Training Load Management: TSS, CTL, ATL & TSB for Cycling
Master the Performance Management Chart to optimize training, prevent overtraining, and peak for your cycling goals
🎯 Key Takeaways: Training Load for Cycling
- Training Stress Score (TSS) quantifies how hard each ride impacts your body, combining power, intensity and duration
- CTL (Chronic Training Load) measures your long-term fitness built over 42 days of consistent training
- ATL (Acute Training Load) tracks recent fatigue from the past 7 days of riding
- TSB (Training Stress Balance) shows your fitness-fatigue balance and readiness to race or recover
- Understanding cycling training load prevents overtraining and optimizes performance timing through data-driven periodization
Foundation: TSS calculations require your Functional Threshold Power (FTP) as the threshold reference point.
What is Training Stress Score (TSS)?
Training Stress Score answers the critical question: How hard was that ride? Not just distance or time, but the true physiological stress imposed on your body by each cycling session.
Training Stress Score (TSS), developed by Dr. Andrew Coggan, provides a standardized method to quantify workout intensity and duration into a single number. TSS revolutionized cycling training by making power-based training accessible and actionable.
The TSS Standard for Cycling
One hour at your Functional Threshold Power (FTP) = 100 TSS
This standardization allows comparison across workouts, weeks, and training cycles. A 30-minute threshold effort = ~50 TSS. A 2-hour threshold ride = ~200 TSS.
How TSS is Calculated
Where:
- NP (Normalized Power) = The physiological "cost" of the ride
- IF (Intensity Factor) = NP / FTP (intensity relative to threshold)
- Duration = Total ride time in seconds
- FTP = Your functional threshold power in watts
Worked Example: 2-Hour Endurance Ride
Rider Profile:
- FTP: 250W
Ride Data:
- Duration: 2 hours (7200 seconds)
- Normalized Power: 200W
Step 1: Calculate Intensity Factor (IF)
IF = 200W / 250W
IF = 0.80
Step 2: Calculate TSS
TSS = (1,152,000) / (900,000) × 100
TSS = 128 TSS
Interpretation: This 2-hour endurance ride at 80% of FTP generated 128 TSS—a solid aerobic training stimulus typical of base building rides.
TSS Guidelines by Workout Type
| Workout Type | TSS Range | Intensity Factor | Description |
|---|---|---|---|
| Recovery Ride | 20-50 TSS | IF < 0.65 | Easy spinning, active recovery, 30-60 minutes |
| Easy Endurance | 50-100 TSS | IF 0.65-0.75 | Conversational pace, aerobic base building, 1-2 hours |
| Moderate Endurance | 100-150 TSS | IF 0.75-0.85 | Steady state riding, group rides, 2-3 hours |
| Tempo Ride | 150-200 TSS | IF 0.85-0.95 | Sweet spot training, sustained tempo efforts, 2-3 hours |
| Threshold Workout | 200-300 TSS | IF 0.95-1.05 | FTP intervals, race simulation, 2-4 hours with quality |
| VO₂max Intervals | 150-250 TSS | IF 1.05-1.15 | Hard intervals at 120% FTP, 1-2 hours with high intensity |
| Race Simulation | 200-400 TSS | IF 0.90-1.05 | Event-specific efforts, criteriums, road races, 2-5 hours |
📊 Weekly TSS Targets by Cyclist Level
- Beginner Cyclist: 200-400 TSS/week (3-4 rides/week)
- Recreational Cyclist: 400-600 TSS/week (4-5 rides/week)
- Competitive Amateur: 600-900 TSS/week (5-7 rides/week)
- Elite/Professional: 900-1500+ TSS/week (8-12+ sessions/week)
These accumulate toward your Chronic Training Load (CTL), the fitness metric explained below.
The Performance Management Chart (PMC)
The PMC visualizes three interconnected metrics that tell the complete story of your cycling training: fitness, fatigue, and form.
CTL - Chronic Training Load
42-day exponentially weighted average of daily TSS. Represents long-term aerobic fitness and training adaptation from consistent riding.
ATL - Acute Training Load
7-day exponentially weighted average of daily TSS. Captures recent training stress and accumulated fatigue from the past week of riding.
TSB - Training Stress Balance
Difference between yesterday's fitness and today's fatigue. Indicates readiness to perform or need to rest before your next quality ride or race.
CTL: Your Cycling Fitness Metric
What CTL Represents for Cyclists
CTL quantifies the training load your body has adapted to over the past 6 weeks. A higher CTL in cycling means:
- Greater aerobic capacity and endurance
- Ability to handle more training volume and intensity
- Improved metabolic efficiency and fat oxidation
- Higher sustainable power output
- Better recovery between hard efforts
Time Constant: 42 Days
CTL has a half-life of approximately 14-15 days. After 42 days, about 36.8% (1/e) of a single workout's impact remains in your fitness calculation.
