Doncaster Rovers: Why Niall Mason and Danny Andrew have both suffered cramp already this season
Grant McCann is determined to put an end to his full backs being forced off with cramp - and he has discovered the reason why it is happening.
Danny Andrew was withdrawn after 66 minutes of Rovers' opening day to trip to Southend United due to cramp.
And Niall Mason lasted 74 minutes of Saturday's win over Wycombe Wanderers before the issue affected him.
As the role of full back forms a major part of McCann's 4-3-3 system with high energy runs up and down the flanks, the Rovers boss is determined to put an end to the need to substitute players.
But he confesses that will only come when Andrew and Mason's bodies are up to speed with the rigours of his style of play.
"Speaking to the sports scientist and the physio, the full backs are not used to covering this kind of distance in terms of high speed running and explosive distance," McCann said.
"They were telling me that the numbers for one was treble from last season in terms of high speed running.
"It's probably the reason why they've cramped after 65 minutes.
"You can play as many pre-season games or train as much as you want, but the League One games can highlight that.
"We're on that with them two. They've taken different measures so they hopefully won't cramp up again.
"Otherwise I might have to put two fullbacks on the bench instead of one."
Rovers' sport science and medical departments are now working closely with the club's full backs in order to reduce the risk of cramping in future games.
"It's about the lads taking stuff on board," McCann said.
"The physio and sports scientist are giving them extra stuff in terms of drills and things they can do to help it and hopefully it won't happen again."
Both Mason and Andrew played a major role in Rovers' dominance over Wycombe at the weekend with each man pushing very high up the pitch and finding space for crosses into the box.
While pleased with their development in what he wants from the position, McCann still wants more from his full backs as the season progresses.
"It was interesting after the game that Gareth Ainsworth [Wycombe manager] said how brave our full backs were," McCann said.
"But I said they aren't brave enough yet.
"I told them that on Monday morning in a meeting.
"They're getting there.
"And when they do get braver you will see how good they are, how high they can be and how threatening they can be for us."