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Completed

NCT Number: NCT07567677

Flywheel vs Traditional Resistance Training for Change of Direction in Elite Soccer Players

The purpose of this randomized controlled trial is to compare the effects of unilateral flywheel resistance training and unilateral traditional resistance training on change-of-direction performance in elite male soccer players.

A total of 22 elite soccer players will be randomly assigned to either a flywheel resistance training group or a traditional resistance training group. Both groups will perform supervised training twice per week for 8 weeks in addition to their regular soccer training.

Performance outcomes will include linear sprint tests (10 m and 30 m), pre-planned change-of-direction tests (Pro-agility, T-test, Arrowhead test), and agility tests under no-ball and with-ball conditions (AFL agility test).

The primary outcome is change-of-direction performance assessed by the T-test. Secondary outcomes include direction-specific change-of-direction ability and agility performance.

It is hypothesized that unilateral flywheel resistance training will produce greater improvements in change-of-direction performance compared with traditional resistance training, particularly in tasks involving braking and re-acceleration.

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Key information

Conditions

Change of Direction Performance Athletic Performance

Age range

18 year–25 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Beijing Sport University

Beijing, 100084, China

About this study

This study is an exploratory randomized controlled trial designed to investigate the effects of unilateral flywheel resistance training (FRT) compared with unilateral traditional resistance training (TRT) on change-of-direction (COD) performance in elite male soccer players.

Participants are highly trained soccer athletes with at least 8 years of training experience and no recent lower-limb injuries. Following baseline testing, participants are randomly allocated in a 1:1 ratio to either the FRT group or the TRT group.

Both groups perform an 8-week training intervention consisting of two supervised sessions per week. The training exercise is the unilateral Bulgarian split squat, performed with either flywheel inertial resistance (FRT) or barbell loading (TRT). Training volume, frequency, and movement pattern are matched between groups. Load prescription is standardized using mean concentric velocity matching.

Outcome measures are assessed before and after the intervention and include:

  • Linear sprint performance (10 m and 30 m)
  • Pre-planned change-of-direction performance (Pro-agility test, T-test)
  • Direction-specific COD performance (Arrowhead test left and right)
  • Agility performance under no-ball and ball conditions (AFL agility test) The primary outcome is T-test performance. Secondary outcomes include Pro-agility, Arrowhead, and AFL agility tests. Exploratory outcomes include linear sprint performance and ball-constrained agility.

The study aims to determine whether eccentric overload provided by flywheel training leads to superior improvements in COD performance compared with traditional resistance training under matched movement conditions.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Male elite or sub-elite soccer players aged 18-25 years
  • Minimum of 3 years of structured soccer training experience
  • Currently participating in regular team training (≥3 sessions per week)
  • Free from musculoskeletal injury within the past 3 months
  • No prior experience with flywheel resistance training
  • Provided written informed consent to participate

Exclusion criteria

  • History of lower-limb surgery within the past 6 months
  • Current musculoskeletal pain or injury affecting performance
  • Neurological or cardiovascular conditions contraindicating high-intensity exercise
  • Participation in additional strength or conditioning programs outside the study
  • Inability to complete the full intervention protocol

Treatment and study plan

Flywheel Resistance Training

Other

Unilateral flywheel resistance training was performed using a Bulgarian split squat exercise on a flywheel device. Participants completed 2 training sessions per week for 8 weeks. Each session consisted of 4 sets of 6 repetitions per leg. The inertial load was individually selected based on mean concentric velocity matching. Participants were instructed to perform the concentric phase explosively and the eccentric phase with maximal braking effort.

Other names: Flywheel training Isoinertial training

Traditional Resistance Training

Other

Unilateral traditional resistance training was performed using a barbell Bulgarian split squat exercise. Participants trained twice per week for 8 weeks. Each session consisted of 4 sets of 6 repetitions per leg at approximately 80% of one-repetition maximum. Movement tempo was controlled with an explosive concentric phase and a controlled eccentric phase.

Primary outcomes

  1. T-test performance (change in completion time, seconds)

    Time frame: Baseline and Week 8

    Change in T-test completion time (seconds) from baseline to post-intervention after 8 weeks of training. The T-test assesses multidirectional change-of-direction ability involving forward sprinting, lateral shuffling, and backward running.

Sponsors and collaborators

Lead sponsor

Beijing Sport University

Other

Registry information

Official study title

The Effects of Unilateral Flywheel Training and Traditional Resistance Training on Change-of-Direction Performance in Elite Soccer Players: A Randomized Controlled Trial

Acronym: UFRT-COD

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
May 5, 2026
Registry last updated
May 8, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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