Running Effectiveness (RE)

Definition

Running Effectiveness (RE) = speed (m/s) ÷ (power ÷ body weight), speed per watt per kilo. It measures running efficiency: how much speed you get for the power you put down. Typical values sit around 0.98–1.05; carbon-plate "super shoes" measurably raise it.

Why it's powerful

RE is purely mechanical (power → speed), so unlike Pa:HR efficiency it isn't confounded by heat, fatigue or cardiac drift. That makes it the right tool to compare:

• Shoes: same segment, two shoes: higher RE = faster per watt.
• Form changes over time on a repeated route.

Stryd only

RE depends on accurate run power. Garmin/optical run power reads ~30% high, which makes RE meaningless and non-comparable, so Grepiac shows RE only for Stryd-powered runs and hides it otherwise. See Run power: Stryd vs Garmin.

Where it appears

• Run segment effort table (compare efforts/shoes on the same stretch)
• A run activity's Session analysis
• The race recap run leg

Compare RE on like terrain (same segment, similar grade), that's what makes the comparison fair.