Pre‐season friendly match‐play as a double‐edged sword: Performance gains and inflammatory cost in semi‐professional soccer players (a natural experiment)

Abstract Pre‐season training prepares soccer players for competition, but the longitudinal effects of friendly match exposure remain unclear. We investigated whether cumulative late pre‐season match‐play is associated with physiological adaptation in semi‐professional players. Twenty‐four male players from a randomly selected semi‐professional team competing at national level were assessed at pre‐season start, mid‐pre‐season and pre‐competition. Measurements included body composition, physical performance, aerobic fitness and blood markers reflecting muscle damage, inflammation, hormonal status and haematological adaptation. Based on cumulative playing time across eight friendly matches, as determined by coaching staff, players were classified retrospectively into extended play (EP) or limited play (LP) groups. Controlling for mid‐pre‐season baseline, the EP group showed significantly lower pre‐competition values for body mass (= 0.276), body fat (= 0.294) and 35 m sprint time (= 0.129) and higher values for lower‐limb power (dominant/non‐dominant; = 0.219–0.424), velocity at maximal oxygen uptake (= 0.441) and at second ventilatory threshold (= 0.708), serum glutamic–oxaloacetic transaminase (= 0.296), myoglobin (= 0.199), high‐sensitivity C‐reactive protein (= 0.920), interleukin‐6 (= 0.893), tumour necrosis factor‐α (= 0.937) and red blood cell count (= 0.190) (all P ≤ 0.038). Across all participants, total match‐play time was correlated significantly with reductions in body fat ( r = −0.47) and increases in lower‐limb power ( r = 0.44–0.67), second ventilatory threshold ( r = 0.55) and inflammatory markers ( r = 0.79–0.86) (all P ≤ 0.033). Greater friendly match‐play exposure during pre‐season was associated with favourable physiological adaptations and a more pronounced physiological and inflammatory response. These findings support friendly match‐play as a meaningful physiological stimulus and highlight the importance of balancing match exposure with recovery during pre‐season preparation.