Examination of EMG normalisation methods for the study of the posterior and posterolateral neck muscles in healthy controls

The purpose of this study was to examine the reliability of normalisation methods used in the study of the posterior and posterolateral neck muscles in a group of healthy controls. Six asymptomatic male subjects performed a total of 12 maximum voluntary isometric contractions (MVIC) and 60%-submaximal isometric contractions (60%-MVIC) against the torque arm of an isokinetic dynamometer whilst surface and intramuscular electromyography (EMG) was recorded unilaterally from representative posterior and posterolateral locations. Reliability was calculated using intra-class correlation coefficient (ICC), relative standard error of measurement (%SEM) and relative coefficient of variation (%CV). Maximal torque output was found to be highly reliable in the directions of extension and right lateral bending when the first of three MVIC contractions was excluded. When averaged across contraction direction, high reliability was found for both surface (MVIC: ICC = 0.986, %SEM = 7.5, %CV = 9.2; 60%-MVIC: ICC = 0.975, %SEM = 10, %CV = 13.7) and intramuscular (MVIC: ICC = 0.910, %SEM = 20, %CV = 19.1; 60%-MVIC: ICC = 0.952, %SEM = 16.5, %CV = 13.5) electrodes. Intramuscular electrodes displayed the least reliability in right lateral bending. The use of visual feedback markedly increased the reliability of 60%-MVIC contractions.

Reliability of normalisation methods for EMG analysis of neck muscles

Acceptable reliability of normalisation contractions in electromyography (EMG) is paramount for testing conducted over a number of days or if normal laboratory strength testing equipment is unavailable. This study examined the reliability of maximal voluntary isometric contractions (MVIC) and sub-maximal (60%) isometric contractions for use in neck muscle EMG studies. Surface EMG was recorded bilaterally from eight sites around the neck at C4/5 level from five healthy male subjects. Subjects performed MVIC and sub-maximal normalisation contractions using an isokinetic dynamometer (ID) and a portable cable dynamometer with attached strain gauge (PCD) in addition to a MVIC against a manual resistance (MR). Subjects were tested in flexion, extension, left and right lateral bending and were retested by the same tester within a two-week period. Intra class correlation co-efficients (ICC) were calculated for each testing method and contraction direction and a mean ICC was calculated across all contraction directions. All normalisation methods produced excellent within-day reliability (mean ICC >0.80) but only the MVICs using the ID and PCD had acceptable reliability when assessed between-days. This study confirmed the validity of using MVICs elicited using the ID and PCD as reliable reference contractions for the normalisation of neck EMG.

Neck exercises compared to muscle activation during aerial combat maneuvers

Introduction: Performing specific neck strengthening exercises has been proposed to decrease the incidence of neck injury and pain in high performance combat pilots. However, there is little known about these exercises in comparison to the demands on the neck musculature in flight.

Methods: Eight male non-pilots performed specific neck exercises using two different modalities (elastic band and resistance machine) at six different intensities in flexion, extension, and lateral bending. Six Royal Australian Air Force Hawk pilots flew a sortie that included combinations of three +Gz levels and four head positions. Surface electromyography (EMG) from selected neck and shoulder muscles was recorded in both activities.

Results: Muscle activation levels recorded during the three elastic band exercises were similar to in-flight EMG collected at +1 Gz (15% MVIC). EMG levels elicited during the 50% resistance machine exercises were between the +3 Gz (9-40% MVIC) and +5 Gz (16-53% MVIC) ranges of muscle activations in most muscles. EMG recorded during 70% and 90% resistance machine exercises were generally higher than in-flight EMG at +5 Gz.

Discussion: Elastic band exercises could possibly be useful to pilots who fly low +Gz missions while 50% resistance machine mimicked neck loads experienced by combat pilots flying high +Gz ACM. The 70% and 90% resistance machine intensities are known to optimize maximal strength but should be administered with care because of the unknown spinal loads and diminished muscle force generating capacity after exercise.

