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

 Variations in plasma volume and 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.

 To investigate the effects of training load on plasma volume variations in elite soccer players.

 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).

 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.

 Changes in body weights, PVV and Ht during preparatory and competitive phases were affected by the training load and competitive play.