Effects of unilateral and bilateral complex training on lower-limb asymmetry and sprint performance in male sprinters

ISRCTN	ISRCTN13078948
DOI	https://doi.org/10.1186/ISRCTN13078948
Sponsor	Guangzhou Sport University
Funder	Guangzhou Sport University

Submission date: 07/07/2026
Registration date: 15/07/2026
Last edited: 14/07/2026

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Other

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Background and study aims
Many sprinters develop strength differences between their left and right legs. These differences may affect movement efficiency and sprint performance.

Who can participate?
Male collegiate sprinters with lower-limb asymmetry.

What does the study involve?
Participants are randomly assigned to one of two training programs. Both groups continue normal sprint training while completing supervised complex training twice each week for 10 weeks. Physical performance is measured before and after training.

What are the possible benefits and risks of participating?
The intervention may improve lower-limb symmetry, strength, and sprint performance. Risks are similar to routine resistance and plyometric training, including temporary muscle soreness and minor sports injuries.

Where is the study run from?
Guangzhou Sport University, China.

When is the study starting and how long is it expected to run for?
March 2024 to April 2025.

Who is funding the study?
Guangzhou Sport University, China.

Who is the main contact?
Changsheng Lyu, lvcs@gzsport.edu.cn.

Contact information

Mr Lyu Changsheng
Principal investigator, Public, Scientific

Guangzhou Sport University, No. 1268 Guangzhou Avenue
Guangzhou City, Guangdong Province
510010
China

ORCID ID	0009-0002-7721-0914
Phone	+86 15915765187
Email	lvcs@gzsport.edu.cn

Study information

Primary study design	Interventional
Allocation	Randomized controlled trial
Masking	Open (masking not used)
Control	Active
Assignment	Parallel
Purpose	Treatment
Scientific title	A parallel-group randomized controlled trial comparing unilateral-emphasized complex training versus bilateral complex training for reducing lower-limb functional asymmetry and improving sprint performance in male sprinters with baseline interlimb asymmetry
Study objectives	To compare the effects of unilateral-emphasized complex training and bilateral complex training on lower-limb functional asymmetry. To compare changes in lower-limb strength, explosive performance, balance, functional movement, and sprint performance. To determine whether improvements in asymmetry are associated with improvements in sprint performance.
Ethics approval(s)	Approved 08/03/2024, Human Experimental Ethics Inspection Committee of Guangzhou Sport University (Guangzhou Sport University, No. 1268 Guangzhou Avenue Middle, Tianhe District, Guangzhou City, Guangdong Province, 510500, China; +86 020 38025032; gztykjc@163.com), ref: 2024LCLL-20
Health condition(s) or problem(s) studied	Lower-limb functional asymmetry in competitive male sprinters
Intervention	Participants are randomly allocated (1:1) to unilateral-emphasized complex training (UCT) or bilateral complex training (BCT). Randomization is generated using a computer-generated random-number table. Both groups continue their regular sprint training and complete supervised complex training twice weekly for 10 weeks. The UCT group performs unilateral resistance and plyometric exercises with a 3:1 training-volume allocation favoring the non-dominant limb, whereas the BCT group performs conventional bilateral complex training with matched total training volume. Outcome measures are assessed before and after the intervention, including isokinetic knee strength, maximal strength, jump performance, balance, functional movement, sprint performance, sprint kinematics, and interlimb asymmetry indices.
Intervention type	Behavioural
Primary outcome measure(s)	Interlimb asymmetry of knee extensor peak torque measured using isokinetic dynamometry and the Asymmetry Index (AI) at baseline and week 12 Knee flexor asymmetry index measured using isokinetic dynamometry at baseline and week 12
Key secondary outcome measure(s)	100-m sprint performance measured using a 100-m sprint test at baseline and week 12 One-repetition maximum (1RM) measured using standard 1RM testing at baseline and week 12 Lower-body explosive power measured using a Countermovement Jump (CMJ) test at baseline and week 12 Single-leg jump asymmetry measured using a unilateral jump testing at baseline and week 12 Y-Balance performance measured using a Y-Balance Test at baseline and week 12 Movement asymmetries measured using a Functional Movement Screen (FMS) at baseline and week 12 Sprint kinematics measured using two-dimensional motion analysis at baseline and week 12
Completion date	01/04/2025

Eligibility

Participant type(s)
Age group	Adult
Lower age limit	18 Years
Upper age limit	30 Years
Sex	Male
Target sample size at registration	16
Total final enrolment	14
Key inclusion criteria	1. Male sprinters 2. At least 3 years of systematic sprint training 3. Training frequency ≥4 sessions per week 4. 100-m performance meeting the Chinese National Second-Class Athlete standard 5. Baseline lower-limb functional asymmetry (ASL >10%) 6. No lower-limb injury within the previous 3 months
Key exclusion criteria	1. Unable to complete the intervention 2. Unable to complete outcome assessment 3. Acute injury during the intervention affecting training or testing
Date of first enrolment	10/03/2024
Date of final enrolment	01/04/2025

Locations

Countries of recruitment

China

Study participating centre

Guangzhou Sport University

Guangzhou Sport University, No. 1268 Guangzhou Avenue, Guangzhou City, Guangdong Province
Guangzhou
China

Results and Publications

Individual participant data (IPD) Intention to share	No

Editorial Notes

07/07/2026: Study’s existence confirmed by the Human Experimental Ethics Inspection of Guangzhou Sport University, China.