Training Glossary
Clear definitions of key endurance training concepts. Each term links to related tools and articles.
Power
Functional Threshold Power (FTP)
The highest power a cyclist can sustain for approximately one hour. Used as the baseline for power training zones and calculating training load.
Normalized Power (NP)
A weighted average power that accounts for the variability of a ride. Better represents the true physiological cost of a workout than simple average power.
Intensity Factor (IF)
The ratio of Normalized Power to FTP (IF = NP / FTP). An IF of 1.0 means you rode at threshold intensity. Used to gauge workout difficulty and calculate TSS.
Power Zones
Seven training intensity zones based on percentage of FTP, from Active Recovery (Zone 1) to Neuromuscular Power (Zone 7). Each zone targets a different energy system.
Watts per Kilogram (W/kg)
Your power-to-weight ratio, calculated as FTP divided by body weight in kilograms. The single most important metric for climbing performance and cross-athlete comparison.
Training Load
Training Stress Score (TSS)
A single number representing the total training load of a workout, calculated from Normalized Power, Intensity Factor, and duration.
Chronic Training Load (CTL)
An exponentially weighted rolling average of daily TSS over 42 days. Represents your accumulated fitness — higher CTL means more training load absorbed over time.
Acute Training Load (ATL)
An exponentially weighted rolling average of daily TSS over 7 days. Represents short-term fatigue from recent training.
Training Stress Balance (TSB)
The difference between CTL and ATL (TSB = CTL minus ATL). Positive values indicate freshness, negative values indicate fatigue. Race day target is typically +15 to +25.
Physiology
VO2max
The maximum rate of oxygen your body can consume during exercise, measured in ml/kg/min. The gold standard measurement of aerobic fitness and your physiological ceiling.
W'bal (W Prime Balance)
A real-time measure of how much anaerobic work capacity (W') remains during a ride. Depletes with efforts above Critical Power and recovers below it.
Periodization
Periodization
The systematic structuring of training into phases — base, build, peak, race, and recovery — to optimize adaptation and peak performance at the right time.
Base Training
The foundation phase of a training plan focused on aerobic development through high-volume, low-intensity riding. Typically 8 to 12 weeks of mostly Zone 2 work.
Pacing
Critical Swim Speed (CSS)
Your threshold pace in the pool, calculated from 400m and 200m time trials. The swimming equivalent of FTP, used to set swim training zones.
Threshold Pace
The running pace you can sustain for approximately 60 minutes. The running equivalent of FTP, used to calculate running training zones and monitor run fitness.