class Testing extends RSAI 
{
    public function Execute()
    {
        $s = new DAOObject;
        $s->QueryName();

        $IS = $s->Cover(new IteratorSheet);

        $sports = array();
        foreach ($IS as $key => $Sport) {
           echo $Sport->FieldName;
           $sports[] = $Sport;
        }
        $this->NAS->Heap->Sports = $sports;
        $this->Render();
}

Then on the other side when you use $NAS->Heap->Sports you will not be able to iterate like you did in the original foreach.

foreach ($NAS->Heap->Sports as $sport) {
    print $sport->FieldName;
}

This is bogus.