Introduction
The widespread use of digital devices, such as smartphones and computers, has led to an increase in postural abnormalities, notably forward head posture (FHP). Globally, approximately 75% of individuals spend a substantial proportion of their time engaged with screen-based technology [1]. FHP is defined as an excessive anterior positioning of the head relative to a vertical line passing through the body’s center of gravity [2].
While conventional rehabilitation approaches primarily target the cervical and thoracic regions, emerging evidence indicates that core stabilization may play a pivotal role in postural control and spinal alignment [3]. However, the direct impact of core stabilization exercises (CSEs) on cervical biomechanics remains inadequately explored. Most existing studies have focused on localized interventions, overlooking the interdependent relationship between core stability and cervical spine alignment [4].
This study aims to address this gap by investigating the radiographic and clinical effects of CSEs on cervical pain and sagittal alignment in individuals with FHP. Analysis of sagittal parameters is critical for assessing cervical spine balance and predicting clinical outcomes. Previous studies suggest that alterations in these parameters may influence patients’ quality of life [5,6].
Ling et al. [7] identified key sagittal balance parameters, including the T1 slope (T1S) and spino-cranial angle (SCA), which have become focal points of investigation. Notably, SCA has been shown to correlate significantly with other critical sagittal parameters, underscoring its relevance in evaluating spinal alignment [8].
By integrating objective radiographic measurements with patient-reported outcomes, this trial aims to clarify whether CSEs should be established as a fundamental component of FHP rehabilitation. The findings may contribute to redefining postural correction strategies and advancing a more comprehensive approach to musculoskeletal health.
Materials and Methods
Ethics statement
The study was conducted in accordance with the ethical principles of the Declaration of Helsinki. This study was approved by the Research Ethical Committee of the Faculty of Physical Therapy, Cairo University (P.T.REC/012/005836). Written informed consent was obtained from all participants after they received detailed information about the study procedures. The trial was prospectively registered with ClinicalTrials.gov (identifier: NCT06160245).
Study design
A randomized controlled trial with a pretest-posttest control group design was conducted to compare the two groups before and after the intervention.
Randomization
The random sequence was generated by a researcher not involved in data collection using computer software. An independent researcher prepared opaque, sequentially numbered, tamper-proof envelopes, which were securely stored and opened only after baseline assessments. Outcome assessors, blinded to group allocation, conducted all evaluations to ensure allocation concealment and minimize selection bias.
Patients
Forty patients of both sexes, diagnosed with FHP, were randomly allocated to two equal groups: an experimental group (group A) and a control group (group B). During the intervention period, four participants withdrew due to personal reasons. Therefore, a per-protocol analysis was conducted on the remaining 36 participants who completed the intervention as allocated. Group A received a combination of CSEs and postural correction exercises (PCEs), whereas group B underwent PCEs alone. The inclusion criteria were as follows: age between 20 and 40 years, craniovertebral angle (CVA) ≤50°, and a history of cervical pain lasting at least 4 weeks [9]. Exclusion criteria included cervical spondylosis, fractures or fixations, history of temporomandibular surgery, vertebrobasilar insufficiency, cervical disc disorders, upper motor neuron symptoms, or cervical rib syndrome [10].
Instrumentation
Radiographic assessment
A GE HealthCare radiography system (GE HealthCare, Chicago, IL, USA) was used to capture lateral-view X-ray images of the cervical spine before and after the intervention (Fig. 1A, B). Imaging was performed with subjects standing barefoot, feet shoulder-width apart, arms relaxed at the sides, and gaze maintained horizontally [11]. Baseline radiographs were taken before the first exercise session; postintervention images were obtained 48 hours after the final session. Image analysis was conducted using ImageJ software (National Institutes of Health, Bethesda, MD, USA), which has demonstrated high test–retest reliability for cervical sagittal balance (CSB) parameters [12]. The analyzed parameters included the T1S and SCA. T1S was defined as the angle formed between the upper endplate of the first thoracic vertebra and a horizontal reference line (Fig. 1C). SCA was defined as the angle formed between a line extending from the center of the sella turcica and the tangent of the upper C7 endplate (Fig. 1D).
Pain assessment
Pain intensity was evaluated using the Pain Rating Scale (PRS), an 11-point numeric scale ranging from 0 (“no pain”) to 10 (“worst imaginable pain”). Participants were asked to rate their pain levels “within the past 24 hours” or an overall average pain level. The PRS has demonstrated excellent reliability in both literate and illiterate populations (r=0.96 and 0.95, respectively), before and after medical consultation [13].
