Effectiveness of Gait Retraining in Female Runners With Patellofemoral Pain: A Randomized Controlled Trial
Phase: NA
Conditions: Patellofemoral Pain, PFP
Sponsor: Beijing Sport University

Version 1.0 Date: 2022.12.20 
Clinical Trial Protocol 
Title 
Effectiveness of Gait Retraining in Female Runners with Patellofemoral Pain: A Randomized 
Controlled Trial 
1. Administrative Information 
Sponsor / Responsible Party: Beijing Sport University  
Collaborators: Sports Medicine Center, West China Hospital, Sichuan University 
Principal Investigator: Haonan Wang, PhD 
Trial Registration: ClinicalTrials.gov (to be assigned) 
Ethics Approval: Approved by Ethics Committee of Beijing Sport University 
Study Period: December 2022 – December 2023 
2. Background and Rationale 
Patellofemoral pain (PFP) is the most common running-related overuse injury, with 
prevalence up to 17% among runners. Increased patellofemoral joint stress (PFJS) is a 
major biomechanical contributor to PFP. Traditional strengthening exercises improve 
function but do not alter running biomechanics. Gait retraining, particularly cadence 
modification, has been proposed as a promising approach to reduce PFJS and alleviate 
symptoms. However, evidence from randomized controlled trials remains limited. This 
study investigates whether wearable device-assisted gait retraining reduces pain, improves 
function, and modifies running biomechanics in female runners with PFP compared to 
education alone. 
3. Objectives 
Primary Objective: To determine the effectiveness of wearable device-assisted gait 
retraining on pain reduction during running in female runners with PFP. 

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Secondary Objectives: 
- To assess improvements in function (Anterior Knee Pain Scale, AKPS) 
- To examine changes in running mechanics (knee kinematics, kinetics, PFJS) 
- To evaluate adherence, feasibility, and safety of wearable device-assisted gait retraining 
4. Study Design 
Type: Randomized, controlled, single-blind, parallel-group trial 
Allocation: 1:1 randomization 
Masking: Outcome assessors blinded; participants not blinded due to intervention nature 
Arms: 
- Intervention Arm: Education + Wearable device-assisted gait retraining 
- Control Arm: Education only 
Study Duration: 18 weeks per participant (6-week intervention + 12-week follow-up) 
5. Participants 
Inclusion Criteria: 
- Female, age 18–45 years 
- Unilateral/bilateral anterior knee pain > 4 weeks 
- VAS pain ≥ 3/10 during running and ≥ 2 of the following: jumping, squatting, kneeling, 
stairs, prolonged sitting, or resisted knee extension 
- Running ≥ 15 km per week 
- Natural rearfoot striker (verified by high-speed video) 
Exclusion Criteria: 
- Acute trauma, history of patellar dislocation, meniscal/chondral lesions 
- Prior knee surgery or injection in past 12 months 
- Rheumatologic, neurologic, or degenerative disease 

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- Pregnancy 
6. Interventions 
6.1 Control Group (Education) 
Delivered via WeChat platform. Content: PFP education, load management strategies, 
symptom-based training modifications, and strengthening exercises (quadriceps & hip). 
Self-monitored running program guided by pain thresholds. 
6.2 Intervention Group (Gait Retraining + Education) 
Same education program as control. Gait retraining protocol: 6-week program, twice per 
week. Step rate increased by 10%, monitored via smartwatch (Huawei GT4). Real-time 
cadence feedback via auditory metronome cues. Feedback frequency: every session (weeks 
1–4), once (week 5), faded (week 6). Duration progressed from 15 min to 30 min per 
session. Pain monitoring: ≤ 3/10 during running, return to baseline within 60 min. 
7. Outcomes 
7.1 Primary Outcome 
Pain during running (VAS-R, 0–100 mm) at baseline, 6 weeks, and 18 weeks 
7.2 Secondary Outcomes 
- VAS-U (usual pain), VAS-W (worst pain) 
- Function: Anterior Knee Pain Scale (AKPS) 
- Running-related measures: weekly mileage, cadence (smartwatch logs) 
- Running mechanics: 3D kinematics, GRF, PFJS and contact force calculations 
7.3 Safety Outcomes 
Adverse events (pain exacerbation, injuries, withdrawal) 

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8. Sample Size 
Sample size estimated with G*Power. Detectable difference: 20 mm VAS (MCID for PFP). 
Power: 80%, α = 0.05. Estimated: 22 participants per group (total n=44), accounting for 15% 
dropout. 
9. Randomization and Blinding 
Random sequence generated by independent statistician. Allocation concealed in sequential 
opaque envelopes. Assessors blinded to group assignment. Participants instructed not to 
disclose intervention to evaluators. 
10. Data Analysis 
Approach: Intention-to-treat and per-protocol. Statistical tests: Repeated measures ANOVA 
and linear regression models (adjusted for baseline, age, BMI, running duration, symptom 
duration). Multiple imputation for missing data. Effect size: Partial eta squared (η²). 
Significance: p < 0.05. 
11. Ethics and Dissemination 
Ethical approval granted by Beijing Sport University Ethics Committee. Informed consent 
obtained from all participants. Results will be disseminated via peer-reviewed journals, 
academic conferences, and ClinicalTrials.gov.