Hailey Bieber shares her better butt workout — after declaring Pilates is ‘over’

Just months after declaring pilates was “over,” Hailey Bieber is showing off the next fitness craze powering her peach.

And experts say it can trick your muscles into working harder for a “crazy pump.”

“I love Pilates, I really do,” she said in an April interview with TIME. “But I think it’s become a little bit of a fad, and it’s really hard to find really good teachers that care about form.”

Less than two months later, Bieber posted a photo wearing a weighted vest, a popular exercise accessory that has exploded across social media, even as experts remain divided over its benefits.

But she was also sporting a less familiar piece of workout equipment that fitness professionals are far more enthusiastic about: Blood Flow Restriction (BFR) training bands.

Paul Comsulea, a personal trainer at Equinox in Southport, Connecticut, told the Post that BFR bands help isolate the glute muscles from the hamstrings, forcing the glutes to do more of the work.

By partially restricting blood flow into the muscle, the bands create metabolic stress — the burning sensation Comsulea and lifters describe as a “crazy pump.” That stress produces a chemical-rich environment that stimulates muscle growth, allowing users to achieve similar training benefits while lifting significantly lighter weights.

“The restricted blood flow tricks your muscles into working way harder than they normally would at that load,” explained Comsulea.

Because the glutes are working harder, lifters can often achieve gains comparable to those from lifting weights that are roughly 20% to 30% heavier.

Comsulea noted that the bands work best when paired with glute isolation exercises, such as kickbacks, bridges and banded movements, rather than heavy compound lifts like hip thrusts or deep squats.

Back that thing up — with research

The Rhode founder certainly seems to be on the right track.

A 2020 study published in the International Journal of Sports Physical Therapy compared eight weeks of BFR training with traditional high-load resistance training and a control group, examining muscular performance, pain and vascular function.

Researchers found that BFR training produced muscular performance improvements — including strength and endurance — and vascular benefits similar to supervised heavy resistance training, despite using much lower exercise intensity. The findings suggest BFR can be an effective alternative for people who cannot or should not lift heavy weights.

Still, experts warn that anyone hoping the bands are a shortcut to a perkier backside should temper their expectations.

BFR bands are not a get-out-of-leg-day-free card

While they can enhance glute activation, the muscles are ultimately built most effectively through compound movements like squats, Romanian deadlifts and lunges, which simultaneously strengthen the quads, hamstrings and glutes.

Skipping those foundational exercises means missing out on some of the most effective glute-building movements.

Hailey, for her part, gets her routine from celebrity trainer Kirsty Godso.

According to Women’s Health, Godso’s go-to combo starts with 12 banded glute medius hip thrust on each leg, is followed by 12 dual elevated hip thrust with a heavy dumbbell, and finishes with 12 single-leg dual elevated hip thrusts on each side.

There’s another downside to relying too heavily on glute isolation: Strong glutes paired with weak hamstrings is a recipe for multiple muscle imbalances that affect pelvic alignment, often leading to lower back tightness or pain over time.

For that reason, Comsulea says BFR bands are best viewed as a supplement to a well-rounded strength program, not a replacement for one.

“I will never recommend them to somebody who just started working out,” he said. “It’s more for advanced training.” Hear that? Mrs. Bieber’s bum is advanced.

Comsulea recently incorporated the bands into a program for a client he has trained for three years. Her current goal is building her glutes to achieve a lifted “bump” effect. The benefits, however, extend beyond aesthetic goals.

Comsulea said BFR bands can also be valuable tools for people recovering from knee or hip surgery who aren’t yet cleared for heavy squats or hip thrusts. By pairing the bands with bodyweight exercises like glute bridges, patients can continue stimulating muscle growth while placing far less stress on healing joints.

Older adults may benefit, too

Strong glutes play a major role in balance, stability and mobility as people age. BFR training allows older clients to challenge those muscles without relying on heavy loads that can place excessive stress on tendons and joints.

That said, Comsulea emphasized that proper placement, pressure and timing are critical. Worn incorrectly, the bands can reduce effecetiveness and increase the risk of injury.

He recommends learning the technique from a qualified trainer or physical therapist before attempting BFR training alone.

Consulting a doctor is also essential.

BFR training is generally not recommended for people with a history of deep vein thrombosis (DVT), blood clotting conditions, uncontrolled high blood pressure, active limb infections or whose who are pregnancy.