Does forward head posture affect postural control in human healthy volunteers?

Recognition of Forward Head Posture Through 3D Human Pose Estimation With a Graph Convolutional Network: Development and Feasibility Study

BACKGROUND

Prolonged improper posture can lead to forward head posture (FHP), causing headaches, impaired respiratory function, and fatigue. This is especially relevant in sedentary scenarios, where individuals often maintain static postures for extended periods-a significant part of daily life for many. The development of a system capable of detecting FHP is crucial, as it would not only alert users to correct their posture but also serve the broader goal of contributing to public health by preventing the progression of chronic injuries associated with this condition. However, despite significant advancements in estimating human poses from standard 2D images, most computational pose models do not include measurements of the craniovertebral angle, which involves the C7 vertebra, crucial for diagnosing FHP.

OBJECTIVE

Accurate diagnosis of FHP typically requires dedicated devices, such as clinical postural assessments or specialized imaging equipment, but their use is impractical for continuous, real-time monitoring in everyday settings. Therefore, developing an accessible, efficient method for regular posture assessment that can be easily integrated into daily activities, providing real-time feedback, and promoting corrective action, is necessary.

METHODS

The system sequentially estimates 2D and 3D human anatomical key points from a provided 2D image, using the Detectron2D and VideoPose3D algorithms, respectively. It then uses a graph convolutional network (GCN), explicitly crafted to analyze the spatial configuration and alignment of the upper body's anatomical key points in 3D space. This GCN aims to implicitly learn the intricate relationship between the estimated 3D key points and the correct posture, specifically to identify FHP.

RESULTS

The test accuracy was 78.27% when inputs included all joints corresponding to the upper body key points. The GCN model demonstrated slightly superior balanced performance across classes with an F1-score (macro) of 77.54%, compared to the baseline feedforward neural network (FFNN) model's 75.88%. Specifically, the GCN model showed a more balanced precision and recall between the classes, suggesting its potential for better generalization in FHP detection across diverse postures. Meanwhile, the baseline FFNN model demonstrates a higher precision for FHP cases but at the cost of lower recall, indicating that while it is more accurate in confirming FHP when detected, it misses a significant number of actual FHP instances. This assertion is further substantiated by the examination of the latent feature space using t-distributed stochastic neighbor embedding, where the GCN model presented an isotropic distribution, unlike the FFNN model, which showed an anisotropic distribution.

CONCLUSIONS

Based on 2D image input using 3D human pose estimation joint inputs, it was found that it is possible to learn FHP-related features using the proposed GCN-based network to develop a posture correction system. We conclude the paper by addressing the limitations of our current system and proposing potential avenues for future work in this area.

Sensory Organization and Postural Control Strategies in Individuals With Mild and Moderate-to-Severe Forward Head Posture: A Comparative Study

OBJECTIVE

This study aimed to compare sensory organization test and postural control strategies between individuals with mild and moderate-to-severe forward head posture (FHP).

METHODS

A sensory organization test (SOT) was performed in 6 conditions using computerized dynamic posturography, to assess postural control. Equilibrium scores representing overall balance, strategy analysis to assess ankle vs hip strategy dominance, and sensory analysis (Somatosensory, visual, vestibular, visual preference ratio) as an indicator of the use of sensory systems were obtained.

RESULTS

Our results revealed a significant difference between the 2 groups in terms of equilibrium score (P < .05) and strategy scores (P < .05) in conditions of 4 to 6 of the SOT. The results of sensory analysis of SOT showed visual and vestibular ratios were significantly different between the 2 study groups (P < .05), but somatosensory and visual preference ratios were not significantly different between these 2 groups (P > .05).

CONCLUSION

Individuals with moderate-to-severe FHP swayed more in comparison with mild FHP ones in conditions with the Sway-referenced platform of the SOT. They tended to rely on the hip strategy more than the ankle strategy excessively when sensory difficulty increased. Overall, it can be concluded that individuals with moderate-to-severe FHP are more likely to have postural deficits.

