Understanding TrainingPeaks Metrics

TrainingPeaks provides powerful tools for understanding your training load and recovery status. This guide explains what these metrics mean and how to use them effectively—without overcomplicating your training.

The Core Principle: Don't Overcomplicate It

Your training plan is already designed to manage these metrics appropriately. You don't need to obsess over daily values or try to manually manipulate them. These tools are for awareness and context, not for micromanagement.

Watch trends, not daily values. Single-day spikes or drops are normal and expected. What matters is the overall pattern over weeks and months.

Training Stress Score (TSS)

What It Is

TSS quantifies the training load of individual workouts by considering both duration and intensity. It's a single number that represents how hard a workout was.

The formula (simplified):

  • Based on Intensity Factor (IF) and duration

  • 100 TSS ≈ 1 hour at threshold intensity

  • Combines how long AND how hard you trained

Examples:

  • Easy 2-hour ride (65% FTP): ~80 TSS

  • 1-hour threshold workout (95% FTP): ~100 TSS

  • 4-hour endurance ride (70% FTP): ~180 TSS

  • 30-minute VO2max session: ~50 TSS

Why It Matters

TSS allows you to compare workouts of different types:

  • Long, easy sessions can have similar TSS to short, hard sessions

  • Helps you understand total training load

  • Used to calculate fitness and fatigue metrics (CTL and ATL)

What You Should Know

For power-based training:

  • TSS is calculated automatically from your power file

  • Accurate representation of physiological stress

For heart rate-based training:

  • Called hrTSS (heart rate Training Stress Score)

  • Less precise than power-based TSS

  • Still useful for tracking trends

For pace-based training (running):

  • Called rTSS

  • Based on pace relative to threshold

Don't stress about:

  • Hitting exact TSS targets daily

  • Comparing TSS across different sports directly (100 swim TSS ≠ 100 bike TSS in terms of overall fatigue)

  • Minor variations in weekly totals

Chronic Training Load (CTL)

What It Is

CTL represents your fitness level—the training load you've accumulated over approximately the past 6 weeks (42 days). It's calculated as an exponentially weighted average of your daily TSS.

Think of it as: Your aerobic fitness level or training capacity

The math: Exponentially weighted 42-day average of daily TSS

  • Recent training weighted more heavily than distant training

  • Changes slowly (by design)

  • Builds gradually over weeks and months

How to Interpret CTL

CTL represents your aerobic fitness level or training capacity. The "right" CTL is highly individual and event-specific:

CTL varies dramatically by:

  • Sport: Swimming inflates CTL significantly compared to cycling or running (90% IF is basic endurance swimming)

  • Event type: Shorter events typically have lower CTL targets; longer events (Ironman, ultra-cycling) require higher CTL

  • Training volume: Ultra-endurance athletes routinely train at CTL values that would indicate overtraining for shorter-event athletes

  • Individual capacity: Two athletes racing the same event may peak at very different CTL values

What matters more than the absolute number:

  • Trend direction: Is CTL building gradually during training blocks?

  • Consistency: Stable CTL without wild swings indicates sustainable training

  • Recovery: Can you absorb the training load and recover between sessions?

  • Performance: Are you getting faster, or just more fatigued?

Don't compare your CTL to others. An Ironman athlete might appropriately train at CTL 120+, while a criterium racer might peak at CTL 80. Your plan is designed for your specific event and goals.

What CTL Tells You

Rising CTL:

  • You're building fitness

  • Training load is increasing

  • Body is adapting (if recovering properly)

Stable CTL:

  • Maintenance phase

  • Consistent training load

  • Common during race season

Falling CTL:

  • Reduced training volume

  • Taper period

  • Detraining if unintentional

How Fast Should CTL Rise?

General principle: Build CTL gradually over weeks and months. The specific rate varies widely based on your plan, event, and training history.

Typical progression: Most well-designed plans increase CTL by approximately 5-20 TSS per month on average, with significant variation based on:

  • Training phase (base building vs. peak weeks)

  • Event distance (longer events = larger CTL increases)

  • Individual response to training

Your plan manages this progression automatically. Focus on executing workouts rather than hitting specific CTL targets.

Red flags to watch for:

  • Very rapid CTL spikes (20+ TSS in a single week) without planned progression

  • Wildly inconsistent training (CTL yo-yos up and down)

  • Continuing to push hard when recovery indicators are poor

  • CTL rising while performance and energy are declining

Acute Training Load (ATL)

What It Is

ATL represents your fatigue level—recent training stress that hasn't yet been absorbed and converted to fitness. It's calculated as an exponentially weighted average of your daily TSS over the past week (7 days).

