Glossary of TrainingPeaks Metrics

Glossary of the most commonly used acronyms and terms related to the advanced metrics in TrainingPeaks such as TSS®, IF® and FTP.

Below is a list of the most commonly used abbreviation and terms related to the advanced metrics in TrainingPeaks. Any metrics with a trademark symbol Ⓡ were developed and are owned by TrainingPeaks.

Pw:Hr/Pa:Hr (Aerobic Decoupling)A measure of how much your power or pace changes relative to your heart rate from the beginning of a ride to the end. A lower value (<5-8%) for long, steady rides may indicate improved aerobic endurance.
ATL (Acute Training Load)A weighted average of daily Training Stress Score for the last seven days. Used to represent acute training load and its short-term contribution to Fatigue. Also called Fatigue.
CTL (Chronic Training Load)A weighted average of daily Training Stress Score for the last 42 days. Used to represent training load and its long-term effects on fitness. Also called Fitness.
EF (Efficiency Factor)The ratio of Normalized Power or Normalized Graded Pace to average heart rate for a given workout. A drop in this number over time for similar workouts indicates a higher power or pace for a given level of effort and an increase in fitness.
FitnessSee CTL (Chronic Training Load)
FatigueSee ATL (Acute Training Load)
FormSee TSB (Training Stress Balance)
FreshnessSee TSB (Training Stress Balance)
FTP (Functional Threshold Power)The power output below which an athlete can sustain for a longer duration (>one hour) and above which fatigue will occur quickly. Estimated by 60-minute max power or 95% of 20-minute max power.
IF® (Intensity Factor®)The relative intensity of a given workout without regard for the duration. One hour at maximum effort is 1.0
kJ (Kilojoules)A unit of work. Riding 200 watts for one hour would accomplish 720 kJ of work. For cyclists, Kilojoules are approximately equivalent to calories expended.
NGP (Normalized Graded Pace)A correction for pace to account for running uphill and downhill to show what the pace would be if the terrain were flat.
NP® (Normalized Power®)An algorithm to estimate the physiological cost of a workout or longer effort within a workout. Higher intensity efforts are weighted to represent the physiological cost of using high-intensity energy systems.
Pa:Hr (Pace-Heart rate decoupling)See Aerobic Decoupling
PMC (Performance Management Chart)A chart of Fitness (CTL), Fatigue (ATL) and Form (TSB) over time. Used to plan and track periodization, training load, and event readiness.
Pw:Hr (Power-Heart Rate Decoupling)See Aerobic Decoupling
Ramp RateThe change in CTL over time, usually the last seven days. A ramp rate that is too high may lead to overtraining or injury; too low may not gain fitness quickly or effectively.
ThresholdA level of effort above which an athlete will fatigue very quickly and below which can be sustained for a longer duration (>one hour). Can be defined by heart rate (LTHR) for all sport types, power (FTP) for running and cycling, and pace (T-Pace) for swimming and running.
TSB (Training Stress Balance)Compares training load for the past week to typical training load over the past six weeks (CTL-ATL). Used to represent readiness to perform at peak potential. High positive values may indicate undertraining, high negative values may indicate overtraining. Also called Form.
TSS® (Training Stress Score®)The training load of a given workout based on duration and intensity. Can be calculated from power, heart rate (hrTSS) or pace (rTSS). One hour at maximum sustainable effort is 100 TSS.
VI (Variability Index)The ratio of Normalized Power to Average Power for a workout. Indicates how steady the power output was. Time trials and long course triathlon bike legs may have low VI’s (<1.05) workouts, or races with a mix of sprinting and coasting (criterium, track, cyclocross) will have higher VIs.
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