S53 Figure 1Rates of mortality against cumulative number of antibiotics received per patient during inpatient spell.[Figure omitted. See PDF]ConclusionIn both COVID-19 waves, antibiotic administration correlated to increased inpatient morbidity and mortality. Given a near-linear relationship of mortality and cumulative antibiotic numbers, antimicrobial stewardship is essential, and tapering an appropriate therapy for likely responsible pathogens will yield lower mortality compared to overlapping coverage and inappropriate escalation. We strongly discourage the use of empirical antibiotics without supporting biochemical evidence of bacterial co-infection for possible future COVID-19 waves.ReferenceRussell C, et al. Lancet Microbe. 2021 Jun 2. https://doi.org/10.1016/S2666-5247(21)00090-2

Background Procalcitonin (PCT) is an established biomarker of acute bacterial infection, and elevated levels of PCT may correlate with increased severity in patients with COVID-19 infection.1 Here, we assess if initial PCT levels are a viable prognostic marker to predict significant morbidity and mortality outcomes for hospitalised patients admitted due to COVID-19 infection. Method We performed retrospective analysis of initial blood results taken from 1189 patients with RT-PCR positive COVID-19 infection presenting to our District General Hospital between 1st November 2020 and 28th February 2021. Mortality encompassed both inpatient and within 28 days post-discharge. Significant morbidity was defined as admission to the Intensive Care Unit (ICU) for organ support. PCT was measured using Brahm's chemiluminescent micro particle assay (CMIA). Elevated PCT was defined at two levels: PCT ≥0.5µg/L and PCT ≥0.2µg/L, to account for variance amongst literature.2 Regression analysis was performed to determine independent significance, accounting for comorbidity and demographics. Results We found elevated PCT levels conferred a significant two-fold increase in mortality and ICU admission. Initial PCT ≥0.5µg/L was associated with a significantly increased risk of mortality than those with PCT <0.5µg/L (46.5% vs 24.2%; OR 2.847, p=0.0001). Significantly higher mortality risk was also observed when using lower cut-off values, i.e, PCT ≥0.2µg/L vs PCT <0.2µg/L (OR 2.042, p=0.00001). A significantly higher rate of ICU admission for initial PCT ≥0.5µg/L (OR 2.041, p=0.007) or PCT ≥0.2µg/L (OR 1.918, p=0.0008) was also observed within our cohort. Conclusions Here, we report the largest single-centre study to date in analysing a UK-based population for procalcitonin in COVID-19. We observed a significant correlation between elevated initial levels of PCT and incidence of ICU admission and mortality within our cohort, thereby demonstrating promise for PCT as an effective prognostic marker. Using a higher cut-off for PCT ≥0.5µg/L increased mortality by almost 50%, but had no effect on morbidity. We suggest that a lower universal cut-off point for PCT should be used for detecting secondary bacterial infections and procalcitonin-guided antimicrobial therapy. References Hu R, et al. International Journal of Antimicrobial Agents 2020;56(2):106051. Vazzana N, et al. Acta Clin Belg. 2020 Sep 23:1–5.

