An injury that builds up over time from repeated stress instead of one sudden event.

"Builds up over time" is the key part. A bad shoulder from years of overhead lifting, numb hands from constant tool vibration, or back damage from repeated bending can all fit. "Repeated stress" does not mean the work has to be dramatic or high-speed. Ordinary motions done day after day can be enough. And "instead of one sudden event" is where people get misled: plenty of valid work injuries do not come from a fall, crash, or one memorable shift. No single accident report does not mean no real injury.

That matters in a workers' compensation claim because employers and insurers often push the myth that pain without a specific date is just aging, a hobby problem, or "wear and tear." Sometimes it is. Sometimes it is not. The real question is whether work substantially contributed to the condition. Medical records, job duties, and when symptoms started usually matter more than whether there was one dramatic incident.

In Maine, cumulative trauma claims are handled under the Maine Workers' Compensation Act of 1992 through the Maine Workers' Compensation Board. Notice rules still apply. Under 39-A M.R.S. § 301, an injured worker generally must give notice within 30 days of the injury, and with gradual injuries, fights often arise over when the worker knew or should have known the condition was work-related. That timing can affect benefits, causation, and whether the claim is denied.