You can edit Notifications in app settings > Notifications
If you have Android 7.0 or older You can manage all notifications there.

If you have Android 8.0 or newer You can manage only email notifications in app settings. Push notifications are managed in Phone Notification settings.

With Android 8.0 update you have had additional modification options for notifications for your phone. With this update some of the settings have been enabled by default. 
To disable the notification go to:
Settings --> Apps & notifications --> Sports Tracker --> App notifications --> Activity recording --> Importance --> Medium (no sound)