THE FIRST thing Brodie Smith remembers after being knocked out cold against Collingwood in round two was Adelaide's medical staff fitting him with a neck brace.

After being flung around in a tackle midway through the final quarter, Smith's head hit the knee of an opponent and he was left face down and unresponsive on the Etihad Stadium turf.

He said his parents, who were watching on from the stands, were "freaking out".

Five weeks later Smith suffered his second-ever concussion when caught in the path of a rampaging Nick Riewoldt at Adelaide Oval.

This time it was Smith's opponent who was left worse for wear, while the Crows' defender was able to walk from the field.

Yet despite the appearance of the incidents, it was the second concussion that hit hardest and forced him sit out the following two games.

Smith trained fully for the first time since colliding with the St Kilda skipper on Wednesday and he told AFL.com.au the two concussions were frightening.

"The first one was [scary] - when I woke up and I had trainers putting the neck brace on and I didn't know what was going on, that was a bit strange and luckily my parents were at the ground but they were freaking out as well," Smith said.

"To be able to walk off after the second one was a bit nicer.

"I probably didn't recover from the second one – although it didn't look as bad –as well as the first one.

"That was really frustrating, I was able to walk off but not be able to play for two weeks.

"You've just got to rest up; I spent a couple of days in my room trying to rest my brain which was pretty weird.

"I was getting tired really quickly and things like that, it was a bit of a frustrating one."

The concussions have been a severe hiccup in a season which Smith is looking to build on his 2014 All Australian selection.

Last year he was ranked second in the League for rebound 50s and averaged a career-high 23 disposals a game.

He'd had 29 possessions before he was stretchered off against the Magpies and had been in great touch the week before against North Melbourne.

But he struggled to reach his expectations in the rounds that followed, averaging fewer than 17 touches a game in the four that led to his run-in with Riewoldt.

Now the lingering effects from the two concussions have subsided, Smith will look to again assert himself one of the AFL's premier rebounding defenders.

"I really was keen to back that up, I didn't want to fall away from my form last year and I had a pretty good game too against Collingwood before I got knocked out," he said.

"I haven't really been able to get the form back from that and then obviously a couple of weeks ago I get another [concussion].

"It's been frustrating, but thankfully the team's not going too bad – we showed on Saturday (against Fremantle) that we can really take it up to the best sides.

"Hopefully now I can come back in and contribute to the side and we can really push for some finals footy."