Principles, techniques, and limitations of near infrared spectroscopy

Marco Ferrari, Leonardo Mottola, Valentina Quaresima

Research output: Contribution to journalArticlepeer-review


In the last decade the study of the human brain and muscle energetics underwent a radical change, thanks to the progressive introduction of noninvasive techniques, including near-infrared (NIR) spectroscopy (NIRS). This review summarizes the most recent literature about the principles, techniques, advantages, limitations, and applications of NIRS in exercise physiology and neuroscience. The main NIRS instrumentations and measurable parameters will be reported. NIR light (700-1000 nm) penetrates superficial layers (skin, subcutaneous fat, skull, etc.) and is either absorbed by chromophores (oxy- and deoxyhemoglobin and myoglobin) or scattered within the tissue. NIRS is a noninvasive and relatively low-cost optical technique that is becoming a widely used instrument for measuring tissue O2 saturation, changes in hemoglobin volume and, indirectly, brain/muscle blood flow and muscle O 2 consumption. Tissue O2 saturation represents a dynamic balance between O2 supply and O2 consumption in the small vessels such as the capillary, arteriolar, and venular bed. The possibility of measuring the cortical activation in response to different stimuli, and the changes in the cortical cytochrome oxidase redox state upon O2 delivery changes, will also be mentioned.

Original languageEnglish
Pages (from-to)463-487
Number of pages25
JournalCanadian Journal of Applied Physiology
Issue number4
Publication statusPublished - Aug 2004


  • Blood flow
  • Exercise physiology
  • Optical imaging
  • Oxidative metabolism
  • Oxygen consumption
  • Tissue oximetry

ASJC Scopus subject areas

  • Physiology
  • Orthopedics and Sports Medicine


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