Plasma Volume Variations in Professional Soccer Players: Difference Between Pre- and Competitive Season

Hematological parameters occur before and after training in soccer players. however, there are no reports on changes in hematological parameters resulting from a half-season of training in professional soccer players. objectives: to investigate the effects of training load on plasma volume variations in elite soccer players. methods: twenty soccer players from the 1st french division soccer league (ligue 1) were included in the study. the training load was evaluated using the rating of perceived exertion (rpe, 10- borg scale) after each training session and each match. anthropometrics characteristics, hematocrit (ht), hemoglobin (hb) and plasma volume variations (pvv) were assessed at 3 different times: t1: baseline (before the first week of pre-season), t2: at the end of pre-season (after 8 weeks of training) and t3: at the end of the first competitive period (after 26 weeks of training and at halfway of the competitive season). results: values of ht and lean body mass (lbm) increased during the first competitive period from t1 to t3 (ht: ∆↑8%, p = 0.037, effect sizes (es) = 1.0; lbm: ∆↑4%, p = 0.041, es = 0.83) and from t2 to t3 (lbm: (∆↑2%; p = 0.05; es = 0.77). moreover, pvv decreased from t2 to t3 (p = 0.002, es = 0.5) and from t1 to t3 (p < 0.05; es = 1.26). there were no differences in hb at t1, t2 or t3. conclusions: changes in body weights, pvv and ht during preparatory and competitive phases were affected by the training load and competitive play.