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SSC-Natick Press Release

U.S. Army Soldier Systems Center-Natick
Public Affairs Office
Kansas Street
Natick, MA 01760-5012

Contact: Chief, Public Affairs Office
(508) 233-5340
amssb-opa@natick.army.mil

Date: July 27, 2004
No: 04-31

Nutrition study guides protein content for future military ration; looks for volunteers

NATICK, Mass. -- Video games and movies play inside the "Doriot Dorm," a classroom in the Doriot Climatic Chambers facility at the U.S. Army Soldier Systems Center here, converted into the main living and data collection area for a study that will help determine the protein content for a new individual military ration.

The activities help pass time for human research volunteers participating in the "Exercise and Nitrogen Balance" study, the most intensive on-site nutrition study conducted by the U.S. Army Research Institute of Environmental Medicine's (USARIEM) Military Nutrition Division, according to Lt. Col. Ann Grediagin, a registered dietician and principal investigator of the study.

Research is specifically measuring the effect of fitness level, caloric intake and protein intake on short-term nitrogen balance during a 1,000-calorie increase in daily energy expenditure. The goal is to determine if fitness level affects a person's requirement for protein and to see if extra protein helps promote a more positive protein balance when energy expenditure exceeds energy consumption during a sudden increase in exercise.

It's the type of situation warfighters find themselves in combat, and the reason why the First Strike Ration ("The Warrior" May-June 2003) will benefit from the recommendations once the study is complete.

"The First Strike Ration is not designed to match Soldier energy expenditure, and we know they have a caloric deficit," Grediagin said. "In a deficit, we want to minimize the loss of lean body tissue and also physical, cognitive and immune function. With the right balance of proteins, carbohydrates and fats (in a calorie-limited ration), maybe we can affect the type of tissue lost, fat vs. muscle."

Nitrogen gains and losses are tracked because the element is found only in proteins. It is a building block in amino acids, a string of amino acids making a protein. When protein from food or muscle is broken down, nitrogen is excreted through waste products and sweat. More nitrogen consumed than excreted causes a positive nitrogen balance or muscle-building state. More nitrogen excreted than consumed brings a negative nitrogen balance or muscle-losing condition.

"Nobody in the civilian population has been able to definitively answer the question of what the impact is of exercise on protein requirements," Grediagin said. "Recommended amounts of protein for a sedentary population may be adequate, but we want to know protein requirements for athletes. Soldiers are athletes."

Started in July 2003 and about halfway finished, the study is composed of three physically fit groups and one sedentary group with seven volunteers in each group. Sedentary individuals making up Group A are tasked with eating and increasing energy expenditure 1,000 extra calories per day through exercise to see how exercise alone affects protein breakdown.

Fit Group B follows the same conditions as Group A, and was set up to examine how fitness level affects protein breakdown. Fit Group C receives no extra food, but exercises their normal amount plus an additional 1,000 calories daily and was designed to learn what happens to protein stores during an exercise-induced energy deficit. Fit Group D retains the same criteria as Group C, but is the only group to double protein intake to discover if loss of body protein stores can be minimized.

The percent of dietary carbohydrate is consistent for all four groups. This is important because the body's preferred source of energy during exercise is carbohydrate, and if carbohydrate varied, the amount of protein used for energy may be altered, Grediagin said.

For 11 days, research volunteers are strictly monitored as they live in a room packed with exercise equipment, bunk beds to sleep overnight and electronic entertainment. Their diet, customized to them based on preliminary measurements and a three-day survey, consists mostly of liquid protein shakes along with solid foods such as carrots, popcorn and low-protein cookies served on a strict schedule by the Diet Team in an adjacent room.

"I control every detail," Grediagin said. "I've scripted every part of the day. I have to know how many calories are used so I can achieve energy balance or create the 1,000 calorie deficit."

Once their diets are stabilized during the first four days, exercise is increased to burn 1,000 calories for the designated groups for each the remaining seven days. On Days 1, 5 and 9, each time the volunteers start a new activity they are hooked up to a machine that measures exhaled gases to determine calories expended. Precision is so high that it makes a large number of volunteers unnecessary, according to Grediagin.

Exercise is performed on equipment including a treadmill, stationary bike and an arm ergometer to simulate energy expenditure of weight resistance. Other measurements are taken while bouncing on an exercise ball, playing video games and even sleeping.

Body fat is measured twice during the study. The biological samples team in a separate room collects blood samples two times over four days to assess physiological response to exercise. Research volunteers collect their own waste products for analysis and wear a patch daily to collect sweat to measure lost nitrogen.

Their opportunity to leave the installation is to travel to Tufts University in Boston for tracer studies used to determine the rates of protein breakdown and synthesis.

"(Tracer studies) explain the end result of nitrogen balance. It answers a basic science question," Grediagin said.

Study sessions are scheduled monthly with two to four volunteers until 28 research volunteers in total are tested. If enough research volunteers are recruited, Grediagin said the study could end as soon as this December.

Qualified volunteers still being recruited for study

Participation in USARIEM's Exercise and Nitrogen Balance study is still open to qualified military and civilian candidates.

Volunteers must be non-smoking males 18-35 years old, able to participate in strenuous exercise, and a normal weight that's been stable within 5 pounds for at least two months before the start of the study. They are categorized as sedentary (less than 30 minutes per day of light exercise) or very fit (minimum of 45 minutes of high intensity exercise five days per week).

Disqualifying factors are medications or disease that affects their ability to use nutrients; heart problems, including abnormal EKG and elevated blood pressure; alcohol or drug abuse; and nutritional supplement or caffeine use during or three weeks before starting study.

Volunteers will visit the Soldier Systems Center on four separate occasions for an informational briefing, medical clearance, aerobic fitness test and food activity records before spending 12 consecutive days and nights for the actual study. Candidates must provide the name of their primary care physician and sign a medical records release. Leaving the site except for study-related activities is disallowed.

Upcoming study dates are Sept. 19-Oct. 1, Nov. 7-19, Dec. 5-17, Jan. 23-Feb. 4 and Feb. 27-March 10. Compensation is up to $1,250 for completion of the study.

Those who meet the criteria and are available during one of the study dates can e-mail USARIEM.proteinstudy@na.amedd.army.mil or call 508-233-4353 to be scheduled for a study briefing.

For more information about the Soldier Systems Center or USARIEM, please visit the websites http://www.natick.army.mil and http://www.usariem.army.mil.


This page last updated on 23 January 2004.