How to backup databases are in (Synchronized) mode

I have a SQL server. Most databases in that server are in "Synchronized" mode (required by the applications). I set up a regular maintenance plan to backup the databases and the logs. But the backup skips these databases. I did a quick search on the web, the solutions I can find are to mirror the databases or using third party application. These two options will not work for us. Anyone has an idea how I can buck up the "Synchronized" databases. Many thanks.