Notebook computer use with different monitor tilt angle: effects on posture, muscle activity and discomfort of neck pain users.
From: Work. 2012 Jan 1;41(0):2591-5
This study aimed to evaluate the posture, muscle activities, and self reported discomforts of neck pain notebook computer users on three monitor tilt conditions: 100°, 115°, and 130°. Six subjects were recruited in this study to completed typing tasks. Results showed subjects have a trend to show the forward head posture in the condition that monitor was set at 100°, and the significant less neck and shoulder discomfort were noted in the condition that monitor was set at 130°. These result suggested neck pain notebook user to set their monitor tilt angle at 130°.
Can a functional postural exercise improve performance in the cranio-cervical flexion test? – A preliminary study.
Man Ther. 2012 Feb 4. [Epub ahead of print]
There is considerable evidence that neck pain is associated with alterations in spatial and temporal behaviors of the neck muscles and changes in muscle properties. Changes have been identified in various neck and axio-scapular muscles and the neck flexors have received particular attention. There is some functional specificity between superficial and deep flexors. Superficial muscles, sternocleidomastoid and anterior scalenes are major contributors to flexion torque while deep neck flexor muscles (longus capitis and colli) have an important role in supporting the normal neck curve and segments in posture and movement.
Of clinical and functional relevance, reduced activation of the deep neck flexor muscles has been identified in association with increased activation of the superficial flexor muscles in studies using the cranio cervical flexion test in patients with a variety of neck disorders. The evidence of reduced deep neck flexor activity comes from laboratory studies using a direct measure of electromyographic (EMG) amplitudes. A number of clinical studies have limited measurement to sternocleidomastoid activity using surface EMG electrodes and have indirectly inferred reduced deep neck flexor function on the evidence of an inverse relationship between sternocleidomastoid, anterior scalenes and deep neck flexor muscle activity from laboratory measures of neck pain patients.
Training the deep neck flexor muscles is regarded as an important component of neck rehabilitation programs because of the functional importance of the deep neck flexor and the evidence suggesting that the altered pattern of activation between the deep and superficial flexors (1) does not correct automatically with pain relief and (2) persists without specific training. Many factors influence the magnitude of neck pain. It is uncertain whether changes in muscle function are a cause or effect of pain, but a relationship has been shown between neck pain intensity and activity in the deep (lesser) and superficial (greater) neck flexor muscles. Concomitantly, the degree of pain reduction in patients with chronic neck pain has a relationship with the change in deep neck flexor activity following training. Clinical trials also support the effectiveness of training the deep neck flexor muscles and restoring their normal temporal relationship with the superficial flexors as a component of a multimodal program for the rehabilitation of neck pain disorders.
(more…)
Differences in end range lumbar flexion during slumped sitting and forward bending between low back pain subgroups and genders
From: Man Ther. 2012 Jan 17. [Epub ahead of print]
Low back pain may be related to patterns of lumbar postures and movements used to perform different tasks, but it is unclear which patterns with which tasks contribute to low back pain. For example, increases in both lumbar flexion and extension have been linked to low back pain. Some studies have reported increased lumbar flexion in people with low back pain during activities involving flexion, such as golfing and cycling. Other studies have reported that increased lumbar extension is associated with low back pain during sitting. Inconsistent findings regarding the direction of increased lumbar movement or the presence of flexed versus extended postural alignment potentially associated with low back pain may be due to the inclusion of subjects with widely varying movement patterns in a single low back pain group. Several researchers have proposed that there are subgroups of people with low back pain whose symptoms are associated with different direction related postures or movement patterns (e.g., flexion or extension related).
If multiple low back pain subgroups are studied as a single population, differences between subgroups demonstrating patterns in opposite directions could average out to suggest no difference in motion between people with and without low back pain. When subgrouping was not included in the study design, several studies found no differences in lumbar postural alignment and motion between people with and without low back pain. Still other studies found that decreased lumbar motion is associated with low back pain. Lumbar postural alignment and motion characteristics associated with low back pain may be more clearly identified when people with low back pain are subgrouped based on lumbar patterns associated with symptoms.
(more…)
Effect of backpack load carriage on cervical posture in primary schoolchildren
From: Work. 2012 Jan 1;41(1):99-108
This study examined the effects of various backpack loads on elementary schoolchildren’s posture and postural compensations as demonstrated by a change in forward head position. A convenience sample of 11 schoolchildren, aged 8-11 years participated. Sagittal digital photographs were taken of each subject standing without a backpack, and then with the loaded backpack before and after walking 6 minutes (6MWT) at free walking speed. This was repeated over three consecutive weeks using backpacks containing randomly assigned weights of 10%, 15%, or 20% body weight of each respective subject. The craniovertebral angle was measured using digitizing software, recorded and analyzed.
