Effects of an ACWR-Guided Load Management Intervention on Time-Loss Injury Incidence in Chinese Elite Youth Footballers: A Cluster Randomised Controlled Trial (ACWR Injury)
Study Overview
Status
Conditions
Intervention / Treatment
Detailed Description
Background: Injury prevention in elite youth football is a public health and performance priority. Approximately two-thirds of players sustain at least one time-loss injury annually, with lower extremity injuries predominating. The acute:chronic workload ratio (ACWR) is widely used in sport science as a practical decision-support tool, yet experimental evidence for its effectiveness in reducing injury incidence remains limited and conflicting, particularly in Asian adolescent populations.
Objectives: This cluster-randomised controlled trial evaluates whether a multi-component ACWR-guided load management intervention reduces time-loss injury incidence in Chinese elite youth football players compared with routine practice.
Study Design: A prospective, two-arm, parallel-group, cluster-randomised controlled trial with 1:1 allocation, stratified by age group (U15/U17/U19).
Participants: Twenty-eight elite youth football teams (U15-U19, n=774, 45.2% female) from 28 academies in Henan Province.
Intervention: The intervention comprises real-time ACWR feedback, automated alerts for values outside the 0.8-1.3 range, coach education workshops, and structured load-adjustment protocols. Control teams follow routine practice without ACWR-derived feedback.
Primary Outcome: Time-loss injury incidence rate per 1000 athlete-exposure hours.
Secondary Outcomes: (1) Severe injury incidence (≥28 days lost); (2) Injury burden (days lost per 1000 h); (3) Proportion of lower-extremity injuries; (4) Proportion of non-contact injuries.
Sample Size: 28 teams (14 per arm) with 774 players (median 27 per team, range 22-31), providing 80% power to detect a 25% reduction in injury incidence (IRR=0.75) with α=0.05 and ICC=0.05.
Statistical Analysis: Mixed-effects Poisson regression with ICC adjustment, Fine-Gray competing risk models, shared frailty Cox models, Kaplan-Meier survival analysis, and E-value sensitivity analysis.
Ethics: The study protocol was approved by the Xinyang Agriculture and Forestry University Ethics Committee (XYAFUAE2024021). Written informed consent was obtained from all participants and their parents/legal guardians.
Study Type
Enrollment (Estimated)
Phase
- Not Applicable
Contacts and Locations
Study Contact
- Name: Jun Li
- Phone Number: 13526075609
- Email: 2005210010@xyafu.edu.cn
Participation Criteria
Eligibility Criteria
Ages Eligible for Study
- Child
- Adult
Accepts Healthy Volunteers
Description
Inclusion Criteria:
- Age 13-19 years Member of a participating U15, U17, or U19 team No injury precluding full participation at enrolment Provided written informed consent (parental consent for minors)
Exclusion Criteria:
- Injury precluding full participation at enrolment Failure to provide informed consent Age outside 13-19 years
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Prevention
- Allocation: N/A
- Interventional Model: Single Group Assignment
- Masking: None (Open Label)
Arms and Interventions
Participant Group / Arm |
Intervention / Treatment |
|---|---|
|
Active Comparator: ACWR Intervention vs Control Trial
Coaches in this group will plan and adjust all training sessions based on published Acute:Chronic Workload Ratio (ACWR) load management principles.
Player training load data will be monitored using a commercially available athlete management system.
The intervention will be implemented for the duration of the complete season.
The ACWR will be used to guide training prescription, with the goal of managing the players' acute and chronic workloads to reduce injury risk
|
Intervention teams implement a structured ACWR-guided load management protocol for the entire season. The protocol comprises four components: Component 1 - Load Monitoring: After each training session and match, players rate perceived exertion on the Borg CR-10 scale. Session-RPE (sRPE) is calculated as duration (minutes) × RPE score. Data are recorded using a dedicated mobile application (CoachMe v3.2). Research staff provide technical support and weekly reminders. Component 2 - Weekly ACWR Reports: The research team generates weekly ACWR reports for each player. Reports are emailed to head coaches each Monday morning, covering the preceding week's data. Component 3-Automated Alerts and Load-Adjustment Recommendations: Coaches receive automated alerts when a player's ACWR falls below 0.8 or exceeds 1.3. When ACWR < 0.8, a progressive increase in training load (10-20% weekly) is suggested. When ACWR > 1.3, coaches are instructed to implement a 10-20% load reduction at the next session, |
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Time-loss injury incidence rate per 1000 athlete-exposure hours.
Time Frame: From enrolment to the end of the 10-month competitive season
|
Definition: Consistent with the football injury consensus statement, a time-loss injury is defined as any physical impairment sustained during structured football training or competitive matches that prevents a player from full participation in subsequent training sessions or matches.
Injuries occurring outside football activities are not recorded.
|
From enrolment to the end of the 10-month competitive season
|
Collaborators and Investigators
Publications and helpful links
Study record dates
Study Major Dates
Study Start (Estimated)
Primary Completion (Estimated)
Study Completion (Estimated)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Actual)
Study Record Updates
Last Update Posted (Actual)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Other Study ID Numbers
- XYAFUAE2026021
Plan for Individual participant data (IPD)
Plan to Share Individual Participant Data (IPD)?
IPD Plan Description
All of the individual participant data collected during the trial, after deidentification. This will include, but is not limited to: baseline demographic and anthropometric data, training load metrics (e.g., acute:chronic workload ratio [ACWR] and its components), time-loss injury incidence and severity data, and exposure hours.
Additional documents to be made available: Study Protocol, Statistical Analysis Plan (SAP), and Informed Consent Form (ICF).
Time frame: Data will be available beginning 9 months and ending 36 months following publication of the primary results.
Access criteria: Data will be made available to researchers who provide a methodologically sound proposal for the purpose of achieving the aims in the approved proposal. Proposals should be directed to the Principal Investigator. To gain access, data requesters will need to sign a data access agreement
IPD Sharing Time Frame
IPD Sharing Access Criteria
IPD Sharing Supporting Information Type
- STUDY_PROTOCOL
- ICF
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
Studies a U.S. FDA-regulated device product
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