How Eccentric Closed Chain Training Affects Knee Strength and Muscle Properties in Soccer Players

NCT06987344 | Completed

• 1 other identifier: 2025015
• Study Type: interventional
• Target: 24
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this study is to learn whether a 6-week lower-body training program using closed kinetic chain (CKC) exercises with slow, controlled movements (called "eccentric time under tension") can improve leg muscle strength and muscle-tendon viscoelastic properties in male university soccer players. The Main Questions Are:

1. 1.Does this type of training improve knee strength?
2. 2.Does it change the way muscles and tendons respond to movement or pressure?
3. 3.Join one of two groups: one does the CKC training program, the other continues regular soccer training
4. 4.Train twice a week for 6 weeks
5. 5.Have their leg strength tested using special equipment
6. 6.Have their muscle and tendon properties measured with a handheld device

Conditions

Healthy

Keywords

Exercise therapy; Muscle strength; Lower extremity; Tendons

Outcome Measures

Primary Outcomes (2)

• Change from baseline in the rotational peak torque relative to body mass at 6 weeks

  Assessed using a Biodex® System 3 Pro isokinetic dynamometer (Shirley, NY, USA), with a validated accuracy of ±1%. Testing was performed at 60°/s angular velocity, a standard velocity for evaluating maximal voluntary muscle contraction. Participants were seated with their hips and knees at approximately 90° flexion. The dominant leg was tested and stabilized using straps at the trunk, thigh, and lower leg. Gravity correction was applied prior to testing. Following a 5-minute warm-up and 3 submaximal practice repetitions, each participant performed 3 maximal concentric repetitions of knee extension and flexion. The dominant leg was defined as the preferred leg for kicking, confirmed via observation of a standardized ball-kicking task.

  From enrollment to the end of closed kinetic chain training protocol at 6 weeks

• Change from baseline in the rotational mean power at 6 weeks

  Assessed using a Biodex® System 3 Pro isokinetic dynamometer (Shirley, NY, USA), with a validated accuracy of ±1%. Testing was performed at 60°/s angular velocity, a standard velocity for evaluating maximal voluntary muscle contraction. Participants were seated with their hips and knees at approximately 90° flexion. The dominant leg was tested and stabilized using straps at the trunk, thigh, and lower leg. Gravity correction was applied prior to testing. Following a 5-minute warm-up and 3 submaximal practice repetitions, each participant performed 3 maximal concentric repetitions of knee extension and flexion. The dominant leg was defined as the preferred leg for kicking, confirmed via observation of a standardized ball-kicking task.

  From enrollment to the end of closed kinetic chain training protocol at 6 weeks

Secondary Outcomes (3)

• Change from baseline in the agonist/antagonist strength ratio at 6 weeks

  From enrollment to the end of closed kinetic chain training protocol at 6 weeks

• Change from Baseline in the muscle oscillation frequency at 6 weeks

  From enrollment to the end of closed kinetic chain training protocol at 6 weeks

• Change from Baseline in the stiffness at 6 weeks

  From enrollment to the end of closed kinetic chain training protocol at 6 weeks

Study Arms (2)

Active Control Group

ACTIVE COMPARATOR

Maintained their customary daily activities and regular soccer training routines: Trained three times a week, two days were dedicated to functional and tactical on-field training, while the third day was reserved for a two-hour gym session focused on flexibility, muscular strength, and endurance development.

Other: Regular soccer training routines

Closed Kinetic Chain Group

EXPERIMENTAL

In addition to the same activities as the active cotrol group, participants performed five to seven different closed kinetic chain drills during the two days of field-based training, completing two to three sets per drill and eight to fourteen repetitions per set. The training volume underwent gradual increments over the course of every week. The total training volume for externally loaded CKC exercises was calculated by summing sets × repetitions × load (kg), yielding a cumulative volume of approximately 10,863 kg over 12 sessions. For exercises involving bodyweight or elastic resistance, training volume was estimated using time under tension (TUT), computed as the product of repetitions and eccentric phase duration. The cumulative TUT throughout the 6-week protocol amounted to 9,300 seconds (155 minutes) of eccentric loading.

Other: Field-based closed kinetic chain exercise with progressively increased time under tension; Other: Regular soccer training routines

Interventions

Field-based closed kinetic chain exercise with progressively increased time under tension OTHER

This intervention is uniquely characterized by the integration of field-based closed kinetic chain (CKC) exercises with a systematically increased eccentric time under tension (TUT), specifically tailored for university-level soccer players. Unlike conventional strength training protocols, which are often gym-based and rely on traditional resistance machines or free weights, this program emphasizes functional, sport-specific movement patterns performed on the field, enhancing ecological validity and transfer to soccer performance.

Closed Kinetic Chain Group

Regular soccer training routines OTHER

Trained three times a week: two days were dedicated to functional and tactical on-field training, while the third day was reserved for a two-hour gym session focused on flexibility, muscular strength, and endurance development.

Active Control Group; Closed Kinetic Chain Group

Eligibility Criteria

• Age: 18 Years - 25 Years
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Absence of any medical conditions that could compromise their ability to participate.
• Active membership in their university's soccer team for a minimum of one year.

You may not qualify if:

• Musculoskeletal injuries reported in the two months prior to the start of the study.
• Surgical interventions involving the lower limbs within the past year.

Sponsors & Collaborators

• University of Americas: lead

Study Sites (1)

Human Movement Analysis Laboratory

Viña del Mar, V región/Valparaíso, 2340000, Chile

Location

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: May 15, 2025
• First Posted: May 23, 2025
• Study Start: January 6, 2025
• Primary Completion: March 28, 2025
• Study Completion: March 31, 2025
• Last Updated: May 29, 2025

Record last verified: 2025-05

Data Sharing

• IPD Sharing: Will not share

Locations

CL (1)