strenuous Synonyms

straining arduous stressful strong taxing tiring tireless toilful toilsome tough operose stiff physical punishing resolute rigorous sedulous serious spirited steep trying unwearied gruelling rough-and-tumble knockabout peppy red-blooded hard-working on the go back-breaking grueling backbreaking uphill upstream vigorous wearing weariless wearisome wearying zealous tensional onerous draining dynamic dynamical eager enepidermic energetic enervating enervative