December 3rd, 2015


Building better fitness apps

Lots of food for thought in this article. I don't entirely agree with it - I think the author doesn't recognize the extent to which competing against oneself and setting and exceeding goals can be an empowering experience for someone who's always struggled with fitness or exercise. Certainly, for me personally, being able to track my progress has really helped me see myself as someone who can actually succeed at exercise.

But it is true that when you grow up as the fat kid who was always picked last in gym class, your early experiences of quantitative fitness tracking are all about people telling you how much you suck. You weigh too much. You ran that mile too slowly. You can't do the right number of push-ups or sit-ups. I think there was a time in my life when tracking my fitness to the extent that I do now would probably have been counterproductive. And with fitness apps and trackers going mainstream, I worry that a lot of people getting started in fitness are going to be deluged with numbers that they just interpret as metrics of how terrible they are. I think there's a ton of room in the market for apps that encourage movement in other ways.

And as much as I've loved some of the health and fitness apps I've used, nearly all of them have assumptions built into them that drive me batty. Back when I used Health Month, for example, it used to annoy me that if I met my goal of running three times a week, it would suggest that next month I set a goal of running four times a week. I didn't want to run four times a week - I needed the time between runs to recover and to do other fitness things I wanted to do. But the app just had the assumption that more was better written into it. (And as the author of this article points out, that assumption is nearly universal in fitness apps.)

And as much as I love my Fitbit, the extent to which it prioritizes steps over other measures of activity can lead to some counter productive incentives. If you look at my Fitbit activity history, you'll notice that the day on which I'm most likely to fail to make 10,000 steps is Monday. Why? Because on Monday I go to the gym and do a fairly intense strength training workout with my personal trainer. During that strength training workout, I might only take 1,000 to 3,000 steps, as opposed to the 5,000 to 6,000 steps that I get on a typical walk or run. So, by Fitbit's most prominently tracked metric, Mondays look like off days for me. But if you look at other metrics, like total calories burned or amount of time that I got my heart rate elevated, Mondays are clear wins.

Now, my personal solution to this is simply to not get too hung up on the numbers. And Fitbit's prioritization of steps has a decidedly virtuous aspect as well: on most days, if I look at my tracker and realize I've been a bit sluggish, I'm much more likely to get up and go for a short walk than I am to pop over to the gym for an unplanned workout. Its net effect on my fitness is definitely positive. But I'm still waiting for the day when someone develops a fitness app/tracker that makes it easy for me to track the things that I consider important, and ignore the things that I don't consider important.

(Obligatory chemist's quibble: I don't know why the author of this piece describes the calorie as an "invented unit". A dietary calorie is what chemists would call a kilocalorie, and is the amount of energy needed to raise the temperature of a kilogram of water by 1 degree Celsius. It's as "invented" as the meter is. We now know that what food calories actually do in your body is more complicated than what simple laboratory measurements would suggest, but that's not the unit's fault.)