gruelling(so difficult or taxing as to make one exhausted) adjective [UK: ˈɡruːəl.ɪŋ] [US: ˈɡruːəl.ɪŋ]
strenuous(requiring great exertion) adjective [UK: ˈstre.njʊəs] [US: ˈstre.njuːəs]The trainer advised Angela to avoid strenuous exercise. = El entrenador aconsejó a Angela evitar el ejercicio extenuante.