Chris Hemsworth's recent Instagram post showing off his fit physique had social media abuzz.

The Marvel star, 37, uploaded a photo of his bulging arm on the set of the latest "Thor" movie filming in Australia but fans couldn't help but comment on his skinny legs. 

"Holding my little man's hand and asking him the age old question, 'What do you want to be when you grow up.' 'Dad i wanna be Superman.' Lucky I have two other kids," he joked in the caption.

Hemsworth's older brother Luke, ripped his sibling in the comments section. "Bro?! You've been skipping leg days again?!" he questioned. The comment received over 70,000 likes.

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Another fan said, "The legs don’t match the top."

"Should really be training legs too bro," agreed another.

Chris Hemsworth arrives at the premiere of "Avengers: Endgame" at the Los Angeles Convention Center on Monday, April 22, 2019.

Chris Hemsworth said his workouts for "Thor" focus on his upper body because that's "what you see the most." (Photo by Jordan Strauss/Invision/AP)

Meanwhile, someone else complimented Hemsworth's insanely buff upper body. "Tricep game on point," he said.

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The action star previously told the Telegraph that his training for "Thor" does focus on his arms, chest, and back because it's "what you see the most."

"Working with my trainer, we consider the costume and if it shows a lot of shoulder, or are we gonna see the bicep or the traps," he explained. "But you want it to be balanced, because there's probably a shirt-off scene somewhere. You don't want to look like Popeye with one section of the body blown up."

This publicity photo released by Walt Disney Studios and Marvel shows Chris Hemsworth in a scene from "Thor: The Dark World." (AP Photo/Walt Disney Studios/Marvel, Jay Maidment)

Chris Hemsworth in a scene from "Thor: The Dark World." (Marvel/THE ASSOCIATED PRESS2013)

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Hemsworth's post also confirms "Fat Thor" will not be returning to the screen. When last viewers saw Thor in "Avengers: Endgame," he had put on several pounds and was unkempt due to the depression he experienced following his first loss to Thanos in the movie "Avengers: Infinity War."

"Thor: Love and Thunder" will also feature Chris Pratt, Natalie Portman, and Tessa Thompson, who are reprising their roles from previous movies. 

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In addition, Christian Bale and Russell Crowe are joining the franchise in the fourth movie, which will be helmed by "Thor: Ragnarok" director Taika Waititi.

The film has a slated release date of February 11, 2022.

Fox News' Tyler McCarthy contributed to this report.