Unilateral Compound Training Reduces Lower-Limb Strength Asymmetry and Enhances Athletic Performance in Female Handball Players: A Randomized Controlled Trial (UCT-HB)

Effects of a Six-Week Unilateral Compound Training Program on Lower-Limb Strength Asymmetry and Athletic Performance in Competitive Female Handball Players: A Randomized Controlled Trial

Lower-limb strength asymmetry is common among female handball players and may negatively affect athletic performance while increasing injury risk. This randomized controlled trial was designed to investigate the effects of a six-week unilateral compound training program on lower-limb strength asymmetry, isokinetic muscle strength, hamstring-to-quadriceps ratio, body composition, and physical performance in competitive female handball players. Participants were randomly assigned to either an experimental group receiving unilateral compound training in addition to regular handball training or a control group continuing regular handball training only. It was hypothesized that unilateral compound training would reduce strength asymmetry and improve neuromuscular performance compared with regular training alone.

Study Overview

• Status: Completed
• Conditions: Athletic Performance; Lower-Limb Strength Asymmetry in Female Handball Players
• Intervention / Treatment: Behavioral: Unilateral Compound Training

Detailed Description

emale handball requires repeated sprinting, jumping, rapid changes of direction, and unilateral movements that may contribute to the development of lower-limb strength asymmetries. Such asymmetries have been associated with impaired athletic performance and an increased risk of injury. Although unilateral resistance and plyometric exercises have shown beneficial effects individually, evidence regarding the effectiveness of unilateral compound training in female handball players remains limited.

This randomized controlled trial aimed to evaluate the effects of a six-week unilateral compound training program on lower-limb strength asymmetry, isokinetic knee extensor and flexor strength, hamstring-to-quadriceps ratios, body composition, sprint performance, change-of-direction ability, countermovement jump performance, and single-leg jump performance in competitive female handball players.

Thirty competitive female handball players were randomly assigned to an experimental group or a control group. The experimental group completed unilateral resistance and plyometric exercises three times per week for six weeks in addition to regular handball training, whereas the control group continued regular handball training only. Outcome measures were assessed before and after the intervention using standardized laboratory procedures. The findings of this study are expected to provide evidence regarding the effectiveness of unilateral compound training for reducing lower-limb asymmetry and improving sport-specific performance in female handball athletes.

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Gaziantep, Turkey (Türkiye), 27310
    • Gaziantep University, Faculty of Sport Sciences

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Female handball players aged 18-25 years.
• Competing in the Turkish Women's 2nd Handball League.
• Regular participation in team training (4 sessions/week) and official matches.
• Voluntary participation with written informed consent.

Exclusion Criteria:

• Current musculoskeletal injury or pain preventing participation in training.
• History of lower-limb surgery within the previous 12 months.
• Neurological, cardiovascular, or other medical conditions affecting exercise participation.
• Failure to complete the intervention or assessment procedures.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Experimental; Participants received a six-week unilateral compound training program three times per week in addition to their regular handball training.	Behavioral: Unilateral Compound Training; Participants in the experimental group completed a supervised unilateral compound training program three times per week for six weeks in addition to their regular handball training. The intervention consisted of progressive unilateral resistance and plyometric exercises designed to improve lower-limb strength asymmetry, isokinetic muscle strength, neuromuscular performance, sprint performance, change-of-direction ability, and jump performance.
No Intervention: Control; Participants continued their regular handball training without additional unilateral compound training.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Lower-Limb Strength Asymmetry	Lower-limb strength asymmetry was assessed using isokinetic dynamometry before and after the intervention. Changes in asymmetry between the dominant and non-dominant lower limbs were compared between the experimental and control groups.	Baseline and immediately after the 6-week intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Isokinetic Knee Extensor Strength	Peak torque of the knee extensor muscles measured using an isokinetic dynamometer before and after the intervention.	Baseline and immediately after the 6-week intervention
Isokinetic Knee Flexor Strength	Peak torque of the knee flexor muscles measured using an isokinetic dynamometer.	Baseline and immediately after the 6-week intervention
Hamstring-to-Quadriceps Ratio	Hamstring-to-quadriceps strength ratio calculated from isokinetic knee muscle strength measurements.	Baseline and immediately after the 6-week intervention
20-m Sprint Performance	Sprint time measured over 20 meters.	Baseline and immediately after the 6-week intervention
Change-of-Direction Performance	Change-of-direction performance assessed using the agility test employed in the study protocol.	Baseline and immediately after the 6-week intervention
Countermovement Jump Height	Vertical jump height assessed using the countermovement jump test.	Baseline and immediately after the 6-week intervention

Collaborators and Investigators

• Sponsor: University of Gaziantep

Study record dates

Study Major Dates

• Study Start (Actual): November 15, 2025
• Primary Completion (Actual): December 30, 2025
• Study Completion (Actual): January 10, 2026

Study Registration Dates

• First Submitted: June 25, 2026
• First Submitted That Met QC Criteria: June 25, 2026
• First Posted (Actual): July 1, 2026

Study Record Updates

• Last Update Posted (Actual): July 1, 2026
• Last Update Submitted That Met QC Criteria: June 25, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Plyometric Training; Isokinetic Strength; Female Handball; Unilateral Training; Strength Asymmetry
• Other Study ID Numbers: 2025-080 (Turkish Medicines and Medical Devices Agency (TITCK))

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

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