Validity of Bioelectrical Impedance Method for the Assessment of Body Composition in Japanese Athletes

Many athletes played an active part in the London Olympics, and there were numerous impressive performances in each event. One factor that affects the performance of athletes is body composition. Methods to evaluate the body composition of athletes include the underwater weighing method and the dual energy X-ray absorptiometry (DXA) method. While these methods are able to evaluate body composition exactly, they are very expensive and difficult to perform, so a less expensive and easier method is needed. Therefore, in the present study, the bioelectrical impedance (BI) method was assessed as an easy method for evaluating body composition for a general adult.

Then, we examined the validity of the BI method in athletes compared with the DXA method as a proper standard. This study used new 12 electrodes BI analysis (Physion MD, Physion Co. Ltd., Kyoto Japan), and the greater number of electrodes makes evaluation of multiple parts (e.g., arms and legs). Thus, we believe that the BI method, which evaluates multiple parts, is suitable for evaluating the body composition of athletes.

The subjects were nine athletes (men: 6, women: 3) belonging to the university track and field club. We measured the body composition in a supine state using new 12 electrodes BI analysis. We then assessed the validity of the BI method for the evaluation of body composition, which includes fat mass, percent of body fat, fat free mass, percent body fat free, and bilateral muscle volume in the arms in legs. In addition, using the DEXA method, we evaluated fat mass, percent of body fat, fat free mass, percent body fat free, and lean tissue mass (LTM) in the right and left arms and legs.

We performed a simple linear regression analysis to examine the correlation of the DEXA method and the BI method. We examined the association with LTM according to the muscle volume in the right and left arms and legs by the DEXA method.

Positive correlations (p<0.001) were observed for all evaluated body compositions. We could more precisely evaluate not only the whole body, but also the muscle volume balance according to right and left arms and legs.

The BI method using new 12 electrodes BI analysis is not only fast, with a measurement time of approximately 2 min, but the method is portable and easier to conduct compared to other methods. We also think that the method is suitable for more precise body composition measurements of athletes, because we can evaluate the balance of right and left muscle volume in the arms and legs fast.