Immediate Effects of the Reverse Plank Exercise on Muscle Thickness and Postural Angle in Individuals with the Forward Shoulder Posture

The forward shoulder posture (FSP) results from shoulders being pulled forward by shortened anterior shoulder girdle muscles. The objective of this study was to investigate the short-term effectiveness of the reverse plank exercise on parascapular muscle thickness and forward shoulder angle (FSA) in patients with FSP. Participants were divided into the FSP and non-FSP (NFSP) groups based on the observed angle between the horizontal line of the C7 spinous process and the acromion process. All participants performed a total of five sets of reverse plank exercises at 30 s per set. FSA and muscle thickness of the pectoralis major (PM), serratus anterior (SA), upper trapezius (UT), and lower trapezius (LT) were measured before and after the reverse plank exercise. The muscle thicknesses of the SA and LT, and the FSA, were significantly increased after exercise in the FSP group (p < 0.05). Muscle thickness of the PM and UT significantly decreased after the exercise. In the NFSP group, muscle thickness of the LT was significantly increased, and muscle thickness of the PM and UT were significantly reduced after exercise (p < 0.05). Upon using between-group analysis, there were significant differences between the FSA, SA, UT, and LT groups (p < 0.05). The reverse plank exercise has the short-term benefit of correcting and preventing FSP by increasing SA and LT thickness while decreasing PM and UT thickness. We believe that the reverse plank exercise significantly improved the ability to prevent FSP in FSP-related muscles and was beneficial in achieving optimal postural alignment.

Effect of Forward Head Posture on Dynamic Balance Based on the Biodex Balance System

Forward Head Posture (FHP) results in spine malalignment, muscle imbalance and cervical proprioception sensory input impairment. Subjective description of FHP is interpreted differently by clinicians and therefore the FHP is classified as slight, moderate and sever. This study aimed to evaluate balance disorder in individuals with severe forward head posture (FHP). Twenty individuals with severe FHP and 20 controls were enrolled. Dynamic postural stability was assessed in all participants using the Biodex Balance System (BBS) in semi dynamic position with eye open/eye closed conditions. Based on the findings, dynamic postural stability in the sagittal plane was different between the groups (P<0.05). It can be concluded that impairment of dynamic postural stability occurs in individuals with severe FHP. The findings suggest that clinicians take into account the importance of dynamic postural stability assessment in FHP subjects and consider the application of intervention programs for improvement of the dynamic balance.

The relationship between forward head posture, postural control and gait: A systematic review

BACKGROUND

Forward head posture (FHP) is a common postural deviation. An increasing number of studies have reported that people with FHP present with impaired postural control and gait; however, there is conflicting evidence. A systematic review focusing on these relationships has been unavailable to date.

RESEARCH QUESTION

Is there a relationship between FHP, postural control and gait?

METHODS

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement (PROSPERO ID: CRD42021231908). Web of Science, PubMed, Scopus, and CINAHL Plus (via EBSCO) were systematically searched, and a manual search was performed using the reference lists of included studies. Eligible studies included observational studies addressing the relationship between FHP, postural control and/or gait. Quality assessment was conducted using the Joanna Briggs Institute Critical Appraisal Checklist for Cross-Sectional Studies.

RESULTS

Nineteen studies were selected for this review. Consistent evidence supported that people with FHP had significant alterations in limits of stability (n = 3), performance-based balance (n = 3), and cervical proprioception (n = 4). Controversial evidence existed for a relationship of FHP with static balance (n = 4) and postural stability control (n = 4). Limited evidence existed to support an alteration in gait and vestibular function. Three studies on induced FHP consistently identified no reduced postural control.

SIGNIFICANCE

Current evidence supports an association between FHP and a detrimental alteration in limits of stability, performance-based balance, and cervical proprioception. Instead of simply indicating impaired overall balance, the findings of this review indicate that a reduction in specific aspects of the postural control requires to be clarified in clinical evaluation for individuals with FHP, which would facilitate the planning and application of appropriate interventions to prevent dysfunctions and disability.

A randomized controlled study of the effect of functional exercises on postural kyphosis: Schroth-based three-dimensional exercises versus postural corrective exercises

PURPOSE

To compare the effects of postural corrective and Schroth-based three-dimensional exercises on thoracic kyphosis angle (TKA), lumbar lordosis angle (LLA), balance and quality of life (QoL) in individuals with postural kyphosis.

