Application of Multiple Vertical Jump Tests in Return-to-Play Assessment for Anterior Cruciate Ligament Reconstruction Athletes (RTP-VJ)

The Application of Vertical Jump Performance in Return-to-Play Assessment for Anterior Cruciate Ligament Reconstruction Athletes

Anterior cruciate ligament (ACL) injury is a common sports-related injury, particularly in sports that require extensive jumping and cutting movements. Although anterior cruciate ligament reconstruction (ACLR) surgery can restore knee stability, many athletes still face the risk of re-injury after returning to competition.Current return-to-play assessment relies primarily on single-plane horizontal hop tests and symmetry indices (LSI ≥ 90%); however, an increasing body of research suggests that these tests may not comprehensively reflect functional deficits in the vertical plane, repeated hopping, or high-intensity sport-specific activities.This study hypothesizes that incorporating multiple vertical jump tests-including single-leg vertical jumps and 10-second repeated vertical jumps-combined with advanced force plate analytics (such as Reactive Strength Index [RSI] and Time to Stabilization [TTS])-can more sensitively reveal residual neuromuscular control deficits following surgery. This approach would provide evidence-based guidance for return-to-play decision-making, thereby improving athletes' long-term athletic performance and safety.

Study Overview

• Status: Not yet recruiting
• Conditions: ACL Reconstruction

Detailed Description

This cross-sectional study compares biomechanical performance between ACLR athletes (>6 months post-op) and healthy controls to evaluate whether vertical jump protocols reveal greater limb asymmetries compared to traditional horizontal hop tests. Following a 5-minute stationary bicycle warm-up and familiarization trials, participants perform four unilateral tasks on both limbs: Single-Legged Hop for Distance (SHD), Crossover Hop for Distance (CHD), Single-Legged Vertical Countermovement Jump (SLVJ), and 10-Second Repeated Single-Legged Vertical Jump (SLVJs). All tasks are performed with hands on hips to minimize compensatory motion. Three successful trials are recorded per limb per task with 3-minute rest intervals between sets. Trials are discarded if participants land on the contralateral limb, lose balance, or fail to land on the force plate. Vertical ground reaction forces are collected using a dual-force plate system (Hawkin Dynamics, 3rd Generation) at 1000 Hz. Data processing calculates Limb Symmetry Index (LSI), Modified Reactive Strength Index (RSI) from SLVJs as Jump Height divided by Movement Time, Time to Stabilization (TTS) defined as the duration for vGRF to stabilize within ±5% of body weight, and eccentric/concentric impulse.

• Study Type: Observational
• Enrollment (Estimated): 36

Contacts and Locations

• Study Contact: Name: Teng C Y Kaohsiung Medical University, Bachelor; Phone Number: +886-958-392-604; Email: a266422a@gmail.com

Study Locations

• Taiwan
  • Kaohsiung City, Taiwan
    • Kaohsiung Medical University
    • Contact: Teng C Y Undergraduate student of Sports Medicine, Bachelor's degree; Phone Number: +886-958-392-604; Email: a266422a@gmail.com
    • Contact: Guo L Y Professor and Dean of the College of Health Sciences, Doctorate; Phone Number: #2646 #614 +8867-3121101; Email: yuen@kmu.edu.tw

Participation Criteria

Eligibility Criteria

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

• Sampling Method: Non-Probability Sample

Study Population

The study population consists of two distinct groups: (1) ACLR athletes: elite athletes aged 18-35 years who have undergone unilateral anterior cruciate ligament reconstruction using hamstring or gracilis autograft with a minimum of 6 months post-operative. These participants will be recruited from orthopedic clinics, sports medicine centers, and rehabilitation facilities in the region. (2) Healthy controls: age, sex, and athletic-level matched individuals aged 18-35 years with no history of lower extremity injuries, recruited from local athletic facilities, university sports programs, and community sports organizations. Both groups must have elite athlete status, defined as prior participation in national-level sports competitions. The ACLR group represents athletes in the late rehabilitation phase preparing for return-to-play, while the healthy control group serves as a reference for normal biomechanical performance.

Description

Inclusion Criteria:

• 1.Age 18-35 years

  2.Unilateral anterior cruciate ligament (ACL) rupture confirmed by magnetic resonance imaging (MRI)

  3.Positive Lachman test grade ≥2 pre-operatively

  4.Anterior cruciate ligament reconstruction (ACLR) using hamstring or gracilis autograft

  5.Post-operative time ≥6 months

  6.Completed rehabilitation program with clearance from orthopedic surgeon or physical therapist

  7.Quadriceps strength symmetry index ≥90%

  .Elite athlete status (prior participation in national-level competitions)

Exclusion Criteria:

1. Other lower extremity injuries or pathologies (including other knee ligament injuries)
2. Contralateral lower limb injury within the past 3 months
3. Quadriceps strength symmetry index <90%
4. Non-elite athlete status (no prior national-level competition participation)
5. Incomplete rehabilitation or lack of medical clearance

