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Plicometry: the unspoken truths
Plicometry: the unspoken truths
Home / MMA

Plicometry: the unspoken truths

Date: July 08, 2021

The evaluation of body composition is now a routine practice in the history of the athlete, because the assessments of total body mass (BM) are fundamental parameters in some disciplines, for example, where there is a specific classification of athletes by weight categories - see combat sports - but, above all, because a wider examination of body composition, in particular lean mass (LM) and fat mass (FM), provides more information to both athletes and their coaches.

This evaluation of FM, reported as a percentage of fat compared to the total body weight (BF%), is particularly relevant even in sports where the excess fat mass can be perceived as "ballast" and that is in antigravitational activities (jumps, runs, etc.).

It is therefore understood how important it is to evaluate in the athlete the body composition (Body Composition, BC) to monitor growth, the results of training, the state of nutrition, to investigate changes in physical development in order to plan appropriate athletic workouts; to have predictive value for aptitude selection in many sports activities and to achieve performance optimisation; reached through the nutritional homeostasis that is obtained when the body weight is in a perfect relationship between fat mass (FM) and lean mass (FFM).

This relationship depends on the age, sex, genetics and characteristics of the sport.
Since the end of 1800 there have been studies (the first studies on the analysis of cadavers have made history) from which the researchers of the time aimed to obtain patterns of study of body composition managing to have the first models of subdivision in compartments.

Countless studies have proposed a wide range of techniques, as well as related devices, useful for the precise and reliable definition of BC, from the most imaginative to the most complicated, but unfortunately, despite efforts to optimise and standardise methods of assessing body composition, including in elite sport, it must be recognised that there is currently no universally accepted and/or shared measurement method, therefore, methods are often used that are simply available or easily accessible, even for costs - in any case to be considered as estimation methods and not measurement methods -This phenomenon still does not always make many operators aware of the limits of these methods.

Among the many methods proposed, it is certainly worth re-evaluating the PLICOMETRIC TECHNIQUE, if only for historical importance. This methodology can be considered as a densitometric method as it leads to the determination of body density starting from the measurement of the thickness of subcutaneous adipose tissue.

The measurement of these thicknesses (folds) allows to go back to the body density and from this to the fat mass compartment (FM) consisting of all body lipids distributed in the subcutaneous and visceral tissue; for difference from the weight will then be obtained the lean mass (FFM) in turn consisting of muscle mass, bone and tissues inter and intra-parenchymal non-adipose.

The measurement of the thickness of the subcutaneous adipose tissue must be determined in specific "finding points" in the various body segments by means of the plicometer. The best known and used plicometers are those of Holtain, Tanner-Whitehouse, Harpender and Lange.
Numerous studies have shown that there is a degree of correlation between subcutaneous and total fat, this is according to age and varies depending on the population considered, and the plicometry allows to define the topography of subcutaneous fat.

Despite the relatively simple measurement of the skin fold, which makes this method very popular, there are however a number of technical limitations that need to be considered when using this technique:
• first of all, there is an assumption of skin thickness and constant compressibility in the double fold between different measuring sites.
• very strong influence given by the practitioner’s ability to find the right sites and the right clamp pressure,
• age, sex and skin temperature of an athlete.
It should also be recognized that the evaluation of skin folds is the method least influenced by daily activities, recently carried out, such as ingestion of a meal and changes in the state of hydration.

In any case, the anthropometrist’s experience is of fundamental importance to obtain precise data on skin folds.

Another crucial aspect is the need to convert the measures of the packages into % BF, the fundamental complexity comes from the transformation of an indirect method into a doubly indirect one. Doubly indirect methods incorporate regression of equations by plotting the results against a standard criterion to create a composition estimate. To better understand the complexity related to the use of these regression equations it is enough to think that there are currently over a hundred such formulas for the estimate of BF% obtainable from the measurements of the thickness of the cutaneous plica.

These formulas are also established by evaluating extremely variable ethnicities, using numerous protocols, with significant differences in the measured sites and therefore with problems of reliability, reproducibility and intra-operator variability.
In fact, there are several examples of different equations that produce glaring differences on the same individual measured according to the equation used.

Therefore, the conversion of skin-fold thickness to % BF should be discouraged by using rather the sum of the 8 skin-fold sites which provide a more accurate and reliable result than body composition assessment expressed in %BF, as is amply shown in a recent study showing that the sum of the thicknesses of the skin folds has a high degree of agreement with the results of the DXA scan.
However, there are some considerations to do with this approach:
• it is not possible to estimate the FFM, often useful information for those working in the field
• many coaches are not familiar with the data provided as "sum of plica in mm" and often continue to require relativized data (%BF).

Below is an example table:

Another interesting model of evaluation of CB by measurement of skinfolds was proposed by introducing a comparison term of the variation of subcutaneous fat during a training program with an image that is obtained by entering the data of the various measurements in a radial plot known as "Plicometric mapping". This technique is easily obtainable by simply inserting the data of the various measurements in a sheet "Excell" from which then to obtain the graph of the figure.

In conclusion, it can be said that plicometry, as well as several other CB evaluation techniques, can offer only a poorly reliable estimate of %BF, as evidently demonstrated in an unpublished study by Prof. Massimiliano Febbi, in which, in addition to the significantly different results obtained by measuring the same athletes compared with the different techniques, the same plicometry gave different results when different equations were used.

At a time when plicometry is used by simply evaluating the sum of the plica within the reference ranges that are developing, this becomes an excellent model able to assess the developments of the integrated strategy "nutrition training". It should always be noted that the operator in charge of "taking" the packages must always be carefully trained according to ISAK standards.               

BIBLIOGRAPHY

Santos DA, Dawson JA, Matias CN, Rocha PM, Minderico CS, Allison DB, Sardinha LB, Silva AM. Reference values for body composition and anthropometric measurements in athletes. PLoS One. 2014 May 15;9(5):e97846

Kasper AM, Langan-Evans C, Hudson JF, Brownlee TE, Harper LD, Naughton RJ, Morton JP, Close GL. Come Back Skinfolds, All Is Forgiven: A Narrative Review of the Efficacy of Common Body Composition Methods in Applied Sports Practice. Nutrients. 2021 Mar 25;13(4):1075.

Ackland TR, Lohman TG, Sundgot-Borgen J, Maughan RJ, Meyer NL, et al. (2012) Current status of body composition assessment in sport: review and position statement on behalf of the ad hoc research working group on body composition health and performance, under the auspices of the I.O.C. Medical Commission. Sports Med 42: 227–249.

Norton K., Olds T., Dolman J. Kinanthropometry VI: Proceedings of the sixth scientific conference of the International Society for the Advancement of Kinanthropometry. Adelaide, 13–16 October 1998.

Hume P., Marfell-Jones M. The Importance of Accurate Site Location for Skinfold Measurement. J. Sports Sci. 2008;26:1333–1340. doi: 10.1080/02640410802165707.

Silva A.M., Fields D.A., Quitério A.L., Sardinha L.B. Are Skinfold-Based Models Accurate and Suitable for Assessing Changes in Body Composition in Highly Trained Athletes? J. Strength Cond. Res. 2009;23:1688–1696.

 




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