Your threshold baseline. It represents the maximum average power (measured in Watts) that you can theoretically sustain for approximately 60 minutes. FTP acts as the anchor point for all power zones, Normalized Power, and Training Stress calculations.

An estimate of the power you could have sustained for the same physiological cost if your effort had been perfectly constant. It accounts for the non-linear metabolic cost of surges and bursts by using a 30-second rolling average raised to the 4th power.

The ratio of your Normalized Power to your FTP (IF = NP / FTP). It scales intensity relative to your current fitness:

• < 0.75: Active Recovery / Easy Endurance
• 0.75 - 0.85: Steady Endurance / Tempo
• 0.85 - 0.95: Sweet Spot / Hard Aerobic
• 0.95 - 1.05: Threshold / Intensive Intervals

A composite metric that quantifies the total physical workload of a session. It combines duration and relative intensity: TSS = (Duration_seconds × NP × IF) / (FTP × 36) *100 TSS is equivalent to riding at your exact FTP limit for 1 hour.

The theoretical maximum power output you can sustain indefinitely using only aerobic pathways without accumulating systemic fatigue. Derived from the slope of your peak work-duration curve (using Monod & Scherrer's model).

The size of your anaerobic "energy tank" (measured in kilojoules - kJ). It is the finite capacity available for efforts above your Critical Power. Riding above CP depletes your W', and riding below CP allows your body to reconstitute this tank.

Calculated as: VI = NP / Average Power.
Shows how steady or punchy your power distribution was:

• 1.00 - 1.05: Extremely steady (typical of time trials, flat triathlons, or steady recovery).
• 1.06 - 1.15: Moderately variable (rolling hills, structured intervals).
• > 1.15: Highly punchy (criteriums, mountain biking, or road racing with intense attacks).

Calculated as: EF = NP / Average Heart Rate.
Measures cardiovascular efficiency—the amount of external work (NP) you produce per heartbeat. An increasing EF over weeks for the same type of workout signals rising aerobic conditioning and improved cardiac stroke volume.