Extended Abstract
1.    Introduction
Adolescent Idiopathic Scoliosis (AIS) is a three-dimensional spinal deformity characterized by a lateral curvature exceeding 10 degrees, often accompanied by vertebral rotation and sagittal misalignment with unknown cause (1-3). It is the most common spinal disorder in adolescents, with a prevalence ranging from 0.5% to 5%, depending on diagnostic criteria (3,4). The impact of AIS on the musculoskeletal system and neuromechanical function has been widely studied (5). This includes asymmetric spinal loading, poor postural control, muscle imbalances, altered muscle fiber-type ratios, and reduced respiratory function (6, 7-10). Spinal asymmetry in AIS disrupts the center of gravity, prompting compensatory postural and movement adaptations (7–10). During walking, these include altered spatiotemporal (e.g., reduced step length, increased step width) and kinematic (e.g., asymmetric pelvic/trunk motion) patterns (11). While some studies report slower speeds, shorter steps, and lower cadence in AIS (7,8,15–17), others found no differences versus controls (13,14). Kim et al. (2020) linked spinal deformity to gait deviations (12), but evidence remains limited and inconsistent. Such compensations may reduce immediate instability but could elevate long-term risks of joint degeneration and chronic pain (19). While gait in AIS has been extensively studied, running, a more dynamic and strenuous activity, has received less attention. Running imposes greater mechanical stress and demands higher neuromuscular control, balance, and coordination. Assessing running in AIS patients helps understand AIS-related biomechanical adaptations.
Chopra et al. (2020) noted that AIS patients often avoid high-intensity activities like running, leading to muscular deconditioning, which may worsen disease progression (24). They recommended running as part of rehabilitation, but whether AIS patients exhibit the same compensatory mechanisms during running as in walking remains unclear. This study aimed to examine spatiotemporal and joint kinematic changes during running in AIS patients compared to healthy controls. The hypotheses were: a) spatiotemporal parameters would differ in AIS patients, and b) joint kinematic patterns would differ in AIS patients. 
2.    Methods
This study consisted of a control group (CG) with 15 healthy active girls and an experimental group with 15 female patients with AIS. The AIS patients had right thoracic and left lumbar curves. Participant characteristics are summarized in Table 1. The inclusion criteria for participants were having a BMI of 20–25 and no neurological or musculoskeletal disorders. In addition, Cobb's angle was between 15–45°, and there was no prior treatment for EG. Participants were excluded from the study if they had a limb length discrepancy of >5 mm and a recent joint/muscle injury (past 6 months). All participants were right-handed and right-footed. Ethical approval was obtained (IR.BASU.REC.1399.003), and written consent was secured.

Spatial positions of body markers and ground reaction forces (GRF) during running were recorded using an 8-camera Qualisys motion analysis system (200 Hz), and two Kistler force plates (2000 Hz; 40 × 60 cm). 42 reflective markers (17 mm diameter) were placed on anatomical landmarks of the pelvis, thighs, shanks, and feet, based on the full-body lumbar spine model (25). Participants ran 12 m at self-selected speed, ensuring two consecutive steps landed on force plates. Data were smoothed using a Butterworth low-pass filter with a cut-off frequency of 6 Hz in Qualisys Track Manager (QTM) software. Then the model was built in the Visual3D software, and the spatiotemporal and kinematic variables were calculated.
Using MANOVA tests (Bonferroni-corrected, p < 0.05), spatiotemporal variables were compared between the two groups. Also, dynamic movement patterns (101-point normalized stance phase) were compared between both groups using Statistical Parametric Mapping (SPM) (26).
3.    Results
Among the various anthropometric variables, body weight (9.34 kg; p= 0.005) and body mass index (2.75 kg/m²; p= 0.021) were significantly lower in the AIS patients compared to the healthy group. No significant differences were observed in other anthropometric variables between the groups. The Cobb angles, kyphosis, and lordosis angles were also measured for the AIS patients only. 
These values were unavailable for the healthy group, as obtaining radiographs for healthy individuals was not ethically permissible. None of the spatiotemporal variables showed significant differences between the two groups. In the AIS patients, a smaller right hip and left knee abduction-adduction (by 3.6°; p= 0.045), and (by 2.4°; p= 0.058), respectively, and greater right ankle inversion-eversion Range of Motion (ROM) (by 6.6°; p= 0.025) were observed. 
4.    Discussion
The findings revealed no significant differences in spatiotemporal variables between both groups, aligning with previous studies by Mahaudens et al. (2005), Yang et al. (2013), and Chen et al. (1998) (13, 14, 16). However, some studies reported differences in spatiotemporal parameters in scoliosis patients (16, 17). Notably, Youn et al. (2024) found that gait spatiotemporal parameters in scoliosis patients are influenced by pelvic tilt, sacral slope, kyphosis, and lordosis (17). These discrepancies may be explained in part by the mild curvature in this study, compared to severe scoliosis in other studies. Giannouri et al. (2023) also demonstrated that foot pressure distribution during walking correlates with scoliosis curve severity (27). We observed some kinematic changes in hip, knee, and ankle ROM. In contrast to this study, Kakar et al. (2019) reported that post-surgical scoliosis patients showed minimal differences in overall movement patterns compared to healthy individuals (20), despite significant changes in spinal alignment. This study's lack of spatiotemporal differences may stem from sampling limitations, necessitating further research. However, significant kinematic differences were observed in the hip and ankle joints. Specifically, reduced hip and knee abduction-adduction and increased ankle inversion-eversion ROM in the scoliosis group suggest neuromuscular adaptations to compensate for spinal asymmetry and maintain balance during running. These findings align with prior studies on gait alterations in scoliosis (7, 10).
The findings suggest that despite unchanged spatiotemporal parameters, AIS patients exhibit significant kinematic adaptations in lower limb joints during running. This underscores the importance of: a) assessing spinal and limb flexibility, b) enhancing inter-limb coordination and muscle strength in rehabilitation, and c) incorporating gait training as a core component of therapy. AIS patients demonstrate altered lower limb joint kinematics during running. Running may serve as a sensitive metric for detecting subtle motor impairments in this population. Understanding these adaptations can guide targeted rehabilitation to improve mobility and reduce injury risk. 

Ethical Considerations
Compliance with ethical guidelines
This study was conducted in accordance with research ethics standards, and its protocol was approved by the University Ethics Committee (IR.BASU.REC.1399.003). In line with these standards, written informed consent was obtained from all participants and their parents.
Funding
This research did not receive any financial support from the government, private, or non-profit organizations. 
Authors' contributions
All authors contributed equally to preparing the article.
Conflicts of interest
The authors declare that there are no conflicts of interest associated with this article.