BuddyPress.org

Thanks for the replies!

so in this case I want to use the metadata to change the content-part of the activity-stream:

add_filter( 'bp_blogs_activity_new_post_content', 'record_post_activity_content', 1, 4 );

function record_post_activity_content($activity_content, $post, $post_permalink, $post_title){
    if( $post->post_type == 'workout' ) {
     	$activity_content = get_post_meta( $post->ID, 'rute', TRUE );   
    }
        return $activity_content;
}

if I inside that function echo $post->ID; it shows the id fine – so it should be able to get the meta?