Sepideh Modrek, a Stanford University medical school lecturer, said the retirement age for most Americans continues to float upward as people delay the date so they can save more money or boost the eventual size of their Social Security checks.
But that's often not a viable option for people with highly physical jobs, such as the 1,500 Alcoa plant workers in Modrek's study.
"Those with heavier jobs retire earlier," Modrek said in a statement. "Those with more sedentary jobs retire later."
The retirement pattern for Alcoa workers suggested men in manufacturing jobs face a unique set of retirement issues related to the physicality of their work. Most of the workers in Stanford's 2001 to 2008 study were employed in aluminum smelters.
The study found men in these demanding jobs retired, on average, at age 60 and six months by choice or due to exhaustion or chronic pain.
In addition, workers who transitioned into less demanding jobs, due to injury or other health issues, were able to work longer, Modrek said.
"Retiring around age 60 is actually a luxury today," Modrek told a recent Retirement Research Consortium conference. "A lot of people are saying 70 is the new 60."
2014: The Year in Fashion [PHOTOS]
CDC: Get your flu vaccine