Sports Illustrated Model Nina Agdal Flexes Muscles in Topless Instagram Pic

We don't know about you, but we wouldn't want to pick a fight with Nina Agdal anytime soon. Gal has got some serious guns. READ: The Most Effective Ways to Tone Your Arms The Sports Illustrated swimsuit model (and cover-girl of the 2014 Swimsuit Issue) flexed her muscles for Instagram on Tuesday, showcasing her sculpted back and toned arms for the world to see. "Skinny doesnt mean weak," the Danish supermodel captioned the photo, along with a hashtag simply reading "#progress." And despite being topless in the pic, Agdal's recent Instagram snapshot somehow seemed tamer than the beach photo she uploaded just hours earlier on Monday, in which she shows off her rear-end in a pair of cheeky bikini bottoms. SEE IT: SI Model Irina Shayk Stuns in Low-Cut Swimsuit on Instagram In addition to flaunting her fantastic physique, Agdal also found time for a good amount of charity work over the past few days. The 22-year-old appeared at a New York Kiehl's location to participate in their Ride for Charity event alongside "Entourage" star Jeremy Piven last Thursday (where Piven reportedly flirted her up), and later attended the New Yorkers for Children gala at the Mandarin Hotel on Monday evening. Take a few more peeks at Agdal's Marchesa Notte dress from the latter event below, and be sure to catch Agdal's cameo in the upcoming "Entourage" film, slated for 2015.