TORONTO - Elliptical trainers have been a longtime presence in gyms and fitness facilities and a go-to piece of equipment for those looking to get their cardio fix.

But for individuals suffering from lower back problems, research suggests they may need to think twice before stamping their ticket to ride on the popular workout machines.

The elliptical trainer, sometimes called a cross-trainer, is a piece of stationary exercise equipment that simulates walking or running without causing pressure to the joints.

Researcher Janice Moreside is a physiotherapist who's been a clinician for more than 30 years. She said she's found that while the majority of people who come in who use the elliptical like it, there's a subset who say the opposite, and point to the fact using the trainer hurts their back.

Moreside, a University of Waterloo PhD candidate, works with Waterloo professor Stuart McGill whose specialty is spine research, specifically the lumbar spine or low back.

The research was part of a larger study looking at the effect of hip mobility on the low back which Moreside presented Friday at the 2010 Congress of the Canadian Physiotherapy Association in St. John's, N.L.

The study involved 43 males aged 19 to 30 who exercised on the elliptical trainer at two speeds: a self-selected speed and 30 per cent faster.

They would change variables, adjusting stride length from 18 to 26 inches (about 46 to 66 centimetres) and hand position from either holding the handles, the central stationary bar of the machine or freehand. Moreside said while individuals don't necessarily move to and fro more while on the elliptical, they do adopt a more flexed posture.

"They bend forward and kind of stay there and oscillate around a more flexed posture on the elliptical trainer than compared to walking, no matter what their hand position or stride length or speed was," she said.

They also twist more on the elliptical trainer than in walking, no matter how much the other variables changed, she said. And for most conditions, they actually bent side to side less than in normal walking.

"So what the elliptical does is it stops you bending side to side, but you end up twisting more and you end up being flexed forwards more," she said.

Moreside said all of those findings do affect the lumbar spine or low back.

"If you are somebody who has a lumbar disc problem, we recommend that you don't bend forwards very much. So for them, the elliptical might not be the choice because you bend forwards more than you do in walking," she said.

On top of that, users also twist more. The repeated flexion and twisting are known scientifically to encourage this degeneration, Moreside said.

"If you're already starting to get a bit of disc breakdown or sensitivity, this may not be the medium of choice for you."

That said, for those who are older and have more joint problems in their low back as opposed to the disc, joints like to be flexed, Moreside said. As a result, some may find they prefer the elliptical.

"It also does not require as much hip extension as normal walking," Moreside said. "If somebody finds that going into hip extension is painful or has had an injury, they may find that this is quite satisfactory because they are safe, they're holding onto something."

For those without any low-back problems and who are pain-free, Moreside said there shouldn't be any issues when it comes to using the elliptical.

"There's a lot of good things about the elliptical," Moreside said. "It's a tremendous workout for your gluteal muscles ... and it's a great cardiovascular workout."