Photographic assessment
Lateral-view photographs were captured using a Canon PowerShot A490 camera (Canon, Tokyo, Japan; 10-megapixel resolution, 3.3× optical zoom) to evaluate the CVA in patients with FHP as part of the inclusion criteria (Fig. 2A) [14]. Image analysis was conducted using Kinovea software (https://www.kinovea.org/), a validated and reliable tool for extracting angular and distance measurements from coordinate data [15]. The CVA was defined as the angle formed between a horizontal line extending from C7 and a line connecting C7 to the tragus of the ear (Fig. 2B).
Pelvic angle assessment using PALM inclinometer
Pelvic angle was measured using a caliper–inclinometer device (PALM; Performance Attainment Associates, Saint Paul, MN, USA). The PALM has demonstrated strong reliability in assessing pelvic position, with intratester reliability rated as very good (0.89) and intertester reliability as excellent (0.98) [16].
Procedures
Patient assessments were conducted before and after a 6-week intervention period [17]. In accordance with the referring orthopedist’s instructions, all participants received a standard course of nonsteroidal anti-inflammatory drugs with or without a muscle relaxant during the first 2 weeks of the 6-week intervention. Analgesic use was discontinued thereafter, and compliance was monitored and recorded at each weekly session. The evaluated outcome measures included T1S, SCA, and the PRS score. The study protocol was structured into three distinct phases: pretraining, training, and posttraining.
Pretraining phase
The study objectives, equipment, and procedures were explained in detail to the participants, who then provided written informed consent. Baseline assessments of pelvic alignment and CVA were conducted. Subsequently, each participant was randomly allocated to one of the two designated groups. Participants were asked to rate the severity of neck pain using the PRS. Cervical X-ray imaging was performed to evaluate the T1S angle and SCA. Group (A) received a combined program of CSEs and PCEs, whereas group (B) received PCEs alone.
Training phase
CSE program: The CSE program was adapted from Akuthota et al. [18]. Each session commenced with warm-up exercises aimed at restoring normal muscle length and mobility, including cat–camel stretches, followed by a brief aerobic component. The full training protocol is presented in Table 1, with selected example exercises illustrated in Fig. 3.
Statistical analysis
Statistical analyses were conducted using IBM SPSS Statistics ver. 25.0 (IBM Corp., Armonk, NY, USA). All analyses were conducted on a per-protocol basis, including only participants who completed the entire intervention and both pre- and posttraining assessments. This approach was selected to accurately reflect the efficacy of the intervention under conditions of full adherence. Data normality was assessed using the Shapiro-Wilk test, along with an evaluation of skewness, kurtosis, and potential outliers. As all variables met normality assumptions, parametric tests were applied.
To examine changes in T1S, SCA, and PRS scores before and after training, a two-way mixed-design multivariate analysis of variance (MANOVA) was performed. The significance level was set at α=0.05, and effect sizes were reported using eta squared (η2).
Owing to a significant baseline difference in SCA between groups (p=0.010), analysis of covariance (ANCOVA) was conducted to control for this potential confounder. ANCOVA was performed with posttraining SCA as the dependent variable, group as the independent variable, and pretraining SCA as the covariate. The assumption of homogeneity of regression slopes (group×SCApre interaction; p=0.059) was satisfied, supporting the validity of this adjustment. This ensured that posttraining differences reflected true intervention effects rather than baseline variability.
The required sample size was estimated using G*Power software ver. 3.1 (Heinrich Heine University, Düsseldorf, Germany). Assuming an anticipated standardized effect size (Cohen’s d) of 0.50, a two-tailed α of 0.05, and a statistical power of 0.80, the minimum sample size was calculated as 37 participants. The selected effect size represents a conventional medium magnitude, chosen based on prior evidence from a conceptually similar randomized controlled trial and on effect sizes commonly reported in exercise-based interventions for neck pain [4]. As the referenced trial did not report an effect size and presented pain outcomes as medians with interquartile ranges, the medium effect size was adopted in line with statistical convention and its clinical relevance to the present study’s primary outcome of pain [4].
Results
General characteristics
A total of 51 patients were screened for eligibility, of whom 11 were excluded for not meeting the inclusion criteria (Fig. 5). The remaining 40 eligible patients were randomly assigned to two equal groups (group A and group B). During the intervention, four patients withdrew, resulting in 36 participants completing the study and being included in the final analysis. Statistical comparison of baseline characteristics revealed no significant differences between the two groups (p>0.05) (Table 2). Adherence to the prescribed analgesic regimen was 100% in both groups; all participants followed their prestudy medication schedules as instructed, with no deviations, missed doses, or changes in medication use reported during the intervention period.
