NP : Normalized Power
LoadA weighted-average power that penalises spikes in intensity.
On hilly or interval rides, average power under-estimates true difficulty (spikes cost disproportionately). NP applies a mathematical transform (30s moving average then ^4) that better reflects the "real" effort. A 200 W avg / 250 W NP ride is much harder than a 200 W avg / 205 W NP ride.
In TriPaced:
TriPaced uses NP to compute the TSS of your rides (TSS = (duration × NP × IF) / (FTP × 3600) × 100). The further NP is above average power, the higher the recovery cost.