The mean of duplicate or the median of triplicate measures (when the first two measures differ by more than 5% for skinfolds and 1% for other measures) is recommended. In some situations only a single set of measures is possible, and the error of the measurer needs to be quantified as this governs the meaning and implication of the data (Pederson and Gore, 1996). This should be in the form of Technical Error of Measurement (TEM), and expressed as a percentage of the measurement value.
where x1and x2are replicate pairs of measures, n is the number of pairs and m is the mean value for that measure across the sample.
%TEM 100·TEM·m1 TEM [冱(x2x1)2]·2n1
Figure 9.1 A triceps skindfold measurement illustrating appropriate technique
Error magnitude varies with the recorder, the measurement type and site.
For serial measurements, a statistical basis for detecting real change should be included. Because the TEM equates to the standard error of a single measure-ment, then overlapping standard errors indicate no significant change in serial measures – either at the 68% (for 1SE) or 95% (for 2SE) level. Clearly, experi-enced anthropometrists with low TEMs are several times more likely to detect real change than others.
The conversion of raw data into indices may be justified in terms of fat patterning (Stewart, 2003b; Eston et al., 2005) (skinfold ratios) corrected girths (Martin et al., 1990), proportions (the ratio of segment lengths or 80 ARTHUR D. STEWART AND ROGER ESTON
Table 9.1 Skinfold measurements
Skinfold Location and landmarking Orientation Body position for measurement Tricepsa Mid-point of a straight line between Vertical Standing
the acromiale and the radiale on the Shoulder slightly
posterior aspect of the arm externally rotated
Subscapular 2 cm lateral and 2 cm inferior to the Oblique – Standing inferior angle of the scapula ~45
dipping laterally
Bicepsa Mid-point level of a straight line Vertical Standing between the acromiale and the Shoulder slightly radiale on the Anterior aspect of externally rotated the arm
Iliac crest Immediately superior to the crest of Near Standing the ilium, on the ilio-axilla line horizontal Right arm placed
across torso Supraspinale The intersection of a horizontal line Oblique Standing
drawn from the crest of the ilium, with a line joining the anterior superior iliac spine and the anterior axillary fold
Abdominal 5 cm lateral of the midpoint of the Vertical Standing umbilicus
Thigha Mid-point of the perpendicular Longitudinal Sitting with leg distance between the inguinal crease extended and foot at the mid-line of the thigh and the supported, the subject mid-point of the posterior border extends the knee and
of the patella when seated clasps hands under
with the knee flexed to 90 hamstrings and lifts gently for measurement Medial calf The most medial aspect of the calf, at Vertical Standing, foot on box,
the level of maximum girth, with with knee at 90
subject standing and weight evenly distributed
Note
a These sites ideally require a wide-spreading caliper or segmometer to locate, because curvature of the skin surface affects site location if a tape is used
Figure 9.2 Skinfold locations Source: M. Svensen
Table 9.2 Girth measurements
Girth Location Body position Notes
Chest At level of mid-sternum Arms abducted Measure at the end of
slightly a normal expiration
Waist Narrowest circumference Arms folded Mid-point between iliac between thorax and pelvis crest and 10th rib, if no
obvious narrowing Hip At the level of maximum Relaxed, feet together Measure from the side,
posterior protuberance of over clothing
buttocks
Upper arm Mid acromiale-radiale Arm abducted slightly, elbow extended
Forearm Maximum Shoulder slightly
flexed, elbow extended Mid-thigh Mid trochanterion – tibiale Weight equally
laterale level distributed
Calf Maximum Weight equally
distributed
anthropometric somatotype (Heath and Carter, 1967). Corrected girths involve subtracting the skinfold multiplied by pi from the limb girth, and are a useful surrogate for muscularity. Predicting tissue masses of fat (Sinning et al., 1985;
Stewart, 2003c) or muscle (Martin et al., 1990; Stewart, 2003a) has obvious appeal but is problematic. Numerous methodological assumptions govern the conversion of linear surface measurements into tissue mass, and sample-specificity restricts the utility of many equations. If used, they should be accompanied by the standard error of the estimate or confidence limits, as well as total error of prediction equations (Stewart and Hannan, 2000), although the use of raw anthropometric data is becoming more accepted and is to be encouraged.
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Eston, R.G., Rowlands, A.V., Charlesworth, S., Davies, A. and Hoppitt, T. (2005).
Prediction of DXA-determined whole body fat from skinfolds: importance of including skinfolds from the thigh and calf in young, healthy men and women.
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82 ARTHUR D. STEWART AND ROGER ESTON
Stewart, A.D. (2003b). Anthropometric fat patterning in male and female subjects. In T. Reilly and M. Marfell-Jones (eds), Kinanthropometry VIII. London, Routledge, pp. 195–202.
Stewart, A.D. (2003c). Mass fractionation in male and female athletes. In T. Reilly and M. Marfell-Jones (eds), Kinanthropometry VIII. London, Routledge, pp. 203–210.
Stewart, A.D. and Hannan, W.J. (2000). Body composition prediction in male athletes using dual X-ray absorptiometry as the reference method. Journal of Sports Sciences, 18: 263–274.
Flexibility has been defined as ‘the intrinsic property of body tissues, which determines the range of motion achievable without injury at a joint or group of joints’ (Holt et al., 1996, p. 172). However the term flexibility has historically involved some confusion or contention. Inconsistencies in terminology used by varying disciplines has been a major factor, where the term often means differ-ent things to differdiffer-ent disciplines. For example, Kisner (2002) defined flexibil-ity as the abilflexibil-ity of a muscle to relax and yield to stretch. This definition emphasises the contractile component of soft tissue structures around a joint rather than the movement available at a specific joint or joints.
Before considering appropriate measures of flexibility it is therefore important to clarify what is meant by flexibility, which type of flexibility you want to measure and whether a test is appropriate for that measure. Accuracy and reliability of testing has been discussed in general in previous chapters but the type of flexibility being measured will have a major impact on the validity of any specific test. When measuring flexibility, it should not be thought of as a whole body component but as a joint or body segment specific issue. Flexibility will often be joint-specific in different sports and measurement should therefore reflect those variations.