Training Stress Score (TSS)

Training Stress Score (TSS)

TSS quantifies the training stress of a workout, allowing coaches and athletes to track training load and prevent overtraining.

TSS Calculation

• TSS = (duration × normalized power × intensity factor) ÷ (FTP × 3600) × 100
• 1 hour at FTP = 100 TSS
• 30 minutes at FTP = 50 TSS
• 2 hours at 70% FTP ≈ 100 TSS

Training Load Metrics

• CTL (Chronic Training Load): 42-day rolling average of TSS - represents fitness
• ATL (Acute Training Load): 7-day rolling average of TSS - represents fatigue
• TSB (Training Stress Balance): CTL - ATL - represents form/freshness

Using TSS for Planning

• Weekly TSS targets: 300-400 TSS = moderate volume, 500-700 = high volume
• Single workout: 150+ TSS = very hard, needs recovery
• CTL progression: Build 5-8 TSS per week safely
• Taper: Reduce TSS by 50% in peak week

TSB and Race Form

Peak performance typically occurs at TSB of +5 to +25. Negative TSB indicates fatigue, positive TSB indicates freshness. Build high CTL (fitness), then reduce training to raise TSB (form) for race day.