LONDON — GPS device-maker Garmin’s online fitness tracking service has gone down, leaving runners and cyclists struggling to upload data from their latest workouts.

Garmin Connect, an app and website that works with the company’s popular line of fitness watches, remained out of service on Friday. The U.S. company had apologized for the disruption a day earlier, when it indicated the problem was more widespread and affected its communications systems.

FlyGarmin, the company’s navigational support service for pilots, also was hit by the outage, which down took the service’s website and mobile app.

“We are currently experiencing an outage that affects Garmin.com and Garmin Connect,” the company said on its Twitter accounts and website. “This outage also affects our call centers, and we are currently unable to receive any calls, emails or online chats. We are working to resolve this issue as quickly as possible and apologize for this inconvenience.”

Fitness enthusiasts took to social media to vent their frustrations, with some complaining they weren’t able to connect since Thursday. Garmin Connect lets users track workout data and share their running and cycling routes.

The U.S. company’s navigational support service and app for pilots, FlyGarmin, was also down.