Due to growing health costs from the 100-pound combat loads soldiers carry, the U.S. Army is searching for technologies to share weight more equally across troops' bodies.
The Army wants a device that can redistribute loads of up to 120 pounds from soldiers' shoulders to other parts of their torsos without preventing the troops from running, crawling or firing their weapons. That request comes at a time when military experts have voiced growing alarm over the crippling effects of heavy loads on otherwise heavy soldiers.
"This device must be comfortable enough to be worn for periods lasting up to three hours," according to the Army's notice, released Dec. 18. "Our end goal is to determine if there is an optimal distribution of the load on the torso that results in an increase in performance and comfort."
Such a device must also work with existing Army body armor and other worn equipment.
A typical U.S. Army rifleman carries a fighting load of about 63 pounds, equivalent to 36 percent of the average soldier's body weight, before putting on a rucksack. But soldiers usually wear an "approach march" load of 96 pounds for most of the day, according to a 2003 study led by Col. Charles Dean, a military-equipment expert. [ US Soldiers Make Real 'Predator' Machine Gun Pack ]
That load is equivalent to 55 percent of the average soldier's body weight, far more than the recommended maximum load, which is equivalent to 30 percent of body weight. The weight for "emergency approach march" loads reaches 127 pounds among riflemen, or even 142 pounds for squad leaders of mortar teams.
Heavy combat loads have already taken a serious toll on the bodies of U.S. troops, according to the Army Times. A Johns Hopkins University study found that one-third of medical evacuations from Iraq and Afghanistan from 2004 to 2007 were caused by weight-related injuries, such as musculoskeletal, connective-tissue or spinal injuries. That figure represented more than double the evacuations due to combat injuries.
The U.S. military faces a tough balancing act between lightening the load for troops and giving them new body armor or gadgets for detecting deadly improvised explosives. The U.S. Marine Corps has already tried to remove heavy batteries from soldiers' packs by experimentally equipping a few units with portable solar-power cells.
A future solution may come from the U.S. Defense Advanced Research Projects Agency's efforts to fund development of a battlefield mule robot known as LS3 (formerly "BigDog"). The four-legged robot would serve the same role as real horses or mules have in the past by carrying some of the combat loads for soldiers.
The Army's Natick Soldier Research, Development and Engineering Center hopes companies can respond with details about possible load-distributing devices in time for testing to begin in Feb. 2013. That would allow the Army to scientifically gauge the best weight distributions by working with human volunteers.