This slow decay means fitness builds gradually but also fades slowly—you can take a week off without major fitness loss.
Typical CTL Values by Cyclist Level
Building base fitness, 3-4 rides/week
Regular training, 4-5 rides/week
High volume racing, 6-8 sessions/week
Professional training load, 10-15+ hours/week
- Safe: +3-8 CTL per week
- Aggressive but sustainable: +8-12 CTL per week
- High risk: >12 CTL per week
Exceeding these rates significantly increases injury and illness risk. Build gradually for sustainable fitness gains.
Building CTL Safely: The Ramp Rate
Example CTL Progression (12-week base phase)
- Week 1: CTL 60 → 65 (+5)
- Week 2: CTL 65 → 70 (+5)
- Week 3: CTL 70 → 75 (+5)
- Week 4: CTL 75 → 78 (+3, recovery week)
- Week 5: CTL 78 → 83 (+5)
- Week 6: CTL 83 → 88 (+5)
- Week 7: CTL 88 → 93 (+5)
- Week 8: CTL 93 → 96 (+3, recovery week)
- Week 9: CTL 96 → 102 (+6)
- Week 10: CTL 102 → 108 (+6)
- Week 11: CTL 108 → 114 (+6)
- Week 12: CTL 114 → 116 (+2, pre-build recovery)
Result: +56 CTL points over 12 weeks (avg 4.7/week) - sustainable progression from recreational to competitive fitness level.
ATL: Your Cycling Fatigue Metric
ATL tracks short-term training stress—the fatigue accumulated in the past week of riding. It rises quickly after hard training and drops quickly during rest, making it essential for managing recovery between quality sessions.
ATL Dynamics in Cycling Training
- Fast Response: 7-day time constant (half-life ~2.4 days)
- Spiky Pattern: Jumps after hard rides, drops during recovery days
- Recovery Indicator: Falling ATL = dissipating fatigue between sessions
- Overtraining Warning: Chronically elevated ATL suggests inadequate recovery
- Training Balance: ATL should track with CTL but fluctuate more
🔬 The Fitness-Fatigue Model
Every training ride produces two effects:
- Fitness stimulus (slow-building, long-lasting)
- Fatigue (fast-building, fast-dissipating)
Performance = Fitness - Fatigue. The PMC visualizes this model, enabling scientific periodization and optimal race timing.
At Steady State
When training load is consistent week-to-week, CTL and ATL converge:
Example: 500 TSS/week consistently
CTL approaches ~71
ATL approaches ~71
TSB approaches 0
Interpretation: Fitness and fatigue are balanced. Sustainable training maintenance—no accumulating deficit or surplus.
During Build Phases
When increasing volume or intensity:
ATL rises faster than CTL due to shorter time constant. TSB becomes negative (fatigue > fitness). This is normal and productive—you're applying overload to stimulate adaptations.
Target TSB: -10 to -30 during productive training blocks
During Taper for Races
When reducing training load before competition:
ATL drops faster than CTL. TSB becomes positive (fitness > fatigue). This is the goal—arrive at race day fresh with legs ready to perform while retaining fitness.
Target TSB: +10 to +25 on race day depending on event
TSB: Your Fitness-Fatigue Balance and Race Readiness
TSB (Training Stress Balance) is the difference between yesterday's fitness (CTL) and today's fatigue (ATL). It indicates whether you're fresh or fatigued, ready to race or in need of recovery days.
TSB Interpretation Guide for Cyclists
| TSB Range | Status | Interpretation | Recommended Action |
|---|---|---|---|
| < -30 | Overtraining Risk | Extreme fatigue. High illness/injury risk. | Immediate recovery needed. Reduce volume 50%+. Consider rest days. |
| -20 to -30 | Optimal Training Block | Productive overload. Building fitness. | Continue plan. Monitor for excessive fatigue or declining power. |
| -10 to -20 | Moderate Training Load | Standard training accumulation. | Normal training. Can handle quality interval or threshold sessions. |
| -10 to +10 | Neutral/Maintenance | Balanced state. Slight fatigue or freshness. | Good for B/C races, testing FTP, or recovery weeks. |
| +10 to +25 | Peak Race Form | Fresh and fit. Optimal performance window. | A-priority races. Expected peak cycling performance. |
| > +25 | Very Fresh/Detraining | Highly rested. May be losing fitness. | Short explosive events OK. Resume training if extended rest. |
🎯 Target TSB by Event Type
- Criterium/Sprints: TSB +5 to +15 (short taper, retain sharpness)
- Road Races: TSB +10 to +20 (10-14 day taper)
- Time Trials: TSB +15 to +25 (14-21 day taper for peak power)
- Gran Fondos/Centuries: TSB +5 to +15 (7-10 day taper, maintain endurance)
- Stage Races: TSB -5 to +10 (arrive slightly tired, need endurance over freshness)
Shorter explosive events need higher TSB. Longer endurance events need moderate TSB to retain endurance.
