The study demonstrates a greater reliance on overtime and temporary and part-time workers has allowed U.S. employers to delay hiring as the economy recovers.

The study by Stacey Schreft and Aarti Singh, found a lack of jobs was not the only issue.

"Just-in-time employment practices give firms more flexibility in employing labor, which is especially valuable early in recoveries," the study said.

"Apart from joblessness, the recovery has a feature that distinguishes it from the typical recovery: the greater use of just-in-time employment practices," they said.

The study said increased reliance on "just-in-time" employment practices appeared to be part of longer-term trends toward a more flexible workforce.

"It is too soon to tell if future recoveries will also be jobless," they said. "There is every reason to expect, however, that the use of just-in-time employment practices will persist."