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Know your metrics.In plain English.

Plain-English definitions of every metric FITIV tracks — HRV, VO2 max, training load, recovery, and more.

Fitness Analytics Glossary

B

Blood Oxygen (SpO2)

Blood oxygen (SpO2) is the share of hemoglobin carrying oxygen. It's usually 95–100%, and dips below your usual overnight range hold back recovery.

F

FTP (Functional Threshold Power)

FTP is the highest average power a cyclist can sustain for about one hour. It's the benchmark that sets every power-based cycling training zone.

H

HRV (Heart Rate Variability)

HRV is the variation in time between heartbeats, measured in milliseconds. It's the main metric for gauging recovery through your nervous system.

R

Respiratory Rate

Respiratory rate is how many breaths you take per minute. Overnight it holds steady, so a rise above your usual rate can signal stress or fatigue.

Resting Heart Rate (RHR)

Resting heart rate (RHR) is your heartbeats per minute at complete rest. It's a reliable sign of cardiovascular fitness and a daily recovery marker.

Running Power

Running power measures the work rate of running in watts, so you can train by intensity without terrain, wind, or heart rate lag skewing it.

T

Training Readiness

Training readiness is a daily score combining HRV, resting heart rate, sleep, and recent training to show if your body is ready to train hard today.

TRIMP (Training Impulse)

TRIMP (Training Impulse) is a heart rate–based training load metric that scores workout stress from intensity and duration, for any HR-monitored sport.

TSS (Training Stress Score)

TSS (Training Stress Score) measures the stress of a cycling workout relative to your FTP, combining intensity and duration into one load number.

V

VO2 Max

VO2 max is the most oxygen your body can use during intense exercise, in mL/kg/min. It's the gold-standard measure of aerobic fitness.

W

Wrist Temperature

Wrist temperature is your skin temperature during sleep. Nights warmer than usual can reflect illness, alcohol, hard training, or a warm room.

Z

Zone 2 (Aerobic Training Zone)

Zone 2 is the aerobic training zone at 60–69% of maximum heart rate. It is the primary stimulus for mitochondrial development and endurance base building.