How Natalie Portman got in serious shape to become The Mighty Thor

Natalie Portman as Mighty Thor in the Thor: Love and Thunder teaser trailer
(Image credit: Marvel)

You don’t need to be a Marvel fanatic to know that playing Thor involves a certain amount of bulking up. And now there's a new Mighty Thor in Thor: Love and Thunder.

You could argue that Chris Hemsworth’s ripped arms were as much a focal point in previous films as his lightning-infused hammer (here’s his exact arm workout, and a review of Centr, his training app). But as Natalie Portman steps into her new role as The Mighty Thor, everyone is talking about how the 40-year-old Black Swan star built those biceps. 

When the Thor: Love and Thunder trailer dropped, social media lit up with a serious appreciation for Portman’s arms — “Good morning to Natalie Portman’s arms and Natalie Portman’s arms only”, one Tweet read. Marvel fans will be thrilled to hear the wait to see Portman's arms in action is nearly over - the film drops this Friday, July 8. Here's what the early reviews of Thor: Love and Thunder are saying. 

But how did Jane Foster get in shape to wield the Mjolnir? Here’s what we know about Natalie Portman’s Thor workout:

How did Natalie Portman build muscle to play The Mighty Thor? 

Unsurprisingly, it seems the main secret behind those arm muscles is a set of dumbbells. "It was really fun. I worked with a trainer, Naomi Pendergast, for, I think it was, four months before shooting, and then obviously all the way through filming," Portman told Vanity Fair. 

“We did a lot of weight training and a lot of protein shakes — heavyweight training that I haven’t ever done before. Of course, I’ve never really aimed to get bulky. It was very physical, so it was a lot of both agility work and also strength work” she added. 

Of course, Portman is no stranger to undergoing a serious body transformation for a role. Pre-Thor, the actress dropped 20 pounds for Black Swan, by restricting her diet and training for long periods of time. That said, Portman was new to strength training when approaching Thor. According to an interview with Women’s Health UK, Portman prefers heading out for long runs a few times a week, and doing regular yoga practice to stay in shape. 

Portman also follows a vegan diet, which proves you don’t have to be eating mouthfuls of chicken to get in superhero shape. 

a photo of natalie portman at the Thor:Love and Thunder premiere

(Image credit: Getty/Gareth Cattermole / Staff)

The best dumbbell arm exercises to try 

Inspired? While Portman hasn’t revealed exactly which dumbbell exercises she favored to build her upper body, we’ve found some of the best arm exercises to add to your routine. Strength training at home? Here are the best adjustable dumbbells and the best resistance bands to shop right now. 

Arnold press 

To do an Arnold press, start by standing with your legs shoulder-width apart, holding a dumbbell in each hand, with your elbows bent, as if you’ve just completed a dumbbell curl, with your palms facing your body. In one fluid motion, raise the dumbbells above your head and rotate your palms out away from your body. Pause at the top of the movement, when your arms are extended straight above your head, before reversing the movement so you are back at your starting position. 

Here’s more on how to do an Arnold press, and the variations to try. 

Bicep curl 

To do a bicep curl, hold one dumbbell in each hand and take it in turns to curl the weight up to your torso, working one arm at a time. Be careful not to swing the weights back and forth — keep the movement slow and controlled and make sure it’s the bicep that’s doing the work. 

Shoulder press 

Holding the dumbbells on your shoulders, press them up above your head, then back to your starting position. Keep the movement controlled. You can bend the knees and bounce upwards slightly if you need the extra momentum. 

Single-arm row 

For a single-arm dumbbell row, you’ll need something to lean on, like a chair, box, or just the side of a coach. Start by placing a dumbbell on the side of your platform, and kneel your left leg and right hand on the bench, so that your upper body is parallel to the ground. Reach down and pick up the dumbbell with your right hand. Keep the grip neutral, so that your palm is facing your body, and keep your arm outstretched. Slowly, and with control, bring the dumbbell up towards your chest, hinging at the elbow.

The movement should come from your back and shoulder muscles, not from your arm. Pause at the top of the movement, before lowering the dumbbell back to your starting position. Do all your reps on one arm before you switch to the other side. 

Here’s more information on how to do a single-arm row, and the best variations to try. 

Chest press 

To perform the chest press, take a dumbbell in each hand and lie down on a bench. Make sure both feet stay firmly planted on the floor. Keep your spine neutral and your core engaged. Bring both your arms out to the side, elbows bent and aligned slightly below the shoulder line, with your forearms perpendicular to your torso and your palms facing in front of you. Lift both dumbbells above your chest, aiming them for right above your breastbone. Squeeze your shoulder blades together and slowly return both weights to the starting position.

Front raises 

To do front raises, start by holding a dumbbell in each hand. Keeping your arms straight and your core engaged, raise your arms out straight in front of you. Pause at the top, before lowering the dumbbells back to your starting position. 

Looking for more workout inspiration? Here are the best resistance band arm exercises to build your arms without weights, how to do an upright row, and the best workout apps for training at home and in the gym. I've also tried Khloe Kardashian’s workout — and it’s intense.

Jane McGuire
Fitness editor

Jane McGuire is Tom's Guide's Fitness editor, which means she looks after everything fitness related - from running gear to yoga mats. An avid runner, Jane has tested and reviewed fitness products for the past five years, so knows what to look for when finding a good running watch or a pair of shorts with pockets big enough for your smartphone. When she's not pounding the pavements, you'll find Jane striding round the Surrey Hills, taking far too many photos of her puppy. 

  • James LaBarre
    It's "Woke Hollywood", why would anyone there think they'd actually have to prepare for a role? That would be like doing actual work, and would require making an effort to not suck.