Exercise Physiology Studies

Overview:

Metabolism is the set of chemical reactions that occur in living organisms in order to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into catabolism that breaks down large molecules to collect energy and anabolism that uses energy to construct molecular components.

The energy produced or used may be measured by calorimetry, which is the science of measuring the heat of chemical reactions or physical changes. This measurement may be performed directly or indirectly. For example in direct calorimetry, the entire organism is placed inside the calorimeter to measure the heat generated by the living organism. Indirect calorimetry calculates heat that living organisms produce from their production of carbon dioxide and nitrogen waste or from their consumption of oxygen. In humans, calorimetry is the measurement of an individual's energy expenditure and is often performed using indirect calorimetry (IC) techniques. The indirect calorimetry measures energy expenditure (caloric burn rate) from the amount of oxygen that is consumed over a period of time.

Method:

Metabolic Measurements in Humans
Indirect calorimetry requires the accurate measurement of oxygen consumption (VO₂) and is easily performed using the Exercise Physiology System. This system includes an:

• An eight channel PowerLab data acquisition unit
• Gas Analyzer for accurate O₂ and CO₂ measurements
• Gas Mixing Chamber for mixing expired gases prior to sampling
• Spirometer for differential pressure measurements of respiratory air flow
• Thermistor Pod for measuring the temperature of expired gases and is necessary to correct for differences between expired and atmospheric conditions.
• Single Channel Bio Amp for optional recordings of biopotentials such as ECG or EMG
• Metabolic Module for LabChart (Win or Mac) software that provides online or offline calculation and display of
  • VE, VO₂, VCO₂ and Respiratory Exchange Ratio (RER)

Metabolic Measurements in Animals
Metabolic function in animals can be measured using a custom configuration that includes the Spirometer and Gas Analyzer. For example, the unrestrained or restrained animal may be kept in a plethysmograph chamber and respiratory air flow and gas concentrations monitored.

Note: For more information on related topics please see:

• Temperature application page for temperature measurements
• Dissolved O₂ application page for direct determination of oxygen concentration in solutions
• Respiratory Gas Analysis application page for O₂ and CO₂ analysis in respiratory gasses

Software:

LabChart
LabChart software (for Windows and Macintosh) combines the familiar simplicity of a traditional strip chart recorder with the powerful analysis features of a digital acquisition system. LabChart software and a PowerLab data acquisition unit provide data integrity, easy selection of hardware settings, powerful online and offline analysis, procedure automation, seamless extraction of experimental data and flexible display options. Acquisition and analysis capabilities can be further increased with LabChart Extensions and LabChart Modules. LabChart Modules are available as part of LabChart Pro and LabChart Extensions are free for download from the website for existing LabChart users.

Respiratory rate can be calculated online or offline using the Cyclic Measurements (Win) or Computed Input/Cycle Variables (Mac) features in LabChart.

Metabolic Module (Windows or Macintosh)
The MLS240/7 Metabolic Module for LabChart in combination with ADInstruments hardware is ideal in the determination of cardiorespiratory function and exercise physiology measurements. Typical applications include:

• Metabolic measurements
• Respiratory gas analysis
• Student exercise testing
• Pulmonary function analysis
• Indirect calorimetry
• Anaerobic threshold
• Biopotential measurements and spirometry.

The Metabolic Module records CO₂ and O₂ concentrations sampled from a gas mixing chamber and interprets these values in real time to provide parameters such as: VCO₂/min, VO₂/min, VE/min and RER. The module also provides options for setting subject details, recording parameters and environmental conditions that includes:

• Hardware preferences: choice of appropriate hardware
• Subject details: name, age, weight, height, gender, id number, comments
• Calibration preferences: settings for automated first and second gas calibrations
• General preferences: Averaging time (data logging) and recording time (duration of experiment) settings
• Environment settings: Expired/inspired, atmospheric and air conditions

GLP and 21 CFR Part 11
For those researchers working within a laboratory requiring GLP and 21 CFR Part 11 compliance the GLP Client and GLP Server are available for use with LabChart (Windows only) and PowerLab data acquisition systems. For more information, visit the Good Laboratory Practice application page or contact your nearest ADInstruments representative.
 

Hardware:

ADInstruments provide a range of data acquisition systems, signal conditioners, respiratory flow heads, pressure transducers and amplifiers that connect to PowerLab data acquisition systems for monitoring air flow and calculating respiratory data.

PowerLab Data Acquisition Systems
The PowerLab is a high-performance data acquisition unit suitable for a wide range of research applications. Typical applications include human and animal physiology, pharmacology, neurophysiology, biology, zoology, biochemistry, and biomedical engineering. Units are capable of recording at speeds of up to 400 000 samples per second continuously to disk (aggregate), and are compatible with instruments, signal conditioners and transducers supplied by ADInstruments, as well as many other brands. In addition to standard single-ended BNC inputs, 4 differential Pod ports are also available for direct connection of Pod signal conditioners and appropriate transducers. These systems include:

• ML866 PowerLab 4/30 - 4 Channels
• ML870 PowerLab 8/30 – 8 Channels
• ML880 PowerLab 16/30 – 16 Channels

System and Instruments
ML870B80 Exercise Physiology System
This is a complete physiology recording system for monitoring cardiorespiratory and metabolic function during exercise. The system records and displays continuous real-time measurements of metabolic parameters such as CO2 and O2 concentrations, airflow, air temperature, ECG or EMG.
The Exercise Physiology System includes:

• ML870 PowerLab 8/30 (LabChart and Scope software)
• MLS260/7 LabChart Pro software
• ML132 Bio Amp
• ML206 Gas Analyzer
• MLA246 Gas Mixing Chamber
• ML141 Spirometer
• ML309 Thermistor Pod
• MLA240 Exercise Physiology Accessory Kit

ML206 Gas Analyzer
The Gas Analyzer can be used for the measurement of respiratory gas concentrations from small animals, such as rats, through to humans. It contains an infrared carbon dioxide sensor and optical oxygen detector fed from a damped microvacuum sampling pump.

Metabolic costs induced by lactate in the toad Bufo marinus: new mechanism behind oxygen debt?
I Pinz and H-O Portner, Journal of Applied Physiology, 1177-1185, 2003

Influence of vestibular activation on respiration in humans
K D Monahan, M K Sharpe, D Drury, A C Ertl and C A Ray, American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, R689-R694, 2002