Justin Clarke Biography

Justin Clarke retires due to ongoing symptoms from a concussion suffered two months ago.

"It's been a long process to get to this decision. I've sought advice from multiple specialists who have all confirmed that the decision to stop playing football is the right one," Clarke said.

Justin Clarke has been ruled out of football indefinitely due to concussion.

Clarke suffered a head knock at training four weeks ago and scans cleared him of any break or fracture to his neck.

However, the 22-year-old has not returned to training since the incident, and has undergone regular concussion testing.

Lions medical staff have consulted concussion specialists in both Brisbane and Melbourne as Clarke's symptoms persisted.

Testing has not shown any damage to his brain, but Lions football manager Matt Francis said the club would take an ultra-cautious approach.

"Our medical staff and Justin are working through his symptoms on a daily basis and there is no timeframe set for his return," Francis said.

"Justin has been completing a university degree during his time with the club and he has very definite plans for his career post-footy - that will influence any decisions going forward."

As Justin Clarke battles to recover from concussion, fellow concussion sufferer Matt Maguire says the young Lion should not risk his future as an academic.

Clarke is one of the smartest men in the AFL, scoring 99.95 per cent on his Australian Tertiary Admission Rank entrance score and is an engineering student whilst being a physics tutor for high school students.

"I'm not worried if I lost a couple of brain cells, but I think that'd be more relevant to Jase (Clarke)," Maguire said.

"Jase has got a really bright academic future in front of him that requires a high level of intellectual application, and that's something I'm sure he'll consider during what I hope is a speedy recovery.

"I reckon if he had to choose between the two, just my read and I could be wrong, he'd say: 'I don't want to risk my head'."

The Brisbane Lions are breathing a collective sigh of a relief after young defender Justin Clarke escaped serious injury following a heavy knock to the head at training on Monday.

Clarke copped a knee to the head in a marking content and fell to the ground heavily during the Lions' training session at Coorparoo.

The 22-year-old was taken to hospital in a neck brace, but scans revealed no break or fracture to Clarke's neck.

He is expected to be discharged from hospital on Monday night and will be further assessed before a decision will be made on when he returns to training.

After being elevated off the rookie list and impressing in 14 games in 2013, Justin Clarke re-signs with the Brisbane Lions until the end of 2016.

"The Lions took a massive leap of faith in drafting me, so I feel a massive sense of loyalty towards the club for giving me this opportunity," Clarke said.

"The club has been incredibly supportive and has really helped in my development as a player. I'm obviously really excited about where this group is headed, and I can't wait to be part of its future."

Justin Clarke is set to buck the trend set by his homesick Brisbane Lions teammates and sign a three-year contract extension with the club.

Justin Clarke makes his AFL debut for Brisbane at the Gabba with 7 disposals (4 kicks and 3 handballs), 3 marks and 3 tackles in a 28-point win over Melbourne.