IF there was an award for the hardest working player in Scotland, then Rob Harley would definitely be on the short list. For "a machine", as one of his previous coaches used to describe him, there is a special sort of frustration on the rare occasions injury does strike.

Worse still, when it is one of those annoying little problems that strikes in training a couple of weeks before the action starts with a new coach to impress. Which is precisely what happened to Harley, who damaged a foot in August.

Now, though, he is back, ready to go and raring to take out his frustrations on Benetton Treviso when they visit Scotstoun tomorrow. It looks as though he is going to get his wish, after a run from the bench last week eased him into the playing side of things.

"It is frustrating, especially with the work you put in during pre-season towards being ready and putting everything out in the game and then not being able to play," he admitted. "The ethos with the squad, though, means it’s important to see results and the coaches are good at keeping everyone involved.

"I was coming in [when he was injured] and keeping on top of the lineout calls. I was throwing in ideas on what we can do tactically there. We kept the engine-room players involved in a lot of what the squad was doing. That’s good for when you are ready to come back and are fully integrated."

So far, Harley has been pretty much bomb-proof in his career. In the eight seasons he has been at Glasgow – he is just starting his ninth – he played 163 club games while also winning 20 caps for Scotland – making an average of around 23 games a season. In 2013-14, he played in every league game and missed only the two Heineken Cup games against Toulon – a remarkable feat given that he plays in such an abrasive way in such a taxing position.

Watching the side win, even it if took until last week before they produced a performance that came remotely close to satisfying their own and their coaches' standards, did help but all the same, all Harley wants is to get back out on the field for 80 minutes.

"It's really good to be back," he said, "In the Cardiff week [a fortnight ago when he travelled as 24th man] I was fit. It was good to go down and be part of the team environment and be a step closer to playing. Then I got another week of building up.”

While he was away, the competition for places in the side has only increased. Adam Ashe has been living up to his potential now that he is injury free and getting a run of games, Callum Gibbins has proved to be an inspired signing at flanker and Ryan Wilson has taken over as captain.

"I’ve played with Ryan since the Under-20s – it's a long, long time. He’s adapted really well to captaincy. He’s respected by the whole squad and leads from the front on the field during games. He’s very easy to get behind,” said Harley of his old colleague.

Added to that Dave Rennie and his fellow coaches are obviously anxious to get promising youngsters like Matt Fagerson and Matt Smith as involved as possible, while there are still the old stagers like Chris Fusaro there to challenge with Samuella Vunisa, the Italian international, yet to come back from injury, and the list of back-row candidates is not just long, but packed with quality.

"It’s a challenge, but also healthy," Harley reflected. "When we train we push each other on and pick up tips from each other. We’re all trying to improve.”

That really is the key. Even though Harley is living testament to the abilities of some players to churn out huge performances week after week, he is the exception, not the rule and, as recent weeks have proved, even he can get injured. They need to be able to swap players in and out without it affecting the quality of the side.

The first big test of that will come tomorrow. It looks as though Rennie is ready to break up some of the key partnerships that have been ever-present in the first four games of the season, with Harley one of the beneficiaries when he comes into the back row.

With the established side having made a bit of a statement last week with their demolition of Munster, it is up to the rest to show that they can match that when pitted against an Italian side full of confidence after winning successive games – though they have not won three in a row since 2012.