Closed-loop control of air supply to whole-room indirect calorimeters to improve accuracy and standardize measurements during 24-hour dynamic metabolic studies.

Objective: The aim of this study was to test proportional-integral-derivative (PID) control of air inflow rate in a whole-room indirect calorimeter to improve accuracy in measuring oxygen (O ) consumption ( ) and carbon dioxide (CO ) production ( ).

Methods: A precision gas blender infused nitrogen (N ) and CO into the calorimeter over 24 hours based on static and dynamic infusion profiles mimicking and patterns during resting and non-resting conditions. Constant (60 L/min) versus time-variant flow set by a PID controller based on the CO concentration was compared based on errors between measured versus expected values for respiratory exchange ratio, and metabolic rate.

Improving temporal accuracy of human metabolic chambers for dynamic metabolic studies.

Metabolic chambers are powerful tools for assessing human energy expenditure, providing flexibility and comfort for the subjects in a near free-living environment. However, the flexibility offered by the large living room size creates challenges in the assessment of dynamic human metabolic signals-such as those generated during high-intensity interval training and short-term involuntary physical activities-with sufficient temporal accuracy. Therefore, this paper presents methods to improve the temporal accuracy of metabolic chambers.

Energy expenditure: measurement of human metabolism.

Obesity is one of the most prevalent chronic diseases globally, especially in the United States. While the United States gained an early lead in unnecessary weight gain, most other countries are quickly closing the gap. The latest U.

Smart phones are useful for food intake and physical activity surveys.

Current self-report methods of recording food intake and Physical Activity (PA) are cumbersome and inaccurate. Food and activity surveys implemented on a smart phone will allow for immediate entry, data transfer to a researcher, and feedback to the user. Ten subjects followed a script, representative of one day, to enter food intake and PA on a smart phone.

Data upload capability of 3G mobile phones.

Mobile phones are becoming an important platform to measure free-living energy balance and to support weight management therapies. Sensor data, camera images and user input are needed by clinicians and researchers in close to real time. We assessed upload (reverse link) data transport rates for 2007-2008 model mobile phones on two major US wireless systems.