Femoral neck geometry and hip fracture risk : the Geelong Osteoporosis Study

To determine the relationship between femoral neck geometry and the risk of hip fracture in post-menopausal Caucasian women, we conducted a retrospective study comparing the femoral neck dimensions of 62 hip fracture cases to those of 608 randomly selected controls. Measurements were made from dual-energy X-ray absorptiometry scans (Lunar DPX-L), using the manufacturers ruler function, and included: hip axis length (HAL), femoral neck axis length (FNAL), femoral neck width (FNW), femoral shaft width (FSW), medial femoral shaft cortical thickness (FSCT_med), and lateral femoral shaft cortical thickness (FSCT_lat). The fracture group was older (median age 78.3 years vs 73.8 years), lighter (median weight 59.9 kg vs 64.5 kg), and, after adjustment for age, taller (mean height 158.7±0.8 cm vs 156.7±0.2 cm) than the controls. Furthermore, bone mineral density was lower in this group (0.682±0.016 g/cm² vs 0.791±0.006 g/cm²). After adjustment for age, bone mineral content (BMC) or height, hip fracture patients had greater FNW (up to 6.6%) and FSW (up to 6.3%) than did the controls. Each standard deviation increase in FNW and FSW was associated with a 1.7-fold (95% CI 1.3–2.3) and a 2.4-fold (95% CI 1.8–3.2) increase in the fracture risk, respectively. BMC-adjusted FNAL was greater in the fracture group (+2.1%) than in the controls, while the age-adjusted FSCT_med was reduced (–7.2%). There was a trend towards longer HAL (up to 2.1%) after adjustment for age or BMC, and thinner age-adjusted FSCT_lat (–1.7%) in fracture patients that did not reach statistical significance. In multivariate analysis, the risk of hip fracture was predicted by the combination of age, FNW, FSW, BMC and FSCT_med. HAL was not analyzed because of the small number of HAL measurements among fracture cases. We conclude that post-menopausal women with hip fractures have wider femoral necks and shafts, thinner femoral cortices and longer femoral neck axis lengths than do women with no fractures. Alteration in hip geometry is associated with the risk of hip fracture.

Interobserver Variability in the Treatment of Little Finger Metacarpal Neck Fractures

Purpose To address the null hypothesis that surgeons shown radiographs of little finger metacarpal neck fractures with measured fracture angulation would recommend surgery as often as surgeons shown unmarked radiographs. Methods Members of the Science of Variation Group, an international collaboration of fully trained orthopedic and trauma surgeons, were asked to review 20 little finger metacarpal neck fracture cases, which included a vignette and 3 high-quality radiographs. Members were then randomized to review radiographs with or without measured fracture angulation on the lateral view and select operative or nonoperative management. Results Surgeons shown radiographs with measured angulation were more likely to recommend surgery, and there was less variability among these surgeons, particularly for fractures with less angular deformity. Conclusions Measured fracture angulation has a small but significant influence on treatment recommendations for little finger metacarpal neck fractures.

Human skeletal muscle atrophy in amyotrophic lateral sclerosis reveals a reduction in Akt and an increase in atrogin-1

The molecular mechanisms influencing muscle atrophy in humans are poorly understood. Atrogin-1 and MuRF1, two ubiquitin E3-ligases, mediate rodent and cell muscle atrophy and are suggested to be regulated by an Akt/Forkhead (FKHR) signaling pathway. Here we investigated the expression of atrogin-1, MuRF1, and the activity of Akt and its catabolic (FKHR and FKHRL1) and anabolic (p70s6k and GSK-3β) targets in human skeletal muscle atrophy. The muscle atrophy model used was amyotrophic lateral sclerosis (ALS). All measurements were performed in biopsies from 22 ALS patients and 16 healthy controls as well as in G93A ALS mice. ALS patients had a significant increase in atrogin-1 mRNA and protein content, which was associated with a decrease in Akt activity. There was no difference in the mRNA and protein content of FKHR, FKHRL1, p70s6k, and GSK-3β. Similar observations were made in the G93A ALS mice. Human skeletal muscle atrophy, as seen in the ALS model, is associated with an increase in atrogin-1 and a decrease in Akt. The transcriptional regulation of human atrogin-1 may be controlled by an Akt-mediated transcription factor other than FKHR or via another signaling pathway.

Properties of slow- and fast-twitch muscle fibres in a mouse model of amyotrophic lateral sclerosis

This investigation was undertaken to determine if there are altered histological, pathological and contractile properties in presymptomatic or endstage diseased muscle fibres from representative slow-twitch and fast-twitch muscles of SOD1 G93A mice in comparison to wildtype mice. In presymptomatic SOD1 G93A mice, there was no detectable peripheral dysfunction, providing evidence that muscle pathology is secondary to motor neuronal dysfunction. At disease endstage however, single muscle fibre contractile analysis demonstrated that fast-twitch muscle fibres and neuromuscular junctions are preferentially affected by amyotrophic lateral sclerosis-induced denervation, being unable to produce the same levels of force when activated by calcium as muscle fibres from their age-matched controls. The levels of transgenic SOD1 expression, aggregation state and activity were also examined in these muscles but there no was no preference for muscle fibre type. Hence, there is no simple correlation between SOD1 protein expression/activity, and muscle fibre type vulnerability in SOD1 G93A mice.

