DESPITE his lack of downtime over the close season, Charlie Mulgrew is the very image of a man revitalised and ready to face the next set of challenges in his career.

Sitting in a sparse dressing room at Celtic's training ground, the midfielder talks just minutes after yet another pre-season session at Lennoxtown. How­ever, there is no panting emanating from the 29-year-old, no beads of sweat trickling down his face, just a look of contentment.

It has been a summer with a difference for Mulgrew. Six months of last season was missed due to a serious knee injury, with only two substitute appearances at the tail end of the season accounting for his contributions in a Celtic jersey during 2015.

After months of rehabilitation on a Lennoxtown treatment room, Scotland manager Gordon Strachan was persuaded to throw Mulgrew into the heat of a crucial European Championship qualifier against the Republic of Ireland last month in the Aviva Stadium; a game in which the former Aberdeen man was a standout.

No sooner had the ferocity and hype surrounding that tie subsided, then it was time to report back for pre-season at Celtic ahead of another early start to the Champions League qualifying campaign.

"It was nice to get a couple of games, feeling fit. I only really had two or three weeks off so I'm feeling good and desperate to get back into it," said Mulgrew, who also crammed in 90 minutes against Qatar for Scotland prior to the trip to Dublin.

"After missing five months and being desperate to get back, I am happy in full training and being available for games. I feel pretty fresh. I've been out that long, I'm just glad to be back training day in, day out.

instead of going to the gym and pool and watching everyone training.

"I cramped up after about 70 minutes in both games. I thought in the Ireland game 'Phew, 20 minutes to go here, I might need to go off because we need to get a result'.

"I went up for a corner and on my way back I never got cramp and I thought I could be all right. I wanted to do two 90 minutes after being out so long. I didn't want to come off, especially with cramp, you don't want to do that playing centre-half. You're not exactly doing a lot of running."

It was still enough to break Mulgrew back in for a pre-season regime that is noticeably different.

Given the early start to Celtic's season these days due to European commitments, it means there is little time for players' fitness levels to slide or, no matter how pain­fully, for them to be built up again. It means Ronny Deila has been able to concentrate on tactics, training drills and systems before facing Stjarnan in the second round of qualifying for the Champions League a week on Wednesday. It is a bit of light relief Mulgrew is more than grateful for.

"I don't think anyone has really had a long time off. The most would be three, four weeks. So it's not really old school running and sand dunes any­more," he said. "It's footballs out for the first day. Everyone is happy that way but still you're getting your work through the games and hard games in training.

"It was never so much sand dunes but I went to the track a few times under Gordon Strachan. That was probably the hardest pre-season I've done. But back then you had seven weeks off, sometimes eight. Finishing in May and back in July.

"I remember doing 800, 1200 and the Cooper run as well - as many laps as you can do in 12 minutes on the first day. It was torture. You had to get at least eight. Paul Telfer set the standard, he was near enough nine.

"Back then Bobo [Balde] took off like a shot and everyone thought he'd get about 20 laps. I think he ended up with about seven and almost blew up after one."

Beyond pre-season, the challenges that await Mulgrew in the short term will go a long way to sealing his long-term future. The man who has now been at Celtic for five years is entering the last year of his contract, with him admitting early talks have already taken place about an extension.

It is an outcome Mulgrew is keen to pursue. However, the utility man is aware that forcing himself back into a well-oiled Celtic team must be the priority in a bid to help his cause. That is easier said than done given the formidable partnership which has developed in the middle of the park between Nir Bitton and Celtic captain Scott Brown.

"Of course it will be hard to break them up but every team and manager wants competition for places," he said. "That will bring out the best in me if I need to fight to get that position and I'm sure it will bring out the best in Broony and Nir too. That's what it's all about. In the long run, it can only be good for the team.

"I spoke briefly to Peter [Lawwell] and the manager, so we will see what happens. I am happy here. Everything is great and going well so we will play it by ear.

"I've been back for five seasons now. It probably is hard to see myself anywhere else. I haven't even thought along those lines. My focus was on getting fit again last season but I am happy at Celtic."