Abstract
Objective:
Running-related injuries (RRIs) represent one of the most frequent overuse conditions encountered in sports medicine, with incidence rates ranging from 15% to 62% among recreational and competitive runners. The etiology of RRIs is multifactorial, involving both intrinsic and extrinsic contributors such as alignment, range of motion, neuromuscular control, training load, and nutrition. Traditional two-dimensional gait evaluations, while widely accessible, lack the resolution to capture subtle compensatory patterns and joint-specific loading strategies that contribute to tissue overload. Therefore, the objective of this study was to develop and demonstrate a clinically feasible, applicable, multimodal running assessment protocol utilizing three-dimensional (3D) markerless motion capture, ground reaction force (GRF) analysis, and surface electromyography (sEMG). We hypothesized that this comprehensive approach would reveal biomechanical and neuromuscular asymmetries linked to RRIs and could be used through more targeted and personalized prevention and treatment protocols for youth and adult athletes.
Methods:
A retrospective review was conducted of 20 runners presenting to an outpatient rehabilitation clinic with musculoskeletal RRIs. Five athletes presented with low back pain (LBP), five with hip pain (HP), five with knee pain (KP), and five with foot or ankle pain (FAP). Fifteen asymptomatic, age- and sex-matched runners served as asymptomatic controls (AC). All participants completed a standardized 10-minute treadmill running trial, during which data were simultaneously captured using an eight-camera markerless motion analysis system (100 Hz), an instrumented dual-belt treadmill with integrated force plates (2000 Hz), and wireless sEMG sensors applied to the tibialis anterior, gastrocnemius medialis, rectus femoris, and semitendinosus bilaterally (Figure 1). Data processing included kinematic reconstruction, event detection for heel strike, mid-stance, and toe-off, GRF normalization, and EMG root mean square (RMS) analysis with submaximal voluntary contraction (sMVC) normalization. Key outcomes included joint angles, moments, power, vertical and anterior-posterior GRF metrics, and muscle activation timing. A representative case of a 16-year-old competitive distance runner with recurrent femoral neck and tibial stress injuries was analyzed in detail to illustrate the protocol's application to youth injury prevention and rehabilitation planning (Figure 2).
Results:
The knee cohort demonstrated a significantly lower mean running speed (2.76 ± 0.38 m/s) compared with controls (3.28 ± 0.62 m/s, p<0.05). Kinematic analysis demonstrated altered trunk and lower limb mechanics, including reduced sagittal trunk angle at heel strike in the knee cohort (3.2 ± 1.8° vs 6.4 ± 3.4°, p<0.01), decreased sagittal knee angle in the spine cohort (16.2 ± 2.2° vs 19.6 ± 4.7°, p<0.05), and lower sagittal pelvic angle at toe-off in the spine cohort (9.3 ± 6.0° vs 12.6 ± 3.4°, p<0.05) compared with controls. EMG analysis revealed significantly greater anterior tibialis activation in the spine cohort (79.9 ± 5.7% vs 60.0 ± 22.7%, p<0.01), reduced gastrocnemius, rectus femoris, and semitendinosus activity in the hip cohort (all p<0.05), diminished semitendinosus activation and lower peak hip extension moment in the knee cohort (0.91 ± 0.35 vs 1.35 ± 0.23 Nm/kg, p<0.05), and reduced rectus femoris muscle usage in the foot/ankle cohort (27.0 ± 3.6% vs 34.7 ± 10.3% of gait cycle, p<0.05), suggesting impaired neuromuscular control. In the representative adolescent case, 3D analysis revealed increased hip and knee flexion on the symptomatic side, decreased hip extension moment, and increased reliance on the knee joint for propulsion (Figure 3). GRF analysis demonstrated elevated vertical impulse and increased propulsive impulse on the right limb, corresponding to the side of recurrent femoral neck stress injury (Figure 4). EMG confirmed reduced quadriceps endurance and altered hamstring activation timing.
Conclusions:
This study establishes a reproducible, multimodal protocol that integrates three-dimensional motion analysis, neuromuscular activation profiling, and kinetic assessment to identify biomechanical and neuromuscular risk factors for running-related injuries in both adult and youth populations. The combination of high-fidelity kinematic, kinetic, and EMG data enables precise detection of gait asymmetries and compensatory loading strategies that are not apparent with conventional two-dimensional assessments. Collectively, these findings demonstrate the potential of advanced, technology-driven biomechanical assessment to optimize athlete performance, reduce injury risk, and inform precision-based rehabilitation strategies. For youth athletes in particular, this framework offers the potential to detect modifiable risk factors before injuries occur, enabling proactive interventions to support safe training, balanced loading, and long-term musculoskeletal health. By integrating into preseason screenings, return-to-sport evaluations, and longitudinal monitoring, this approach can help reduce injury incidence, lower recurrence risk, and preserve participation in sport during critical stages of growth and development.
