Assessment of height (or stature) is conducted by direct measurement of the length from the bottom of the feet to the highest point of the head.
Standing height can be measured in participants that can stand without assistance and who are cooperative (typically 2 to 3 years of age and older). For individuals such as infants who are unable to stand, recumbent length (also known as crown to heel length) can be measured. Alternatively, height can be inferred using equations from other measurements, such as knee height, arm-span or half-span.
The instrument used to measure height varies depending upon whether it is being measured directly (i.e. standing height), measured using recumbent length, or inferred from arm-span, half-span, or knee height. In each case there are both recommended tools and alternatives which can be used if these are not available, as described in Table A.3.1.
The instrument needs to be calibrated using a standardised one-metre rod, especially when using flexible measurement tapes as these may stretch. It is common practice to carry out calibration procedures on a monthly basis.
Table A.3.1 Recommended and alternative equipment for measurement of length.
|Stature (standing height)||Stadiometer or solid height board (in cms) with sliding head piece||Measurement tape (in cms) fixed to wall. Ruler or wood as head piece|
|Recumbent length (crown to heel length)||Recumbent length board||Measurement tape (in cms)|
|Arm-span||Steel or fibreglass measuring tape (in cms) with metal tip for placement at end of fingers||Measurement tape (in cms)|
|Half-span (demi-span)||Steel or fibreglass measuring tape (in cms) with metal tip for placement at end of fingers||Measurement tape (in cms)|
|Knee height||Broad blade sliding knee height calipers, also known as anthropometer||Measurement tape (in cms)|
Procedure: standing height
Figure A.3.1 The Frankfort horizontal plane. This plane is represented by an imaginary line between the lowest point on the margin of the orbit of the eye (the bony socket of the eye) and the tragion (the notch above the tragus, the cartilaginous projection just anterior to the external opening of the ear).
Procedure: recumbent length (crown to heel length)
Recumbent length, sometimes referred to as crown to heel length, is obtained with the participant in the supine position. It is generally reserved for children under the age of two and children under the age of three who are unable to stand without assistance.
It may not be possible to measure standing height in some participants due to curvature of the spine, weakness of back muscles or weakness in the leg muscles. In these cases, height can be estimated using arm-span. In order to do so, the participant must be able to stretch out their arms, hands and fingers in straight line (see Figure A.3.2). This measure requires two people. If only one person is present, or the participant is unable to stretch out both arms, half-span may be used instead.
Height can be estimated by measuring half-span for participants that are unable to stand up straight or fully outstretch both arms. This measure requires two people.
Figure A.3.2 Measurement of arm-span and half-span.
Procedure: knee height
Knee height can be used to estimate standing height in non-ambulatory participants. Measurements should be made on the left leg in order to be consistent with the leg used to derive height estimation equations.
Figure A.3.3 Measurement of knee height in sitting (left) or supine positions (right).
Replicate measures should be taken in all the above procedures. If two measurements are not the same, the difference between two measurements of the same participant should be calculated by subtracting the smaller value from the larger one. If the difference between two measures is greater than the largest acceptable difference for that dimension (see Table A.3.2), they should be repeated and re-checked.
Table A.3.2 Largest acceptable differences between replicate measures by dimension.
|Anthropometric dimension||Largest acceptable difference between replicate measures|
|Standing height||1 cm|
|Recumbent length||1 cm|
|Knee height||0.5 cm|
Assessment of height is a fundamental anthropometric measurement and is very commonly used in a variety of health related studies. Estimation of height is important for assessing growth and development, the construction of anthropometric indices such as weight for height, and for estimating physiological outcomes such as basal energy expenditure.
In addition to being used in isolation, height is used in combination with other anthropometric dimensions to derive the following anthropometric indices:
The steps taken to estimate height vary depending upon the type of initial raw measurement taken.
Standing height and recumbent length
Raw measures of standing height and recumbent length require very little data processing to derive final estimates of height. Estimates should be quality checked during data processing in the same manner as other health-related variables, for example by checking for outliers and data entry errors. There are no specific steps which are unique to height. In some circumstances it may be necessary to convert units taken in imperial units to metric units.
