Changes in Muscles Hydration for Training Dues

PURPOSE Physical training may induce changes in muscle hydration. Hydration in athletes is studied mainly after a single bout of training session. Muscles mostly trained in soccer players are those in the lower limbs. Recently a new approach in hydration assessment is represented by muscle bio impedance analysis. The purpose of this study is to verify the effects of 50 days training on muscle hydration in athletes. METHODS 97 elite soccer players (age 21.3±5.1 yrs, height 180±0.1) were enrolled. Total hydration status and muscle hydration of quadriceps, hamstrings and calf were evaluated before starting the first training session of the season and before the first official match of championship. Bio impedance analysis (BIA 101 Sport Edition - Akern – Italy) was carried out in the morning and no physical activity in the previous 12 hours. The values of Resistance (Rz) and Reactance (Xc) were normalized per height for total assessment (Rz/h, Xc/h), per thigh length for quadriceps and hamstrings and per leg length for calf (Rz/l, Xc/l). Phase Angle (PA) was also studied. Data before and after 50 days of soccer training were compared (t-test for paired data). RESULTS Anthropometric parameters showed an increase in BMI (22.9±1.8; 23.0±1.7; p<0.01). Total bio impedance didn’t show any statistical difference: - Rz/h from 262.3±26.3 to 263.1±25.1ohm/m; - Xc/h from 35.9±4.0 to 35.0±3.8 ohm/m; - PA from 7.8±0.6 to 7.6±0.6°. Muscle bio impedance showed a significant reduction in Rz/l in all muscles: - quadriceps from 125.2±17.6 to 116.6±15.8 ohm/m, p<0.001; - hamstrings from 122.7±19.6 to 116.8±16.4 ohm/m, p<0.001; - calf from 206.2±26.8 to 199.8±26.1 ohm/m, p<0.001. No differences were found in Xc/l and PA in muscle impedance. CONCLUSION A simple assessment of body weight could provide some information in athletes. Total body assessment does not seem to be sensitive enough to investigate changes in hydration for training dues. Muscle hydration assessment seems to provide specific information in elite athletes. The reduction of Rz/l related to physical training indicates an increase in muscle water. Further research is needed in order to understand the behavior of muscle hydration changes in different populations.