index = (ΔHRV + ΔRHR_inv + ΔRecovery + ΔSleep score + ΔRestorative + ΔConsistency + ¼·ΔCardio_cap + ¼·ΔZ4–Z5_cap + ¼·ΔStrength_cap) / 6.75

• Each signal is a 28-day rolling average, expressed as the % change from where it stood a year ago (the dashed zero line).
• Resting heart rate is inverted — lower is better, so a drop counts as a positive change.
• Restorative sleep is the share of the night spent in deep (SWS) or REM stages; consistency is Whoop’s measure of how regular my bed and wake times are.
• Cardio counts only time with heart rate in zone 2 or above (ambling doesn’t inflate it), Z4–Z5 is the all-out subset of it, and strength is time in strength sessions. Rest days count as zero. All three are capped at ±50% and weighted a quarter of a physiology signal — this is a body-trend index; training volume only nudges it. Spotlighting one plots real hours per week instead of the index.
• Nothing else is tuned or hidden. The headline number compares the last 28 days to the 28 days before.