straining

nouns

an intense or violent exertion

strain, straining

is derived from

the act of distorting something so it seems to mean something it was not intended to mean

taxing to the utmost; testing powers of endurance

"his final, straining burst of speed"; "a strenuous task"; "your willingness after these six arduous days to remain here"- F.D.Roosevelt

arduous, straining, strenuous