Author(s): LIPCÁK, A., KALINA, T., CACEK, K., CHYTRÝ, J., PALUDO, A.C., Institution: MASARYK UNIVERSITY, Country: CZECH REPUBLIC, Abstract-ID: 2624

INTRODUCTION:
Pre-season training camps in soccer are characterized by substantial accumulated external load, which potentially may induce neuromuscular fatigue or early adaptive responses. Understanding these responses may help optimize load management during intensive training periods. Therefore, this study aimed to examine changes in neuromuscular performance, hamstring strength and inter-limb asymetry during a pre-season training camp in a professional soccer team from Czech Republic.
METHODS:
Sixteen male professional soccer players (age: ±27.4), height: ±183.5, weight: ±79.2) were monitoried during a pre-season training camp. The camp included technical/tactical sessions, strenght and conditioning training, and friendly matches (n = 2) over a period of 10 days. Neuromuscular performance was assessed using the countermovement jump (CMJ). Hamstring strength was evaluated via Nordic Curl test, and inter-limb asymmetry was calculated as percentage difference between limbs. External load was monitored during the camp using global positioning system (GPS)-derived metrics, including total distance (TD), high-speed running (HSR), and sprint distance (SD). Pre–post differences were analyzed using paired t-tests, and effect sizes were calculated following Cohen’s d.
RESULTS:
CMJ performance increased significantly 4.8 % (p = 0.005, d = 0.83). A decrease but not significant were observed in left (−2.4 %, p = 0.34, d = 0.24) or right (−0.7 %, p = 0.64, d = 0.12) hamstring strength. Inter-limb asymmetry showed a non-significant increase 2.3 % (p = 0.10, d = 0.44). Accumulated HSR demonstrated a large negative correlation with post-camp asymmetry (r = - 0.60, p = 0.015), while sprint distance showed a moderate negative assocation (r = -0.47, p = 0.068). No meaningful associations were observed between total distance and neuromuscular outcomes.
CONCLUSION:
Despite the high external load accumulated during the pre-season camp, CMJ performance improved, suggesting early neuromuscular adaptation rather than fatigue. Hamstring strength remained stable, indicating resilience to short-term load exposure. Although inter-limb asymmetry showed a small, non-significant increase, the magnitude of change was modest and unlikely to represent a meaningful imbalance over this short period. Overall, a short-term pre-season camp may enhance explosive performance without compromising hamstring strength, while maintaining relatively stable inter-limb symmetry in professional soccer players.