Background Coronavirus infection (COVID-19) typically presents with mild symptoms;however, 15% of patients develop significant illness with up to 5% overall mortality Hence, there is an urgent and unmet need for identifying definitive pharmacological interventions Repurposing of Azithromycin presents encouraging early findings given its antiinflammatory properties and proven antiviral efficacy during the Ebola and Zika virus outbreaks To date, studies are limited to using Azithromycin and Hydroxychloroquine in conjunction Here, we present our findings on the isolated use of Azithromycin in the management of COVID-19 Methods We performed retrospective analysis of patients admitted between 1st March and 20th June 2020 to one of the most pressurised Greater London District General Hospitals during the early stages of the pandemic Pearson's Chisquared test was utilised to compare mortality outcomes between two patient groups;those receiving Azithromycin (500 mg once daily, prescribed for five days) and those of a non-Azithromycin control group, comprising those with contraindication or allergy Independent T-test analysed length of stay Results Overall, 628 patients were analysed (mean age 71 6;41 9% female);448 (71 3%) were COVID-19 PCR swab positive, and an additional 70 (11 1%) had negative PCR but positive radiology 394 (62 7%) received Azithromycin, whilst 234 (37 3%) constituted the non-Azithromycin control group We observed notably improved mortality rates in Azithromycin patients (41 1%;162/394) compared to control patients (50 4%;118/234;p=0 14) Interestingly, length of stay was similar between Azithromycin administration (11 92±10 85) and control groups (10 82±12 30) Conclusion To our knowledge, this is the first large-scale analysis of Azithromycin as a stand-alone pharmacological treatment of COVID-19 The combination of Hydroxychloroquine and Azithromcyin has been widely discussed, however mortality data is adversely skewed by significant antagonistic cardiac side-effects which hinders interpretation of their individual therapeutic efficacy Our preliminary results suggest, whilst just shy of statistical significance, a short course of Azithromycin in COVID-19 patients may reduce mortality, without negatively impacting length of stay This highlights the need for prospective validation of this data with randomised control trials;preceding this, we advocate the use of Azithromycin in clinically selected patient populations until other licensed therapies become available

Background Recent multicentre registries have shown cancer patients infected with SARS-CoV-2 have significantly higher mortality compared to patients without cancer1. Cancer-specific features associated with worse outcomes include advanced tumour stage, disease progression and lung cancer.1 Systemic anti-cancer treatments (SACT – chemotherapy, immunotherapy, targeted and hormone therapy) have been postulated to increase mortality from COVID-19 in cancer patients. Here, we aim to determine if cancer patients on SACT have a higher risk of mortality than those not on active treatment. Methods We retrospectively analysed cancer patients admitted to a Greater London District General Hospital between 1st November 2020 and 28th February 2021 with RT-PCR positive COVID-19. SACT was considered present if administered within 3 months of admission. Mortality encompassed hospitalised patients and those up to 28 days post-discharge. Association of cancer-specific demographics and mortality was assessed using logistic regression analyses adjusting for age, sex and comorbidities. Results Mortality rate was significantly higher in 122 cancer patients with COVID-19 than 1220 patients without cancer (OR 1.653, p=0.014), especially in patients with lung cancer (OR 4.664, p=0.002). 55 patients diagnosed with cancer within one year had a significantly higher mortality (OR 2.32, p=0.004). Stage 4, but not earlier stages of, cancer at diagnosis had much higher mortality (OR 2.82, p<0.001). Progression of cancer was highly predictive of mortality (OR 4.60, p=0.00002). SACT had no significant effect on mortality from COVID-19 disease when compared with cancer patients who had no active treatment. However, cancer patients that did not have SACT within 3 months were more likely to die (OR 1.80, p=0.025). Conclusion Among patients with cancer and COVID-19, mortality was high and associated with cancer-specific features. There was no evidence cancer patients on systemic anti-cancer treatments possessed higher mortality from COVID-19 disease, which correlates with findings from COVID-19 and cancer registries1. Patients that did not receive SACT within 3 months before COVID-19 and therefore more likely to have palliative treatment did demonstrate high mortality. Larger studies are needed to confirm the risk of mortality and timing of SACT before COVID-19 disease. Reference Lee AJ, et al. British Journal of Cancer 2021;124:1777–1784.