Data analysis
The repeated-measures MANOVA revealed a significant main effect of time across all measured variables (F=19.461, p<0.001, partial η2=0.715), indicating a large effect and substantial within-subject changes over time. A significant time × group interaction was also observed (F=9.726, p<0.001, partial η2=0.557), confirming that the trajectories of postural alignment and pain outcomes differed significantly between groups. Specifically, participants in group A (CSEs+PCEs) demonstrated significantly greater improvements than those in group B (PCEs only).
Pairwise comparisons showed significant posttraining improvements in T1S in both groups compared with baseline (p<0.05). For SCA, a significant increase was observed only in the experimental group (p<0.05), with no comparable change in the control group. PRS scores improved significantly in group A following training, whereas the reduction observed in group B was not statistically significant (p>0.05). These findings underscore the added benefit of core stabilization when combined with PCEs in improving sagittal alignment and reducing cervical pain.
In the analysis of between-group effects, no significant baseline differences were observed in T1S and PRS scores, confirming homogeneity of the groups for these variables. However, SCA differed significantly between groups at baseline. Following the training, between-group analysis revealed a significant effect for T1S, whereas neither SCA nor PRS demonstrated statistically significant posttraining differences. These findings suggest that, although both groups improved over time, the intervention’s differential impact was most evident in T1S. The results of the statistical analyses are presented in Table 3.
To account for the baseline difference in SCA, ANCOVA was performed. Posttraining SCA served as the dependent variable, group as the independent variable, and pretraining SCA as the covariate. The assumption of homogeneity of regression slopes (group×SCApre interaction term; p=0.059) was satisfied, supporting the use of ANCOVA. By adjusting for initial discrepancies, this method enhanced the study’s internal validity and provided a more precise estimation of the intervention’s impact on SCA.
Discussion
Conventional approaches to neck pain management primarily target the cervical region while often overlooking the contribution of other spinal segments. Although substantial evidence highlights the interdependence of spinal segments [20,21], relatively few studies have investigated the effectiveness of whole-spine interventions in patients with neck pain [3].
In the present study, both groups demonstrated significant improvement in T1S after training. This improvement was anticipated in the experimental group, given the established relationship between T1S and lumbopelvic sagittal alignment. An increase in T1S may result from thoracic hyperkyphosis, particularly in the upper thoracic region, or from lumbopelvic sagittal malalignment, both of which lead to cervical spine anterior tilt and FHP through increased cervical sagittal vertical alignment (cSVA) [22]. Moreover, thoracolumbar alignment directly influences the T1S angle, which is considered a reliable predictor of global sagittal alignment. Cervical alignment, in turn, adapts according to T1S, highlighting the role of thoracolumbar posture in determining cervical posture. These findings are consistent with and extend previous reports [23].
The significant posttraining reduction in mean T1S values observed in the control group (group B) compared with the experimental group (group A) may be explained by the established relationship between T1S and cSVA. The greater improvements in cSVA in the experimental group likely contributed to symptom relief, reducing the need for further compensatory adjustment in T1S. In contrast, the control group demonstrated only modest improvement in cSVA, which may have necessitated compensatory changes in related sagittal parameters [3].
A key finding of this study was the significant posttraining increase in SCA observed in the experimental group, whereas the control group demonstrated no comparable improvement. This highlights the efficacy of the intervention in promoting craniovertebral and spino-cranial realignment, likely mediated by neuromuscular adaptations and enhanced postural awareness induced by the training program. Wang et al. [24] reported a significant negative correlation between SCA and T1S, whereby an increase in SCA was associated with a decrease in T1S and cervical lordosis. This relationship was evident in the present study, as the significant reduction in T1S coincided with a notable increase in SCA. The interplay between these parameters may be explained by the influence of lumbopelvic parameters on T1S, as demonstrated by Patwardhan et al. [22].
