High intensity laser therapy versus scapular stabilization exercises on ventilatory function in forward head posture

Introduction

Forward head posture (FHP), i.e. an anterior displacement of the head relative to the trunk, is characterized by an abnormal head position in the sagittal plane, leading to a diminished craniovertebral angle (CVA) [1]. A smaller CVA (CVA < 49°) is linked to neck discomfort, with the intensity of pain being associated with the extent of functional impairment [2]. Therefore, FHP resulting from extension of the head and upper cervical vertebrae (C1-C3) and flexion of the lower cervical vertebrae is closely connected with restrictions in functional mobility and greater discomfort [3]. Increased FHP has been linked with more significant impairments in cervical range of motion (ROM), especially in neck rotation and flexion [4].
In addition to the patients and their families, neck discomfort has a significant effect on communities and healthcare systems [5]. The annual incidence of neck pain is 10.4 to 21.3%, and the overall prevalence neck discomfort in the entire population is 86.8% [6,7]. In a study of various chronic musculoskeletal pain syndromes and their effect on breathing, almost 83% of individuals experiencing neck pain exhibited altered breathing patterns, suggesting a correlation between neck pain and respiration [8]. Typically, FHP restricts rib cage extension by impairing the accessory respiratory muscles, thus reducing the amount of air entering the lungs [9]. Research has indicated that a decreased CVA correlates with reduced carbon dioxide emissions, implying that individuals with FHP have decreased pulmonary function compared to individuals with a neutral head posture [10]. In addition, patients with FHP have been found to have lower forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) levels compared to those without FHP. Additionally, those with FHP experienced significantly altered FVC, FEV1, FEV1/FVC ratio, maximum inspiratory pressure (MIP), PEF, and CVA [11].
Research indicates that high-intensity LASER treatment (HILT) effectively minimizes pain levels in people with musculoskeletal diseases, such as neck discomfort, and improves their ability to perform functional activities [12]. Furthermore, HILT may mitigate pain stimuli by increasing vascular permeability and exerting an anti-inflammatory effect; its photothermic effects enhance metabolic rate and blood flow, while its photochemical and photomechanical effects stimulate cellular metabolism, proliferation, and differentiation [13].
A systematic review has provided robust evidence that a two- to twelve-week course of HILT achieved pain alleviation and disability recovery among patients reporting back, neck, shoulder, arm, and hand pain. These findings were obtained by studies of moderate quality, indicating that they can be considered credible [14]. A prior study on patients with plantar fasciitis found HILT to be superior in alleviating pain during the initial steps of treatment, and enhancing the quality of life compared to low-level laser therapy or extracorporeal shock wave therapy, at least in the short term, i.e. three months [15].
Research has shown that scapular stabilization exercises (SSE) aimed at enhancing and restoring normal muscle function may alleviate pain and improve posture in those experiencing FHP and neck discomfort. Results can be seen after exercising three times weekly for six weeks, and greater improvements are observed when combined with cervical stabilization exercise [16]. In addition, a three-week course of a combination of SSE and relaxation techniques yielded significant enhancements in patients with chronic neck pain; these benefits included less pain and disability, enhanced cervical ROM, and improved flexion and extension [17]. SSE is believed to improve posture by engaging the lower trapezius, the neck muscles and the serratus anterior [18]; mitigating these compensatory FHP-related muscle movements improves neck alignment [19].
While both HILT and SSE are popular treatments for neck pain, no previous studies have compared their effectiveness and their effect on ventilatory function. We hypothesized that HILT and SSE do not differ significantly in terms of their impact on ventilatory function in patients with FHPs. Accordingly, the aim of the study was to compare the impact of HILT and SSE on ventilatory function in FHP patients.

