• body fat
• footballers
• skinfold thickness
• Tanita body fat analyser

Much attention is directed to measuring body composition, particularly fat mass, the aim being to estimate the untoward health consequences of excessive amounts of fat or to assess physical fitness. There are two main types of method of measurement: reference and prediction techniques. The former consist of measuring body density or total body water and dual energy x ray absorptiometry, and the latter include measurement of skinfold thickness and bioelectrical impedance analysis.¹ The Tanita body fat analyser is a commercially available foot to foot bioelectrical impedance analysis system.² It is a novel method because it measures the weight and percentage of body fat simultaneously while the subject stands barefoot, in contrast with traditional impedance devices which comprise a tetrapolar surface electrode system whereby the weight and height of the subjects are manually entered. In this study, we performed comparative body fat analysis of 29 elite football players using a Tanita analyser and skinfold thickness (SFT) measurements and subsequent predictive equations.

Body fat measurements were carried out using a Tanita TBF-350 (Tanita Corp, Tokyo, Japan). Early in the morning after an overnight fast, subjects stood still on the metal sole plates of the machine wearing only light football shorts. SFTs were measured using Holtain calipers (Crymych, UK) at nine sites on the non-dominant side of the body: biceps, triceps, abdomen, subscapula, suprailiac 1 (midaxillary), suprailiac 2 (anterior axillary), thigh, calf, and chest. All measurements were performed by the same examiner. Predicted body density was calculated as described by Durnin and Womersley³ using biceps, triceps, subscapula, and suprailiac values. The proportion of body fat was calculated from body density using the equation of Siri,⁴ and two equations were used to estimate body fat mass, namely those of Siri⁴ and Zorba.⁵ Weight was measured using a digital scale and height with a wall mounted stadiometer. Statistical analysis was performed using Pearson correlation coefficients.

Table 1 summarises the basic details and SFT values of the subjects. It seems that the subjects accumulated fat mainly in the abdomen and suprailiac regions and least in the biceps. Table 2 shows correlations between the predictive fat measurements. There were strong correlations between the Tanita measurements and the other estimates. In addition, all the measurements, excluding biceps, triceps, chest, and suprailiac 1, also tended to increase in direct proportion with weight (p<0.05 for all values). Body density was found to correlate negatively with all the other measurements (p<0.001 for all values).

A similar study to ours was conducted by Utter et al⁶ in collegiate wrestlers in which three SFT measurements were compared with those obtained with a Tanita analyser (TBF-305). They also showed significant correlations. Cable et al⁷ studied a group of 192 heterogeneous men, measuring the validity of measurements with a Tanita analyser (TBF-105) compared with underwater weighing and concluded that the bioelectrical impedance system accurately assessed fat free mass.

Although there is some scepticism about using the Tanita body fat analyser and other conventional bioelectrical impedance systems in patients with cardiac disease,⁸ we advocate its use in normal subjects, especially in the field of sports medicine, in addition to the reliable conventional SFT measurements,⁹ for evaluation of physical fitness.