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Chronic Training Load (CTL) Calculator

Calculate your Chronic Training Load (CTL) to track long-term fitness and training stress over several weeks.

Chronic Training Load (CTL) Calculator

Estimate long-term fitness by updating CTL using daily Training Stress Scores and time constants.

Understanding the Inputs

Ensure reliable CTL projections with accurate data

  • Current CTL (optional): Existing chronic training load value. Leave blank if starting from zero or calculating from scratch.
  • Daily TSS: Average Training Stress Score for the day. Use the value from your workout or daily training log.
  • Time Constant (days): The decay constant that governs fitness response. Common defaults: 42 days for cycling/running, 30 for swimming.

Related Calculators

Monitor complementary training load metrics

Acute Training Load (ATL)

Understand short-term fatigue alongside long-term fitness.

Training Stress Score (TSS)

Daily TSS values feed CTL calculations—plan each workout accordingly.

Training Impulse (TRIMP)

Heart-rate-based load metric to correlate with CTL trends.

Power-to-HR Efficiency

Diagnose aerobic efficiency changes as CTL evolves.

Complete Guide: Managing Long-Term Training Load

Use CTL to balance fitness and recovery

Chronic Training Load reflects the cumulative effect of your workouts. Tracking CTL helps athletes periodize training, minimize surprise fatigue, and align workload with competition schedules. Combine CTL with qualitative feedback—sleep quality, mood, appetite—and objective markers like heart rate variability for a comprehensive view of readiness.

Remember that CTL is a tool, not a goal. Deliberate rises followed by strategic recovery maintain performance momentum while protecting long-term health. Adjust CTL targets according to personal history, available training time, and life demands.

Frequently Asked Questions

CTL essentials for endurance planning

What is Chronic Training Load (CTL)?

CTL is the exponentially weighted average of daily TSS over several weeks. It reflects long-term fitness or training capacity rather than acute fatigue.

How is the CTL formula derived?

CTL = CTL_previous × e^(−1/TC) + TSS_today × (1 − e^(−1/TC)), where TC is the time constant (usually 42 days). This gives more weight to recent workouts while preserving historical contributions.

What CTL range is appropriate?

Recreational athletes might maintain CTL between 40–60, while competitive endurance athletes may accumulate 80–120 or more, depending on discipline and experience.

How quickly can CTL increase?

A safe ramp rate is typically 5–8 CTL points per week. Aggressive jumps beyond 10 points can elevate injury or burnout risk.

Why does CTL drop during rest weeks?

Because older workouts decay exponentially, reduced TSS during recovery weeks lowers CTL slightly—this is normal and necessary for supercompensation.

How does CTL relate to ATL and TSB?

ATL (Acute Training Load) tracks short-term fatigue, while TSB (Training Stress Balance) = CTL − ATL. Positive TSB indicates freshness, negative values signal accumulated fatigue.

Can CTL be sport-specific?

Yes. Many athletes track separate CTL values for swim, bike, and run disciplines to tailor training stress per sport.

What happens if I miss days of training?

Daily TSS of zero causes CTL to decay toward zero over time. Longer breaks will reduce CTL but allow for recovery; ramp back up gradually.

Is a higher CTL always better?

Not necessarily. CTL should align with performance goals, recovery capacity, and life stressors. Sustainably maintaining a moderate CTL often yields better outcomes than chasing extremes.

How often should I monitor CTL?

Daily monitoring helps spot trends, but weekly reviews are sufficient for most athletes. Pay attention to how CTL interacts with subjective fatigue and performance.

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Chronic Training Load (CTL) Calculator

Calculate your Chronic Training Load (CTL) to track long-term fitness and training stress over several weeks.

How to use Chronic Training Load (CTL) Calculator

Step-by-step guide to using the Chronic Training Load (CTL) Calculator:

  1. Enter your values. Input the required values in the calculator form
  2. Calculate. The calculator will automatically compute and display your results
  3. Review results. Review the calculated results and any additional information provided

Frequently asked questions

How do I use the Chronic Training Load (CTL) Calculator?

Simply enter your values in the input fields and the calculator will automatically compute the results. The Chronic Training Load (CTL) Calculator is designed to be user-friendly and provide instant calculations.

Is the Chronic Training Load (CTL) Calculator free to use?

Yes, the Chronic Training Load (CTL) Calculator is completely free to use. No registration or payment is required.

Can I use this calculator on mobile devices?

Yes, the Chronic Training Load (CTL) Calculator is fully responsive and works perfectly on mobile phones, tablets, and desktop computers.

Are the results from Chronic Training Load (CTL) Calculator accurate?

Yes, our calculators use standard formulas and are regularly tested for accuracy. However, results should be used for informational purposes and not as a substitute for professional advice.