Purpose: To show the importance of the study of body composition in functional capacity evaluation of athletes who play professional football, during periods of very hard training (before the beginning of the championship), in order to appreciate every kind of adaptation to the training itself more precisely.
Materials and methods: 18 semiprofessional football players, ages 18-32 yr., weight 75.2 +/- 8.1 kg, height 180.8 +/- 5.5 cm have been subjected to body composition evaluation, using Biolectrical Impedance Analysis (B.I.A) and antropometrics measurements, the day before the beginning of the trainings and at the end of them (just before the beginning of the championship).
Results: The athletes at end the training period (15 day) showed significant loss of weight (1.6 kg; p < 0.001). This reduction was attributed to a loss of the fat mass (2.8 kg; p < 0.001). Fat free mass increased 1.2 kg (p < 0.05); at the same time total body water increased too (1.0 l; p < 0.05) proving that, in spite of hard training, the athletes mateined a good hydratation.
Conclusions: The results suggest that is very important to analyse body composition in the football players, since otherwise we couldn't attained the variation of weight in a quantitative and qualitative way.