ST KILDA's Luke Dunstan wants to emulate the efforts of teammate David Armitage this summer and shed the kilos as he looks to recapture his promising first-year form.

The 20-year-old, who was often tagged as Lenny Hayes' obvious midfield replacement going into 2015, admits he failed to reach the heights he expected to in his second season.

While he played 19 games, he found himself constantly having to deal with pain associated with the shoulder reconstruction that ended his 2014 early.

"It was on-going pain. Some days it was better than others, but early on in the season I lost a bit of confidence in my ability to tackle and my contest, which is the main strength of my game," Dunstan told AFL.com.au.

"With that dropping off a little bit, my confidence went downhill.

"It wasn't where I needed to be at. Obviously I didn't play the football I wanted to play.

"I still tried my guts out and did the best I could, but the running and the physical side of the game – my two strengths – dropped off and exposed my football."

Surgery August 2014 meant he didn't do any contact work until after Christmas that year. It also restricted his weights program in what was meant to be his first full AFL pre-season.

Despite his reduced work load, Dunstan was surprised at how affected he was in 2015.

"I didn't really know what to expect going into the surgery. I sort of just thought I'd do my rehab and everything would be fine, because I didn't know any better," he said.

"Now that I've been through it, it definitely did surprise me, how long the niggle can hang around.

"It just plays on the back of your mind, more subconsciously than consciously.

"Your body sort of adapts if it feels any pain and goes back into its shell so it doesn't hurt itself."

Two weeks after last season ended, with his shoulder rested, Dunstan already felt better.

He came back to face a full pre-season program with new weights and running challenges set down by the coaches.

Armitage, 27, was used as an example by senior coach Alan Richardson.

The much-improved midfielder shed kilos over last pre-season, improved his running ability, and with Jack Steven ran the Saints' midfield in 2015.

"I saw what he did last year and it sort of surprised me a little bit, how much you can improve your running just from dropping a couple of kilos," Dunstan said.

"I spoke to 'Spud' [Danny Frawley] and he said to try running around with a bag of oranges in each hand.

"That sort of put it into perspective a little bit.

"What Dave's done has given me a bit of hope."

Dunstan missed the Saints' first time trial because of calf soreness that kept him out for a week but has since beaten his personal best after losing two kilos.

He's been working with midfield coach Adam Kingsley on improving his contested work, having also taken plenty from a pre-season address from tennis great Pat Rafter.

"He spoke about focusing on your strengths more than your weaknesses – that's what took him to the next level," Dunstan said.

"We just put a massive emphasis on my strengths and just getting them as good as they can be and turning them into weapons.

"The main focus is the contest and getting the confidence back with that and tackling and then winning the ball as well.

"The other side of that is the running, and I really feel like I'm improving in both of them at the moment."