Reformer pilates studios in the United Kingdom have increased ten-fold since 2024, but experts warn of severe injury risks from unqualified instructors.
The resistance based workout is performed on a sliding wooden carriage with a foot bar, pulleys and straps. Classes can cost up to 80 pounds in parts of London, compared with about 15 pounds for a standard floor mat session.
While enthusiasts say the machines build muscle tone and growth faster than bodyweight exercises, the Managing Director of training body Health and Fitness Education has described the classes as a 'wild west'. He called the reformer a 'human catapult' and warned that many instructors have 'no supervised training', leading to traumatic injuries.
Several users have suffered serious accidents on the machines. Last year, Kirsty Morgan, a 30-year-old pilates teacher from Essex, required four layers of stitches and a tetanus shot after a metal frame separated from a reformer and hit her head. Doctors told Morgan she could have died if the 20 kilogram structure had struck her temple.
In 2019, the acclaimed violinist Maya Meron successfully sued a London pilates studio after a reformer machine collapsed on her, breaking her left elbow and injuring her abdomen.
Reformer pilates is a low-impact, full-body workout. It is based on the methods of Joseph Pilates, the founding father of the exercise, who attached springs to hospital beds during the First World War to help rehabilitate patients using resistance training. Some say the modern wooden contraption still resembles a 1950s hospital bed.
Today, fans argue that the machines offer a better workout because they involve pushing and pulling a heavier weight than simply a person's own body.
Added resistance
Rhian Cowburn, a pilates instructor and co-owner of the London studio Strong and Bendy, said the machine offers versatility.
"A beneficial class, mat or otherwise, will challenge all the major muscle groups," Cowburn said. "But by adding in extra resistance with the reformer you can create pulling movements that you don't get with mat pilates. It broadens the range of exercises you can do, recruiting a wider selection of muscle groups."
Cowburn said pushing movements strengthen the chest and shoulders, while pulling activates the major back muscles that govern upper-body strength and posture, which many people struggle to build.
"For instance, pulling the straps on a reformer will strengthen the muscles required to do a pull up, which is an exercise most people can't do," she said. "Regular mat pilates might get you there, but it would take far longer."
The external resistance is the main difference between reformer and mat classes. Springs attached to the pulleys and straps increase the load on the glute and core muscles, ensuring they are consistently engaged during a particular exercise. On a floor mat, participants must consciously squeeze those parts of the body to guarantee muscle gains.
Because of this constant engagement, Cowburn said people often progress more quickly on a machine, finding they require fewer sessions to see changes in control and strength.
Rehabilitation and mobility
Springs also allow movements to be performed through a greater range of motion, which can improve joint stability and flexibility while still providing support.
Cowburn said that while genetics remain the main driver of body shape and a reformer will not completely transform a physique, it can visibly tone muscle in multiple areas.
"It's far easier to achieve this with added resistance," she said.
The machine is also used to overcome injuries, an often overlooked benefit.
"The springs reduce pressure on the joints, so you can build strength without aggravating pain," Cowburn said.
Controlled resistance makes movements such as lunges and squats more accessible for people with mobility issues or arthritis, challenging the muscles that support joints without adding strain.
Reformer machines also allow for standing exercises, which is useful for older adults who struggle to get on and off the floor.
"Most of the people who come to my classes are aged between 25 and 45, but the benefits extend far beyond the 50s," Cowburn said.
Avoiding injury
Despite the warnings about unqualified instructors, Cowburn said the risk of injury is low at reputable studios that ask teachers to hold recognised certifications, such as a Level three pilates qualification.
She said the most common mistakes are made by participants who adjust the springs themselves, hoping to increase the challenge without understanding how the machine works.
"In classes that involve lifting weights, the heavier the weight the harder the exercise becomes, but this isn't necessarily true of reformer," Cowburn said. "So there's danger when people change springs with the hope of 'increasing' their challenge, without understanding what they’re actually doing."
Pregnancy also requires caution, as some movements are more difficult to modify on a reformer than on a floor mat. However, Cowburn stressed that serious accidents are rare.
"The risk of being injured is really low if you’re listening to what the teacher is telling you," she said.
