Acute Effects of Isometric Conditioning on Sprint, Jump and Change of Direction Performance in Youth Soccer Players

This study aims to examine the acute effects of an isometric conditioning activity on sprinting, jumping, and change-of-direction performance in elite youth soccer players. Twelve male soccer players aged 15-19 years from a professional academy will participate in a randomized crossover study. Each participant will complete two experimental sessions separated by one week. During each session, participants will perform a standardized warm-up followed by baseline performance tests including countermovement jumps, drop jumps, a 30-m sprint test, and a 505 change-of-direction test. After baseline testing, participants will complete one of two conditions in randomized order: (1) an isometric conditioning activity consisting of unilateral standing isometric calf raises, or (2) a control condition consisting of low-intensity treadmill walking. Performance tests will be repeated seven minutes after the intervention to assess acute changes in neuromuscular performance. Jump performance will be assessed using a dual force plate system sampling at 1000 Hz, and sprint performance will be measured using electronic timing gates. The study will be conducted on an indoor athletics runway located in a gymnasium. The results will help determine whether isometric conditioning activities can acutely enhance explosive performance in youth soccer players.

Inclusion Criteria: * Male soccer players aged 14-19 years * Currently participating in organized soccer training within a competitive soccer academy * Minimum of one year of experience in resistance training * Regular participation in both soccer training and resistance training for at least one year prior to the study * Free from neuromuscular and musculoskeletal disorders that could affect performance Exclusion Criteria: * Presence of any current musculoskeletal injury affecting the lower limbs. * History of neuromuscular disorders or medical conditions that could influence physical performance * Any injury or health condition preventing maximal sprinting or jumping efforts during testing.