Materials and methods

Participants
Sixty (26 male and 34 female) patients participated in this study. Assuming a power of 0.8 and a three-group design with an α level of 0.05 and effect size 0.42, the minimum sample size was calculated as 20 participants per group using G-power statistical software (version 3.1.9.2; Franz Faul, Universitat Kiel, Germany).
All participants were enrolled from the Outpatient Clinic of the Suez Canal Authority Physical Therapy Center, Port Said, Egypt. They were examined by a single physiotherapist, who screened them for the study based on the following inclusion criteria: age 30-40 years, BMI between 25 and 29.9, chronic neck discomfort symptoms, evidence of FHP (CVA < 49°) [20], decreased ventilatory function due to FHP, assessed using spirometry, a minimum score of 40% on the neck disability index (NDI), medically and psychologically stable.
The following exclusion criteria were applied: congenital abnormalities in the neck and thoracic cage, unstable cardiovascular conditions, pulmonary disorders (restrictive or obstructive lung disease), malignancies, cochlear implants, potential precancerous growths, febrile conditions, pregnancy, endocrine disease, epilepsy, freckles or tattoos, and those taking photosensitive medication [21].
The participants were assigned into three equal-sized groups at random. Group A performed traditional exercises, Group B performed traditional exercises along with SSE, and Group C performed traditional exercises along with HILT. Each group exercised three times weekly for 12 weeks (Figure 1).
Fig. 1. Flowchart of patients
Ethics and randomization
In this prospective randomized control trial, randomization was conducted using random number generation in an Excel spreadsheet. Ethical approval was given by the Physical Therapy Department Ethical Review Board (No: P.T.REC 012/003967) and was registered in ClinicalTrials.gov [NCT06270563]. The study followed the guidelines of the Declaration of Helsinki and World Health Organization recommendations. The study protocol was fully outlined to each participant, who subsequently provided informed consent before taking part.
Procedure
Traditional neck exercise
One aim of the workout regimen was to develop deep flexor muscles. This was gradually achieved by adding chin tucks with head lifts, starting from the second week. This progression continued throughout the whole period, with an increase of 2 s each week. In addition, chin drops and pectoral stretches were performed in a standing stance at the corner of the wall. The participants were instructed to perform three series of 12 repetitions of strengthening exercises, as well as three stretching activities, with each stretch held for 30 s [22].
Scapular stabilization exercises
The patients lay in a prone position and performed four exercises: scapular retraction, mobilization, and dynamic stabilization I/II exercises. Subsequently, the patients assumed a seated posture on their knees, with a 90° flexion, and proceeded to do the same exercises while placing a Swiss ball between their chest and stomach. After four weeks, the intensity of the exercise was increased by incorporating dumbbells as additional weight [23].
High-intensity laser therapy
The upper trapezius muscle (UTM) belly, encompassing a 100 cm2 area, was scanned: twelve locations for HILT were identified by algometry with a 12 W BTL-6000 device (BTL Industries, Greeneville, TN, USA) using the spot method [24]. In each treatment, 1060 J of energy was delivered to each side of the body by combining scanning and spotting techniques, with 60 J delivered per point (10 J per point for HILT). In addition, 100 cm2 of the top section was manually scanned with 1000 J, split into two phases of 500 J each.
The therapy regimen was performed in three distinct phases. During Phase 1, scanning was carried out in continuous mode with a 12 W peak power for 42 s, thus delivering precisely 500 J to the UTM belly. In Phase 2, the spot approach was used: pulsed mode was engaged for 10 s with a duty cycle of 25% and an average power of 1 W, providing 10 J of energy per point and completing 60 J for each side. During Phase 3, the scanning process was carried out in continuous mode, with a 6 W peak power applied for 83 s. The UTM belly, measuring 100 cm2, received 500 J [25].
Outcome measures
Ventilatory function
The ventilatory functions: FVC, FEV1, FEV1/FVC, and maximum voluntary ventilation (MVV) were evaluated with an Autospiro AS-507 spirometer (Minato Medical Science, Osaka, Japan).
Craniovertebral angle (CVA)
The CVA was measured with a modified universal goniometer, which is a reliable method used to objectively assesses FHP in day-to-day clinical physiotherapy practice [26]. The participant was asked to expose the neck and perform cervical flexion and extension to identify the C7 spinous process, onto which an adhesive pin marking was affixed at its most conspicuous point. The participant was then instructed to maintain a neutral neck posture, and an additional adhesive pin marker was affixed to the tragus of the ear. The participant was directed to stand by the goniometer; both axes were positioned at C7, with one axis directed towards the tragus, and the CVA was documented [27].
Chest expansion
Chest expansion was quantified for comparative analysis at the axillary and xiphisternum levels [22]. The participant was instructed to expose bare skin, and a measuring tape was applied around each landmark to quantify the chest expansion at various levels in cm. All participants received verbal instructions to exhale, followed by inhalation. For the upper chest region, the fifth thoracic spinous process (T5) and the third intercostal gap were delineated at the mid-clavicular line. For the inferior chest region, the T10 and the apex of the xiphoid process were measured. Chest expansion is heterogeneous, and varies in response to various disorders; however, it typically ranges from 4 to 7 cm in healthy individuals [Intraclass correlation coefficient (ICC) = 0.86–0.97] [28].
Neck disability index (NDI)
The NDI includes ten questions used to evaluate the level of disability related to neck discomfort and whiplash. These comprised (1) four questions pertaining to subjective symptoms, including concentration, headache, pain severity and sleeping, and (2) six categories pertaining to daily life activities, including driving, work, lifting, personal care and leisure. A score lower than 4 indicated no disability, 5-14 mild disability, 15-24 moderate disability, 25-34 severe disability, and over 35, complete disability; 0.69-0.70 indicated moderately high Pearson correlations [29].
Pain intensity assessment
The severity of neck discomfort was indicated by a visual analog scale (VAS) consisting of a 10 cm horizontal line. The leftmost value (0) signifies a painless state, and the rightmost score (10) indicates severe pain. The ICC for measuring neck discomfort utilizing the VAS was 0.97 [30].
Statistical analysis
Statistical analysis was conducted with SPSS software, version 25 for Windows (IBM SPSS, Chicago, IL, USA). Differences in participant characteristics between groups were evaluated using an ANOVA test. The sex distribution between the groups was compared with the chi-squared test. The normality of the data distribution was confirmed with the Shapiro-Wilk test, and homogeneity of variance with Levene's test. The impact of within-group and between-group differences on FVC, FEV1, FEV1/FVC ratio, MVV, CVA, VAS, NDI, and chest expansion were assessed with a mixed MANOVA. Post hoc tests were performed with the Bonferroni correction for several group comparisons. P < 0.05 was regarded as statistically significant.