Subjects demonstrated immediate and statistically significant changes in craniovertebral angle, indicating increased forward head positions upon donning the backpacks containing 15% and 20% body weight. Following the 6MWT, the craniovertebral angle demonstrated further statistically significant changes for all backpack loads indicating increased forward head postures. For the 15 & 20% body weight conditions, more than 50% of the subjects reported discomfort after walking, with the neck as the primary location of reported pain. Backpack loads carried by schoolchildren should be limited to 10% body weight due to increased forward head positions and subjective complaints, primarily neck pain, at 15% and 20% body weight loads.
Relative importance of expertise, lifting height and weight lifted on posture and lumbar external loading during a transfer task in manual material handling
From: Ergonomics. 2012 Jan;55(1):87-102
The objective of this study was to measure the effect size of three important factors in manual material handling, namely expertise, lifting height and weight lifted. The effect of expertise was evaluated by contrasting 15 expert and 15 novice handlers, the effect of the weight lifted with a 15-kg box and a 23-kg box and the effect of lifting height with two different box heights: ground level and a 32 cm height. The task consisted of transferring a series of boxes from a conveyor to a hand trolley.
Lifting height and weight lifted had more effect size than expertise on external back loading variables (moments) while expertise had low impact. On the other hand, expertise showed a significant effect of posture variables on the lumbar spine and knees. All three factors are important, but for a reduction of external back loading, the focus should be on the lifting height and weight lifted.
The objective was to measure the effect size of three important factors in a transfer of boxes from a conveyor to a hand trolley. Lifting height and weight lifted had more effect size than expertise on external back loading variables but expertise was a major determinant in back posture.
Dynamic and functional balance tasks in subjects with persistent whiplash: a pilot trial
Man Ther. 2011 Aug;16(4):394-8.
Static balance tests using posturography and force plates have been used to identify and evaluate postural stability in subjects with persistent whiplash and postural stability deficits in various stance and visual conditions have been found in these patients. Subjects with persistent whiplash also commonly report dizziness and or unsteadiness (70%) and complain of episodes of loss of standing balance (48%) and of actual falls (21%). Subjects who report these symptoms have also demonstrated greater deficits in static standing balance when compared to those who don’t report these symptoms. It is thought that these symptoms are a direct result of the cervical injury although vestibular damage is also possible.
The disturbances in static standing balance seen in patients with trauma induced persistent neck pain, may contribute to consequent difficulties in the completion of dynamic and functional balance tasks but to date there has only been one other study to look at some functional and dynamic measures and they demonstrated altered trunk angular velocity and sway angle during the tests in a whiplash compared to a control group. Simple and easy to conduct dynamic and functional balance tests using clinical measures with minimal equipment are thought to more adequately evaluate performance on the types of tasks in which falls may potentially occur.
Such clinical measures of dynamic and functional tests have been used in the assessment of balance in subjects with neurological and vestibular conditions and recently some tests have been measured in an elderly population with neck pain, where the dynamic balance measures were found to be impaired in addition to force plate evaluations of static balance. The findings suggested that neck pain in the elderly contributes to disturbance in balance and gait parameters over and above that which occurs with normal ageing. Specifically, a slower self-selected gait speed and cadence when walking with side to side head turning, and a significantly longer gait cycle duration when walking both without and with head turns was observed when compared to healthy control subjects. Dynamic balance deficits have also been found in subjects with unilateral vestibular loss in the step test, tandem walk and Dynamic Gait Index.
(more…)
Reality about migration of the nucleus pulposus within the intervertebral disc with changing postures
From: Clin Biomech (Bristol, Avon). 2011 Oct 18. [Epub ahead of print]
Previous studies reported that, in non-degenerate discs, the nucleus pulposus migrates posteriorly during flexion and anteriorly during extension within the intervertebral disc. However, in these studies the differences between anterior and posterior distances have been regarded as an indicator of nucleus pulposus migration. This study investigated the reality of migration of the nucleus pulposus within the intervertebral disc with changing postures.