METHODS

This was a single-blind randomized controlled clinical trial with a total of 63 subjects (57 women, 6 men) with TKA of ≥40°. Subjects were separated into three groups: postural corrective exercise group (PCEG), Schroth-based three-dimensional exercise group (SBEG) and control group (CG). Participants in the exercise groups participated in the exercise program twice a week for eight weeks under the supervision of a physiotherapist: CG performed no exercise but was generally informed. The primary outcome variable was TKA. Secondary outcome variables were LLA, balance and QoL.

RESULTS

After the functional exercise programs, TKA (mean change for PCEG, SBEG: -9.71, -14.76, p < 0.001), static postural stability index overall (-0.22, -0.40, p < 0.05), and QoL (-0.41, -0.37, p < 0.001) significantly improved in both training groups compared with CG. The LLA (-3.95, p = 0.003) was significantly lower in the SBEG group than in CG.

CONCLUSION

This study demonstrated that Schroth-based three-dimensional exercises are an effective treatment for individuals with postural kyphosis and have a large effect size that improves TKA, LLA, balance and QoL. Clinical trial registration number: NCT03706495 Implications for rehabilitationEight weeks of postural corrective or Schroth-based three-dimensional functional exercise programs are effective in addressing thoracic kyphosis angle (TKA), balance, and quality of life in individuals with postural kyphosis.An eight-week Schroth-based three-dimensional exercise program was more effective than postural corrective exercises in improving TKA, lumbar lordosis angle, and balance for patients with postural kyphosis.Schroth-based three-dimensional exercise programs could promote balance and spinal health in young adults with thoracic kyphosis.

The Ergonomic Association between Shoulder, Neck/Head Disorders and Sedentary Activity: A Systematic Review

Background

Work-associated upper limb and neck disorders are common occupational disorders throughout the world. These disorders are usually observed more in workers who spend a long time sitting, referred to as sedentary activity (SA). The immediate and distorted risk of sedentary-related problems was considered high in Europe, Australia, and the United States. Even though mediation is convenient, it is likely to reduce office workers' risks of developing cervical and upper body pain due to sedentary work. This systematic review addresses risk factors and evaluates the relationship between SA and upper body disorders in office workers (i.e., shoulder and neck/head).

Methods

PubMed, Scopus, and Web of Science were searched for articles published between January 2010 and August 2021 in the English language. The three keywords “sedentary,” “upper body elements,” and “work” (and their derivatives) were searched to identify studies and carry out this systematic review. The articles were searched so that all three keywords or at least a derivation of each keyword should appear. Findings. Of the 40 articles that met the enclosure criteria, 32 studies examined the association of SA and upper body elements during both office and computer work. However, three articles were evaluated in the sit-stand work environment, and in the remaining five studies, one was evaluated during teaching, two during hospital work, and two during mixed working conditions.

Conclusions

Research related to SA focuses mainly on extended risk factors, but there was no focus on other aspects, such as muscle and tendon contractions. As there is a convincing connection between SA and the upper body, our close examination identifies the need to institutionalize a system for collecting, analyzing, and describing the impact and short-term effects of SA on the upper body. Additionally, some suggestions were made to minimize the risk in a sedentary working environment.

Correlation between craniovertebral angle in the sagittal plane and angles and indices measured in the frontal plane at the moment of inducing forward head posture

BACKGROUND

Forward head posture (FHP) is the most common malposition in the head and neck area. With the growing use of digital devices, the prevalence of FHP may be expected to increase dramatically. Thus far, FHP has been evaluated only in the sagittal plane.

OBJECTIVE

The objective of this study was to measure angles and indices from anatomical landmarks in the frontal plane and determine the possible correlations between these variables and craniovertebral angle (CVA) as an index of FHP in the sagittal plane.

METHODS

Fifty eight healthy individuals (29 men, 29 women) between 18 and 40 years old participated in this cross-sectional study. Participants were evaluated with an 8-camera motion analysis system. After markers were placed on predetermined landmarks, the participants were asked to maintain their head and neck in the neutral position for 5 seconds. Then participants induced FHP by flexing and lowering their head. The correlation between CVA and a set of angles and indices was calculated at the moment of FHP induction.

RESULTS

A moderate correlation was observed between 3-D CVA and the angle formed between the sternum and both tragi for the whole sample and separately in both sexes. A moderate negative correlation was observed between 3-D CVA and height, weight, and BMI in women. A moderate negative correlation was observed between 3-D CVA and height, weight, BMI, and hours on digital devices in men.

