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

NCT07482254 | Enrolling By Invitation

• 1 other identifier: 2-X/2025
• Study Type: interventional
• Target: 12
• Locations: 1 country
• Sites: 1

Brief 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. 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.

Conditions

Athletic Performance; Soccer; Isometric Strength Training

Keywords

post activation performance enhancement; strength and conditioning

Outcome Measures

Primary Outcomes (2)

• 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.

  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.

  Baseline and 7 minutes post-intervention

Secondary Outcomes (2)

• Countermovement Jump Height

  Baseline and 7 minutes post-intervention

• Drop Jump Reactive Strength Index

  Baseline and 7 minutes post-intervention

Study Arms (2)

Isometric Conditioning Activity

EXPERIMENTAL

Participants perform an isometric conditioning activity consisting of unilateral standing isometric calf raises before post-intervention performance testing.

Behavioral: Isometric Conditioning Activity

Control Condition

ACTIVE COMPARATOR

Participants perform low-intensity treadmill walking before post-intervention performance testing.

Behavioral: Control Condition

Interventions

Isometric Conditioning Activity BEHAVIORAL

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.

Isometric Conditioning Activity

Control Condition BEHAVIORAL

Participants perform low-intensity treadmill walking at a speed of 6 km·h-¹ for 9 minutes.

Control Condition

Eligibility Criteria

• Age: 14 Years - 19 Years
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• 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

You may not qualify if:

• 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.

Sponsors & Collaborators

• The Jerzy Kukuczka Academy of Physical Education in Katowice: lead

Study Sites (1)

Academy of Physical Education in Katowice

Katowice, Silesian Voivodeship, 40-065, Poland

Location

Related Publications (5)

• 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.

  PMID: 40943974 BACKGROUND

• Krzysztofik 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.

  PMID: 36523899 BACKGROUND

• Helbin J,Gawel D,Terbalyan A,Wilk M,Krzysztofik M,Lum D,Jarosz J

  BACKGROUND

• Krzysztofik 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.

  PMID: 36752742 BACKGROUND

• Lum 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.

  PMID: 30943568 BACKGROUND

Related Links

• 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.

Study Officials

• Jonatan Helbin, MSc

  Academy of Physical Education in Katowice

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: This study is conducted as an open-label trial. Participants and investigators are aware of the assigned condition. Performance outcomes are measured using objective instrumentation including force plates and electronic timing gates. The order of experimental conditions was randomized using a computer generated randomization sequence "random.org".
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: 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.

Study Record Dates

• First Submitted: March 12, 2026
• First Posted: March 19, 2026
• Study Start: March 10, 2026
• Primary Completion: March 17, 2026
• Study Completion: March 17, 2026
• Last Updated: March 19, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will share

Locations

PL (1)