With respect to pain outcomes, Alijani and Rasoulian [25] reported that alterations in global sagittal alignment are strongly associated with poor health-related quality of life. Similarly, cervical spine malalignment in the sagittal plane has been linked to headaches, neck pain, and poor health-related quality of life [22]. In this context, the greater reduction in PRS scores observed in the experimental group may be attributed to superior improvements in both global and regional sagittal alignment. From a biomechanical perspective, the suboccipital triangle, formed by the rectus capitis posterior major and minor, along with the obliquus capitis superior and inferior, plays a crucial role in cervical posture. Prolonged contraction of these muscles can cause painful trigger points, contributing to the neck pain associated with FHP [22]. Moreover, excessive contraction of suboccipital muscles may produce pain and cervicogenic headache by exerting continuous strain on the pain-sensitive dura mater through myodural bridges. Long-term tension on these structures in conditions of persistent occipital extension, such as chronic FHP, has been proposed to trigger neck pain and cervicogenic headache [26]. Collectively, these mechanisms provide a plausible explanation for the significant reduction in PRS scores in the experimental group, likely reflecting decreased suboccipital muscle contraction following the intervention.
From a clinical and surgical perspective, the SCA plays a crucial role in maintaining CSB and is a key predictor of both surgical and clinical outcomes, particularly in procedures such as anterior cervical discectomy and fusion (ACDF) and laminoplasty. Wang et al. demonstrated that multi-level ACDF significantly alters CSB, with postoperative changes in SCA influencing alignment outcomes [24]. Preserving optimal SCA may help prevent kyphotic progression and minimize strain on adjacent segments. Similarly, Bębenek et al. [27] reported that SCA is linked to postoperative subsidence, where sagittal malalignment can lead to implant failure and gradual loss of correction. Furthermore, Wang et al. [28] identified SCA as a key predictor of cervical lordosis preservation following laminoplasty, highlighting its clinical relevance. A preoperative SCA within the optimal range (approximately 76°–92°) is associated with favorable postoperative sagittal alignment, whereas values outside this range increase the risk of cervical kyphosis or imbalance. In the present study, the addition of CSEs significantly increased SCA beyond the lower threshold, suggesting that such exercises may help optimize preoperative cervical alignment, reduce the risk of postoperative loss of lordosis, and improve overall surgical outcomes [28]. Collectively, these findings position SCA not only as a diagnostic parameter but also as a potentially modifiable therapeutic target in both conservative and surgical approaches for managing FHP-related sagittal imbalance.
These surgical implications are reinforced by the present findings, which demonstrated significant improvements in postural alignment and pain relief following the intervention. Cervical postural correction was facilitated through improvements in SCA, supporting its role in maintaining spinal balance and reducing strain on the cervical musculature. Concurrent improvements in T1S further confirmed the relationship between cervical alignment and lumbopelvic parameters, as previously described by Patwardhan et al. [22]. Together, these changes likely enhanced postural stability and functional outcomes while minimizing compensatory mechanisms that could otherwise contribute to discomfort and progressive structural deterioration.
Beyond its surgical relevance, the clinical significance of SCA is reflected in the symptom relief observed following the intervention. The reductions in pain perception and improvements in postural control in the experimental group suggest that optimizing SCA plays a pivotal role in alleviating musculoskeletal discomfort and enhancing overall spinal function. Maintaining an optimal SCA has been linked to improved functional recovery and reduced pain, whereas excessive reductions in SCA contribute to FHP and increased cervical strain [24]. The strong relationship between SCA and T1S further emphasizes the need for a holistic rehabilitation strategy that addresses both regional and global postural alignment [27]. Collectively, these findings highlight the value of incorporating SCA assessments into both surgical planning and rehabilitative strategies, with the goal of optimizing spinal alignment, enhancing stability, and improving patient outcomes.
Overall, our findings indicate that the intervention effectively improved spinal alignment and reduced pain, particularly in terms of SCA and PRS outcomes in the experimental group. However, the lack of significant between-group differences posttraining suggests that factors such as individual variability in treatment response or differences in adherence may have influenced comparative outcomes. Future studies should address these considerations by recruiting larger cohorts, incorporating extended follow-up periods, and evaluating the long-term sustainability of the observed improvements. Despite these limitations, the present results provide meaningful evidence supporting postural training as a viable strategy for enhancing spinal health and reducing pain-related disability.
Conclusions
This study provides evidence that CSEs are an effective strategy for improving spinal alignment and alleviating cervical pain in individuals with FHP. By highlighting the relationship between cervical posture and overall sagittal balance, the findings support the integration of CSEs into comprehensive rehabilitation protocols and suggest their potential relevance in preoperative planning for cervical spine surgery.
Key Points
Core stabilization exercises significantly improved cervical sagittal alignment and pain in patients with forward head posture.
Spino-cranial angle and T1 slope showed measurable radiographic improvements, supporting their role as therapeutic targets in posture-related cervical disorders.
Findings underscore the value of trunk stabilization in conservative management of cervical sagittal imbalance.
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