Strava released their global heatmap. 13 trillion GPS points from their users (turning off data sharing is an option). medium.com/strava-enginee… … It looks very pretty, but not amazing for Op-Sec. US Bases are clearly identifiable and mappable 
Not just US bases. Here is a Turkish patrol N of Manbij 
You can see the Russian operating area in Khmeimim, but also the guard patrol to the NE. 
Here are some FOBs in Afghanistan. 
If soldiers use the app like normal people do, by turning it on tracking when they go to do exercise, it could be especially dangerous. This particular track looks like it logs a regular jogging route. I shouldn't be able to establish any Pattern of life info from this far away 
Note - It was 3 billion GPS points, 13 billion pixels rendered my mistake.
