Paolo Di Canio has warned any players moaning about his "constant" fitness drive to shut up.
says his squad have had just one day off all summer, and is convinced they will eventually reap the rewards.
Di Canio has only won twice in ten games in charge and faces a tough run of fixtures including Arsenal at this weekend.
But he has insisted there will be no resting up for the big games.
He said: "People talk about saving energy for the game but why would you do that? Why would you save energy to be fit for Manchester United when the reality is that you have to build all that energy up to be fit for Manchester United in the first place?
"In my view you have to keep training constantly to be fit. The majority of the squad had just one day off training all summer but I think this is a good thing because in my view if you train hard, you have less, not more chance of injury.
"If players are only, say 40-50 per cent of their potential fitness, and they strain to put in more, or stretch for a ball they are not fit enough to reach – that’s when you’re in trouble.
"If your centre is not strong, you cannot run for 60 minutes or push to go again. What I am saying is that with the fitness levels we have, we will pick up far fewer injuries over the course of the season and that has got to benefit us in the long run.
"The simple fact is that if you train hard, you can press hard and run for the full 90 minutes. Over the years this club has had many, many injuries."
Di Canio is set to appear in Hull City keeper Steve Harper’s testimonial tonight, which will feature former Newcastle and Milan stars.