CONCLUSIONS

Changes in CVA in the sagittal plane can be predicted from changes in the angle formed between the midpoint of the sternum and the left and right tragi in the frontal plane.

The impact of forward head posture on the electromyographic activity of the spinal muscles

Objective

This study aims to examine the electromyographic activity of the regional spinal muscle between patients with forward head posture (FHP) and those with a normal cranio-vertebral (CV) angle.

Methods

We recruited 60 adult women aged between 18 and 29 years from a single institution. The CV angle was measured in the sagittal plane, which helped us to assign the participants in the FHP group (n = 30) with a large CV angle (53.1 ± 2.3) and the control group (n = 30) with a normal CV angle (43.0 ± 3.6). The surface electromyography (EMG) was used to measure the magnitude of normalised muscle activity of eight spinal muscles (cervical, lumbar, and thoracic levels) while standing and performing a specific manual handling task.

Results

The CV angle was significantly lower in the FHP group than in the control group (p = .001). The cervical erector spinae (CES) muscle activity was significantly increased in the FHP group compared to that in the control group. The right and left CES of those in the FHP group exhibited 73% and 87%, respectively, higher normalised muscle activity than those in the control group while performing the manual handling task (p = .001). No significant difference was detected for the thoracic or lumbar segment muscles between groups.

Conclusion

Our results indicate that greater neck muscle demands result from anterior head translation in FHP. This effect is a counterbalance to the reduced CV angle and to support the neck. The increased activity of the neck muscles in FHP could demand more support from the neck muscles and might increase the risk of spinal injuries. Management of FHP is essential to avoid overloading the spinal muscles.

Influence of Forward Head Posture on Cervicocephalic Kinesthesia and Electromyographic Activity of Neck Musculature in Asymptomatic Individuals

OBJECTIVE

The purpose of this study was to compare cervicocephalic kinesthesia and electromyographic (EMG) activity of neck muscles-upper trapezius (UT) and sternocleidomastoid (SCM)-between individuals with and without forward head posture (FHP) and to examine the correlation between cervicocephalic kinesthesia and craniovertebral angle (CVA).

METHODS

Twenty-two asymptomatic individuals with FHP and 22 without FHP were recruited for the present study. Craniovertebral angle was measured, and those with CVA ≤53° were assigned to the FHP group, whereas those with CVA >53° were assigned to the control group. Thereafter, cervicocephalic kinesthesia and EMG activity of the neck muscles were assessed. Cervicocephalic kinesthesia was measured using a head repositioning accuracy test for all cervical spine motions. EMG activity of the UT and SCM muscles was recorded at rest and during activity.

RESULTS

Position-sense error values were found to be significantly greater for all directions-ie, flexion, extension, side flexion, and rotation-in participants with FHP than those without (P < .05). EMG activity of the UT and SCM muscles was found to be significantly raised both at rest and during activity in individuals with FHP relative to the non-FHP group (P < .05). Position-sense error values showed a significant inverse correlation with CVA (P < .05).

CONCLUSION

Findings of the present study suggest that cervicocephalic kinesthesia and activation patterns of the neck muscles may be significantly altered in individuals with FHP. Also, cervicocephalic kinesthesia is significantly associated with the severity of FHP.

Improvement of dynamic postural stability by an exercise program

BACKGROUND

Central processing of multi-sensory feedback and motor commands responsible for force production are critical for postural control. An exercise program was developed to realign spinal curvature, but its effect on postural control is unknown.

RESEARCH QUESTION

To what extent would the exercise program influence on center of pressure (CoP) sway on stable and unstable surfaces?

METHODS

Subjects (n = 30) were randomly assigned into one of three groups: exercise on a cylinder-shaped tube (98-cm length, 15-cm diameter, n = 10), exercise on a flat surface (n = 10), and a control group that laid supine on a flat surface (n = 10). Standing posture of each subject was quantified using anterior-, posterior-, and lateral-view photography. Each subject's CoP sway was measured while standing on a static and dynamic platform with eyes open and eyes closed. Subjects were instructed to stand still when the platform was held stationary (e.g., no tilt) during the static condition. During the dynamic condition the platform was allowed to tilt in response to changes of CoP and subjects were instructed to maintain the platform in a horizontal position.

