load Score (per workout) fully model training load – both the shorter-term impacts and the longer-term improvements?
The Research
Research into the impacts of training has resulted in various models:
- Rowbottom proposed a Stimulus, Fatigue, Recovery, Adaptation model, sometimes referred to as the supercompensation model
- Banister proposed an Impulse-Response model, popularised in the TRIMP metric based on Heart Rate measurements
- Allen, Coggan and McGregor adapted the Impulse-Response model for use with power, encapsulating it in the Performance Manager model.
The Performance Manager model
The model has the following components:
- A Training Load Score, which the model calls a Training Stress Score (TSS)
- An Acute Training Load (ATL), modelling shorter-term impacts
- A Chronic Training Load (CTL), modelling longer-term adaptations
- A Training Load Balance, which the model calls a Training Stress Balance (TSB), representing the balance between ATL and CTL
The Performance Manager model uses your Training Load Scores to calculate personal training metrics that indicate whether your training is productive – not too much, not too little, just right for you.
And with the two different load metrics (ATL and CTL), the model includes both the shorter-term impacts and the longer-term improvements.
You may have encountered ATL and CTL already (without knowing it) – they have equivalents in other models:
- ATL is known as ‘7d avg’ in Stryd’s model, and ‘fatigue’ in heartrate-based models
- CTL is known as ’42d avg’ in Stryd’s model, and ‘fitness’ in heartrate-based models
For more information on the models, see:
🔹 Rowbottom, D.J., (2000), in Garrett, W.E., Kirkendall, D.T., (eds.). Periodization of Training. Philadelphia: Lippincott Williams & Wilkins.
🔹 Calvert, T.W., Banister, E.W., Savage, M.V., Bach, T., (1976) A Systems Model of the Effects of Training on Physical Performance
🔹 Allen, H., Coggan, A. & McGregor, S. (2019) Training+Racing with a Power Meter, 3rd Edition (pp. 158-160). Boulder: Velopress.
🔹 The Science of the TrainingPeaks Performance Manager on the TrainingPeaks website