NATICK, Mass. (March 21, 2013) -- To better understand how carrying heavy loads affects Soldiers, Tyler Brown, Ph.D., looks at them as if they were athletes.
In the past, biomechanics load-carriage studies typically focused on Soldiers walking over long periods of time in a straight line. But Brown of the Natick Soldier Research, Development and Engineering Center's Biomechanics Team has his subjects run, cut, stop and jump -- movements that mirror what would actually happen in combat.
Athletes have been studied in this way to assess injury risk, but not Soldiers, according to Brown.
"Nobody's put a load on somebody's back," said Brown, "and asked the Soldier to speed up, slow down or change direction of movement."
Except Brown, who is measuring how 16 human research volunteers, or HRVs, are affected when they carry different loads and make "anticipated and unanticipated" movements in the study, part of a three-year effort that began in 2012 and was funded by a Department of the Army competitive In-House Laboratory Independent Research award.
The Soldiers run, cut and jump on force plates -- basically, precise weight scales -- that measure how much force is created as they move up and down, back and forth, and side to side under different loads. Brown then collects and analyzes the data.
"This is just another data point that shows how much load is affecting our Soldiers," said Jeffrey Schiffman, Ph.D., the Biomechanics Team leader. "Now we're starting to get more into react-to-contact type moments."
Brown has put Soldiers in the study through their paces with three weight loads -- no load, which consists of a helmet and weapon; a fighting load, which includes body armor and a tactical assault panel; and an approach load, which adds a backpack to the fighting load.
"The no load is like six or seven pounds, the fighting load (is) about 40 (pounds), and then the approach load is about 88 pounds," Brown said. "We have basically four or five different movements we're looking at."
Pfc. Jeremy Vasquez of Bronx, New York, took part in the study as an HRV. An accomplished amateur boxer before joining the Army, Vasquez is no stranger to athletic movements, but the heavy loads proved challenging for the 5-foot-3-inch, 153-pounder.
In Basic Training, said Vasquez, the "biggest problem, I know, for me was the ruck marches and was getting used to that weight. I'm a smaller guy, and when you get that weight on you, it limits you a lot."
Vasquez said that he hopes his participation in the study will help Soldiers to cope with those loads and to stay healthy.
"It could cause damage in the long run," Vasquez said. "I guess that's what the whole logic of the study was. That's why I'm really glad I was able to participate in it, because I feel like I did contribute to that and help future Soldiers."
The researchers expect that their data will show that Soldiers use different mechanics when carrying heavier loads.
"The idea is if you can anticipate or pre-plan a movement, you're going to perform it better," Brown said. "They've shown that athletes, when they have to react to something, use different mechanics, postures, and they activate their muscles differently, and even without loads."
Schiffman said a follow-up study is already planned.
"We, as researchers, want to make sure we're documenting everything we can about how load affects human performance," Schiffman said. "It's been a nice opportunity for us to grow our human sciences program here."