Albert Arnó
Physician. Founder of onmedic, a health-technology studio in Barcelona working in eHealth since 2000.
These days I build measurement software for the body — sports and health analytics apps that read what your watch already recorded and compute the models a coach would actually use. The maths runs on the phone, not on my servers. This is where I write about what that is like.
Writing
Reading Apple Health without fooling yourself
Apple Health holds dozens of metrics from several devices, recorded at wildly different qualities. The skill is knowing which ones were measured and which were inferred.
Sleep stages from a wrist: what the device is really doing
Your watch reports deep, core and REM in minutes. A sleep lab needs electrodes on your scalp to do that. Here is what the wrist is actually inferring, and which parts of it you can trust.
Training load does not add up across sports
Triathletes have been summing swim, bike and run load for years. The arithmetic is tidy and the physiology does not support it. What a multisport load number can and cannot mean.
Critical swim speed: the only pool test worth repeating
Two time trials, one subtraction, and a threshold pace that actually holds up. Why CSS beats heart rate and perceived effort in the water.
The gait metric your phone already records
Walking asymmetry has been sitting in Apple Health for years, measured continuously, read by almost nobody. It is one of the few consumer metrics with real clinical grounding.
What a wrist can and cannot tell you about VO₂max
Your watch reports a VO₂max to one decimal place. It has never measured your oxygen consumption. Here is what the number actually is, and the one thing it is genuinely good for.
W′ balance, or what a match actually costs
Cyclists have said 'burning matches' for decades. W′ balance turns the metaphor into kilojoules you can watch drain and refill during a ride.
What I learned deleting 93% of my own website
AnalyticsZone had 15,004 URLs across eleven hostnames and almost no readers. Cutting it to about 1,100 pages on one host was the most useful thing I did all year.
Restarting this blog, seven years later
This site published 194 posts between 2012 and 2019, and I wrote none of them. Here is what it actually was, why it stopped, and what it is now.
The maths runs on your phone, and that costs me things
Computing sports metrics on the device instead of the server is easy to say in a privacy policy and harder to live with. What it actually forecloses.
Currently building
- AnalyticsZone — A family of sports-analytics apps for running, swimming, cycling, walking, sleep and general health. They read what your watch already recorded and compute the models coaches actually use — critical power and W′ balance, critical swim speed, gait asymmetry, HRV-based recovery.
- onmedic — The health-technology studio behind the rest. Clinical data systems and research software for hospitals, research centres and laboratories, most of it confidential.
- Pelvisana — Pelvic-floor education and training, written with clinicians and reviewed by them, in Catalan, Spanish and English.