NEW YORK, July 04 (Reuters) -- Back support belts worn to protect the back from injuries due to lifting heavy objects may offer little or no protection at all, and may even be a liability, according to a recent study conducted at Ohio State University.
"If you already have a back injury, and you wear a belt, it helps you recover a little bit faster. But if you've never had a back problem, there doesn't seem to be a whole lot of evidence that it does any good, and there seems to be a whole lot of evidence that it does some harm," says Dr. William Marras, professor of industrial welding and systems engineering and physical medicine and rehabilitation at Ohio State.
Marras led a team of researchers to determine the protective value of three different types of lifting belts for 15 healthy, young males, engaged in a variety of "typical box-moving motions in industry." The three types of belts included: a nylon elastic belt with suspenders (elastic belt); a leather weightlifting style belt (leather belt); and a fabric belt with a rigid posterior support which maintains the natural curve of the spine (orthotic belt).
The results, reported in a recent issue of Clinical Biomechanics, revealed that the elastic belt decreased the weight placed on the spine during lifting by about 10%, while the other belts had no significant effect. Previous research suggested that the amount of force exerted on the spine is associated with low back pain and injuries. Marras believes that elastic belts reduce spinal load because they are wider. "They connect your pelvis and your rib cage, so you have to turn your trunk as a unit, without twisting your back. If you can independently move your back and your pelvis, then you twist your spine, which means you work your muscles harder and put more force on your spine when you lift something."
Despite the limited protection elastic belts seem to offer, Marras does not think they will be helpful for movers, construction workers, or other workers who lift heavy objects. "We found that elastic belts offered some protection when people firmly planted their feet on the ground before lifting. But in real world situations, most people don't plant their feet; they shuffle their feet and move around. So if back belts offer any help at all under realistic circumstances, it's a very small effect."
He also warns that, "you can lift about 20% more weight when you wear a back belt, but that doesn't mean that you have 20% more protection on your spine. So you may try to lift more than you can handle and hurt yourself."
The researchers found that the use of the elastic or leather belt can cause people to rely more on their pelvis than their trunk during lifting because the belts prevent a full range of trunk motions. Although reducing the degree of bending and twisting of the trunk can decrease the risk for back injuries, back belts typically do not restrict the range of trunk motions sufficiently to reduce the risk of injury, according to the study. Furthermore, the researchers do not know if the resulting transfer of weight onto the pelvis could cause pelvic complications.
Indeed, there has been much debate over the years regarding the protective value of lifting belts. Previous studies have produced conflicting data -- one study found that back support belts reduce the risk of low back disorders, while another found that using a belt did not protect against injury, but instead, found an increased risk for more severe back injuries among belt users. Most of these studies were deemed inconclusive, however, because of factors such as small sample sizes, confounding variables, and inconsistent methods.
Marras refers to another study which showed that the constant use of back belts prevents adequate exercise of the back muscles, eventually leading to muscle atrophy. Once this has occurred, subsequent lifting without the back belt would result in a greater likelihood of back injury.
So, what is the role of back belts? "If you've had a back injury, and a back belt is prescribed by an occupational physician, then I think it's okay to wear it. My warning to people is, 'balance the positive effect of back belts with the possible negative effects that are out there,'" says Marras.
SOURCE: Clinical Biomechanics (1997;12(2):107-115)