Think of it as: Your current level of fatigue

The math: Exponentially weighted 7-day average of daily TSS

  • Responds quickly to recent training

  • Spikes after hard training blocks

  • Drops quickly with rest

How ATL Relates to Training

High ATL:

  • You've been training hard recently

  • Accumulated fatigue

  • Normal during build weeks

Low ATL:

  • You've been resting or training easy

  • Recovered state

  • Normal during recovery weeks and taper

ATL rising faster than CTL:

  • Training load increased recently

  • Building fatigue (potentially overreaching)

  • Normal in build weeks, watch for recovery signs

ATL dropping while CTL stable:

  • Recovery week

  • Taper period

  • Freshness returning

Training Stress Balance (TSB)

What It Is

TSB is the difference between your fitness (CTL) and fatigue (ATL). It indicates your current freshness level.

The formula: TSB = CTL - ATL

Think of it as: How fresh or fatigued you are relative to your fitness level

Interpreting TSB

Negative TSB (fatigue > fitness):

  • You're accumulating training stress

  • Normal and expected during training blocks

  • Common range: -10 to -30 during hard training weeks

  • Temporary deep negatives (-40 to -60) are normal with stacked training (e.g., big weekend blocks followed by recovery)

TSB near zero:

  • Balanced state

  • Moderate freshness

  • Typical during race season or moderate training periods

Positive TSB (fitness > fatigue):

  • Fresh and recovered

  • Ready for hard efforts or racing

  • Achieved through taper

  • Target: +10 to +25 for important races

Using TSB Effectively

The pattern matters more than single values:

During hard training weeks:

  • Expect negative TSB, sometimes deeply negative

  • Large stacked training weekends can temporarily push TSB to -40, -50, or lower

  • This is by design when followed by appropriate recovery

  • Monitor recovery early in the following week

During recovery weeks:

  • TSB should rise toward zero or positive

  • Sign that you're recovering from the training block

  • Usually happens naturally if you follow your planned recovery

For key races:

  • Target positive TSB (usually +10 to +25)

  • Achieved through taper

  • Too much rest (TSB > +30) can mean loss of sharpness

Red flags - when TSB indicates a problem:

  • TSB stays deeply negative (-40+) for 2+ weeks without recovery

  • TSB not recovering during scheduled rest weeks

  • Feeling terrible despite positive TSB (plan may not fit your current fitness)

Important context: Athletes starting a plan without the assumed fitness base may see prolonged negative TSB values initially. This often resolves as you adapt to the training load, but pay close attention to recovery indicators (sleep, resting heart rate, motivation) and adjust intensity if needed.

The Performance Management Chart (PMC)

What It Shows

The PMC is a graph that displays CTL, ATL, and TSB over time. It provides visual representation of your fitness, fatigue, and form.

The three lines:

  • Blue line (CTL): Fitness—should trend gradually upward during training

  • Pink line (ATL): Fatigue—spikes and drops based on recent training

  • Yellow bars (TSB): Form—positive when fresh, negative when fatigued

Reading the PMC

Successful training progression:

  • CTL gradually rising (fitness building)

  • ATL spiking during hard weeks, dropping during recovery weeks

  • TSB oscillating negative during training, positive for key events

Warning signs:

  • CTL declining when it should be building (insufficient training)

  • CTL rising too fast (injury risk)

  • ATL consistently very high without recovery (overtraining risk)

  • TSB deeply negative for weeks without improvement

Common PMC Patterns

Build weeks:

  • ATL rises above CTL

  • TSB goes negative

  • Accumulating productive stress

Recovery weeks:

  • ATL drops significantly

  • TSB returns toward zero or positive

  • Absorbing training adaptations

Taper:

  • CTL stable or slight decline

  • ATL drops substantially

  • TSB rises to positive (freshness for race)

Race season:

  • CTL relatively stable (maintaining fitness)

  • ATL and TSB oscillate around race schedule

  • Small peaks for races

Intensity Factor (IF)

What It Is

IF represents the relative intensity of a workout as a ratio to your FTP (Functional Threshold Power).

The calculation: IF = Normalized Power / FTP

Examples:

  • Easy endurance ride: IF = 0.55-0.70

  • Tempo ride: IF = 0.75-0.85

  • Sweet spot: IF = 0.85-0.95

  • Threshold: IF = 0.95-1.05

  • VO2max intervals: IF = 1.05-1.20

Why It Matters

IF helps you understand whether you're hitting target intensities:

  • Endurance rides should have low IF

  • Interval sessions should have higher IF

  • Confirms you're training in intended zones

Don't obsess over exact IF targets. Some variation is normal and expected.

Normalized Power (NP)

What It Is

NP is an estimate of the physiological "cost" of a variable-power workout. It accounts for the fact that variable efforts are harder than steady efforts at the same average power.