RESULTS

Only when subjects performed the exercise program on the tube, the angles of neck flexion and pelvis tilt decreased, and CoP sway in the sagittal, but not frontal plane, decreased during the dynamic platform conditions with both eyes open and eyes closed (p < 0.05).

SIGNIFICANCE

It is speculated that performing the exercise program on the tube might enhance a) central processing of somatosensory and vestibular inputs, b) motor commands responsible for force production in postural control, and c) biomechanical advantage by the realigned posture. The exercise program can be used by a variety of populations as home-exercise to realign the neck and pelvic posture and improve dynamic postural stability.

A temporary forward head posture decreases function of cervical proprioception

Increased use of smartphones can cause abnormal alignment of head and neck, resulting in forward head posture (FHP). This can lead to change in the structures and function of the cervical vertebrae. The purpose of this study was to determine the impact on deep neck flexor muscles, proprioception, vestibular function, and balance of subjects with induced FHP by using smartphone. Twenty-two healthy persons were randomly divided into two groups. The FHP group maintained a craniovertebral angle (CVA) of <49° and a normal head posture group maintained a CVA of >50° watching the smartphone for 40 min. We measured the area of the longus colli and longus capitis muscles, cervical joint position sense, Romberg test, subjective visual vertical test, and subjective visual horizontal test. There was no significant difference in the deep neck flexor muscles, vestibular function, and static balance between the groups. However, there was a significant difference in the cervical proprioception (P<0.05). Proprioception may be considered to be the most influential factor in induced FHP by smartphone viewing.

Postural Control Underlying Head Movements While Tracking Visual Targets

The aim of this study was to investigate the relationship between postural regulation and tracking accuracy under static and moving visual target conditions in unipedal and bipedal standing postures. Postural time-to-contact stability boundaries decreased under more challenging visual target conditions for the unipedal posture, but this decrease was associated with lower visual tracking error. During bipedal support, there was independent control of the head and foot center of pressure, as higher frequencies at the head during the static visual task were associated with longer time-to-contact. These results demonstrate that decreased time-to-contact stability boundaries is a functional adaptation in postural tasks requiring visual control and provide evidence of the dependency of postural control on the nature of the suprapostural task.

The effect of cervical spine subtypes on center of pressure parameters in a large asymptomatic young adult population

BACKGROUND

Recent research highlighted that non-lordotic subtypes are common within an asymptomatic population of young adults. The potential mechanisms responsible for the decreased postural control witnessed in healthy participants exhibiting non-lordotic cervical alignment are unclear.

RESEARCH QUESTION

Therefore, the aim of this study is to compare and contrast asymptomatic radiographically derived sagittal cervical alignment subtypes with Center of Pressure (CoP) parameters.

METHODS

In this cross-sectional study strict asymptomatic inclusion criteria were met by 150 of the original 182 volunteers. All radiographs were assessed using a multi-method subtype system with participants classified into lordotic and non-lordotic groups. Participants performed 90s narrow stance trials with their eyes closed whilst standing on both a firm surface (FS) and compliant surface (CS) (3 trials per surface). CoP parameters were recorded from a force platform sampling at 100 Hz. Nonparametric statistical tests were conducted to assess differences between groups for each surface type and to determine differences in CoP parameters between FS and CS types.

RESULTS

Significant differences were found between groups on both surfaces for the anterior to posterior range (FS: p = 0.013; CS: p = 0.023), total excursion (FS: p = 0.029; CS: p = 0.005) and mean velocity of total excursion (FS: p = 0.032; CS: p = 0.004).

SIGNIFICANCE

Our data suggest that sagittal plane cervical alignment is a measure capable of distinguishing between the postural control of asymptomatic lordotic and non-lordotic young adult participants on both surfaces types. Furthermore, decreased postural control is present in asymptomatic participants across all non-lordotic subtypes and is not isolated exclusively to those with forward head posture. Consequently, future research endeavours should investigate the clinical significance of these non-lordotic findings in relation to both the potential for early cervical osseous degeneration and the transitional stages of non-specific pain sufferers from previously asymptomatic young adults.