Periodization with the Performance Management Chart
16-Week Training Cycle Example
Weeks 1-4: Base Phase
- Goal: Build CTL steadily at 3-5 points/week
- Weekly TSS: 400 → 450 → 500 → 450 (recovery week)
- CTL progression: 60 → 73
- TSB range: -5 to -15 (manageable fatigue)
- Focus: Long steady rides, Zone 2 endurance, building aerobic base
Weeks 5-8: Build Phase
- Goal: Continue CTL growth at 5-8 points/week with harder workouts
- Weekly TSS: 500 → 550 → 600 → 500 (recovery week)
- CTL progression: 73 → 93
- TSB range: -15 to -25 (productive overload)
- Focus: Sweet spot intervals, threshold work, longer tempo rides
Weeks 9-12: Peak Phase
- Goal: Maximize CTL, highest training load
- Weekly TSS: 600 → 650 → 650 → 550 (recovery week)
- CTL progression: 93 → 108
- TSB range: -20 to -30 (maximum stimulus)
- Focus: Race-specific intervals, VO₂max work, event simulation
Weeks 13-14: Recovery Block
- Goal: Let body absorb training, prepare for taper
- Weekly TSS: 400 → 400
- CTL progression: 108 → 103 (slight drop, fitness retained)
- TSB range: -5 to +5 (neutral)
- Focus: Easy endurance, fun rides, reduce intensity
Weeks 15-16: Taper + Race Week
- Goal: Peak for race day with TSB +15-20
- Weekly TSS: 350 → 250 + race
- CTL progression: 103 → 98 (minimal fitness loss)
- ATL progression: Drops rapidly from ~85 to ~50
- TSB on race day: +18 to +22
- Result: Fresh legs, retained fitness, ready for peak performance
✅ Why Taper Works
The different time constants (42 days for CTL, 7 days for ATL) create the taper effect:
- ATL responds quickly → Fatigue disappears within 7-10 days
- CTL responds slowly → Fitness persists for weeks
- Result: Fitness remains while fatigue vanishes = fresh legs for peak performance
Road Cycling vs Mountain Biking Training Load
| Aspect | Road Cycling | Mountain Biking |
|---|---|---|
| Power Profile | Steady, sustained efforts with minimal fluctuation | Highly variable "bursty" power with frequent surges |
| Variability Index (VI) | 1.02-1.05 (very steady) | 1.10-1.20+ (highly variable) |
| TSS Accumulation | Predictable, can plan precisely | Variable, trail difficulty affects TSS greatly |
| Normalized Power | Close to average power | Significantly higher than average power |
| Key Training Focus | Sustained threshold, tempo work | Burst intervals, W' management, technical skills |
| CTL Interpretation | Direct fitness indicator | Fitness indicator but technical skill = 50% of performance |
MTB-Specific Considerations
Mountain biking requires different PMC interpretation:
- Same trail, different TSS: Trail difficulty massively affects TSS for the same route
- Burst detection: Count surges above threshold—XC races can have 88+ surges in 2 hours
- Skills matter more: Technical ability accounts for ~50% of MTB performance vs ~20% in road cycling
- Use short power windows: 3-5 second averages matter for MTB vs 30-second for road
Common Training Load Management Mistakes
1️⃣ Building CTL Too Fast
Mistake: Jumping 15-20 CTL points per week trying to "catch up" to a target fitness level.
Solution: Limit increases to 3-8 CTL/week. Be patient—fitness takes time to build safely.
2️⃣ Never Tapering
Mistake: Training hard continuously, arriving at races with TSB of -20 to -30.
Solution: Reduce volume 7-14 days before key events. Let TSB rise to +10-25 for peak performance.
3️⃣ Ignoring TSB Warnings
Mistake: Continuing to push when TSB drops below -30 for extended periods.
Solution: Take mandatory recovery when TSB < -30. Your body is telling you it needs rest.
4️⃣ Chasing Random Workouts
Mistake: Following whatever feels good rather than progressive load increases.
