Oct. 14 (HealthDay News) -- Bicyclists are facing higher injury rates and longer hospital stays, with both worsening over the past 11 years at a Denver trauma center, according to the results of a study of biking injuries.

Chest injuries rose by 15 percent and abdominal injuries tripled over the last five years, the study authors found. Cyclists themselves appear to be part of the problem: Helmet use did not go up over the study period, and more than 33 percent of 329 injured cyclists had a significant head injury.

"We were astounded by that data," said Dr. Jeffry Kashuk, professor of surgery at the University of Colorado School of Medicine and senior attending surgeon at the Rocky Mountain Regional Trauma Center at Denver Health Medical Center. "We're talking about injured spleens and livers, internal bleeding, rib fractures, and hemothorax [blood in the chest]," he stated in a news release from the American College of Surgeons.

The study was scheduled be presented during the 2009 Clinical Congress of the American College of Surgeons, held Oct. 11 to 15 in Chicago.

"Denver is very much a bicycle community. If we are seeing an increase in injuries in a metropolitan area that has fairly mature bike infrastructure from the standpoint of bike pathways, there's reason for concern about what's happening in metropolitan areas that don't have that level of maturity," Kashuk said. "There seems to be a significant increase nationally in the use of the bicycle for urban transportation. If our data is a microcosm of what is going on nationally, we may be on the cusp of an injury epidemic."

Researchers at the University of Colorado want to further study the issue of biking injuries.

"On a local and national level, people need to be aware of the fact that a push for bike transportation for the sake of health, the environment, and lower transportation costs has real potential to raise medical costs because our infrastructure may not be ready for it," Kashuk added. "Look at all the safety factors that have been incorporated in automobiles and streets and highways. If even a percentage of that kind of investment went into safety vis-a-vis bike paths and community infrastructure, we would protect people from major injury."

SOURCE: American College of Surgeons, news release, Oct. 13, 2009