Results

No significant difference in age, weight, height, BMI or sex distribution were found between groups (p > 0.05; Table 1).
Tab. 1. Participant characteristics
The mixed MANOVA outcomes indicated a significant interaction between time and treatment (F = 20.06, p = 0.001, η2 = 0.78). The primary effect of time (F = 757.49, p = 0.001, η2 = 0.99) and treatment (F = 3.91, p = 0.001, η2 = 0.42) were significant.
In all groups the FVC, FEV1, FEV1/FVC, and MVV values following therapy were significantly higher than the pre-intervention values (p < 0.001). All three groups demonstrated significantly elevated CVA after treatment, and significantly lower VAS and NDI, compared to pre-treatment values (p < 0.001). Following therapy, all three groups exhibited significant improvements in both upper and lower chest expansion compared to pre-treatment values (p < 0.001; Tables 2-4).
Tab. 2. Mean FVC, FEV1, FEV1/FVC, and MVV pre-treatment and post-treatment
No significant differences were found between the groups for any indicators at the start of treatment (p > 0.05). However, after therapy, group B demonstrated a significant rise in FVC, FEV1, MVV, CVA, and chest expansion, with a large effect size, relative to groups A and C (p < 0.05). Also, group C exhibited significant improvements relative to group A (p < 0.05). No significant difference in FEV1/FVC was found between groups post-therapy (p > 0.05; Tables 2,4-5).
Group C had significantly lower VAS and NDI compared with groups A and B, with a large effect size (p < 0.05). Additionally, group B demonstrated significant improvements in VAS and NDI relative to group A (p < 0.05; Tables 3-5).
Tab. 3. Mean CVA, VAS, and NDI pre-treatment and post-treatment
Table 4. Mean upper and lower chest expansion pre- and post-treatment
Table 5. Comparison between group A, B and C post-treatment

