Athletic PerformanceNCT07482254
Acute Effects of Isometric Conditioning on Sprint, Jump and Change of Direction Performance in Youth Soccer Players
A study testing Isometric Conditioning Activity in people with Athletic Performance and Soccer, run by The Jerzy Kukuczka Academy of Physical Education in Katowice at 1 site in Poland.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 14 to 19 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Athletic Performance, Soccer, Isometric Strength Training
- What is being tested?
- Isometric Conditioning Activity
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 13 participants
- Where
- 1 sitePoland
- Study dates
- 10 Mar 2026to 17 Mar 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 14 to 19 years
- Men only
- Healthy volunteers accepted
- Child, Adult
Who may be able to join
- 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
Who cannot join
- 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.
Trial locations and contacts
1 site in 1 country.
Poland1 site
Academy of Physical Education in Katowice
Katowice, Silesian Voivodeship, 40-065
About this study
Official title: Acute Effects of Unilateral Isometric Conditioning Activity on Sprinting Speed, Jump Performance, Change of Direction Ability and Neuromuscular Function in Elite Youth Soccer Players (U15-U19)
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.
Read the detailed description
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:
- 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.
- Conditions
- Athletic Performance, Soccer, Isometric Strength Training
- Being tested
- Isometric Conditioning Activity, Control Condition
- Keywords
- post activation performance enhancement, strength and conditioning
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Isometric Conditioning ActivityBehavioural
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.
Control ConditionBehavioural
Participants perform low-intensity treadmill walking at a speed of 6 km·h-¹ for 9 minutes.
| Study group | Role | What they receive |
|---|---|---|
| Isometric Conditioning Activity | Experimental | Participants perform an isometric conditioning activity consisting of unilateral standing isometric calf raises before post-intervention performance testing. Receives: Behavioral: Isometric Conditioning Activity |
| Control Condition | Active comparator | Participants perform low-intensity treadmill walking before post-intervention performance testing. Receives: Behavioral: Control Condition |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: 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.
Measured: Baseline and 7 minutes post-intervention
Secondary outcomes (2)
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.
Measured: 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.
Measured: Baseline and 7 minutes post-intervention
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Mar 2026
- Study start10 Mar 2026
- Primary completion17 Mar 2026
- Study completion17 Mar 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for Athletic PerformanceStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- This study uses a randomized crossover design in which all participants complete two experimental conditions in a randomized order. The conditions include an isometric conditioning activity and a control condition consisting of low-intensity treadmill walking. Each participant completes both conditions in two separate sessions conducted one week apart.
- Masking
- None (open label)
- Enrolment
- 13 participants (actual)
Sponsor and investigators
- Lead sponsor
- The Jerzy Kukuczka Academy of Physical Education in Katowice
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Jonatan Helbin, MSc, Principal investigator, Academy of Physical Education in Katowice
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07482254
- Sponsor's protocol ID
- 2-X/2025
- Status last verified
- Mar 2026
- First submitted
- 12 Mar 2026
- Last updated
- 15 Jul 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual participant data will be available upon reasonable request after publication of the study results.
Publications
Jarosz J, Szwarc A. Isometric Conditioning Activity and Jump Performance: Impact of Training Status in Male Participants. J Clin Med. 2025 Sep 3;14(17):6214. doi: 10.3390/jcm14176214.
PubMed 40943974Krzysztofik M, Wilk M, Pisz A, Kolinger D, Tsoukos A, Aschenbrenner P, Stastny P, Bogdanis GC. Effects of Unilateral Conditioning Activity on Acute Performance Enhancement: A Systematic Review. J Sports Sci Med. 2022 Dec 1;21(4):625-639. doi: 10.52082/jssm.2022.625. eCollection 2022 Dec.
PubMed 36523899Helbin J, Gawel D, Terbalyan A, Wilk M, Krzysztofik M, Lum D, Jarosz J. Acute Effects of Isometric Contraction Distribution on Jump Performance in Volleyball Players. J Funct Morphol Kinesiol. 2025 Sep 9;10(3):343. doi: 10.3390/jfmk10030343.
PubMed 40981042Krzysztofik M, Spieszny M, Trybulski R, Wilk M, Pisz A, Kolinger D, Filip-Stachnik A, Stastny P. Acute Effects of Isometric Conditioning Activity on the Viscoelastic Properties of Muscles and Sprint and Jumping Performance in Handball Players. J Strength Cond Res. 2023 Jul 1;37(7):1486-1494. doi: 10.1519/JSC.0000000000004404. Epub 2023 Feb 7.
PubMed 36752742Lum D, Barbosa TM. Brief Review: Effects of Isometric Strength Training on Strength and Dynamic Performance. Int J Sports Med. 2019 May;40(6):363-375. doi: 10.1055/a-0863-4539. Epub 2019 Apr 3.
