January 7, 2015

Shilpa Dogra
Ontario University Institute of Technology

Research indicates that body mass index (BMI) is a reliable indicator of total body fat at the population level. However, among two individuals with the same total body fat, risk could differ based on location of fat. As such, waist circumference (WC) and skinfold calipers are used to provide a comprehensive picture of body composition and health risk. Unfortunately, the latter of these two requires high skill and extensive practice to do reliably, and is an uncomfortable procedure for the overweight client. Further, the utility of such measures is poorly understood among individuals with a BMI>30kg/m2. We therefore assessed the association between skinfolds and health risk in the general population, and the value of skinfolds compared to WC across the BMI spectrum of Canadian adults (aged 15-69 years).

Objectively measured data from the Canadian Health Measures Survey (cycle 1 and 2) were used for analysis (n=5,217). Technical error of measurement, an indicator of reliability, was poor for skinfold measurements. The measures for the biceps, iliac crest and medial calf skinfolds were above the acceptable 5% cut-off in all age groups. For WC, all scores were within 0.5 of the acceptable 1% cut-off, except for women in the 60-69 year age group.

As per linear regression models, inclusion of skinfolds in models that contained WC and sociodemographic variables did not change the variance explained i.e. skinfolds did not add value to the association between WC and health outcomes of blood pressure, lung function, cholesterol, blood glucose, self-rated health or life satisfaction. Further, skinfolds did not improve the sensitivity or specificity of self-reported chronic disease among middle-aged and older adults when WC and BMI were already accounted for.

Most importantly, WC was able to differentiate health risk in normal weight and overweight participants using WC cut-points suggested by Ardern et al. (2004); however, skinfolds were not able to distinguish risk using the established categorization. This is important as BMI refined by WC was able to identify individuals at high risk even though they were within the normal weight and overweight BMI categories.

These findings have important implications for exercise professionals and researchers. First, skinfolds should not be used when working with the general population for indication of health related fitness as they do not add value to the more valid and reliable measures of BMI and WC. This is the reason skinfolds were removed from the testing protocols for the CSEP-CPT in the CSEP-PATH. Second, the WC cut-points suggested for males and females in Ardern et al. (2004) should be used to stratify health risk by BMI when working with the general population, particularly with those who are non-obese. Ethnic specific cut-points should be used when possible. Finally, it is possible to elect not to perform WC in obese individuals for health related indication as BMI showed strongest relationship to health outcomes in obese categories; however, baseline measurement would provide a valuable comparison point after a period of training, as reduction in WC is a commonly identified outcome after a period of training, even without changes in BMI. Of note, those with reliable skill level can use skinfolds to monitor subtle changes in body fat, particularly among athletic populations.

Original Article:

Dogra S, Clarke J, Roy J, Fowles J. An assessment of current practices for body composition assessment and health risk determination in the general population. In Press with Applied Physiology, Nutrition and Metabolism http://www.nrcresearchpress.com/doi/abs/10.1139/apnm-2014-0323#.VHOI37EtRyU

If you intend citing any information in this article, please consult the original article and cite that source. This summary was written for the Canadian Society for Exercise Physiology and it has been reviewed by the CSEP Knowledge Transfer Committee.