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Health: Control group; The group include athletes with no lower limbs injury.Participants must be aged 18-35 years and must be elite athletes who have competed in national-level competitions.
ACL reconstruction; Participants must be aged 18-35 years with unilateral ACL rupture confirmed by MRI, Lachman test grade ≥2, and reconstruction using hamstring or gracilis autograft with at least 6 months post-operative. Participants must have completed rehabilitation with clearance from an orthopedic surgeon or physical therapist, demonstrate no other lower extremity injuries, and have no contralateral lower limb injury within the past 3 months. Additionally, quadriceps strength symmetry index must be ≥90%, and participants must be elite athletes who have competed in national-level competitions.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Limb asymmetry index,LSI	Limb Symmetry Index (LSI) calculated as (|Uninvolved limb value - Involved limb value| / (Uninvolved limb value + Involved limb value)) × 100% for each of the four jump tasks: Single-Legged Hop for Distance (SHD), Crossover Hop for Distance (CHD), Single-Legged Vertical Countermovement Jump (SLVJ), and 10-Second Repeated Single-Legged Vertical Jump (SLVJs). LSI values will be compared between ACLR athletes and healthy controls to determine whether vertical jump protocols reveal greater limb asymmetries than traditional horizontal hop tests. Primary analysis will examine whether LSI differences in vertical jump tasks are statistically significantly lower (indicating greater asymmetry) than horizontal hop tasks, revealing residual neuromuscular deficits not detected by conventional return-to-play assessment.	At baseline (single testing session; no longitudinal follow-up)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Modified Reactive Strength Index	Modified Reactive Strength Index (mRSI) calculated as Flight Time(s) divided by Time to Take-off(s) for the 10-Second Repeated Single-Legged Vertical Jump (SLVJs) task.	At baseline (single testing session; no longitudinal follow-up)
Time to Stabilization (seconds)	Time to Stabilization (TTS) measured during the Single-Legged Vertical Countermovement Jump (SLVJ) task, defined as the time required for vertical ground reaction force (vGRF) to return to and stabilize within ±5% of the participant's body weight following landing.	At baseline (single testing session; no longitudinal follow-up)
Single-Legged Hop for Distance (centimeter)	Single-Legged Hop for Distance (SHD) measured as the maximum horizontal distance(centimeter) achieved during a single maximal hop on the tested leg, performed bilaterally.	At baseline (single testing session; no longitudinal follow-up)
Crossover Hop for Distance (centimeter)	Crossover Hop for Distance (CHD) measured as the total horizontal distance covered during three consecutive hops crossing a centerline, performed bilaterally with emphasis on stability and continuity.	At baseline (single testing session; no longitudinal follow-up)
Jump Height(meter)	Jump Height measured during the Single-Legged Vertical Countermovement Jump (SLVJ) and 10-Second Repeated Single-Legged Vertical Jump (SLVJs) tasks, calculated from the flight time (time from takeoff to landing) using force plate data.	At baseline (single testing session; no longitudinal follow-up)

Collaborators and Investigators

• Sponsor: Kaohsiung Medical University
• Investigators: Study Chair: GUO L Y Professor and Dean of college, Ph.D., Department of Sports Science, Kaohsiung Medical University, Taiwan

Study record dates

Study Major Dates

• Study Start (Estimated): December 29, 2025
• Primary Completion (Estimated): January 30, 2026
• Study Completion (Estimated): January 30, 2026

Study Registration Dates

• First Submitted: December 9, 2025
• First Submitted That Met QC Criteria: December 9, 2025
• First Posted (Actual): December 22, 2025

Study Record Updates

• Last Update Posted (Actual): December 22, 2025
• Last Update Submitted That Met QC Criteria: December 9, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: ACL reconstruction; return to play; vertical jump test
• Other Study ID Numbers: KMUHIRB-F(II)-202 20046 (Other Identifier: Kaohsiung Medical University Chung-Ho Memorial Hospital Institutional Review Board)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: De-identified individual participant data (IPD) that underlie the main published results, including demographic characteristics and biomechanical outcome measures (e.g., jump height, limb symmetry index, RSI, TTS, and impulse), will be shared with qualified researchers upon reasonable request, after approval of a data use agreement and in accordance with applicable ethical and regulatory requirements.
• IPD Sharing Time Frame: De-identified individual participate data (IPD) and supporting information will be available starting 2 years after the publication of the primary study results and will remain accessible for 5 years.
• IPD Sharing Access Criteria: The related supporting documents will only be made available to qualified researchers affiliated with academic institutions, medical organizations, or public health agencies. Applicants must submit a detailed research proposal and ethical approval documents, and access will be granted only upon approval.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE; CSR

Drug and device information, study documents

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