Evaluation of cervial range of motion and isometric nech muscle strngth: reliability and validity

Objective: To examine the test–retest reliability and construct validity of cervical active range of motion and isometric neck muscle strength as measured by the Multi Cervical Rehabilitation Unit (Hanoun Medical Inc., Ontario).
Design: A cross-sectional study.
Setting: Institutional practice.
Subjects: Twenty-one patients with neck pain and 25 healthy volunteers.
Methods: After a trial-run session, active range of motion (AROM) was measured in the subsequent two sessions, with 2–3 days in between. During each session, three measurements were taken for each direction (flexion, extension, lateral flexions and rotations). The measurement of isometric strength was after a 15-minute break following completion of the measurement of AROM. Three measurements were made for each of the six directions (flexion, extension, lateral flexions, protraction and retraction). The software of the Multi Cervical Rehabilitation Unit automatically recorded and calculated the maximum AROM and isometric strength.
Results: There was a good to high level of reliability in the measurement of AROM for both groups of subjects, with intraclass correlation coefficients (ICCs) ranging from 0.81 to 0.96. Results also demonstrated very good to excellent reliability in isometric strength measurement (ICCs ranged from 0.92 to 0.99). Moreover, there was a significant difference in isometric neck muscle strength (p = 0.001) and in AROM (p = 0.034) between the two groups.
Conclusions: The Multi Cervical Rehabilitation Unit was found to be reliable and valid for testing the cervical active range of motion and isometric neck muscle strength for both normal and patient subjects.

Quality-of-life measurement in patients undergoing radiation therapy for head and neck cancer: a Hong Kong experience

The aims of this study are (1) to establish a reliable and valid quality-of-life (QOL) questionnaire for Chinese patients with head and neck (H&N) cancer who are treated with radiation therapy and (2) to evaluate the impact of the immediate side effects of treatment on the QOL of these patients. The 39-item "Quality of Life Radiation Therapy Instrument with Head and Neck Companion Module" (QOL-RTI/H&N) was translated into Chinese. In the reliability evaluation phase (study module 1), the questionnaire was administered twice to 56 H&N cancer patients, 7 days apart, during the second and third week of radiation therapy. In the validity evaluation phase (study module 2), 138 patients completed the QOL-RTI/H&N before starting and at the end of radiation therapy. Sixty-nine of these 138 patients also completed the QOL-RTI/H&N during the second week of their radiation therapy, at the same time as completing the Functional Assessment of Cancer Therapy-Head and Neck (FACT-H&N) questionnaire. Cronbach alpha coefficients were 0.88 for the general-tool QOL-RTI and 0.90 for the H&N subscale. Test-retest reliability was satisfactory with intraclass correlation coefficients of 0.89 for the general-tool QOL-RTI and 0.75 for the H&N subscale. The instrument can discriminate between patients with stage I or II disease and those with stage III or IV disease (P < .05). Concurrent validity was established by the good agreement with the FACT-H&N (r = 0.86, P < .001). A highly significant deterioration was in the QOL from the baseline to the end of treatment (mean difference for general tool = 1.95, P < .001; mean difference for H&N subscale = 4.85, P < .001). The Chinese QOL-RTI/H&N is a reliable and valid tool for determining the QOL in H&N cancer patients receiving radiation therapy. The immediate side effects of treatment had a significantly negative impact on the patients' QOL. The impact was relatively large for the functional and treatment-site aspects.

An electromyographic comparison of neck conditioning exercises in healthy controls

The purpose of this study was to compare surface electromyography (EMG) activation levels of selected neck muscles for two common neck-training modalities (Thera-Band and Cybex). Seventeen asymptomatic subjects (eight men and nine women) with a mean age 23.4 years were recruited. EMG activation normalized to maximal voluntary isometric contraction (MVIC) was measured with subjects performing exercises with green, blue, and black Thera-Bands and 50%, 70%, and 90% of 3RM for the Cybex modality. Four variables were used to depict exercise intensity: average and peak EMG activation in the concentric and eccentric phases. Significant differences (P <= 0.05) in EMG activation were evident when comparing intensities of the Cybex modality with each other and when comparing the Cybex intensities with Thera-Band intensities in most cases. Minimal differences were found among differing intensities of Thera-Band. Thera-Band exercise resulted in low-level EMG activation (range, flexion 3.8-15.7% MVIC; range, extension 20.2-34.8% MVIC); therefore, such exercise may be useful in rehabilitation programs. Cybex exercise (range, flexion 20.9-83.5% MVIC; range, extension 40.6-95.8% MVIC) may be useful for occupation-related injury prevention. However, exercise prescription should be undertaken with care as the mechanical loading on passive spinal structures is unknown.

