What is an Apple Watch exercise minute?

Somewhere amid all the big themes in life, the sweep of politics and the question of what the economy will be there’s something that’s been bugging me: How does my Apple Watch decide what a minute of exercise is for the green activity ring?

Well, in June, I got at least part of the answer. It’s 3.3 miles per hour or 5.3 km/h.

At a event associated with Apple’s Worldwide Developer’s Conference (WWDC) early in June, I had a short talk with one of the engineers involved in the Apple Watch activity tracking software. For running and walking at least, 3.3 miles per hour is the magic speed at which a walk goes from being a casual stroll, to actual tracked exercise.

Since the Watch tracks things internally in metric units, I’d guess that the engineer, who sounded American, had translated the units into something familiar for daily use. This speed works out to be 18:10.9 minute/mile pace and 11:29.7 minutes/km pace. In my walks when I’ve maintained this pace or faster, I accumulate exercise minutes. When I’m slower than this pace, I don’t. (Fortunately, my running, while slow, is always substantially faster than this pace!)

Although I wasn’t able to follow up, I would guess that for other workout types, pulse rate would have something to do with exercise minutes rather than speed. Swimming that pace would be a lot harder than walking it for example. But that will have to be left to future questions.

Change the Display!

It’s hard with the standard display for walking to see your current pace as the regular screen shows total cumulative pace. That total is an average from your start to the end. It takes a while for that average to get down to the magic 18:10 (11:29). For me that adds another four or five minutes that I’m walking on an exercise pace, but that isn’t being counted.

However, I was fiddling around and found that I could change the walking workout display and the running workout display to show the current pace as well as total pace. The current pace, I’ve found, updates every 10 seconds.

(I’m sure I made an interesting picture holding my watch hand raise while running and walking so I could see when the pace updated. Raised hand so I could still safely see where I was going. Triping and falling would affect my pace! But of course, experiment and science requires us to forego our minor concerns about appearance.)

And surprisingly, the exercise minutes tracking seems to use that current pace instead of the total pace if the current pace is displayed. So that ramp-up time of 4–5 minutes drops sharply.

To change your display:

  1. Open your Watch app on your iPhone (the iPhone that you’ve paired with your Apple Watch).
  2. Scroll down, tap on “Workout” app.
  3. Tap “Workout View”
  4. Tap “Multiple Metric” — this will let you put several things on one screen.
  5. Tap “Outdoor Walk” (or tap whichever workout display you want to change).
  6. Tap “Edit” and shuffle the items to display around as you like. The “Current Pace” item is the one you want to add. Tap “Done” to save the new list of items. I use the list below:

I hope this helps you reach your exercise goals and close your rings. It has certainly sovled some little frustrations on my part!

iOS developer since 2009. Previously UNIX/Linux/Mac networking software. Pro geek, runner, voracious reader.

iOS developer since 2009. Previously UNIX/Linux/Mac networking software. Pro geek, runner, voracious reader.