characterized by effort to the point of exhaustion; especially physical effort;
"worked their arduous way up the mining valley"
"a grueling campaign"
"spent many laborious hours on the project"
"set a punishing pace"
- To get a state licence, MSBs have to go through a gruelling vetting process.
Lendl's training programme is so gruelling that few people could keep up with it.出自：Tennis