SPEEDSTER Nakia Cockatoo completed his biggest session of the summer on Geelong's first day back for 2019 as he eyes an early-season return.

Pushing to overcome a left PCL injury that ruined his campaign last season, Cockatoo trained away from the main group alongside Zach Tuohy (knee) at Deakin University on Thursday.

The pair sat out the early morning Yo-Yo testing before they were put through a series of high-intensity skill-based drills.

Cockatoo, who had a shortened Christmas break compared to the rest of his teammates, then completed a series of 1km runs around the boundary line.

FULL FIXTURE Every round, every game

After he complained of knee soreness early in the summer and then had his tonsils removed, the sight of Cockatoo running freely will have excited the Cats' hierarchy.

Tuohy is still recovering from post-season knee surgery and is expected to ramp up his running loads in the next fortnight.

Biggest conditioning session of the summer yet for Nakia Cockatoo on Cats' first day back. Trained away from main group with Zach Tuohy then completed a series of 1km runs @AFLcomau pic.twitter.com/zqJDwAE26R — Mitch Cleary (@cleary_mitch) January 10, 2019

Midfielder Sam Menegola was also a notable absentee as he also works back from his own knee cleanout, while captain Joel Selwood only completed running in the first 45 minutes.

The entire session lasted more than two-and-a-half hours with Tim Kelly, Brandan Parfitt and Luke Dahlhaus among the standouts in a prolonged period of match simulation.

MUST-WATCH GAMES The 22 you won't want to miss

Assistants Nigel Lappin, Matthew Knights, Corey Enright and Matthew Scarlett took much of the session, with coach Chris Scott still absent having been granted longer leave.

Small forward Lachie Fogarty was back for his first full session of the pre-season, while defender Jed Bews and ruckman Ryan Abbott took part after enjoying modified programs pre-Christmas.

Fellow big man Zac Smith, who has battled recently back troubles, ran laps after taking part in early contested drills.