A minor flare-up of a back injury has halted Michael Hurley's standout pre-season, but the Essendon utility is set to resume full training on Friday.

The 24-year-old has been restricted to light duties for nearly two weeks as he manages the complaint, which is similar to the lower back injury which forced him to miss two games in the middle of last season.

Essendon's football manager of high performance, Neil Craig, said the club had taken a cautious approach with Hurley.  

"He got a bit stiff and sore in the lower back. He's had a heavy workload. He's been quite exceptional in the pre-season this year," Craig told AFL.com.au.

"It's a bit of a niggle so … we're prepared to back people off for one or two sessions. This is not the time of the year to keep pushing on. Sometimes you've got to do that, but clearly this is not the time of the year to do it

"I would expect him to be back into some drills by Friday."

Craig said the injury had not reached the stage where Hurley required an epidural to free the area of pain, likening it to the back issue that occasionally causes Jake Carlisle to lighten his training load.

"We're getting better at managing them ourselves, as a support and conditioning group. And importantly, they (Hurley and Carlisle) are getting better at managing their own bodies and what they can and can't do," he said.

The positioning of Hurley and Carlisle will again be the centre of much debate this season, particularly with coach James Hird back at the helm.

Under Hird in 2013, Carlisle enjoyed a breakthrough season in defence and Hurley was used mainly as a forward, kicking 24 goals. However, last year stand-in coach Mark Thompson switched the pair with varying success.

Hurley thrived in the backline with his most consistent and productive season, but Carlisle struggled at times until some match-winning performances at the back end of the year.

Craig said the club would continue to swap the damaging pair depending on the circumstances, and that each offered a diverse range of skills.

"We've got Hurley who can play back at a really high level and go forward. When he went forward last year he gave us something a bit different - even though he's got some size he actually attracts the ball more by leading," Craig said.

"Whereas Jake Carlisle tends to stand and deliver up in the forward line and we all saw Jake when he went back into defence.

"Any AFL club would give their left arm to have two guys who can go back and forward with their playing ability. That gives us great flexibility and you can change it from week to week and within the game and have confidence they will go and perform."

Hurley was already going to sit out at least the Bombers' first two NAB Challenge games as he was on the club's list in 2012, when the supplements program investigated by ASADA was underway.

The club had six top-up players arrive on Wednesday for their first training session with the VFL team, and they will be eased into training with the senior squad over the next week ahead of the Bombers’ first NAB Challenge game on March 7 against St Kilda.