What is the verb from strenuous?

The verb form of "strenuous" is "strenuous" itself. It can be used as both a verb and an adjective.

As a verb:

* "He strenuously objected to the proposal." (meaning he objected with great effort or force)

As an adjective:

* "The hike was strenuous." (meaning it required a lot of effort)

It's important to note that "strenuous" as a verb is less common than its use as an adjective.