Region-Specific Associations Between Q-Angle and Plantar Loading in Physically Active Young Adults
Conditions: Q-angle, Plantar Loading Patterns
Sponsor: Harran University

Study Protocol 
Official Title 
Region-Specific Associations Between Q-Angle and Plantar Loading in Physically Active 
Young Adults 
Brief Title 
Q-Angle and Plantar Loading in Active Young Adults 
Document Date: 2026-03-16 
Brief Summary 
This observational study aims to examine the association between Q-angle and plantar 
loading characteristics in physically active young adults. Q-angle is a commonly used clinical 
measure of lower-extremity alignment, but its relationship with regional plantar loading 
during gait remains unclear. Participants will undergo bilateral Q-angle assessment and 
plantar pressure evaluation during walking. The study will investigate whether Q-angle is 
associated with specific plantar loading variables across different foot regions in active young 
adults. 
Detailed Description 
This observational study is designed to investigate the association between Q-angle and 
plantar loading characteristics in physically active young adults. Q-angle is a commonly used 
measure of lower-extremity alignment, but its relationship with regional plantar loading 
during gait has not been fully clarified. 
Participants will undergo bilateral Q-angle assessment under standardized conditions and 
dynamic pedobarographic evaluation during walking. Plantar pressure variables will be 
obtained for different foot regions, including the toes, forefoot, midfoot, hindfoot, and total 
foot. The primary objective is to determine whether Q-angle is associated with selected 
regional plantar loading variables. Secondary analyses will explore whether these associations 
differ according to sex and limb dominance. 
Statistical analyses will be performed using linear mixed-effects models to account for within-
subject dependence between bilateral measurements.This study focuses on the relationship 
between lower-extremity alignment and regional plantar loading patterns in physically active 
young adults. 
Study Design 
 
Study Type: Observational 
 
Observational Model: Other 
 
Time Perspective: Cross-Sectional 

 
Enrollment: 92 participants 
 
Enrollment Type: Actual 
 
Number of Groups/Cohorts: 1 
Study Population 
Physically active young adults aged 18 years and older who are able to walk independently 
and who have no current lower-extremity injury, previous lower-extremity surgery, 
neurological disorder, vestibular disorder, structural deformity, or musculoskeletal pain 
affecting gait or balance. 
Sampling Method 
Non-Probability Sample 
Group/Cohort 
Group/Cohort Label 
Physically active young adults 
Group/Cohort Description 
Physically active young adults who underwent Q-angle measurement and plantar pressure 
assessment during walking. No therapeutic or preventive intervention was applied. 
Intervention / Exposure 
Intervention Name 
Q-angle and plantar pressure assessment 
Intervention Description 
Participants underwent observational Q-angle measurement and dynamic plantar pressure 
assessment during walking. No therapeutic or preventive intervention was administered. 
Eligibility Criteria 
Inclusion Criteria 
1. Age 18 to 27 years 
2. High physical activity level according to the International Physical Activity 
Questionnaire-Short Form (IPAQ-SF) classification 
3. Ability to complete the assessment procedures independently 
4. Voluntary agreement to participate 

Exclusion Criteria 
1. History of lower-extremity injury within the previous 6 months 
2. Previous lower-extremity fracture or surgery 
3. Known neurological or vestibular disorder affecting gait or balance 
4. Current musculoskeletal pain in the spine or lower extremities during assessment 
5. Diagnosed structural lower-extremity deformity 
6. Inability to complete the assessment procedures independently 
Outcome Measures 
Primary Outcome Measure 
Association between Q-angle and regional pedobarography outcomes 
Description: Regional plantar pressure, force, contact area, and contact time outcomes 
assessed in relation to Q-angle. 
Time Frame: At baseline 
Outcome Variables 
 
Peak pressure (kPa) 
 
Contact area (cm²) 
 
Contact time (ms) 
 
Maximum force (N) 
 
Maximum force normalized to body weight (%BW) 
Plantar Regions 
 
Toes 
 
Forefoot 
 
Midfoot 
 
Hindfoot 
 
Total foot 
Study Procedures 
Q-Angle Assessment 
Bilateral Q-angle measurements are obtained under standardized conditions with participants 
in the supine position, knees extended, and quadriceps relaxed. Each extremity is measured 
three times using a standard goniometer, and the mean of the three trials is used for analysis. 
All measurements are performed by the same examiner. 
Dominance Determination 
Lower-extremity dominance is determined according to the participant’s self-reported 
preferred leg for kicking a ball. 

Dynamic Pedobarographic Assessment 
Dynamic plantar pressure measurements are collected using an Emed®-a50/D 
pedobarography system (Novel GmbH, Munich, Germany). Participants walk barefoot at a 
self-selected comfortable speed along a 4-meter walkway with the pressure platform 
embedded flush with the floor. A mid-gait protocol is used. Familiarization trials are 
completed before formal data collection. At least three valid trials are recorded for each foot, 
and the mean of three valid trials is used in analysis. 
Statistical Analysis Plan 
Descriptive statistics are reported as mean ± standard deviation for continuous variables and 
frequency (n) and percentage (%) for categorical variables. Intra-rater reliability of repeated 
Q-angle measurements is evaluated using the intraclass correlation coefficient (ICC) with 
95% confidence intervals. Standard error of measurement (SEM) and minimal detectable 
change at the 95% confidence level (MDC95) are also calculated. 
Because bilateral extremity data are obtained from the same participant, observations are not 
considered independent. Therefore, linear mixed-effects models are used to account for 
within-subject correlation, with participant included as a random intercept. Q-angle is entered 
as a fixed effect in the main models. Separate models are fitted for each pedobarographic 
outcome and plantar region. Additional interaction analyses are conducted for sex and 
extremity dominance. To control for multiple comparisons, p-values are adjusted using the 
false discovery rate (FDR) method. Statistical significance is defined as a two-sided p-value 
of less than 0.05. 
Ethics and Informed Consent 
The study protocol was approved by the Clinical Research Ethics Committee of Harran 
University (Ethics Committee No: 25.14.83). The study was conducted in accordance with 
the Declaration of Helsinki. All participants were informed verbally and in writing about the 
study objectives, procedures, and voluntary nature of participation, and written informed 
consent was obtained from all participants. 
Funding 
This research did not receive any specific grant from funding agencies in the public, 
commercial, or not-for-profit sectors. 
Data Sharing Statement 
Individual participant data sharing has not yet been determined. Any future data sharing will 
depend on ethical approval, participant consent, institutional policies, and data de-
identification requirements.