Estimation of height using arm-span, half-span and knee height
Height can be estimated from arm-span, half-span and knee height using published equations. Various equations are available, and whether or not equations are generalisable from the population in which they were derived to the population being studies should be carefully considered. Examples of equations are shown below.
Height can be estimated from arm-span using equations based upon the correlation between the two, which has been reported to be strong (r = 0.989). The following equation can be used to calculate height:
However, the arm-span measurement to height relationship has been reported to be significantly different in Afro-Caribbean and Asian males. Ethnic differences should therefore be considered when making calculations. For example, separate equations have been developed for black and white women:
Similar to the use of arm-span, half-span can also be used to estimate height. Equations which are commonly used are:
Knee height can be used to estimate height using published equations, a number of which are shown in Table A.3.3.
Table A.3.3 Published equations for estimation of height from knee height.
|Population||Equation||Standard error of estimate (cm)|
|Non-Hispanic white men (U.S.)||78.31 + (1.94 x knee height) – (0.14 x age)||3.74|
|Non-Hispanic black men (U.S.)||79.69 + (1.85 x knee height) – (0.14 x age)||3.80|
|Mexican-American men (U.S.)||82.77 + (1.83 x knee height) – (0.16 x age)||3.68|
|Non-Hispanic white women (U.S.)||82.21 + (1.85 x knee height) – (0.21 x age)||3.98|
|Non-Hispanic black women (U.S.)||89.58 + (1.61 x knee height) – (0.17 x age)||3.82|
|Mexican-American women (U.S.)||84.25 + (1.82 x knee height) – (0.26 x age)||3.77|
|Taiwanese men||85.10 + (1.73 x knee height) – (0.11 x age)||3.86|
|Taiwanese women||91.45 + (1.53 x knee height) – (0.16 x age)||3.79|
|Elderly Italian men||94.87 + (1.58 x knee height) – (0.23 x age) + 4.8||4.30|
|Elderly Italian women||94.87 + (1.58 x knee height) – (0.23 x age)||4.30|
|French men||74.7 + (2.07 x knee height) – (-0.21 x age)||3.80|
|French women||67.00 + (2.2 x knee height) – (0.25 x age)||3.50|
|Mexican men||52.6 + (2.17 x knee height)||3.31|
|Mexican women||73.70 + (1.99 x knee height) – (0.23 x age)||2.99|
|Filipino Men||96.50 + (1.38 x knee height) – (0.08 x age)|
|Filipino women||89.63 + (1.53 x knee height) – (0.17 x age)|
|Malaysian men||(1.924 x knee height) + 69.38||3.51|
|Malaysian women||(2.225 x knee height) + 50.25||3.40|
Adapted from: mna-elderly.com
An overview of height methods is outlined in Table A.3.4.
Table A.3.4 Characteristics of height methods.
|Number of participants||Large|
|Researcher burden of data collection||Low|
|Researcher burden of coding and data analysis||Low|
|Risk of reactivity bias||No|
|Risk of recall bias||No|
|Risk of social desirability bias||No|
|Risk of observer bias||Yes|
|Suitability for field use||High|
|Participant literacy required||No|
Considerations relating to the use of height methods in specific populations are described in Table A.3.5.
Table A.3.5 Use of height methods in different populations.
|Pregnancy||May be difficult for participant to stand directly against stadiometer. May require estimation of height using arm-span, half-span, or knee height.|
|Infancy and lactation||Recumbent length should be used in place of standing height.|
|Toddlers and young children||Recumbent length may be used if participant cannot stand unaided or is uncooperative.|
|Older Adults||It may be difficult for older individuals to stand up straight due to curvature of the spine, weakness of back muscles and weakness in the leg muscles.|
|Ethnic groups||There may be ethnicity dependent differences in the relationships between height and proxy measures such as knee height, half-span and arm-span.|
|Other||Wearing of religious head-wear may impede measurement. Measure height with head-wear, and then subtract the measurement of the height of the head-wear. Record this deviation from standard measurement.|
Refer to section: practical considerations for objective anthropometry
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.