More people bike to work or play due to record-high gasoline prices, the slowdown in the economy, and increasing environmental sensitivity.

But an adequate infrastructure may not be in place to protect cyclists from serious injury according to surgeons who presented a new study on the issue during a scientific paper session at the 2009 Clinical Congress of the American College of Surgeons.

The researchers found that the severity of injury and hospital length-of-stay for bicycle injuries at one trauma center has increased significantly over the past 11 years. Despite the wide-spread attention paid to the importance of wearing helmets, helmet use did not change during the time period of the study, and more than 33 percent of 329 bicycle injury victims had a significant head injury. Even more alarming, the number of chest injuries increased by 15 percent and abdominal injuries rose three-fold over the last five years. "We were astounded by that data," said Jeffry Kashuk, MD, FACS, associate 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, Denver. "We''re talking about injured spleens and livers, internal bleeding, rib fractures, and hemothorax [blood in the chest]. Those kinds of injuries are reflected by an increase in injury severity score," he added.

The study was conducted in Denver, which has one of the most well-developed bicycle path networks in the country. "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. 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," Dr. Kashuk said.