TASMANIAN Olympic runner Tristan Thomas remains confident he can return to elite competition despite making the difficult decision to withdraw from the Commonwealth Games.

Niggling injuries have plagued the 28-year-old 400-metre hurdler's career, prompting him to pull the pin on next month's event, eight years after he first graced the international arena on the same stage.

``If everything had gone well, I was confident I could have been a competitor but if you really want to achieve anything, everything has got to be working,'' Thomas told The Examiner from his base in Canberra yesterday.

``I would be leaving Australia in a couple of weeks and I'm not even running, so really it's a no-brainer.

``It's still a hard decision and gets harder the older you get because when you're 19 and looking at missing a team you think you've got many more to come, but the older you get, every year becomes special.

``My body just has not healed. Some injuries are very straightforward and you can say will be four weeks or six weeks, but this is one that does not present normally. 

``It's really frustrating. It's like keeping a bird but not letting it fly.''

Thomas's withdrawal, which reduces Tasmania's Commonwealth Games contingent to six with hockey yet to be named, was brought on by a persistent problem with his glute and sciatic nerve.

``I don't know exactly what the problem is but it's difficult to manage and I cannot run properly,'' said the Sandy Bay Harrier.

``Even if you are only 90 per cent you're going to get destroyed and there is no likelihood of a good result because it will be a very strong competition. Just making the final will be difficult.

``Mentally, it does your head in, but in the end I just got dealt a bad card.''

A three-time national champion, Thomas ran the 400m hurdles at the 2006 Commonwealth Games in Melbourne and was a semi-finalist at the 2012 London Olympics, but finished second at the Australian titles this year after smashing into the fifth hurdle.

He had also been selected for Glasgow in the 4x400m relay, an event in which he helped Australia to a bronze medal at the 2009 world championships, but said national head coach Eric Hollingsworth was understanding when he withdrew.

Thomas has returned to his architecture studies in the national capital where he is restricted to slow jogs and gym work.

``I still believe I can run fast and won't stop until I do,'' he said. 

``I'm enjoying my degree and life's good up here so I can't complain.

``My last competitive experience was smashing into a hurdle at nationals and that's not a great motivator, but I have no choice but to keep going if I don't want to just become someone who could have been.

``Every morning when you wake up and see what results other athletes have achieved, it does make you hungry to come back.''