The usefulness of densitometry as a method of assessing the nutritional status of athletes. Comparison with body mass index

Abstract

The body mass index (BMI) is used to assess nutritional status. The result in athletes may be overestimated due to increase in muscle mass.

Objective: To assess the usefulness of fat mass index (FMI) and lean mass index (LMI) determination as indicators of nutritional status and to compare the results with BMI.

Material and methods: We studied 28 amateur rugby players, male. After being subjected to whole body densitometry by dual X-ray absorptiometry, we determined fat and lean body mass together with other parameters. FMI (fat in kg/height in meters(2)), LMI (lean in kg/height in meters(2)) and appendicular muscle mass index (AMMI, arms and legs musculature in kg/height in meters(2)) were calculated.

Results: Using BMI, 18 players were overweight and 4 obese type I. Considering FMI, 7 of them had normal values and high LMI and AMMI, one of them changed from overweight to obese and another one from obese to overweight. Of the 6 players with normal BMI, one of them showed fat excess and another one fat defect. The results changed the assessment of nutritional status in 39% of players.

Conclusions: Although BMI is an appropriate parameter in general population for the assessment of nutritional status, in athletes should be taken into account fat and muscle body percentage and their corresponding indexes. The whole body densitometry appears to be a simple and reliable technique for this purpose.

Keywords: Athlete; Body mass index; Densitometry; Densitometría; Deportista; Fat mass index; Lean mass index; Índice de masa corporal; Índice de masa grasa; Índice de masa magra.