Introduction Due to the novelty of COVID-19, uncertainty about the factors contributing to mortality, unavailability of definitive treatment options, limited access to medical, social support and rehabilitation in the community during the covid-19 peak; compounded with anxiety and reluctance to seek medical help in timely manner, it was anticipated that vulnerable patients would be affected the worst. We report post-discharge mortality and the associated risk factors. Method This is a retrospective study of all the patients admitted at a busy district general hospital during the peak period of the COVID-19 pandemic i.e. 1st March to 20 June 2020. We included all patients aged 18 and above in data analysis. Results A total of 628 patients were admitted during the study period with 481 having positive swab PCR. Of these, 389 (62%) patients had two or more comorbidities, 311 (49.5%) hypertensive and 166 (26.4%) diabetic. In-hospital mortality: 226/628 (35.9%) patient died in hospital, of which 194 (85.8%) had a positive Coronavirus nasopharyngeal swab. This was statistically significant with p-value of 0.001. Post-discharge mortality of patients: 54/402 (13.4%) of those patients discharged home following hospitalisation died within 28 days of discharge. 42/54 (77.7%) were swab positive. Swab positive patients 42/54 (77.8%) had a higher risk of death. Two thirds of swab positive patient were older than 75 years and 81% had two or more pre-existing co-morbidities. There was no difference in length of stay between the survivors and non-survivors. Conclusion As expected, age, male gender, COVID-19 PCR-positivity, multiple comorbidities, high BMI and raised CRP were associated with higher in-hospital and post-discharge mortality. It is unsurprising that antibiotic treatment without bacterial infection was associated with higher but statistically insignificant mortality rate, while therapeutic anticoagulation and steroids were associated with better outcomes. There is an urgent need for further analysis of root cause to mitigate the modifiable factors and devise a robust post-discharge management plan in collaboration with all stakeholders. Reference Deaths involving COVID-19, England and Wales: deaths occurring inJune 2020: https://www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/deaths/bulletins/deathsinvolvingcovid19englandandwales/deathsoccurringinjune2020

Background Bacterial infection has previously been observed in only 8% of COVID-19 patients,1 yet antibiotics are administered to 85% of inpatients. Typically, Gram negative organisms and Staphylococcus aureus are isolated as responsible pathogens.2 Here, we investigate the rates of bacterial infection during the second UK COVID-19 wave, its sources, the responsible organisms, and its impact on morbidity and mortality. Methods 1342 RT-PCR positive COVID-19 patients admitted to a Greater London District General Hospital between 1st November 2020 and 28th February 2021 were retrospectively analysed (44.6% female; mean age 68.8; mortality 26.9%). Mortality encompassed hospitalised patients and those up to 28 days post-discharge. Morbidity was assessed by length-of-stay and need for intensive care. Positive cultures due to contaminants were excluded. Independent correlation was assessed with multilinear regression analysis adjusting for demographics and comorbidities. Results 226 patients (16.8%) with COVID-19 had ≥1 bacterial infection. These patients possessed significantly higher independent mortality (35.0% vs. 25.3%, p<0.009), more frequently required intensive care support (19.5% vs 10.6%, p<0.00004), and required longer inpatient spells (19.6 days vs 9.46 days, p<0.0001). Greater number of positive culture types cumulatively increased mean length-of-stay (OR 9.08, p<0.00001); ≥2 culture type positivity (n=44) related to 31.5 days; ≥3 culture type positivity (n=12) 46.0 days. There was significantly higher mortality rate in patients receiving ≥1 antibiotic (30.2%) compared to no antibiotics (6.4%, p<0.00001). Conclusion Bacterial infection is observed far more frequently in COVID-19 patients than previously reported and adversely affects morbidity and mortality. Multiple sites of bacterial infection prolongs inpatient stay and increases mortality. Thorough culture collection should be encouraged in COVID-19 patients with biochemical evidence of bacterial infection to identify responsible pathogens and respective antimicrobial sensitivity. Given the higher mortality rates, empirical use of antibiotics in COVID-19 patients without supporting evidence of bacterial infection is strongly discouraged. References Lansbury, et al. J Infect. 2020 Aug;81(2):266–2. Russell C, et al. Lancet Microbe. 2021 Jun 2. https://doi.org/10.1016/S2666-5247(21)00090-2