Neck Pain in Adults with Forward Head Posture: Effects of Craniovertebral Angle and Cervical Range of Motion

Objectives

The purpose of this study was to determine whether the cranial vertebral angle (CVA) and the range of motion (ROM) was different between participants with a forward head posture (FHP), with or without pain.

Methods

Forty-four participants who had FHP participated in this study. The FHP was assessed digitally by measuring a lateral view the CVA for each subject. A cervical ROM device measured the cervical ROM. The volunteers were allocated to either, with pain (n = 22), or without pain (n = 22) groups, and pain was evaluated using the Numeric Pain Rating Scale.

Results

The FHP in the pain group showed a significant difference in the CVA, and the cervical ROM in both flexion and extension, compared with those in the FHP without pain group (p < 0.05). Logistic regression analysis indicated that the occurrence of cervical area pain was higher amongst subjects who had a decreased CVA and flexion motion.

Conclusion

This study suggested that decreased CVA and cervical flexion range, were predictive factors for the occurrence of pain in the cervical region.

Effect of Different Head-Neck Postures on the Respiratory Function in Healthy Males

Normal respiration is a very intricate function that comprises mechanical as well as nonmechanical components. It is shown to be affected by various factors including age, lifestyle, disease, and change in posture. With the increased use of hand held devices, everyone is prone to poor sitting postures like forward head posture. The purpose of this study was to evaluate the effect of assumed forward head posture and torticollis on the diaphragm muscle strength. A sample of 15 healthy males, aged 18-35 years, was recruited for this study. All subjects performed spirometry to measure the forced expiratory volume in 1 second (FEV₁), the forced vital capacity (FVC), and FEV₁/FVC ratio. SNIP was measured during upright sitting, induced forward head posture, and torticollis. Subject's mean age (SD) was 23(6) years. The SNIP score of the subjects during sitting with FHP was lower as compared to that during upright sitting. It decreased significantly during induced right torticollis position. This is the first study exploring the impact of different head and neck positions on respiratory function. Alteration of head and neck positions had an immediate negative impact on respiratory function. Clinicians should be prompted to assess respiratory function when assessing individuals with mal-posture.

A preliminary study of the influence of sagittal plane neck alignment on mylohyoid activity during oropharyngeal swallowing: A surface electromyographic analysis

OBJECTIVE

Forward head posture lengthens mylohyoid muscles, but its impact on swallowing is unknown. This study determined the effect of sagittal plane neck alignment on surface electromyographic parameters from mylohyoid muscles during oropharyngeal swallowing in healthy, young women.

METHODS

Surface EMG over bilateral mylohyoid muscles was recorded in 10 female subjects (22-37 y, Mean = 30 (5.1)) for average peak amplitude (μV). Percent time to peak activity and duration [s] were recorded in three different sitting postures: habitual posture (HP), exaggerated forward head posture (FHP), and optimal posture (OP) with head positioned in alignment with the spine.

RESULTS

Paired t-tests revealed that HP produced lower mylohyoid average peak amplitude than the FHP or OP. OP had greater average percent time to peak mylohyoid activity than HP.

DISCUSSION

HP yielded the most efficient mylohyoid activity. Muscle activation during swallowing should be addressed when training young women about OP.

Effects of oculo-motor exercise, functional electrical stimulation and proprioceptive neuromuscular stimulation on visual perception of spatial neglect patients

[Purpose] The purpose of this study was to identify the effects of oculo-motor exercise, functional electrical stimulation (FES), and proprioceptive neuromuscular facilitation (PNF) on the visual perception of spatial neglect patients. [Subjects and Methods] The subjects were randomly allocated to 3 groups: an oculo-motor exercise (OME) group, a FES with oculo-motor exercise (FOME) group, and a PNF with oculo-motor exercise (POME) group. The line bisection test (LBT), motor free visual test (MVPT), and Catherine Bergego Scale (CBS) were used to measure visual perception. These were performed 5 times per week for 6 weeks. [Results] The OME group and POME group showed significant improvements according to the LBT and MVPT results, but the FOME group showed no significant improvement. According to the CBS, all 3 groups showed significant improvements. The OME and POME groups showed improvement over the FOME group in the LBT and MVPT. However, there was no significant difference among the three groups according to the CBS. [Conclusion] These results indicate that oculo-motor exercise and PNF with oculo-motor exercise had more positive effects than FES with oculo-motor exercise on the visual perception of spatial neglect patients.

