Body composition in sport: a comparison of a novel ultrasound imaging technique to measure subcutaneous fat tissue compared with skinfold measurement.
BACKGROUND
Extremely low weight and rapid changes in weight and body composition have become major concerns in many sports, but sufficiently accurate field methods for body composition assessment in athletes are missing. This study aimed to explore the use of ultrasound methods for assessment of body fat content in athletes.


METHODS
19 female athletes (stature: 1.67(± 0.06) m, weight: 59.6(± 7.6) kg; age: 19.5(± 3.3) years) were investigated by three observers using a novel ultrasound method for thickness measurement of uncompressed subcutaneous adipose tissue and of embedded structures. Two observers also measured skinfold thickness at eight International Society for the Advancement of Kinanthrometry (ISAK) sites; mean skinfold values were compared to mean subcutaneous adipose tissue thicknesses measured by ultrasound. Interobserver reliability of imaging and evaluation obtained by this ultrasound technique: intraclass correlation coefficient ICC=0.968 (95% CI 0.957 to 0.977); evaluation of given images: ICC=0.997 (0.993 to 0.999).


RESULTS
Skinfold compared to ultrasound thickness showed that compressibility of subcutaneous adipose tissue depends largely on the site and the person: regression slopes ranged from 0.61 (biceps) to 1.59 (thigh) and CIs were large. Limits of agreement ranged from 2.6 to 8.6 mm. Regression lines did not intercept the skinfold axis at zero because of the skin thickness being included in the skinfold. The four ISAK trunk sites caused ultrasound imaging problems in 13 of 152 sites (8 ISAK sites, 19 athletes).


CONCLUSIONS
The ultrasound method allows measurement of uncompressed subcutaneous adipose tissue thickness with an accuracy of 0.1-0.5 mm, depending on the probe frequency. Compressibility of the skinfold depends on the anatomical site, and skin thickness varies by a factor of two. This inevitably limits the skinfold methods for body fat estimation. Ultrasound accuracy for subcutaneous adipose tissue measurement is limited by the plasticity of fat and furrowed tissue borders. Comparative US measurements show that skinfold measurements do not allow accurate assessment of subcutaneous adipose tissue thickness.
Institute of Biophysics, Medical University of Graz, , Graz, Austria.
Wolfram
W
Müller
Martin
M
Horn
Alfred
A
Fürhapter-Rieger
Philipp
P
Kainz
Julia M
JM
Kröpfl
Ronald J
RJ
Maughan
Helmut
H
Ahammer
D001823:Body Composition / Q000502:physiology*; D005260:Female; D006173:Gymnastics / Q000502:physiology*; D006801:Humans; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D015588:Observer Variation; D012885:Skinfold Thickness; D012916:Soccer / Q000502:physiology*; D013178:Sports Medicine / Q000379:methods; D050151:Subcutaneous Fat / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D055815:Young Adult
Assessing validity and reliability of test of physiological parameters; Body composition methodology; Eating disorders; Ultrasound; Weight loss