Training Stress Score (TSS) Calculator

For recreational riders new to structured training, 250-400 TSS per week is a good starting range. Club riders targeting local races typically train 500-800 TSS per week. A commonly cited rule is to limit weekly TSS increases to 5-10% per week to avoid overtraining. Sudden jumps above 20% in a single week significantly elevate injury and illness risk.

Kilojoules (kJ) measure only the mechanical work your legs produced, independent of your fitness level. A 1,000 kJ ride is more stressful for a rider with FTP 200 W than one with FTP 300 W. TSS normalises by your threshold, so 100 TSS represents the same relative stress for any rider, making it the better metric for comparing training load across people and across time.

Yes, with less accuracy. HeartRateTSS (hrTSS) in TrainingPeaks uses your heart rate data with LTHR (Lactate Threshold Heart Rate) as the reference. Perceived Effort TSS (peTSS) uses RPE on a scale. Both are much less accurate than power-based TSS because heart rate and RPE lag behind actual intensity and drift with heat, fatigue, and hydration.

When you raise your FTP, the same ride now represents a smaller fraction of your new threshold. That is mathematically correct - the ride was genuinely easier relative to your improved fitness. Your zones and training targets should all shift up accordingly. Some coaches keep the old FTP for one more week to avoid a sudden zone jump mid-training block.