USDA/ARS Children's Nutrition Research Center

Energy Metabolism Measures

Master
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Whole Room Indirect Calorimeters

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Each calorimeter precisely measures the oxygen uptake (VO2) and carbon dioxide production (VCO2) of research subjects from childhood through adulthood, including pregnant and lactating women, in a controlled environmental chamber. The VO2 and VCO2 (in liters per minute) are measured in real time and are converted into kilocalories per minute to provide measurements of sleeping metabolic rate, basal metabolic rate, 24-hour total energy expenditure, and exercise energy expenditure (e.g. biking, walking, running, aerobics, or video game play). All research volunteers are closely monitored during the entire stay in the calorimeter whether short or long term. Heart rate, activity, body temperature, blood and urine collection are also available to be measured during any calorimeter study.

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Metabolic Cart

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Resting or basal metabolic rate (RMR or BMR) is measured using a portable Viasys Encore Metabolic Cart. Measurements of resting VO2 (liters per min), VCO2 (liters per minute), Respiratory Quotient (RQ), and Energy Expenditure (kcal/min) are provided.

Uses for Calorimetry 

Applications for the calorimeters include studies of obesity, diet, exercise, brown adipose tissue, pregnancy energy requirements; childhood, and adolescent growth, energy needs of individuals with certain conditions such as muscular dystrophy, cystic fibrosis, sickle cell anemia, etc.; validation of field methods of activity monitors, steppers, and body dashboards.
 

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Exercise Laboratory

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Equipment

This lab utilizes state of the art metabolic carts for assessment of sub-maximum and maximum VO2 in children and adults while on a treadmill or stationary bicycle to aid in the diverse energy expenditure protocols.

  • Viasys VMAX Encore metabolic cart- measures expired VO2 and VCO2
  • Treadmill
  • Stationary bicycle

Testing

  • A VO2 max test measures the maximal oxygen consumption that an individual can utilize during intense or maximal exercise. It is the gold standard for determining cardiorespiratory fitness. Testing is done with the individual wearing a face mask and heart rate monitor while exercising on a treadmill or stationary ergometer (bike). Expired air is measured on a metabolic cart as the intensity of the exercise is increased gradually until the individual reach exhaustion (max/peak level of exercise).
  • Fitness Testing- A sub-maximum fitness test follows a similar procedure as the VO2 max test except only heart rate is measured. A test is ended once the individual has reached a predetermined intensity level based on heart rate, age, and/or mobility. 

Activity Monitor Setup and/or Processing

  • Actigraph: An activity monitor that records continuous, high resolution physical activity and sleep/wake information. It is a body worn device that measures, and records physical movement associated with daily activity. and sleep. Daily sleep, sedentary time, light, moderate, and vigorous activity levels are calculated for analysis. It can be worn up to 30 days without recharging.
  • Actiheart: An activity and heart rate monitor that is worn on the chest. It records inter-beat intervals (beats per minute), heart rate variability and activity levels. It can be worn up to 14 days without recharging.

Monitor Setup, Processing, and Consulting

  • Activity monitor setup and/or processing of the activity data.