In any event, growth during the Bush years has not been healthy; rather, it has been abnormally lopsided. Corporate profits have soared (until recently) and the rich have become richer, while most Americans have treaded water or lost ground, their troubling circumstances masked by an unprecedented borrowing binge, now exacting its toll.
ロングマン英々辞典は、以下のように長々と説明してます。
"to stay upright in deep water with the head above the surface by moving the feet up and down as if one is riding a bicycle" (水中で、自転車をこぐように両足を上げ下げして、首だけを水面上に出して、体を垂直に保つこと)