Collingwood's Arizona AFL training squad have been drug-tested twice in two days, which suggests they are the subject of target testing.

Midfield star Dane Swan, one of four Magpies undergoing heavy training at altitude in Flagstaff, Arizona, said the quartet were woken early on Tuesday.

"Nice of the drug testers to wake us up this morning for another test. I really hope they come tomorrow too. Please send them again," Swan quipped through his Twitter account.

They were also tested on Monday, prompting a similarly-sarcastic tweet from Swan: "I knew coming to Flagstaff to pump ourselves full of steroids would backfire!"

An AFL spokesman said players could be tested at any time or location, at any stage of the year, entirely at the discretion of the Australian Sports Anti-Doping Authority (ASADA).

Ruckman Darren Jolly, forward Brent Macaffer and key defender Nathan Brown were also in Arizona, where coach Mick Malthouse said they were building their fitness with a huge training load.

The mid-year trip is an attempt to build on the success Collingwood have had in taking their entire squad on an annual pre-season training camp to Arizona.

Magpies' midfielder Sharrod Wellingham said the team credited their phenomenal record in last quarters this season to those trips.

"You can probably put that down to the guys, like they're over there in Arizona now, that gives us a lot of confidence in the fitness base that we have," Wellingham said.

"I think later on in the year, we'll get even more from it, because we'll draw on that and we know what we've done in the past.

"We'll have a lot of confidence to be able to run out games right to the end without getting too fatigued, especially with the substitute rule now."

Collingwood outscored Melbourne 8.5 to 1.0 in the final term on Monday at the MCG.

In their 11 games this season, they are an average 26 points better in last quarters than their opposition.

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