Running Training Stress Score (TSS) Explained

What is TSS in running? Training Stress Score (TSS) is a single number that quantifies the overall training load of a workout, combining intensity and duration into one metric.

TSS helps you:

• Compare different types of workouts
• Plan appropriate training loads
• Prevent overtraining
• Time your peak fitness for races

Use our Running TSS Calculator to calculate TSS for any workout.

How TSS Works

TSS combines two factors:

TSS = (Duration × Intensity Factor × Intensity Factor) ÷ (Threshold Duration × 100)

In simpler terms:

• A harder workout = higher TSS
• A longer workout = higher TSS
• One hour at threshold = 100 TSS

Key Concepts

Term	Definition
Threshold	The pace/effort you can sustain for ~1 hour
Intensity Factor (IF)	How hard compared to threshold (0.0-1.2+)
Normalized Power/Pace	Average effort accounting for variability

Intensity Factor Examples

Effort Level	Intensity Factor	Example Workout
Recovery	0.55-0.70	Very easy jogging
Easy	0.70-0.80	Standard easy run
Moderate	0.80-0.90	Faster easy run
Threshold	0.95-1.05	Tempo run, race pace
Hard intervals	1.05-1.20	VO2 max work

TSS for Common Running Workouts

By Workout Type (Approximate)

Workout	Duration	TSS
Easy 30 min	30 min	20-25
Easy 45 min	45 min	30-40
Easy 60 min	60 min	40-55
Tempo 20 min (w/ warmup)	45 min	50-60
Intervals (5×1000m)	50 min	55-70
Long run easy (90 min)	90 min	60-80
Long run w/ tempo	100 min	90-120
5K race	20-40 min	40-65
10K race	40-70 min	70-100
Half marathon race	90-150 min	130-200
Marathon race	180-300 min	250-350

Use our Running TSS Calculator for precise calculations based on your threshold and actual workout data.

Weekly TSS Targets

Guidelines by Training Phase

Training Phase	Weekly TSS	Description
Recovery	150-250	Active recovery, deload
Base building	250-400	Foundation phase
Build phase	400-550	Increasing load
Peak training	500-700	Maximum sustainable load
Race week	200-350	Taper for performance

By Experience Level

Level	Weekly TSS Range	Notes
Beginner	150-300	Build gradually
Intermediate	300-500	Sustainable training
Advanced	450-650	High training tolerance
Elite	600-800+	Exceptional recovery

These are general guidelines—individual responses vary significantly.

Calculating Your Weekly TSS

Example Week (Intermediate Runner)

Day	Workout	TSS
Monday	Rest	0
Tuesday	8km easy	45
Wednesday	6×800m intervals	65
Thursday	7km easy	40
Friday	Rest or 5km easy	25
Saturday	15km long run	90
Sunday	6km recovery	30
Total		295 TSS

This represents moderate training load appropriate for a recreational-competitive runner.

TSS and Fatigue Management

Acute Training Load (ATL)

Your recent training stress—typically a 7-day rolling average of daily TSS.

Chronic Training Load (CTL)

Your fitness—typically a 42-day rolling average of daily TSS.

Training Stress Balance (TSB)

The difference between CTL and ATL:

• Positive TSB: Fresh, rested (but may lose fitness if too long)
• Near zero TSB: Balanced training and recovery
• Negative TSB: Fatigued, building fitness

Optimal Race Readiness

TSB	Status	Best For
+15 to +25	Fresh	A-race, peak performance
+5 to +15	Ready	Important race
-5 to +5	Balanced	Training race, time trial
-10 to -5	Tired	Only if building fitness
< -20	Fatigued	Risk of overtraining

Preventing Overtraining With TSS

Warning Signs

Indicator	Concern Level
Weekly TSS jump >20%	Moderate
Negative TSB > -30	High
High TSS for 3+ weeks	High
Performance declining despite training	Very high

Safe Progression

• Increase weekly TSS by max 10-15% per week
• Include recovery weeks every 3-4 weeks (reduce TSS by 30-40%)
• Monitor how you feel—TSS is a guide, not an absolute

Recovery Week Example

Normal week: 450 TSS Recovery week: 270-315 TSS (60-70% of normal)

TSS for Race Planning

Taper Example for Half Marathon

Weeks Out	Weekly TSS	% of Peak
4	475 (peak)	100%
3	400	84%
2	310	65%
1	200	42%
Race week	180 + race	—

Marathon Taper

Weeks Out	Weekly TSS	% of Peak
4	550 (peak)	100%
3	440	80%
2	330	60%
1	220	40%
Race week	150 + race	—

TSS vs Other Metrics

How TSS Compares

Metric	What It Measures	Best For
TSS	Training load (intensity × duration)	Overall training management
Mileage	Total distance	Volume tracking
Time	Total duration	Consistency
Pace	Speed	Performance tracking
Heart Rate	Cardiovascular stress	Internal load

When to Use Each

• TSS: Comparing different types of workouts, planning load
• Mileage: Traditional volume tracking, baseline fitness
• Heart Rate: Ensuring appropriate recovery on easy days

Combining TSS With Other Calculators

Training Pace Integration

Use our Running Interval Pace Calculator to find your threshold pace, which is essential for accurate TSS calculations.

VO2 Max Connection

Your VO2 max correlates with threshold pace. Higher VO2 max typically means faster threshold, affecting how TSS is calculated.

Calorie Tracking

Higher TSS workouts burn more calories. Compare with our Running Calorie Calculator for fueling needs.

Sample Training Blocks Using TSS

5K Training (12 weeks)

Phase	Weeks	Weekly TSS	Focus
Base	1-4	250-300	Easy running, building
Build	5-8	350-420	Adding intervals
Peak	9-11	400-450	Race-specific work
Taper	12	250	Freshness

Half Marathon Training (16 weeks)

Phase	Weeks	Weekly TSS	Focus
Base	1-5	280-350	Mileage building
Build 1	6-9	380-450	Tempo development
Build 2	10-13	450-520	Peak loading
Peak	14-15	480-500	Race-specific
Taper	16	280-320	Freshness

For complete training plans, see our Half Marathon Training Plan and Marathon Training Plan.

Calculate Your TSS

Ready to track your training load?

1. Find your threshold pace: Use Running Interval Pace Calculator

2. Calculate workout TSS: Use Running TSS Calculator

3. Track weekly totals: Sum daily TSS for overall load

4. Plan appropriately: Use guidelines above for your experience level

TSS is a powerful tool for managing training load, but remember:

• It's a guide, not a prescription
• Listen to your body alongside the numbers
• Consistency beats perfection
• Recovery is when you get stronger

Visit our Running Calculators hub for all our free running tools.