Magnetic resonance images were obtained of the lumbar spines of 25 asymptomatic volunteers in sitting, standing and supine postures. The anterior and posterior height of the intervertebral disc, the anterior-posterior length of the intervertebral disc and nucleus pulposus, and the positions of the anterior and posterior margins of the nucleus were measured from mid-line sagittal images.
Changing postures altered the anterior and posterior height of the disc and three types of morphological changes, including changes in the anterior-posterior lengths of the intervertebral disc and nucleus pulposus, together with the position of the nucleus in the disc were found. The length of the intervertebral disc and nucleus pulposus changed under the variations in spinal loading caused by posture.
The results of this study indicated that the apparent nucleus pulposus migration within intervertebral disc is actually deformation of the nucleus pulposus length which depends on posture and the magnitude of the load. In other words, adopting different postures deforms the nucleus pulposus and therefore, changes the position of the nucleus pulposus but there is no apparent nucleus pulposus migration within the intervertebral disc.
Poor sitting posture and a heavy schoolbag as contributors to musculoskeletal pain in children: an ergonomic school education intervention program
From: J Pain Res. 2011;4:287-96.
The purpose of this study was to evaluate a multidisciplinary, interventional, ergonomic education program designed to reduce the risk of musculoskeletal problems by reducing schoolbag weight and correcting poor sitting posture.
Data were collected twice before and twice following intervention using the Standardized Nordic Body Map Questionnaire, a rapid upper limb assessment for posture evaluation, and schoolbag weight measurement in children aged 8 and 11 years attending two schools within the central region of Malaysia.
Students who received the ergonomic intervention reported significant improvements in their sitting posture in a classroom environment and reduction of schoolbag weight as compared with the controls.
A single-session, early intervention, group ergonomics education program for children aged 8 and 11 years is appropriate and effective, and should be considered as a strategy to reduce musculoskeletal pain among schoolchildren in this age group.
Face Piercing (Body Art): Choosing Pleasure vs. Possible Pain and Posture Instability
From: Front Physiol. 2011;2:64. Epub 2011 Sep 21.
Piercings (body art, i.e., with jewelry) are more and more widespread. They can induce various complications such as infections, allergies, headaches, and various skin, cartilage, or dental problems, and represent a public health problem. We draw attention to possible side effects resulting from face piercing complications observed on four young adults such as eye misalignment, decreased postural control efficiency, and non-specific chronic back pain with associated comorbidity. The authors found that the origin was pierced jewelry on the face. Removing the jewelry restored eye alignment, improved postural control, and alleviated back pain in a lasting way.
The authors suggest that pierced facial jewelry can disturb somaesthetic signals driven by the trigeminal nerve, and thus interfere with central integration processes, notably in the cerebellum and the vestibular nucleus involved in postural control and eye alignment. Facial piercings could induce sensory-motor conflict, exacerbate, or precipitate a pre-existing undetermined conflict, which leads pain and complaints. These findings are significant for health; further investigations would be of interest.
(more…)
Range of motion in the upper and lower cervical spine in people with chronic neck pain.
From: Man Ther. 2011 Sep 24. [Epub ahead of print]
Reduced cervical range of motion is a common finding in people with neck pain. Exercises targeting cervical range of motion has also been recommended for this patient group. In research, different methodologies for range of motion measurements have been used, but with a few exceptions, only the angle between head and thorax has been measured. Thus, the neck has been modelled as one joint.
The upper and lower parts of the cervical spine differ substantially with respect to the biomechanics. In addition, specific diagnoses, such as cervicogenic headache, have been linked to dysfunctions in the upper cervical segments. Also the lower cervical segments may be the source of neck pain in some patients.
Thus, objective measures of cervical range of motion that can separate the movement of the upper and lower cervical spine can be valuable for characterisation of patients and treatment evaluation. A simple method for separating upper and lower cervical levels in flexion-extension has been used for other kinematic investigations. In this method the thorax, cervical spine and head form a three-segment model that allows measurement of flexion and extension at the upper and lower cervical levels. The first aim of this study was to use such a model to compare active cervical flexion and extension, separate for upper and lower cervical levels, between people with chronic neck pain and controls.
Despite the wide use of range of motion tests in studies on neck pain, few researchers have studied relationships between the degree of restriction of range of motion and self-rated disability. Therefore, the second aim was to investigate associations between range of motion measures of flexion-extension and self-rated characteristics such as health, functioning and symptoms. In addition, the authors investigated associations between axial range of motion and self-rated characteristics since axial rotations are important in many functional tasks.
(more…)
