The assessment of body composition is now a routine practice in the sports history, as the assessments of the total body mass (BM) are fundamental parameters in some disciplines, for example where there is a specific classification of athletes by weight categories - as in combat sports - but above all because a broader examination of body composition, in particular of lean mass (LBM - Lean Body Mass or FFM - Fat Free Mass) and fat mass (FM - Fat Mass), provides more information both to athletes and their coaches. The evaluation of FM, reported as a percentage of fat with respect to the total body weight (BF% - Body Fat, expressed as a percentage), is particularly relevant also in sports where excess fat mass can be perceived as "ballast".
It is therefore clear how important it is to evaluate body composition (BC) in the athlete to monitor growth, training results, nutrition status and to investigate the changes that occur on physical development in order to plan workouts. appropriate athletic; it is also important to have the predictive value for aptitude selection in many sports activities, and thus achieve an optimization of performance, achievable through the nutritional homeostasis that is obtained when the body weight is in a perfect ratio between fat mass (FM) and lean mass (FFM). This ratio depends on age, sex, genetics and the characteristics of the sport practiced.
Since the end of 1800 there have been studies (the first studies carried out on the analysis of corpses made history) from which the researchers of the time aimed to obtain study schemes of body composition, managing to have the first models of subdivision into compartments .
Countless studies have proposed a series of techniques with related devices useful for the precise and reliable definition of BC, from the most imaginative to the most complicated, but unfortunately, despite the efforts made to optimize and standardize methods of body composition assessment, even in elite sport , it must be recognized that there is currently no universally accepted and / or shared method of measurement. Per this reason, simply available or easily accessible methods are often used (which are in any case to be considered as methods of estimation and not of measurement), also for costs. This is a phenomenon that still makes many operators not always aware of the limits of the aforementioned methods.
Among the various systems proposed for the estimation of BC, it is certainly worthwhile, also for historical importance, to re-evaluate the PLICOMETRIC TECHNIQUE. 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 the subcutaneous adipose tissue.
The measurement of these thicknesses (which are called pliche in technical jargon) allows us to trace the body density, and starting from this to the compartment of the fat mass (FM), consisting of all body lipids distributed in the subcutaneous and visceral tissue; by difference from the weight, the lean mass (FFM) will then be obtained , in turn made up of muscle masses, bone and non-adipose inter and intra-parenchymal tissues.
The measurement of the thickness of the subcutaneous adipose tissue must be determined in specific "landmarks" in the various body segments by means of the skinfolder. The best known and most used skinfinders 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 a function of age and varies according to the population considered. In addition, plicometry allows to define the topography of the subcutaneous fat.
Despite the relative simplicity of skin fold measurement, which makes this method very popular, there are nevertheless a number of technical limitations that need to be considered when using this technique:
- First, there is an assumption of skin thickness and constant compressibility in the double fold between different measurement sites;
- The influence given by the practitioner's ability to find the right sites and the right pressure of the forceps is very strong;
- An athlete's age, gender, and skin temperature can influence the measurement.
However, it should be emphasized that the assessment of skin folds is the method least influenced by daily activities, even recently carried out, such as the ingestion of a meal and changes in the state of hydration. In any case, the operator's experience is of fundamental importance to obtain precise data on skin folds.
Another crucial aspect relates to the need to convert the measurements of the folds into% BF. The complexity derives from the transformation of an indirect method, such as the detection of the folds, into a doubly indirect one, or the use of predictive formulas. The doubly indirect methods incorporate the regression of equations by plotting the results against a standard criterion to create a composition estimate. To better understand the complexity of using these regression equations, just think that there are currently over a hundred of these formulas for estimating the BF%, obtainable from measurements of the thickness of the skin fold.
These formulas are also established by evaluating extremely variable ethnic groups, using numerous protocols, with considerable differences between the sites measured and therefore with problems of reliability, reproducibility and intra-operator variability.
In fact, there are several examples of equations that produce sensational differences on the same individual, measured according to the equation used.
Therefore, the conversion of skinfold thickness to% BF should be discouraged, rather using the sum of the 8 skinfold sites. This, in fact, provides a more accurate and reliable result than the assessment of body composition expressed in% BF, as is amply shown in a recent study, which shows that the sum of the thicknesses of the skin folds has a high degree of agreement with the results. scanning from DXA (Dual Energy X-ray Absorptionmetry, gold standard for the assessment of body composition).
However, there are some considerations to make with this approach:
- It is not possible to estimate the FFM with precision, often useful information for those who work in the field;
- Many coaches are unfamiliar with the data provided as "sum of folds in mm" and often continue to request relativized data (% BF).
Below is an example table:
Another interesting model for evaluating BC by measuring skin folds has been proposed by introducing a term for comparing the variation of subcutaneous fat during a training program, with an image that is obtained by inserting the data of the various measurements in a radial plot. known as "skin fold mapping". This technique is easily obtained by simply inserting the data of the various measurements in an “Excell” sheet from which the graph of the figure is then obtained.
In conclusion, it can be stated that plicometry, as well as various other BC assessment techniques, is able to offer only a poorly reliable estimate of the% BF, as evidently demonstrated in an unpublished study conducted by Prof. Massimiliano Febbi, to which I collaborated, and in which, in addition to the notably different results obtained by measuring the same athletes compared with the different techniques, the same skin test gave several different results when different equations were used.
When the skinfold is used by simply evaluating the sum of the skinfolds, within the reference ranges that are gradually developing, this becomes an excellent model, capable of evaluating the developments of the integrated "training-nutrition" strategy. It should be noted that the operator in charge of "taking" the packages must always be carefully trained according to ISAK standards.
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