Lateral positioning for critically ill adult patients

We aim to assess the effect of the lateral position compared to other body positions on patient outcomes (mortality, morbidity and clinical adverse events during and following positioning) in critically ill adult patients. We will examine the single use of the lateral position (that is on the right or left side) and repeat use of the lateral position(s) in a positioning schedule (that is lateral positioning). We plan to undertake subgroup analysis for primary disease and condition, severity of illness, the presence of assisted ventilation and angle of lateral rotation.

Living with amyotrophic lateral sclerosis/motor neurone disease (ALS/MND) : decision-making about 'ongoing change and adaptation

Aims and objectives. To present a model that explicates the dimensions of change and adaptation as revealed by people who are diagnosed and live with amyotrophic lateral sclerosis/motor neurone disease.

Background. Most research about amyotrophic lateral sclerosis/motor neurone disease is medically focused on cause and cure for the illness. Although psychological studies have sought to understand the illness experience through questionnaires, little is known about the experience of living with amyotrophic lateral sclerosis/motor neurone disease as described by people with the disease.

Design. A grounded theory method of simultaneous data collection and constant comparative analysis was chosen for the conduct of this study.

Methods. Data collection involved in-depth interviews, electronic correspondence, field notes, as well as stories, prose, songs and photographs important to participants. QSR NVivo 2® software was used to manage the data and modelling used to illustrate concepts.

Findings. Participants used a cyclic, decision-making pattern about 'ongoing change and adaptation' as they lived with the disease. This pattern formed the basis of the model that is presented in this paper.

Conclusion. The lives of people living with amyotrophic lateral sclerosis/motor neurone disease revolve around the need to make decisions about how to live with the disease progression and their deteriorating abilities. Life decisions were negotiated by participants to maintain a sense of self and well-being in the face of change.

Relevance to clinical practice. The 'ongoing change and adaptation' model is a framework that can guide practitioners to understand the decision-making processes of people living with amyotrophic lateral sclerosis/motor neurone disease. Such understanding will enhance caring and promote models of care that are person-centred. The model may also have relevance for people with other life limiting diseases and their care.

Influence of posture on the range of axial rotation and coupled lateral flexion of the thoracic spine

Objective
This study examines the influence of posture on the range of axial rotation of the thorax and the range and direction of the coupled lateral flexion.

Methods
The ranges of mid thoracic axial rotation and coupled lateral flexion were measured in 52 asymptomatic subjects (aged 18-43 years) using an optical motion analysis system. To examine the influence of posture on primary and coupled motion, we initiated axial rotation from a neutral sitting posture and from end-range thoracic flexion and extension.

Results
There was a significant decrease in the range of thoracic rotation in flexion compared with the neutral and extended postures (P < .001). The mean range of coupled lateral flexion was 8.9% of the axial rotation range in the neutral posture and increased to 14.3% and 23.2% in the extended and flexed postures, respectively. Patterns of coupled motion varied between subjects, but an ipsilateral pattern was more common in the flexed posture, whereas a contralateral pattern was more common in the neutral and extended postures.

Conclusions
The ranges and patterns of coupled motion of the thorax appear to be strongly influenced by the posture from which the movement is initiated. This has important implications in relation to the interpretation of clinical tests of thoracic motion and in consideration of mechanisms of development of thoracic pain disorders.

Postural neck pain : an investigation of habitual sitting posture, perception of 'good' posture and cervicothoracic kinaesthesia

Impairments of cervico-cephalic kinaesthesia and habitual forward head posture have been considered important in the aetiology of postural neck pain, yet these factors have not been specifically examined in a homogeneous clinical population. The objective of this study was to compare the habitual sitting posture (HSP), perception of good posture and postural repositioning error (PRE) of the cervico-thoracic (CT) spine in individuals with postural neck pain, with a matched group of asymptomatic subjects. Twenty-one subjects with postural neck pain and 22 asymptomatic control subjects were recruited into the study. An optical motion analysis system was used to measure the HSP and perceived ‘good’ sitting posture. PRE was measured over six trials where the subject attempted to replicate their self-selected ‘good’ posture. There was no difference between the groups in the HSP but significant differences were identified in the perception of ‘good’ posture. Posture repositioning error was higher for the head posture variables than for CT and shoulder girdle variables in both groups. However, there was no significant difference in posture repositioning error between groups for any of the posture measures. The findings suggest that individuals with postural neck pain may have a different perception of ‘good’ posture, but no significant difference in HSP or kinaesthetic sensibility compared with matched asymptomatic subjects.