Typical backpacks, which don't have bungee cords, rise and fall with your stride. That means extra work for your body, and possibly muscle strain if the backpack is too heavy.
Heavy backpacks can be a hazard for school kids, the bungee backpack inventors, including biology professor Lawrence Rome, Ph.D., note in Nature. In addition to teaching at the university, Rome is a Whitman investigator at the Marine Biological Laboratory in Woods Hole, Mass.
The bungee backpack has a rigid frame suspended from a bungee cord on each shoulder. The bungee cords have a simple job — hold the backpack steady.
"Essentially, the bungee cord permits the load to stay at nearly constant height from the ground while the wearer walks or runs," Rome says. People spend less energy walking with the bungee backpack on their shoulders than with a conventional backpack, Rome's team reports.
The bungee cords may be especially helpful for people who run while wearing backpacks, such as rescue workers toting heavy gear to disaster sites, note the inventors.
Rome has formed a company to further develop the backpacks, according to the Marine Biological news release.
SOURCES: Rome, L. Nature, Dec. 21, 2006; Vol. 444: pp. 1023-1024. News release, Marine Biological Laboratory. News release, University of Pennsylvania. News release, Nature.
By Miranda Hitti
Reviewed by Louise Chang, M.D