No treadmill, no lab, no all-out sprint. Walk a flat mile and Wend VO₂ reads your pace and heart rate to estimate the single best predictor of your cardio fitness.
The Rockport Walk Test has been used since the 1980s to estimate VO₂ max without pushing anyone to exhaustion. Wend VO₂ brings it to your wrist: your watch handles the timing, distance, and heart rate automatically.
Find a flat route and walk it as briskly as you comfortably can. Wend VO₂ tracks distance with GPS and flags any hills that would skew your result.
The moment you finish, your time and ending heart rate go into the validated Rockport equation — adjusted for your age, sex, and weight from Apple Health.
One clear number, with a plain-language rating and where you land for your age. Re-test anytime to watch it climb.
VO₂ max is how much oxygen your body can use at peak effort — and one of the strongest predictors of long-term health and longevity. The encouraging part: it's highly trainable, so the work you put in shows up right here.
Wend VO₂ turns an abstract lab metric into something you can check on a Sunday walk and improve over months.
Bands shown for illustration; Wend VO₂ personalizes them to your exact age and sex.
The Rockport one-mile walk equation and VO₂ max's link to longevity are both well established in the literature. These are the studies and protocol behind how Wend VO₂ estimates and contextualizes your number.
A cohort of 122,007 adults found fitness inversely associated with all-cause mortality — with no observed upper limit of benefit.
Mandsager K, Harb S, Cremer P, Phelan D, Nissen SE, Jaber W.
JAMA Network Open · 2018 · 1(6):e183605
Cureton KJ, Sloniger MA, O'Bannon JP, et al.
Med Sci Sports Exerc · 1995 · PMID 7752874
Pober DM, Freedson PS, Kline GM, et al.
Can J Appl Physiol · 2002 · PMID 12500996
Weiglein L, Herrick J, Kirk S, Kirk EP.
Military Medicine · 2011 · PMID 21702386
Ontario Sport & Health Foundation
Protocol reference · PDF
Hills break the Rockport equation. We detect elevation change segment-by-segment and tell you if a walk was flat enough to trust — green means valid, grey means too hilly.
Your ending heart rate is half the equation. Wend VO₂ captures it precisely at the finish line and accounts for recovery drift.
Every test is logged, so you can watch your VO₂ max climb across weeks and months — and see your training actually pay off.
Pulls your age, sex, and weight automatically, and writes each result back to Apple Health's Cardio Fitness so everything lives in one place.
Add Wend VO₂ to any complication slot. It's not just a launch button — the arc fills toward the 'elite' mark for your age and your latest number is always right there. Tap to start a fresh test.
The companion iPhone app keeps every test in one timeline and reveals the details behind each result, right down to the equation that produced it.
Each walk you log, in order — watch your VO₂ max trend climb and tap any entry to revisit it.
Open a test for pace, finishing heart rate, elevation profile, and whether the terrain was flat enough to score.
See the exact Rockport equation and the inputs that produced your number — every value laid bare.
Free to download. Your first VO₂ max is one walk away.