Discussion

Our aim was to compare the effects of HILT and SSE on ventilatory function in individuals with FHP. Our findings indicate significant variation between HILT and SSE in terms of their impact on ventilatory performance in patients with FHP. Group B demonstrated significantly greater increase in FVC, FEV1, MVV and chest expansion than groups A and C (p < 0.05). Similarly, Kang et al. [23] report that the integration of SSE and thoracic extension exercise, when performed for 40 min daily, three times weekly for six weeks, enhanced pulmonary functions, MIP, MEP, FVC and FEV1 (p < 0.05), and propose that this is accomplished by rectifying FHP-induced imbalances in the muscles involved in respiration.
In the present study, group B exhibited significantly higher post-intervention CVA than groups A and C (p < 0.05). This finding is supported by those of a previous study, which found SSE to be an efficient technique for ameliorating aberrant FHP when conducted three times per week for 10 weeks; this program increased CVA (p < 0.05) and resulted in improved FHP [31]. Similarly to the present study, a prior investigation found a three-week course comprising sets of 10 SSEs combined with relaxation techniques three times per week, on alternate days, to yield significant benefits for persistent neck pain (p < 0.05) in NDI and neck ROM [32].
However, these findings directly contradict those of Buttagat et al. [33], who found a treatment program consisting of a combination of traditional Thai massage, SSE, and chest mobilization to have no significant effect on FVC (p > 0.05) after 12 treatment sessions at week 4, or during a subsequent assessment on week 8. This lack of effect may be attributed to the limited period of therapy, i.e. a four-week program, which may not have been long enough to induce changes in FVC in individuals with FHP.
In the current study, group B demonstrated a significantly greater increase in chest expansion than groups A and C (p < 0.05). A previous study found that an integrated exercise program of pectoral muscle stretching and SSE for eight weeks (five days/week) reduced forward shoulder posture and alleviated the restriction in the lower part of the chest (p = 0.010) but not in the upper (p = 0.813) or middle parts (p = 0.912) [34].
Moreover, Group C demonstrated a significantly decreased VAS and NDI compared with groups A and B (p < 0.05). The HILT provides several advantages compared to LLLT as it allows greater energy levels to be delivered over a longer period, thus depositing more energy in deep tissues. While LLLT exerts physiological effects, HILT can transfer photothermal energy into deeper tissue when applied over myofascial trigger points; this can alleviate the energy need or crisis as some photothermal energy may be transferred into deep tissue. The local energy demand or energy crisis near the muscle trigger points may therefore be resolved. Furthermore, the photochemical and thermic impacts of HILT could enhance vascular permeability, blood flow, and cellular metabolism, thus aiding in the restoration of injured muscles and alleviating pain [25].
Our outcomes are in line with a prior study indicating that HILT combined with a bilateral passive stretching protocol targeting the upper trapezius, levator scapulae and scalenes muscles, applied twice weekly for one month, yielded enhanced cervical ROM and lower NDI and pain intensity compared to a sham HILT group [35]. Furthermore, a previous investigation found that the combination of HILT and exercise (12 sessions over six weeks) proved to be successful in enhancing neck ROM and reducing VAS and NDI scores (p < 0.05) in patients with cervical spondylosis but with no peripheral neurological problems; this improvement was recognized after a month follow-up [36]. In another study, laser treatment was found to enhance ventilatory function, which was partially ascribed to decreased neck discomfort; it appears that reducing neck discomfort may have a positive mediating influence on ventilatory function in this group (p < 0.05) [37].
Consequently, we propose that incorporating HILT into treatment plans for patients with FHP could improve respiratory function, even if SSE had significantly higher outcomes. More precisely, HILT can reduce pain and NDI scores, thus aiding muscle restoration and pain alleviation. Combining HILT with exercise can enhance ROM and reduce VAS and NDI scores.
Strengths and limitations
This investigation has several strengths. It is the first randomized controlled trial to compare the effectiveness of HILT with SSE in FHP. Additionally, our findings indicate that HILT provides a non-invasive method to reduce pain and enhance pulmonary function, thereby improving daily living activities. Moreover, the inclusion of a control group makes it easy to determine the specific impact of the interventions compared to traditional exercises.
A limitation of the study was the limited sample size. Also, the short follow-up period may not fully capture the long-term effects of the interventions, limiting our understanding of sustained benefits or potential recurrences. Additionally, the sample is limited to a specific age range and physical conditions, which may not represent the broader population with FHP.
Consequently, we recommend conducting further studies with larger sample sizes and broader age groups, particularly those applicable to people with medical disorders such as fibromyalgia, COPD or asthma. Further studies should compare the effect of HILT with those of other modalities, such as ultrasound or acupuncture, on pulmonary function in FHP.

Conclusions

Both HILT and SSE are effective in addressing FHP when applied to patients aged 30-40 years with a CVA < 49°. However, while SSE appears superior for enhancing neck alignment, ventilatory function and chest expansion, HILT is more advantageous for reducing pain and enhancing NDI scores and relieving FHP impairment. Accordingly, combining HILT with exercises will maximize the efficacy of the rehabilitation program, although this needs to be validated by further research.

Funding

This research received no external funding.

Conflicts of interest

The authors declare no conflict of interest.

References