Training Load (CTL/TSS)

Concept

Training Stress Score (TSS) or similar metrics attempt to quantify the stress of a single workout based on duration and intensity relative to your threshold. Chronic Training Load (CTL) is a rolling average (often 42 days, exponentially weighted) of daily TSS, representing your fitness or sustainable load.

Application & Correlation with Performance

This method allows for accumulating a high Chronic Training Load (CTL) due to the repeatability of sub-threshold work. Research and anecdotal evidence strongly suggest a correlation between the highest sustained CTL an athlete can manage and their race performance potential (as illustrated conceptually in the provided document’s graph showing Critical Power vs. Sustained CTL). While not a perfect predictor, and absolute CTL values aren’t directly comparable between individuals, tracking your own CTL trend is a key indicator of fitness progression. The goal is to maximize sustainable load over time.

Intensity Management & Equivalent Stress

  • Balancing Load: The aim is to find the “green zone” (as conceptualized in the provided document) – a level of weekly sub-threshold work that maximizes stimulus without inducing excessive fatigue or hindering recovery for subsequent sessions. This allows for consistent high-quality training week after week.
  • Equivalent Stress: Different sub-threshold workout structures (e.g., varying interval length, rest, and pace slightly) can be designed to elicit a similar overall training stress or stimulus (as explored in the document’s ANNEX A). This allows for variety in training while maintaining a consistent load on the body. For example, a session of 10x1000m with shorter rest might be physiologically similar in stress to 3x3000m with longer rest, provided both are executed at the appropriate sub-threshold intensity for that duration.

Tracking Tools

Tools like Intervals.icu, TrainingPeaks, or Runalyze calculate TSS/CTL. Consistent data input (accurate threshold values, chosen metric) is key. Pace-based TSS (rTSS) is often preferred for consistency if running routes/conditions are stable, but requires accurate threshold pace updates. Heart rate-based TSS (hrTSS) or power-based TSS can also be used, depending on your primary intensity monitoring method.