Effect of eye movements and proprioceptive neuromuscular facilitation on balance and head alignment in stroke patients with neglect syndrome

[Purpose] The purpose of this study was to assess the effect of eye movements and proprioceptive neuromuscular facilitation (PNF) on patients with neglect syndrome. [Subjects and Methods] The subjects were randomly allocated to 2 groups: the eye movements (EM) group; and the PNF with eye movements (PEM) group. The program was conducted five times each week for 6 weeks. Balance (both static and dynamic) and head alignment (craniovertebral angle and cranial rotation angle) were measured before and after testing. [Results] In measurements of static balance, the EM group showed significant improvement in sway length and sway area when examined in the eyes-open condition, but not when examined in the eyes-closed condition. The PEM group showed significant improvement when examined under both conditions. In the assessment of dynamic balance, both groups showed significant improvement in measurements of sway areas. With respect to head alignment, there were no significant differences pre- and post-testing in either the craniovertebral angle or the cranial rotation angle in the EM group, but the PEM group showed significant differences in both measurements. [Conclusion] These results suggest that in stroke patients with neglect syndrome, PNF with eye movements, rather than eye movements alone, has a greater positive effect on balance and head alignment.

Effects of forward head posture on static and dynamic balance control

[Purpose] To determine the effects of forward head posture on static and dynamic balance control. [Subjects and Methods] This study included 30 participants who were included into a forward head posture group (n = 14) and a control group (n = 16) according to their craniovertebral angles. Static balance control was assessed according to center of gravity sway velocity and total sway distance using an automatic balance calibration system. Dynamic balance control was assessed using the diagnosis mode of a body-tilt training and measurement system. [Results] Sway velocities on a hard surface with eyes open and closed and those on an unstable sponge surface with eyes closed were significantly higher in the forward head posture group than in the control group. Furthermore, on both the hard and sponge surfaces in the eyes open and closed conditions, total sway distances were significantly higher in the forward head posture group than in the control group. Results of dynamic balance control were not significantly different between groups. [Conclusion] Forward head posture has a greater effect on static balance control than on dynamic balance control.

Which biomechanical models are currently used in standing posture analysis?

In 1995, David Winter concluded that postural analysis of upright stance was often restricted to studying the trajectory of the center of pressure (CoP). However, postural control means regulation of the center of mass (CoM) with respect to CoP. As CoM is only accessible by using a biomechanical model of the human body, the present article proposes to determine which models are actually used in postural analysis, twenty years after Winter's observation. To do so, a selection of 252 representative articles dealing with upright posture and published during the four last years has been checked. It appears that the CoP model largely remains the most common one (accounting for nearly two thirds of the selection). Other models, CoP/CoM and segmental models (with one, two or more segments) are much less used. The choice of the model does not appear to be guided by the population studied. Conversely, while some confusion remains between postural control and the associated concepts of stability or strategy, this choice is better justified for real methodological concerns when dealing with such high-level parameters. Finally, the computation of the CoM continues to be a limitation in achieving a more complete postural analysis. This unfortunately implies that the model is chosen for technological reasons in many cases (choice being a euphemism here). Some effort still has to be made so that bioengineering developments allow us to go beyond this limit.

Relationships between craniocervical posture and pain-related disability in patients with cervico-craniofacial pain

Objectives

This cross-sectional correlation study explored the relationships between craniocervical posture and pain-related disability in patients with chronic cervico-craniofacial pain (CCFP). Moreover, we investigated the test–retest intrarater reliability of two craniocervical posture measurements: head posture (HP) and the sternomental distance (SMD).

Methods

Fifty-three asymptomatic subjects and 60 CCFP patients were recruited. One rater measured HP and the SMD using a cervical range of motion device and a digital caliper, respectively. The Spanish versions of the neck disability index and the craniofacial pain and disability inventory were used to assess pain-related disability (neck disability and craniofacial disability, respectively).

