Economy & Efficiency | Physiology

Description

How economical are you at the pace or power you actually race at — and does that hold up, or fall away, over the length of the effort?

This is a single continuous constant-effort test: no incrementing stages, no step changes. You warm up, settle into your target pace (running) or target power (cycling), and hold it — mask on, breath-by-breath gas exchange recorded without a break — for long enough to give a genuine early window and a genuine late window in the same effort.

We compare those two windows on three markers: your oxygen cost (economy), your fuel mix (RER — fat versus carbohydrate), and your ventilation. Each is banded independently, so you can see not just whether something changed but how much, and whether it matters.

Because this is one continuous effort rather than two separate tests, there’s a real trap we test for directly: a genuine drop in pace or power late in the effort can look like an “improvement” in economy that isn’t real. We flag it explicitly whenever it’s detected, so any drift result you’re shown can be trusted at face value.

What you’ll get:
– Your initial economy range, and whether it’s genuinely economical for you at that intensity
– Early-to-late drift on economy, substrate, and ventilation, each banded
– A pace- or power-consistency flag, so you know whether any drift is real
– Your fat-versus-carbohydrate burn (g/hr and kcal/hr) at the tested intensity — direct input for race fuelling
– A training-emphasis recommendation targeted at whichever marker actually moved

Built for runners and cyclists preparing for a specific target pace or power — marathon effort, an FTP-adjacent ride, an Ironman leg — who want to know whether their engine holds up for as long as they’ll need it to, not just what it can do in a short burst.