Solution: Follow a structured plan with planned CTL progression and recovery weeks.
5️⃣ Comparing to Others
Mistake: "My teammate has CTL of 120, I need that too!"
Solution: CTL is individual. Your sustainable CTL depends on your training history and genetics.
6️⃣ Skipping Recovery Weeks
Mistake: Building CTL continuously without scheduled recovery weeks.
Solution: Every 3-4 weeks, reduce volume 30-40% to consolidate fitness adaptations.
Research & Scientific Validation
The Performance Management Chart and TSS methodology are backed by decades of sports science research:
Key Research Papers
- Allen, H., & Coggan, A.R. (2019). Training and Racing with a Power Meter (3rd Edition). VeloPress. — Foundational text introducing TSS, NP, IF, CTL, ATL, TSB.
- Banister, E.W., Calvert, T.W., Savage, M.V., & Bach, T. (1975). A Systems Model of Training for Athletic Performance. Australian Journal of Sports Medicine, 7, 57-61. — Original impulse-response fitness-fatigue model.
- Murray, N.B., et al. (2017). Training Load Monitoring Using Exponentially Weighted Moving Averages. — Validates EWMA for acute/chronic load monitoring.
- Jones, A.M., et al. (2019). Critical Power: Theory and Applications. Journal of Applied Physiology, 126(6), 1905-1915. — Critical Power model underlying FTP concepts.
💡 TrainingPeaks & WKO5
TSS, CTL, ATL, and TSB are proprietary metrics developed by Dr. Andrew Coggan and licensed to TrainingPeaks. They're considered industry standards for power-based training load management in cycling.
Frequently Asked Questions: Training Load for Cycling
How much TSS per week should I do?
Weekly TSS depends on your level: Beginners: 200-400 TSS/week, Recreational: 400-600 TSS/week, Competitive amateur: 600-900 TSS/week, Elite/Pro: 900-1500+ TSS/week. Start conservatively and increase gradually by 3-8 CTL points per week.
What's a good CTL for my cycling level?
Typical CTL values: Beginners 20-40, Recreational cyclists 40-80, Competitive amateurs 80-120, Elite/Professional 120-200+. Your sustainable CTL depends on training history, available time, and recovery ability. Focus on progressive improvement rather than absolute numbers.
How long should I taper before a race?
Taper duration depends on event type: Short races/criteriums: 7-10 days, Road races: 10-14 days, Time trials: 14-21 days (need maximum freshness), Stage races: 7-10 days (don't want to be too fresh). Target TSB of +10 to +25 on race day depending on event demands.
Can I train when TSB is -30 or lower?
TSB below -30 indicates extreme fatigue and high overtraining risk. It's not recommended to continue hard training at this level. Reduce volume by 50%+ and take easy recovery rides until TSB rises to -20 or higher. Listen to your body—persistent fatigue, declining power, poor sleep, or illness are warning signs.
How do I use PMC for mountain bike racing?
MTB racing requires modified PMC interpretation: Focus on burst/surge detection above threshold (88+ in XC races), use shorter power windows (3-5 seconds), recognize that technical skills account for ~50% of performance (vs ~20% road cycling), and understand that trail difficulty greatly affects TSS accumulation for the same route.
Why does my CTL drop during taper?
CTL dropping slightly during taper is normal and expected. A 5-10 point CTL drop over 2 weeks of tapering represents minimal fitness loss (the 42-day time constant means fitness is retained). Meanwhile, ATL drops much faster (7-day time constant), eliminating fatigue. This creates positive TSB and fresh legs for racing.
What's the difference between TSS and kilojoules?
Kilojoules measure total work done (energy expenditure), while TSS measures training stress relative to your FTP. A 200W ride for 1 hour = 720 kJ for everyone, but TSS depends on your FTP. If your FTP is 200W, TSS = 100. If your FTP is 300W, TSS = 44. TSS accounts for individual fitness level; kJ does not.
Should I track TSS for indoor training?
Absolutely. TSS is ideal for indoor training because power data is consistent and environmental variables are controlled. Indoor TSS directly contributes to your CTL/ATL/TSB calculations. However, some cyclists find they can handle slightly higher indoor TSS than outdoor due to no coasting or descents.
Master Your Cycling Training Load
Understanding Training Stress Score and the Performance Management Chart transforms subjective training into objective, data-driven performance optimization. By monitoring TSS, CTL, ATL, and TSB, you gain precise control over fitness progression, fatigue management, and peak race timing.
The CTL-ATL-TSB system prevents overtraining, optimizes recovery timing, and ensures you arrive at goal races with the perfect fitness-fatigue balance for peak cycling performance.