As she raised her hand and swore that the evidence she gave would be the truth, the whole truth, and nothing but the truth so help her God, she seemed somehow fragile-looking, but when she sat facing us in the witness chair she became what she was, a thick-bodied girl accustomed to strenuous labor.
There are no more uses of "strenuous" in the book.
Show samples from other sources
The doctor recommended strenuous exercise three times a week.
Landscaping is strenuous work in the Texas summer.