She looked very fit while running around Los Angeles on set of Shameless on Friday.
But Emmy Rossum joked that she had a hard time delivering her lines while out of breath.
The actress was spotted filming with Cameron Monaghan, while showing off her flat stomach and slender legs in a black sports bra and blue shorts.
‘Filming a scene today where Fiona and Ian are jogging and talking,’ she tweeted that morning to update her 418,000 followers.
‘I'm sorry. People can actually speak while running?! #shameless’
To top off her workout wear, Emmy wore a pair of red trainers, and had her brunette locks tied in a ponytail. She appeared to be make-up free, although was likely wearing a little for the cameras. Emmy wisely decided to protect her porcelain skin from the harsh rays of the sun while spending a good deal of time outside, as she strolled under an umbrella.
Once she had finished shooting, the 27-year-old slipped on a grey T-shirt and headed into a trailer.
In the scene, Emmy and Cameron, 20, push their on-screen half-brother Liam as well as another child in a stroller.
Cameron is also dressed in gym gear in the form of a green tank top, grey shorts and matching trainers.
On Monday, Emmy posted a photo on Instagram of her character Fiona getting hit with a drink as she revealed cameras were rolling on the Shameless set again.
‘Season 5 starts filming today. It's a true Gallagher summer. Let's hope it goes better for Fiona than last time we saw her during summer,’ she wrote.
Aside from Shameless, Emmy has three films out this year.