Results

We found no statistically significant correlations between craniocervical posture and pain-related disability variables (HP and neck disability [r=0.105; P>0.05]; HP and craniofacial disability [r=0.132; P>0.05]; SMD and neck disability [r=0.126; P>0.05]; SMD and craniofacial disability [r=0.195; P>0.05]). A moderate positive correlation was observed between HP and SMD for both groups (asymptomatic subjects, r=0.447; CCFP patients, r=0.52). Neck disability was strongly positively correlated with craniofacial disability (r=0.79; P<0.001). The test–retest intrarater reliability of the HP measurement was high for asymptomatic subjects and CCFP patients (intraclass correlation coefficients =0.93 and 0.81, respectively) and for SMD (intra-class correlation coefficient range between 0.76 and 0.99); the test–retest intrarater reliability remained high when evaluated 9 days later. The HP standard error of measurement range was 0.54–0.75 cm, and the minimal detectable change was 1.27–1.74 cm. The SMD standard error of measurement was 2.75–6.24 mm, and the minimal detectable change was 6.42–14.55 mm. Independent t-tests showed statistically significant differences between the asymptomatic individuals and CCFP patients for measures of craniocervical posture, but these differences were very small (mean difference =1.44 cm for HP; 6.24 mm for SMD). The effect sizes reached by these values were estimated to be small for SMD (d=0.38) and medium for HP (d=0.76).

Conclusion

The results showed no statistically significant correlations between craniocervical posture and variables of pain-related disability, but a strong correlation between the two variables of disability was found. Our findings suggest that small differences between CCFP patients and asymptomatic subjects exist with respect to the two measurements used to assess craniocervical posture (HP and SMD), and these measures demonstrated high test–retest intrarater reliability for both CCFP patients and asymptomatic subjects.

Effects of craniocervical flexion exercise on upper-limb postural stability during a goal-directed pointing task

[Purpose] This study investigated the effects of craniocervical flexion exercise on upper-limb postural stability by measuring upper-limb postural tremor during a goal-directed pointing task. [Subjects and Methods] Twenty-four subjects were randomly assigned to the exercise or control group. The exercise group performed craniocervical flexion exercise four days per week for five weeks. Upper-limb postural tremor was measured by using a three-dimensional electromagnetic motion tracking system (trakSTAR™, Ascension Technology Corporation, Burlington, VT, USA) during a goal-directed pointing task. [Results] In the exercise group, the range and velocity of the trajectories of the shoulder, wrist, and finger in the lateral direction improved significantly. However, no significant changes were observed in the control group. [Conclusion] Craniocervical flexion exercise reduces the range and velocity of upper-limb postural tremor, thereby increasing postural stability.

Changes in upper-extremity muscle activities due to head position in subjects with a forward head posture and rounded shoulders

[Purpose] This study investigated upper-extremity muscle activities in natural, ideal, and corrected head positions. [Subjects and Methods] Forty subjects with a forward head posture and rounded shoulder were recruited and randomly assigned to the natural head position group (n = 13), ideal head position group (n = 14), or corrected head position group (n = 13). Muscle activities were measured using a four-channel surface electromyography system at the sternocleidomastoideus, upper and lower trapezius, and serratus anterior muscles on the right side during an overhead reaching task. [Results] The muscle activities of the upper trapezius and serratus anterior differed significantly among head positions. Post hoc tests revealed significant differences between natural and ideal head positions, and natural and ideal head positions for both the upper trapezius and serratus anterior. [Conclusion] Recovery of normal upper trapezius and serratus anterior muscle functions plays an important role in correcting forward head posture and rounded shoulders.

Characteristics of cervical position sense in subjects with forward head posture

[Purpose] The purpose of this study was to investigate the effect of forward head posture (FHP) on proprioception by determining the cervical position-reposition error. [Subjects and Methods] A sample population was divided into two groups in accordance with the craniovertebral angle: the FHP group and the control group. We measured the craniovertebral angle, which is defined as the angle between a horizontal line passing through C7 and a line extending from the tragus of the ear to C7. The error value of the cervical position sense after cervical flexion, extension, and rotation was evaluated using the head repositioning accuracy test. [Results] There were significant differences in the error value of the joint position sense (cervical flexion, extension, and rotation) between the FHP and control groups. In addition, there was an inverse correlation between the craniovertebral angle and error value of the joint position sense. [Conclusion] FHP is associated with reduced proprioception. This result implies that the change in the muscle length caused by FHP decreases the joint position sense. Also, proprioception becomes worse as FHP becomes more severe.