Study Design. A comparative analysis of electromyogram (EMG) signals of patients of cervical pain and normal controls. Objectives. To determine the differences between frequency and time domain parameters of EMG signals of patients of cervical pain and normal controls. Summary of Background Data. No diagnostic technique has emerged as a satisfactory tool for identification of spinal pain. Method. Seventeen male and 17 female chronic neck pain patients without cervical radiculopathy were recruited through neurology EMG clinic. The controls consisted of 30 male and 33 female subjects with no history of neck pain in the past 12 months. All subjects performed flexion, left anterolateral flexion, left lateral flexion, left posterolateral extension, and extension to pain threshold/20% maximum voluntary contraction and pain tolerance/maximum voluntary contraction in random order. The descriptive statistics for body weight normalized strength, normalized peak EMG, time to onset, time to peak, median frequency, mean power frequency, and frequency bands were calculated. These variables were subjected to analysis of variance and logistic regression to distinguish between patients and controls. Results. The normalized peak EMG of patients was significantly greater than those of controls in both maximal and submaximal exertions (P < 0.01). Whereas there was no consistent pattern in time to peak EMG, the time to onset of EMG revealed that the left sternocleidomastoid was always recruited before the onset of torque. A lack of significant difference in the median frequency of the 2 samples indicates that the pain did not disturb the muscle conduction velocity. Using discriminant logistic regression on frequency domain and time domain parameters, up to 97% of patients and controls were correctly classified with the resubstitution method. Conclusion. Surface EMG can be used successfully in distinguishing chronic pain patients and controls, and efficacy of treatment regimes.

STUDY DESIGN:Seventeen healthy volunteers were subjected to right and left lateral impacts 5.0, 6.8, 9.2, and 16.8 m/s acceleration while positioned in a Volvo car seat with lap and shoulder seat belt restraint in laboratory setting. OBJECTIVES:The purpose of this study was to determine the effect of using a standard 3-point lap and shoulder seat belt and Volvo car seat on the response of the cervical muscles to increasing low-velocity lateral impacts. SUMMARY OF BACKGROUND DATA:A previous study of lateral impacts in a 5-point harness restraint with head and trunk in neutral posture suggests that the burden of impact is borne primarily by the splenius capitis muscle contralateral to the direction of impact. That study, however, used a nonstandard harness for automobiles, and other studies suggest that a lap-and-shoulder seat belt may increase the risk of whiplash injury. METHODS:Triaxial accelerometers recorded the acceleration of the 1) sled, 2) torso at the shoulder level, and 3) head of the participant, while bilateral electromyograms of the sternocleidomastoids, trapezii, and splenii capitis were also recorded. RESULTS:For participants experiencing a right or left lateral impact, the muscle responses increased with increasing levels of acceleration (P < 0.05). The time to onset and time to peak electromyogram for most muscles also showed a trend to progressively decrease with increasing levels of acceleration. The peak head accelerations relative to the sled ranged from 2.5 to 10.6 m/s. When the impact was a right lateral impact, at the highest sled acceleration, the left splenius capitis generated 47% of its maximal voluntary contraction (MVC), and the left trapezius also 46% of its MVC; the left and right sternocleidomastoid, right splenius capitis, and right trapezius generated 29% or less of their MVC. For the highest level of acceleration in a left lateral impact, the right splenius capitis generated 48% of its MVC and the right trapezius 57% of the MVC, the left and right sternocleidomastoid, left splenius capitis, and left trapezius generated 29% or less of their MVC. In both directions of impact, the contralateral splenius capitis and trapezius showed a statistically significant difference in the EMG response compared with other muscles (P < 0.05). For participants experiencing a frontal impact, whether straight-on, right or left anterolateral, the muscle responses increased with increasing levels of acceleration (P < 0.05). The time to onset and time to peak electromyogram for most muscles also showed a trend to progressively decrease with increasing levels of acceleration. In a straight-on frontal impact, the trapezii (TRPs) muscles showed the greatest EMG response compared with the remaining muscles (P < 0.05). CONCLUSIONS:Compared with previously reported impact studies with a 5-point harness and rigid seat, the use of a 3-point lap and shoulder seat belt with car seat does not appear to adversely affect the cervical muscle response. In very-low- and low-velocity impact experiments, seat belt and seat type may thus not be particularly relevant to cervical EMG and kinematics.

