A few days ago, Strava upset its users over some restrictive API changes. It might seem odd for one app’s users to fume over an API, but at the heart of the matter is the inherent messiness of fitness data.

Here’s a typical scenario. Say you’re all in on Garmin’s platform. You use their watches for running and strength training. Then, you pick up a Peloton bike for indoor cycling. Well, Garmin devices aren’t compatible with Peloton bikes because the two companies haven’t struck a direct deal with one another for data sharing. So, to get your heart rate on the Peloton bike, you buy a chest strap. And then you decide to train for a race, so you sign up for one of those digital coaching platforms — the kind where a personal trainer reviews your workouts and builds you a customized plan.

The dilemma is now you have three separate apps where your workout history is stored, with three separate interfaces — and none of them with the whole picture of your training.

There are a number of ways you could consolidate that data, but in this scenario, the simplest is to upload all your workouts into Strava and then import all that Strava data into the coaching app.

This kind of scenario has come up dozens of times throughout my wearables testing. Most recently, it came up when I reviewed a Mobvoi connected desk treadmill. I didn’t like its native app, but trying to get the data into my preferred apps was a nightmare. At the end of the day, it was easiest for me to go through Strava.

The reality is many smaller fitness apps and wearable makers don’t have the resources to strike up direct data integrations with the thousands of other fitness apps and devices on the market. It’s much easier for everyone to use Strava’s API and call it a day. And unlike Apple’s HealthKit API or Google’s Health Connect, Strava is platform-agnostic.

Where things get really murky is third-party fitness platforms that extrapolate their own insights from Strava data — a no-no under the new API terms.

Take a third-party platform like VeloViewer. The whole idea behind VeloViewer is to give more in-depth insights into Strava data, including 3D maps, charts, yearly activity recaps, and leaderboards. This is a great option for folks who want more info than what’s natively available in Strava, but the new API changes break many of the aforementioned features. As you might imagine, VeloViewer users — many of whom say they only pay a Strava subscription to use VeloViewer — are pissed. VeloViewer has since released a statement saying it’s working with Strava to resolve the issue, but it doesn’t change the fact that Strava holds all the cards.

Admittedly, this is a niche problem. Most people use one or maybe two fitness apps with their smartwatch, and this isn’t really an issue. But for those of us who want the freedom of using multiple devices and apps across various platforms? It’s a sobering reminder that it only takes Strava changing the rules to break a carefully crafted system.