An interventional study of Isometric Conditioning Activity and Control Condition in Athletic Performance, Soccer and Isometric Strength Training, sponsored by The Jerzy Kukuczka Academy of Physical Education in Katowice. Completed at 1 site in Poland. Open to male participants aged 14 Years to 19 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-07-15.
Sponsored by The Jerzy Kukuczka Academy of Physical Education in Katowice · Not applicable, Interventional, and Basic science
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.
This study investigates the acute effects of an isometric conditioning activity on neuromuscular performance in elite youth soccer players. The study uses a randomized crossover design in which participants complete two experimental conditions in a randomized order.
Twelve male soccer players aged 15-19 years from a professional soccer academy competing in the Polish league system will be recruited. Eligible participants must have at least one year of resistance training experience, regularly participate in organized soccer and strength training and be free from neuromuscular or musculoskeletal disorders.
Each participant will complete two testing sessions separated by seven days. Each session will begin with a standardized warm-up consisting of cycling, dynamic mobility exercises and submaximal jumps. Baseline testing will include two countermovement jumps (CMJ), two drop jumps (DJ) from a 45-cm box, one maximal 30-m sprint and two 505 change-of-direction tests performed using the dominant and non-dominant leg.
Following baseline testing, participants will complete one of two conditions:
i) Isometric conditioning activity (experimental condition): unilateral standing isometric calf raises performed as 3 sets of 3 repetitions with a 3-second contraction for each repetition with a 3-minute rest period between sets.
ii) Control condition: low-intensity treadmill walking at 6 km·h-¹ for 9 minutes.
Seven minutes after completing the assigned condition, participants will repeat the performance tests to assess acute changes in neuromuscular performance.
Jump performance will be measured using a dual force plate system (Dual Force Plate System, CC Athletics, Denmark) sampling at 1000 Hz. Force-time data will be recorded and processed using the manufacturer's software according to standardized procedures. Linear sprint performance will be assessed using a 30-m sprint test performed from a two-point staggered start. Sprint time will be recorded using electronic timing gates (Witty Timing System, Microgate, Bolzano, Italy) positioned at 0, 5 and 30 m.
All testing will be conducted on a short indoor athletics runway located inside a gymnasium. The study aims to determine whether an isometric conditioning activity can acutely enhance explosive performance in youth soccer players and provide practical recommendations for warm-up strategies in soccer.
The Jerzy Kukuczka Academy of Physical Education in Katowice is the lead sponsor of 30 studies on the registry; 14 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Participants perform an isometric conditioning activity consisting of unilateral standing isometric calf raises before post-intervention performance testing.
Behavioral: Isometric Conditioning Activity
Participants perform low-intensity treadmill walking before post-intervention performance testing.
Behavioral: Control Condition
Participants perform unilateral standing isometric calf raises consisting of 3 sets of 3 repetitions with a 3-second contraction for each repetition. A 3-minute rest period is provided between sets.
Participants perform low-intensity treadmill walking at a speed of 6 km·h-¹ for 9 minutes.
Sprint time at 5 m and 30 m
Sprint time measured during a maximal 30-m sprint from a two-point staggered start using electronic timing gates. Split times are recorded at 5 m and 30 m to assess acceleration and overall sprint performance.
Time frame: Baseline and 7 minutes post-intervention
505 Change of Direction Test Time
Time required to complete the 505 change-of-direction test performed using both the dominant and non-dominant leg.
Time frame: Baseline and 7 minutes post-intervention
Countermovement Jump Height
Jump height during a countermovement jump measured using a dual force plate system sampling at 1000 Hz. Participants perform maximal countermovement jumps with hands on hips. Force-time data are recorded and processed using manufacturer software.
Time frame: Baseline and 7 minutes post-intervention
Drop Jump Reactive Strength Index
Reactive strength index calculated from drop jumps performed from a 45 cm box using a dual force plate system. The variable is calculated as jump height divided by ground contact time.
Time frame: Baseline and 7 minutes post-intervention
Plan to share: Yes — De-identified individual participant data will be available upon reasonable request after publication of the study results.
This study is completed, as verified in Mar 2026. You cannot join it, but the record below documents what was studied.
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The Jerzy Kukuczka Academy of Physical Education in Katowice