Flywheel vs Traditional Resistance Training for Change of Direction in Elite Soccer Players (UFRT-COD)

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

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.

Study Overview

• Status: Completed
• Conditions: Athletic Performance; Change of Direction Performance
• Intervention / Treatment: Other: Flywheel Resistance Training; Other: Traditional Resistance Training

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Actual): 22
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Beijing, China, 100084
    • Beijing Sport University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Flywheel Resistance Training; Participants perform unilateral flywheel resistance training using a Bulgarian split squat exercise twice per week for 8 weeks in addition to regular soccer training.	Other: Flywheel Resistance Training; 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
Active Comparator: Traditional Resistance Training; Participants perform unilateral traditional resistance training using a barbell Bulgarian split squat exercise twice per week for 8 weeks in addition to regular soccer training.	Other: Traditional Resistance Training; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
T-test performance (change in completion time, seconds)	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.	Baseline and Week 8

Collaborators and Investigators

• Sponsor: Beijing Sport University

Study record dates

Study Major Dates

• Study Start (Actual): February 20, 2026
• Primary Completion (Actual): April 20, 2026
• Study Completion (Actual): April 21, 2026

Study Registration Dates

• First Submitted: April 28, 2026
• First Submitted That Met QC Criteria: April 28, 2026
• First Posted (Actual): May 5, 2026

Study Record Updates

• Last Update Posted (Actual): May 8, 2026
• Last Update Submitted That Met QC Criteria: May 5, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: soccer players; flywheel training; unilateral resistance training; change-of-direction speed; eccentric overload; agility performance
• Other Study ID Numbers: BSU2025611H-FRTCOD

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data (IPD) will not be shared due to privacy concerns and the limited sample size. Aggregated data will be reported in peer-reviewed publications.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No