PubMed 30943568
Study at a glance
From the registry record, last updated by the sponsor on 15 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Acute Effects of Unilateral Isometric Conditioning Activity on Sprinting Speed, Jump Performance, Change of Direction Ability and Neuromuscular Function in Elite Youth Soccer Players (U15-U19)
- ClinicalTrials.gov ID
- NCT07482254
- Acronym / sponsor ID
- 2-X/2025
- Conditions
- Athletic Performance, Soccer, Isometric Strength Training
- Keywords
- post activation performance enhancement, strength and conditioning
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 13 participants (actual)
- Lead sponsor
- The Jerzy Kukuczka Academy of Physical Education in KatowiceUniversity, hospital or other
- Study start
- 10 Mar 2026 (actual)
- Primary completion
- 17 Mar 2026 (actual)
- Study completion
- 17 Mar 2026 (actual)
- First posted
- 19 Mar 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
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:
- 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.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- This study uses a randomized crossover design in which all participants complete two experimental conditions in a randomized order. The conditions include an isometric conditioning activity and a control condition consisting of low-intensity treadmill walking. Each participant completes both conditions in two separate sessions conducted one week apart.
| Arm | Type | Receives |
|---|---|---|
| Isometric Conditioning Activity | Experimental | Behavioral: Isometric Conditioning ActivityParticipants perform an isometric conditioning activity consisting of unilateral standing isometric calf raises before post-intervention performance testing. |
| Control Condition | Active comparator | Behavioral: Control ConditionParticipants perform low-intensity treadmill walking before post-intervention performance testing. |
Who may qualify
- Ages
- 14 to 19 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult
Key inclusion criteria (5 listed)
- 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
Key exclusion criteria (3 listed)
- 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.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Isometric Conditioning ActivityParticipants 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. | Behavioural | Isometric Conditioning Activity |
| Control ConditionParticipants perform low-intensity treadmill walking at a speed of 6 km·h-¹ for 9 minutes. | Behavioural | Control Condition |
Primary outcome
Sprint time at 5 m and 30 m
Time frame: Baseline and 7 minutes post-intervention
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.
505 Change of Direction Test Time
Time frame: Baseline and 7 minutes post-intervention
Time required to complete the 505 change-of-direction test performed using both the dominant and non-dominant leg.
2 secondary outcomes
Countermovement Jump Height
Time frame: Baseline and 7 minutes post-intervention
Drop Jump Reactive Strength Index
Time frame: Baseline and 7 minutes post-intervention
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Jul 2026.
- Background: PubMed 40943974Jarosz J, Szwarc A. Isometric Conditioning Activity and Jump Performance: Impact of Training Status in Male Participants. J Clin Med. 2025 Sep 3;14(17):6214. doi: 10.3390/jcm14176214.
- Background: PubMed 36523899Krzysztofik M, Wilk M, Pisz A, Kolinger D, Tsoukos A, Aschenbrenner P, Stastny P, Bogdanis GC. Effects of Unilateral Conditioning Activity on Acute Performance Enhancement: A Systematic Review. J Sports Sci Med. 2022 Dec 1;21(4):625-639. doi: 10.52082/jssm.2022.625. eCollection 2022 Dec.
- Background: PubMed 40981042Helbin J, Gawel D, Terbalyan A, Wilk M, Krzysztofik M, Lum D, Jarosz J. Acute Effects of Isometric Contraction Distribution on Jump Performance in Volleyball Players. J Funct Morphol Kinesiol. 2025 Sep 9;10(3):343. doi: 10.3390/jfmk10030343.
- Background: PubMed 36752742Krzysztofik M, Spieszny M, Trybulski R, Wilk M, Pisz A, Kolinger D, Filip-Stachnik A, Stastny P. Acute Effects of Isometric Conditioning Activity on the Viscoelastic Properties of Muscles and Sprint and Jumping Performance in Handball Players. J Strength Cond Res. 2023 Jul 1;37(7):1486-1494. doi: 10.1519/JSC.0000000000004404. Epub 2023 Feb 7.
- Background: PubMed 30943568Lum D, Barbosa TM. Brief Review: Effects of Isometric Strength Training on Strength and Dynamic Performance. Int J Sports Med. 2019 May;40(6):363-375. doi: 10.1055/a-0863-4539. Epub 2019 Apr 3.
- Article describing types of isometric strength training and their potential benefits for force production, neuromuscular adaptations, and transfer to sport-specific actions such as sprinting.Link provided by the sponsor.
- Individual participant dataSharing planned: Yes. De-identified individual participant data will be available upon reasonable request after publication of the study results.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Jonatan Helbin, MSc principal investigator
Academy of Physical Education in Katowice
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Isometric Conditioning Activity in people with Athletic Performance and Soccer, run by The Jerzy Kukuczka Academy of Physical Education in Katowice at 1 site in Poland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 15 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Poland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Sprint time at 5 m and 30 m (time frame: Baseline and 7 minutes post-intervention). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07482254, which also lists 5 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Jul 2026.