Why it exists:

  • Surges and intervals create more fatigue than steady efforts

  • Average power doesn't capture this reality

  • NP attempts to represent actual physiological stress

Example:

  • Ride A: 200W steady for 1 hour = 200W average, ~200W NP

  • Ride B: Intervals averaging 200W = 200W average, ~220W NP

  • Ride B is harder despite same average power

Using NP

For understanding workout difficulty:

  • NP closer to average power = steady effort

  • NP significantly higher than average = very variable effort

For calculating TSS and IF:

  • Both use NP rather than average power

  • Provides more accurate training load estimate

Don't worry about:

  • Making NP match average power perfectly

  • Comparing NP across very different workout types

A Simple Analogy: Your Fitness Bank Account

Think of these metrics like a bank account:

  • CTL (fitness) = Your account balance. Built up gradually over months of deposits.

  • TSS (training) = Withdrawals. Each workout costs something.

  • ATL (fatigue) = Your recent spending. High when you've been withdrawing a lot lately.

  • TSB (form) = What's left to spend today. Negative = overdraft (fatigued). Positive = surplus (fresh).

Just like finances: You can't spend more than you have indefinitely, but strategic "overdrafts" (negative TSB during training) are part of building wealth (CTL) long-term. The key is managing your spending (training) to build your balance (fitness) without going so far into the red that you can't recover.

Practical Application: Using Metrics Without Obsessing

What to Monitor

Weekly TSS:

  • Track trends, not exact numbers

  • Big swings (50%+ increase) deserve attention

  • Gradual progression is ideal

CTL trends:

  • Should build gradually during training blocks

  • Sudden drops indicate missed training

  • Plateaus during race season are normal

TSB for key events:

  • Aim for positive TSB (recovered/fresh)

  • Usually +10 to +25 for important races

  • Too much rest (TSB > +30) can mean detraining

What NOT to Worry About

Daily TSS fluctuations:

  • Individual workouts vary—that's normal

  • Some days higher, some lower

  • Weekly totals matter more than daily

Exact CTL targets:

  • No magic number for race-readiness

  • Highly individual and event-specific

  • Your plan manages this

Perfect metric alignment:

  • Metrics are estimates, not gospel

  • How you feel matters more

  • Trust subjective assessment over numbers

When Metrics Conflict with How You Feel

If metrics say "recovered" but you feel terrible:

  • Trust how you feel

  • Take easier day

  • Metrics are tools, not commands

If metrics say "fatigued" but you feel great:

  • Proceed with caution

  • You can train, but monitor closely

  • Could indicate early overtraining (feeling good temporarily before crash)

Common Mistakes

Mistake #1: Chasing CTL Numbers

The error: "I need CTL of 100 to race well"

  • CTL targets are meaningless without context

  • Individual variation is enormous

  • Quality of training matters more than CTL

Better approach: Follow your training plan, let CTL be what it will be

Mistake #2: Panicking Over Negative TSB

The error: "My TSB is -25, I must be overtraining!"

  • Negative TSB during training blocks is normal

  • It's called "training," not "being fresh all the time"

  • Recovery weeks will address this

Better approach: Expect negative TSB during hard training, positive during taper

Mistake #3: Micromanaging Daily TSS

The error: "Yesterday was 120 TSS, today must be exactly 115 TSS"

  • Rigid adherence to daily targets misses the point

  • Training isn't that precise

  • Weekly totals and trends matter more

Better approach: Execute the planned workout, don't obsess over resulting TSS

Mistake #4: Ignoring Subjective Feedback

The error: "Metrics say I'm recovered, so I'll do the hard workout even though I feel terrible"

  • Metrics are estimates

  • You know your body better than an algorithm

  • Subjective assessment matters

Better approach: Use metrics to inform decisions, not dictate them

Summary: The Right Way to Use These Metrics

Do:

  • Monitor weekly trends

  • Use metrics for awareness and context

  • Let your training plan manage the progression

  • Trust how you feel when metrics conflict

Don't:

  • Obsess over daily fluctuations

  • Try to manually manipulate metrics

  • Compare your numbers to other athletes

  • Override subjective assessment based on metrics

Remember: These tools exist to support your training, not complicate it. Your plan is designed to manage CTL progression, TSB for key events, and appropriate recovery. Trust the structure, use metrics for awareness, and focus on executing quality training.

Additional Resources

TrainingPeaks University:

Important reminder: All of this information is useful for understanding your training, but executing quality workouts and recovering properly will always matter more than perfect metric management.

Key Sources

The metrics and interpretations in this guide are based on:

These metrics are estimation tools, not absolute measures. Your subjective assessment and how you feel during training remain the most important indicators.

← Back to Getting Started