Training Stress Score (TSS) is a single number that estimates how much physiological stress a workout creates, based on duration and intensity relative to your threshold. Coaches use TSS to track weekly load, plan recovery weeks, and avoid overtraining.
Who this is for
Athletes who track power or pace and want a consistent way to compare easy rides, hard intervals, and long endurance sessions.
You need a threshold value to calculate TSS accurately: FTP (watts) for cycling or threshold pace/heart rate for running.
How TSS is calculated
For cycling with a power meter, TSS uses normalized power (NP), your FTP, and ride duration. A 1-hour ride at exactly FTP equals 100 TSS. Easier rides score lower; harder or longer rides score higher.
Running TSS uses a similar concept with pace or heart rate relative to lactate threshold. The exact formula varies by platform, but the principle is the same: intensity × duration = stress.
Weekly TSS targets
Most trained amateur cyclists accumulate 300–550 TSS per week during build phases, with recovery weeks dropping 30–40% below their recent average.
Beginners often start around 200–350 TSS per week and progress gradually. Jumping volume by more than 10% week over week increases injury and burnout risk.
Sample week TSS distribution
A balanced cycling week might look like:
- Monday: Rest (0 TSS)
- Tuesday: VO2 intervals — 85 TSS
- Wednesday: Recovery spin — 35 TSS
- Thursday: Sweet spot — 75 TSS
- Saturday: Long endurance — 180 TSS
- Sunday: Easy aerobic — 55 TSS
- Weekly total: ~430 TSS
Common mistakes
- Chasing high TSS without enough easy volume — most weeks should be 75–80% low intensity.
- Ignoring recovery weeks because TSS feels 'too low'.
- Comparing TSS across different sports or athletes without context.
Sources
Using Vo2Max
Vo2Max tracks weekly TSS automatically when you sync rides from Strava or Intervals.icu, and adjusts your plan so load progresses toward your race date without spiking too fast.