characterized by toilsome effort to the point of exhaustion; especially physical effort; "worked their arduous way up the mining valley"; "a grueling campaign"; "hard labor"; "heavy work"; "heavy going"; "spent many laborious hours on the project"; "set a punishing pace"
gru·el·ling in AM, use grueling A gruelling activity is extremely difficult and tiring to do. He had complained of exhaustion after his gruelling schedule over the past week This flight was more gruelling than I had expected. = exhausting. very difficult and tiring (gruel (1800-1900), from gruel ; because people were given gruel as a punishment)