MARCUS Bontempelli is set to build on his outstanding debut season after returning to training noticeably bigger.

The young Western Bulldog has been an early star of the pre-season, according to assistant coach Steven King, having added about 7kg to his 193cm frame.

It's an enticing prospect for fans who watched the teenager shrug opponents off with ease at times in his first season, most notably when he kicked a match-winning goal against Melbourne in round 15.

"He has dominated. He came back looking really good," King told the Herald Sun of Bontempelli, who finished one vote behind young Lion Lewie Taylor in last season's NAB AFL Rising Star Award.

"He has put on a bit of weight and is about 93 kilos now. That's about seven kilos more than he was (at the start of last year). He is starting to fill into his frame."

While Bontempelli is flying, another high-profile Bulldog pup is being eased into training.

Prized recruit Tom Boyd, lured from Greater Western Sydney on a seven-year deal reportedly worth more than $6 million, is yet to hit the track with his new teammates after recovering from appendicitis.

Instead, the key forward has spent time training indoors. But he could be back on the track as early as Thursday, King said.

"He's been here since last Wednesday, but we are just keeping an eye on him at the moment. He is just doing some screening work before he really gets started," he said.

"He reminds me of when Tom Hawkins first came into Geelong - he's a real big lump of a kid."

The Bulldogs' first-to-fourth-year players have been undergoing testing and screening for the past week, with the club's senior group to return next week.

"It's an exciting young group we have in at the moment," he said. "They are the ones who are going to hold the place to account a bit.

"If they are up and about early with their testing, it provides a good example to the other guys."