When the first trailers for The Better Sister dropped, the internet didn't just talk about the plot. They talked about the white dress. More specifically, they talked about Jessica Biel arms and that incredibly defined back. It’s one of those "stop and rewind" fitness moments that happens once every few years in Hollywood. Suddenly, everyone wanted to know the "secret" to those delts and that razor-sharp tricep definition.
Honestly, the truth is a bit more complicated than just doing a bunch of bicep curls.
Most people assume that to get arms like that, you have to spend two hours a day punishing your upper body with heavy iron. That’s actually the first thing people get wrong. Jessica Biel isn't living in the gym 24/7, and her trainer, Ben Bruno, is pretty vocal about the fact that they don't even do a traditional "arm day."
If you're looking for a magic pill, you won't find it here. But if you want to know how a 43-year-old mother of two builds world-class muscle while balancing a chaotic life, the actual blueprint is surprisingly logical.
The "Anti-Arm Day" Approach to Sculpting
You’ve probably seen the viral clips. Jessica is on the floor, legs locked in an L-sit, pulling her entire body weight up using gymnastic rings. It looks intense because it is. But here’s the kicker: Ben Bruno revealed that she doesn't actually do those L-sit pull-ups all the time. That was a "peak" move used right before filming to sharpen her conditioning.
Basically, her routine is built on efficiency.
Instead of isolating just the biceps or triceps, she performs full-body circuits that force her arms to work as stabilizers. Think about it. When you do a Bulgarian split squat while holding a heavy dumbbell in one hand for a lateral raise, your arm isn't just "working"—it's fighting to keep you from toppling over.
That constant tension is what creates the "pop" in the muscle.
A Typical Session Breakdown
In a given workout, she usually hits one exercise for the back (which naturally hammers the biceps), one for the shoulders, and one for the triceps. Then, she sprinkles in heavy leg work and core.
📖 Related: Mila Kunis Explained: What Most People Get Wrong About Her Career Right Now
- The Back/Bicep Hybrid: Usually something like ring rows or assisted pull-ups.
- The Shoulder Burner: Single-arm lateral raises, often done while balancing on one leg to spike the heart rate.
- The Tricep Finisher: Skull crushers, but with a twist—like holding a bridge or a single-leg raise to keep the core engaged.
Why "The White Dress" Look Isn't Permanent
We need to talk about the "peak shape" myth.
Jessica was incredibly transparent on TikTok about this recently. She admitted that the physique everyone saw in The Better Sister—the one where every fiber of her back and arms was visible—isn't maintainable year-round. She called it a "stricter, more rigid lifestyle" that she can't (and won't) sustain indefinitely.
Usually, she operates at a "7 out of 10" intensity.
She ramps it up for a few weeks before a big role or the Met Gala, then slides back into a more balanced routine of yoga, Pilates, and moderate lifting. It's a refreshing bit of honesty in an industry full of filters. She’s not trying to look like a superhero 365 days a year. She’s trying to be "older and stronger," a mantra she shares with her Pilates guru, Ashley Brown.
👉 See also: Sarah Michelle Gellar Bra Size: Why It Matters Less Than You Think
The Role of Variety and "Boring" Habits
If you look back at her fitness history, she’s been an athlete her whole life. In her 20s, it was about how much she could bench press. Now? It’s about mobility. She doesn't want to live in pain. This shift led her to embrace things like the Norwegian 4x4 protocol on the Airdyne bike—a brutal form of cardio that maximizes oxygen hit—and consistent yoga sessions.
She also sticks to the "boring" stuff that most people skip:
- Epsom Salt Baths: She famously used 20 pounds of Epsom salt before the Met Gala to shed water weight and soothe muscles.
- The Garden Diet: She eats a ton of greens literally pulled from her own backyard—radishes, spinach, and salads are her staples.
- Hydration and Sleep: She’s gone on record saying these are the most "boring" but effective parts of her routine.
Practical Steps for Real-World Results
You don't need a Hollywood trainer to see progress, but you do need to stop training like a bodybuilder from the 90s.
If you want to emulate the Jessica Biel arms aesthetic, stop doing 15 different types of curls. Instead, focus on multi-joint movements that require your arms to stabilize your body weight. Start incorporating gymnastic rings or TRX straps for your rows. The instability forces the smaller, "sculpting" muscles in your shoulders to fire in ways a standard machine won't.
More importantly, adopt her "7 out of 10" rule. Be consistent with your movement every day, but don't burn yourself out trying to reach a "peak" that was meant for a camera lens. Focus on being able to move without pain, and the definition will follow as a byproduct of that strength.
What to Do Next
- Swap one "arm day" for a full-body circuit: Combine a pulling movement (row) with a balance element (single-leg hold).
- Incorporate Unilateral Work: Use one dumbbell at a time for overhead presses or rows to force your core to stabilize.
- Prioritize Mobility: Add 15 minutes of yoga or dynamic stretching after your lifts to keep the muscles long and prevent the "bulky" feeling Jessica mentioned she used to struggle with as a gymnast.
Strength isn't about the number on the dumbbell; it's about the tension you can create and the consistency you can keep when the cameras aren't rolling.