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DAPA Measurement Toolkit

 

Near infrared interactance

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  • The near infrared interactance (NIR) method of assessing body composition is based on the principles of light absorption reflectance, and near infrared spectroscopy.
  • More specifically it is based on the ability of fat tissues to "absorb" more infrared light than lean tissue which can then be measured as a change in the infrared level.
  • The use of infrared (IR) light to measure fat was developed by the US Department of Agriculture to measure the fat contained in beef and pork carcasses after slaughter.
  • At approximately 928 nanometers, a direct measure of how much fat exists is provided by the absorption of the infrared portion of the spectrum.

A mono-chromator or light "wand" (see Figure 1), sends a low-energy beam of near-infrared light at about 900 nanometers into the biceps area that penetrates the underlying tissue to a depth of one centimetre. The energy is either reflected, absorbed, or transmitted, depending on the scattering and absorption properties of the biceps. A detector within the wand measures the intensity of the re-emitted light. Shifts in the wavelength of the reflected beam and a prediction equation are used to compute the percent body fat.

This measure is rarely used for the assessment of body composition. Although it has good repeatability, it lacks validity in humans and its inability to accurately predict body fat across a broad range of fat levels is problematic. It assumes fat in the arm is proportional to total body fat, and research suggests that NIR may overestimate body fatness in lean people and underestimate it in people who are overweight.

The NIR data (density measurements) are entered into a prediction equation with the person's height, weight, age, gender, frame size, and level of physical activity. A digital read out including percentage body fat and lean tissue are displayed.

Figure 1 Example of Near Infrared Interactance.
Source: wikiHow.

An overview of the characteristics of NIR is outlined in Table 1.

Strengths

  • NIR measurement is safe and the equipment is portable and lightweight.
  • It requires little training to use.
  • The tool has a high level of repeatability.

Limitations

  • The amount of pressure applied to the fiber optic probe, skin color and hydration levels may cause results to differ and be inaccurate.
  • Some instruments have been shown to underestimated body fat by more than 4% in subjects greater than 30% fat and overestimated body fat by 4% in subjects less than 8% fat.
  • Poor validity.

Table 1 Characteristic of near infrared interactance.

Characteristic Comment
Number of participants High
Relative cost Low
Participant burden Low
Researcher burden of data collection Low
Researcher burden of coding and data analysis Low
Risk of reactivity bias Depends on blinding
Risk of recall bias No
Risk of social desirability bias No
Risk of observer bias No
Space required Low
Test accuracy Low
Availability High
Suitability for field use High
Participant literacy required No
Cognitively demanding No

Considerations relating to the use of NIR are summarised by population in Table 2.

There are no specific population for whom NIR cannot be implemented. It is easily administered and has shown a high level of repeatability. However, there is no research to support this method of body composition assessment in some populations and in the remainder, evidence highlights its poor accuracy and validity levels when compared to other more well established techniques such as hydrostatic weighing.

Table 2 Anthropometry by near infrared interactance in different populations.

Population Comment
Pregnancy No research to support
Infancy and lactation No research to support
Toddlers and young children Not suitable *
Adolescents Not suitable *
Adults Not suitable *
Older Adults Not suitable *
Ethnic groups Not suitable *
Other (obesity) Not suitable *
*Based on poor validity.

The only known possible restriction on NIR is to avoid measurements on an extremely black tattooed location. The low energy NIR light might be totally absorbed by a very black tattoo.

Refer to section: practical considerations for objective anthropometry

  • NIR (Futrex) Body Composition Analyser
  • NIR (SCiO consumer physics) scanners with supporting devise requiring application with web interface

A method specific instrument library is being developed for this section. In the meantime, please refer to the overall instrument library page by clicking here to open in a new page.

NIR (SCiO consumer physics) scanners is a new device. However, no validation work has been carried out to date to assess its use in the assessment of body composition.

References

  1. Ackland TR, Lohman TG, Sundgot-Borgen J, Maughan RJ, Meyer NL, Stewart AD, Muller W: Current Status f Body Composition in Sport – Review and Position Statement on Behalf of the Ad Hoc Research Working Group on Body Composition Health and Performance, Under the Auspices of the I.O.C. Medical Commission Sports Med 2012: 42; 227
  2. Batterham M: A comparison of bioelectrical impedance and near infra-red interactance with dual energy x-ray absorptiometry for the determination of body fat J Diet Assoc Australia 2002: 59; 120
  3. Cassady SL, Nielsen DH, Janz KF, Wu YT, Cook JS, Hansen JR: Validity of near infrared body composition analysis in children and adolescents. Med Sci Sports Exerc. 1993: 25; 1185
  4. Duren DL, Sherwood RJ, Czerwinski SA, Lee M, Choh AC, Siervogel RM, Chumlea WC: Body Composition Methods: Comparisons and Interpretations J Diab Sci Technol 2008: 2; 1139
  5. Heymsfield SB, Lohman TG, Wang Z, et al: Human body composition. 2nd ed. Human kinetics; Champaigh, IL: 2005
  6. Housh TJ, Johnson GO, Housh DJ, Cramer JT, Eckerson JM, Stout JR, Bull AJ, Rana SR: Accuracy of Near-Infrared Interactance instruments and population specific equations for estimating body composition in young wrestlers Journal Strength Cond 2004: 18;12
  7. Housh T, Johnson G, Housh D, Eckerson J, Stout J, Evetovich T, Smith D, Ebersole K, Perry S, Bull A: Validity of Near-Infrared Interactance and Bioelectrical Impedance for estimating percent fat in male swimmers Med Sci Sports Exerc 1998: 30; 147
  8. Kasa N, Heinonen KM: Near-infrared interactance in assessing superficial body fat in exclusively beast-fed, full term neonates Acta Paediatrica 1993: 82; 1
  9. McLean KP, Skinner JS: Validity of Futrex-5000 for body composition determination Med Sci Sports Exerc 1992: 24; 253
  10. Schreiner PJ, Pitkaniemi J, Pekkanen J, Salomaa W: Reliability of near-infrared interactance body fat assessment relative to standard anthropometric techniques J Clin Epidemiol 1995: 48; 1361
  11. Panotopoulos G, Ruiz JC, Guy-Grand B, Basdevent A: Dual x-ray absorptiometry, bioelectrical impedance and near infrared interactance in obese women Med Sci Sports Exerc 2001: 33; 665
  12. Wells JCK, Fewtrell MS; Measuring body composition Arch Dis Child 2006: 91; 612
  13. Yeong Lee S, Gallagher D: Assessment methods in human body composition Curr Opin Clin Nutr Metab Care 2008: 11; 566