Skinfold thickness varies directly with spring coefficient and inversely with jaw pressure

Gore, Christopher J., Carlyon, Robert G., Franks, Steven W. and Woolford, Sarah M. (2000) Skinfold thickness varies directly with spring coefficient and inversely with jaw pressure. Medicine and Science in Sports and Exercise, 32 2: 540-546. doi:10.1097/00005768-200002000-00042


Author Gore, Christopher J.
Carlyon, Robert G.
Franks, Steven W.
Woolford, Sarah M.
Title Skinfold thickness varies directly with spring coefficient and inversely with jaw pressure
Journal name Medicine and Science in Sports and Exercise   Check publisher's open access policy
ISSN 0195-9131
Publication date 2000-02
Sub-type Article (original research)
DOI 10.1097/00005768-200002000-00042
Volume 32
Issue 2
Start page 540
End page 546
Total pages 7
Place of publication Philadelphia, PA
Publisher Lippincott Williams & Wilkins
Collection year 2000
Language eng
Subject C1
321499 Human Movement and Sports Science not elsewhere classified
780199 Other
Abstract Purpose: The main aims of this study were to: 1) determine whether heavy use of Harpenden calipers caused deterioration of the spring coefficient (force per unit length), 2) to quantify the change in skinfold thickness per unit change in jaw closing (downscale) pressure, and 3) to develop a calibration range for these calipers. Methods: Part a) The change in spring force per unit length after at least 100,000 cycles of opening and closing five different springs was measured on a load cell. Part b) The dynamic downscale jaw pressure exerted by six pairs of Harpenden springs was measured on one caliper. Two were new pairs of springs (N1 and N2), two were 25-yr-old springs (O1 and O2), and two pairs (S1 and S2) had been used for less 1 yr. The six spring pairs were used to measure skinfold thicknesses at nine sites, in triplicate, on 20 subjects with the order of springs randomized and counterbalanced. Part c) The downscale jaw pressure of 78 Harpenden calipers was measured at eight jaw gaps. Results: Part a) The springs did not change their characteristics after > 100,000 cycles. Part b) At each skinfold site, the lowest thickness was recorded for S2 which exerted the highest jaw pressure (9.04 g.mm(-2)) and conversely the highest thickness was for N1 which exerted the lowest jaw pressure (8.02 g.mm(-2)). Increasing the downscale jaw closing pressure from 8.0 to 9.0 g.mm(-2) reduced a skinfold thickness by approximately 10%. Part c) The mean downscale jaw pressure was 7.82 +/- 0.25 g.mm(-2) Conclusions: In summary, it is suggested that if accurate skinfold measures between different Harpenden calipers are required, the downscale jaw pressure should be in the range of 7.40-7.82 and 7.85-8.21 g.mm(-2), at jaw gaps of 5 and 40 mm, respectively. These jaw pressures can be achieved by servicing the caliper pivot and indicator gauge to minimize frictional losses, adjusting the caliper jaw alignment, and by selecting springs that have a spring coefficient in the range 1.10-1.15 N.mm(-1).
Keyword Sport sciences
Calibration
Skinfold calipers
Harpenden
Calipers
Q-Index Code C1
Additional Notes Published under "Special Communications - Technical Note".

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Human Movement and Nutrition Sciences Publications
 
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Created: Tue, 10 Jun 2008, 11:15:18 EST