Using aoData.push with POST

I looked everywhere and couldn't find an answer so I thought I'd ask!
I'm trying to post the value extradata to the workouts.php file using the aoData.push. I can receive it in workouts.php when I use GET and load the page for the first time but anytime after that its not being passed through.

Is there something I'm just forgetting to do or can you only receive data that has been "pushed" using GET? The rest of the data in the row is accessible all the time in workouts.php regardless. Any more info on this would be great!

 // DataTables init
    $('#example').dataTable( {
        type: \"POST\",
        \"sAjaxSource\": \"php/workouts.php\",
        \"fnServerParams\": function ( aoData ) {
                aoData.push( { \"name\": \"extradata\", \"value\": \"14\"  } );
         },
        \"aoColumns\": [
            { \"mDataProp\": \"name\", \"sClass\": \"center\" },
            { \"mDataProp\": \"date\", \"sClass\": \"center\" },
            { \"mDataProp\": \"type\", \"sClass\": \"center\" },
            { \"mDataProp\": \"target\", \"sClass\": \"center\" },
            { \"mDataProp\": \"time\", \"sClass\": \"center\" },
            { \"mDataProp\": \"distance\", \"sClass\": \"center\" },
            { \"mDataProp\": \"speed\", \"sClass\": \"center\" },
            { \"mDataProp\": \"notes\", \"sClass\": \"center\" },
            {
                \"mDataProp\": null,
                \"sClass\": \"center\",
                \"sDefaultContent\": '<a href=\"\" class=\"editor_edit\">Edit</a>',
                \"bSortable\": false,
                \"bSearchable\": false
            },
            {
                \"mDataProp\": null,
                \"sClass\": \"center\",
                \"sDefaultContent\": '<a href=\"\" class=\"editor_remove\">Delete</a>',
                \"bSortable\": false,
                \"bSearchable\": false
            }
            
            
        ],
        
        \"fnInitComplete\": function () {
            keys.fnSetPosition( 0, 0 );
        }