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

March 16, 2026 updated by: The Jerzy Kukuczka Academy of Physical Education in Katowice

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.

Study Overview

Status

Enrolling by invitation

Conditions

Intervention / Treatment

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:

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.

Study Type

Interventional

Enrollment (Estimated)

12

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Poland
    • Silesian Voivodeship
      • Katowice, Silesian Voivodeship, Poland, 40-065
        • Academy of Physical Education in Katowice

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult

Accepts Healthy Volunteers

Yes

Description

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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Isometric Conditioning Activity
Participants perform an isometric conditioning activity consisting of unilateral standing isometric calf raises before post-intervention performance testing.
Behavioral: Isometric Conditioning Activity
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.
Active Comparator: Control Condition
Participants perform low-intensity treadmill walking before post-intervention performance testing.
Behavioral: Control Condition
Participants perform low-intensity treadmill walking at a speed of 6 km·h-¹ for 9 minutes.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
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.
Baseline and 7 minutes post-intervention
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.
Baseline and 7 minutes post-intervention

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Countermovement Jump Height
Time Frame: Baseline and 7 minutes post-intervention
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.
Baseline and 7 minutes post-intervention
Drop Jump Reactive Strength Index
Time Frame: Baseline and 7 minutes post-intervention
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.
Baseline and 7 minutes post-intervention

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

The Jerzy Kukuczka Academy of Physical Education in Katowice

Investigators

  • Principal Investigator: Jonatan Helbin, MSc, Academy of Physical Education in Katowice

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 10, 2026

Primary Completion (Estimated)

March 17, 2026

Study Completion (Estimated)

March 17, 2026

Study Registration Dates

First Submitted

March 12, 2026

First Submitted That Met QC Criteria

March 16, 2026

First Posted (Actual)

March 19, 2026

Study Record Updates

Last Update Posted (Actual)

March 19, 2026

Last Update Submitted That Met QC Criteria

March 16, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • 2-X/2025

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data will be available upon reasonable request after publication of the study results.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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