The Defense Department is studying whether a boost of testosterone can keep military muscle and brains operating in top form during long periods of combat.

When troops are engaged in prolonged physical activity like war and contingency operations, they are unable to consume the calories needed to sustain high physical and mental function, according to medical researchers.

The calorie deficit -- sometimes as much as 50 percent to 60 percent below the needed amount -- can result in muscle loss, fatigue, cognitive decline and, in men, a drop in testosterone, leaving them vulnerable to injury, illness, wounds or death.

Scientists at Louisiana State University's Pennington Biomedical Research Facility and the Army Research Institute of Environmental Medicine are conducting a study to see if maintaining normal testosterone levels during periods of calorie restriction will improve performance, or at least minimize negative consequences.

The results will provide insight into the role of testosterone in maintaining strength, agility and brain function, according to Stefan Pasiakos, a research physiologist at USARIEM.

"We are truly trying to understand the mechanism of the hormone in terms of operations," Pasiakos said.

The research, known as the Optimizing Performance in Soldiers Study, is underway in Baton Rouge, Louisiana. It will involve 50 men, ages 18 to 39 who, in the study’s first phase, will be provided food and monitored on an outpatient basis. During Phase Two, participants will live at the research facility, consuming the same amount of calories as a soldier would ingest in the field. They also will be put through rigorous physical activity mimicking the rigor of combat, creating a calorie deficit of 55 percent below energy expenditure.

During this phase, half the participants will recieve weekly testosterone shots to maintain normal levels of the hormone while the rest will receive a placebo.

After the 28-day Phase Two, participants will be returned to normal levels of food and exercise, and monitored for weight gain.

"The idea is to see if you can stop a soldier from breaking down muscle during calorie restriction and whether they will be better able to perform a repeat mission," Pasiakos said. "What we are trying to look at is if we are not keeping up the right hormonal levels, are they going to be worse off in the next mission or next training exercise."

The study is not aimed at seeing whether all soldiers could be made into super warriors from testosterone injections, the researchers said. Instead, the $5 million research is geared toward "high-intensity stressful conditions" endured by special operations personnel and combat arms troops engaged in prolonged warfare, explained Dr. Jennifer Rood, the study’s lead investigator.

"This is for the most extreme conditions, the rare cases," Pasiakos added.

The LSU-USARIEM study is just one of several ongoing Defense Department studies to look at the impact of diet and supplements on cognitive function and muscle mass.

The Air Force Research Laboratory is working with the Center of Nutrition, Learning and Memory -- a collaboration between the University of Illinois and Abbott Laboratories -- on the role the nutrient lutein may play in brain performance.

Lutein, a pigment found in many fruits and vegetables, may play a role in cognition, learning and memory.

The Army also is studying whether Omega-3 fatty acids can help recruits and special operations soldiers focus.

"We’re hoping to learn if we can improve cognitive performances under stress because these young people who are going through [the Infantry Basic Officer Leaders Course] and Ranger [School] are clearly under stress during specific times in their programs," said Bernadette Marriott, a professor at the university and the director of the nutrition section of the division of gastroenterology and hepatology.

Pasiakos said nutrition is an important piece of soldier fitness but he is hoping the testosterone study may reveal additional insight into what happens when troops simply can’t eat or drink enough to maintain high levels of function.

"We have tried to match energy requirements and we can’t do it. I’m not discounting the importance of nutrition … but what we are trying to do here is understand why some of the nutritional interventions may not be as effective as they are in a normal individual," Pasiakos said.

Patricia Kime covers military and veterans health care and medicine for Military Times. She can be reached at

Patricia Kime is a senior writer covering military and veterans health care, medicine and personnel issues.

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