Core TrainingPeaks Metrics Explained: Fitness, Form, Fatigue
TrainingPeaks offers essential metrics like Training Stress Score (TSS), Chronic Training Load (CTL) or Fitness, Acute Training Load (ATL) or Fatigue, and Training Stress Balance (TSB) or Form. Using these metrics, cyclists can accurately measure progress, predict fitness and fatigue, and strategically peak for competitions. The accuracy of these metrics relies on correctly setting Functional Threshold Power (FTP) in TrainingPeaks, or threshold and maximum heart rate for those using heart rate monitors.
Accurate FTP Settings
It is crucial to test and adjust FTP settings in TrainingPeaks approximately once a month to ensure metrics are correct. For athletes without power meters, accurate heart rate thresholds are vital and should be adjusted annually to reflect physiological changes.
Training Stress Score (TSS): Measuring Workout Impact
Training Stress Score (TSS) quantifies the intensity of a workout relative to the individual's fitness level. It measures the total workload of a training session and helps in comparing the stress imposed by different types of workouts. TSS is essential for calculating core TrainingPeaks metrics: fitness, form & fatigue. If you don't have power data, you can use hrTSS, calculated based on your heart rate zones.
How is TSS Calculated?
TSS is calculated by considering the duration and intensity of a workout relative to the athlete’s Functional Threshold Power (FTP). The formula is as follows:
TSS = (duration in seconds x NP x IF) / (FTP x 3600) x 100
- Normalized Power (NP): The average power adjusted for variation.
- Intensity Factor (IF): The ratio of NP to FTP.
An hour-long workout at FTP yields a TSS of 100.
What is Considered a Good TSS?
A 'good' TSS varies based on the workout's goal and the athlete's training plan.
- High-Intensity Workouts: A TSS of 100 for a 1.5-hour session indicates challenging training.
- Moderate Effort: A TSS of 70 for 1.5 hours suggests a steady state or tempo effort.
- Light Effort/Recovery Rides: A TSS of 40 for 1.5 hours is typical for recovery-focused sessions.
Fitness (Chronic Training Load, CTL): A Measure of Endurance Fitness
Chronic Training Load (CTL) or Fitness quantifies an athlete’s fitness level over time. It reflects the average daily training load sustained over the past 42 days, indicating endurance fitness accumulated from consistent training.
How is CTL Calculated?
CTL is calculated through an exponential moving average of daily Training Stress Score (TSS) values.
CTLtoday = CTLyesterday + (TSStoday - CTLyesterday) * (1/42)
What is Considered Good CTL?
The ideal CTL varies based on an athlete's experience, training history, age, and competitive goals.
- Non-professional cyclists: A CTL between 100-110 is typically ideal.
- World Tour professionals: These athletes often achieve a CTL of 140-150, sometimes climbing towards 170 post-major tours.
To achieve a CTL of 100, you would typically need to average about 700-750 TSS per week starting from a CTL of about 70.
Form (Training Stress Balance, TSB): Monitoring Readiness and Fatigue
Training Stress Balance (TSB) measures an athlete's balance between fitness and fatigue, essentially measuring their readiness to perform. It represents the difference between the fatigue from recent training loads and the fitness accumulated over a longer period.
How is TSB Calculated?
TSB is calculated by subtracting the Acute Training Load (ATL) from the Chronic Training Load (CTL):
TSB = CTL - ATL
What TSB Score Should I Aim For?
TSB scores should fluctuate based on the training cycle:
- Intensive Training Phases: TSB typically drops into the negative, ranging from -20 to -30.
- Recovery or Adaptation Weeks: TSB should move into positive territory, typically between +5 to +15.
- Pre-Race or Key Event Days: Aim for a TSB around +5.
- Multi-Day Events: Around +10 TSB may be more advantageous.
Fatigue (Acute Training Load, ATL): Understanding Short-Term Fatigue
Acute Training Load (ATL) represents an athlete's short-term fatigue and is calculated from the daily training loads over a recent period (7-10 days). ATL indicates how tired an athlete might feel in the short run and can influence day-to-day training decisions.
How is ATL Calculated?
ATL is calculated using an exponential moving average of the daily Training Stress Score (TSS) values over a short-term period (commonly 7 days).
ATLtoday = ATLyesterday + (TSStoday - ATLyesterday) * (1/7)
Importance of Tracking ATL
ATL serves primarily as a contextual metric to adjust immediate training loads and recovery strategies. It’s particularly useful in preventing overtraining by signaling when too much training stress is accumulating too quickly.
Conclusion
TrainingPeaks provides endurance athletes and coaches with powerful metrics to measure and manage training stress, fitness, fatigue, and form. By understanding and applying TSS, CTL, ATL, and TSB effectively, athletes can tailor their training programs to maximize their potential and peak at just the right moment.
If you would like to dive deeper into your data, you can explore this detailed article about advanced data analytics for cycling in WKO5
We hope this helps you design long-term training plans using key TrainingPeaks metrics, ensuring you understand the training phases and the purpose behind them. You can contact us if you have any questions or if you'd like to explore how could we help you!