Paul Hartley can remember a time when the close season lasted eight or nine weeks and players would return to pre-season training substantially heavier than when they departed.

Now, even Scottish football, that last bastion of unrefined machismo where once a good swally and a sausage supper represented the traditional post-match meal, is embracing the benefits of year-round fitness programmes. The summer break has been slashed to just three or four weeks. Most senior clubs now employ a sports scientist among their medical staff, and players are encouraged to take personal responsibility for their condition even when away from the club.

Adopting a healthy lifestyle, once thought of as a strange phenomenon that only applied to soft foreigners, has become the norm. Hartley, now midway through his 16th pre-season programme, has experienced both the old and new regimes and has no doubts about which he prefers.

"I feel the fittest I've ever felt in my career," he said as he launched Celtic's new home kit for the coming season yesterday. "When I first started out playing you were probably getting eight or nine weeks off but that's all changed. Now it's three weeks at most. You maybe take two weeks off on holiday then spend a week trying to get yourself in as good a shape as possible.

"With the way we train and play this is the best shape I've ever been in. Before pre-season training was just running until you dropped. You always remember guys would come back a stone or two overweight and pre-season was spent trying to get rid of the weight after having a nice summer.

"It's all changed now. Players come back a lot sharper and fitter and you spend a lot more time on the ball on your first day back. Having a sports scientist has changed things a lot. They tend to know what your body needs and what rest you need and things like that. We've got Gregory Dupont, who's very good, and who knows his stuff well. Even going back to how it was when I first joined Hearts five years ago, football has changed a lot with the medical side of it, sports scientists, what you eat and drink, and what you do before a game and training.

"I think it was a thing the foreigners have always done but now every team in the SPL probably has a sports scientist. To be honest, if you get any more than three or four weeks off you get bored anyway and want to get back training again."

Hartley still has plenty to offer Celtic. Traditionally a dashing, attacking midfielder during his time with Hearts, the 31-year-old has developed under Gordon Strachan into a steady holding midfielder whose job it is to create an impenetrable barrier in front of his defence.

It is where he hopes to feature when the competitive action gets underway again next month but he said he will happily fill in as and when required, as he did on several occasions last season. "I ended the season in that sitting midfield role, which I enjoy the most," he added.

"I played there the last two or three months of the season and I like playing in there. Sometimes you have to adjust your position when you go to another team as they have that many attacking players. But it's a position I really enjoy. I hope I can play there for the next five or six years. I obviously have a preferred position but if the manager asks you to do a job then you do it the best that you can.

It didn't really bother me, I was just happy to be playing whether it was right-back, left-back, wide right or wide left - it didn't affect me.

I just wanted to play."

Gordon Strachan, the Celtic manager, is not short of options for the central midfield areas. As well as Hartley, Barry Robson, Massimo Donati, and Scott Brown also all have designs on filling one of the two berths between Shunsuke Nakamura and Aiden McGeady, likely starters on either flank, while Strachan may yet delve into the transfer market to further intensify the level of competition.

"It's probably the strongest area in the team," Hartley acknowledged. "Me and Barry finished the season strongly but we will have to battle to earn the right to play again. There's been talk over the summer that they Celtic are looking for one or two more midfielders which will make it much more challenging."