Low back disorder is related to physical workload, genetic disposition, personal traits and habits. Not all risk factors can be controlled. Preventative programs frequently focus on workload, organizational and psychophysical issues. Smoking, no-exercise, and overweight generally receive less attention. This study assessed the association between smoking, no-exercise, and overweight and low back disorder in welders and nurses. A retrospective epidemiological study and a questionnaire survey were conducted. The records of injuries were examined and 111 workers (64 welders and 47 nurses) from a steel company and a hospital completed a questionnaire on their personal traits, life style and occupational factors. The annual and lifetime rates of work-related low back disorder were, respectively, 3.4% and 58% of the sample, and the point prevalence of low back pain was 27% of the sample. The low back discomfort score was 5 (SD = 3) on a 10-point scale. Forty percent of the workers smoked and 49% did not exercise regularly. The lifetime rate of low back disorder was 86% (odds ratio of 2) for the workers that smoked and did not exercise, and 66% (odds ratio of 1.38) for the overweight workers. This study shows that low back disorder is common among welders and nurses. These workers have high low back discomfort by the end of the shift. Besides the recognized biomechanical factors, smoking, no-exercise, and overweight are personal factors related to low back disorder. Thus, low back disorder preventative programs in industry should include smoking cessation, regular physical activity campaigns, and healthy eating promotion.PrecisThis study evaluated smoking, no-exercise, and overweight as possible risk factors for low back disorder in welders and nurses. A questionnaire was responded to 111 workers. The results showed that no-exercise, smoking, and overweight increased the risk of having low back disorder. (C) 2006 Elsevier B.V. All rights reserved.

Aim. This paper reports a study that aimed to evaluate the workload, to identify problems leading to the higher incidence rate of work‐related low back injury among nurses in the orthopaedic and intensive care unit departments of the hospital, and to gather information about improvements that the nurses would like in the workplace.Background. The literature shows that low back injuries are common among nurses, and intervention programmes are needed to address this problem.Method. The hospital injury records were examined in a retrospective study. In addition, a validated questionnaire was administered between January and May 2005 to 47 nurses (23 orthopaedic and 24 intensive care nurses). The questionnaire contained questions on workload, history of back injuries, problems, possible solutions and psychophysical measures of exertion.Findings. The life‐time incidence and point prevalence of low back pain were 65% and 30%, respectively, in orthopaedic nurses, and 58% and 25%, respectively, in the intensive care nurses. The mean weight handled was reported to be 47 ± 30 kg by the orthopaedic nurses and 26 ± 10 kg by the intensive care nurses. The low back scored highest for body‐part discomfort – 4·6 and 4·0, respectively, on a 10‐point scale. The rate of perceived job exertion was 6·7 ± 1·8 (very strong), and 5·8 ± 1·9 (strong) on Borg's 10‐point scale. The total effort required by the job, rated on Visual Analogue Scales, was 67 ± 14% and 68 ± 15% of the maximum, respectively. The Borg scores and the total effort according to the Visual Analogue Scale, and the Borg scores and force effort on the Visual Analogue Scale were moderately correlated (r = 0·53, P < 0·01 for both comparisons).Conclusion. The methodology proposed here is practical for job evaluation and to design a participatory ergonomic intervention aiming at reducing low back injuries in nursing jobs. There are workload differences between nursing jobs. Lifting devices, biomechanical training, bigger rooms, adequate set‐up and additional staff are suggested improvements.

Aim. This paper reports a study that aimed to evaluate the workload, to identify problems leading to the higher incidence rate of work-related low back injury among nurses in the orthopaedic and intensive care unit departments of the hospital, and to gather information about improvements that the nurses would like in the workplace. Background. The literature shows that low back injuries are common among nurses, and intervention programmes are needed to address this problem. Method. The hospital injury records were examined in a retrospective study. In addition, a validated questionnaire was administered between January and May 2005 to 47 nurses (23 orthopaedic and 24 intensive care nurses). The questionnaire contained questions on workload, history of back injuries, problems, possible solutions and psychophysical measures of exertion. Findings. The life-time incidence and point prevalence of low back pain were 65% and 30%, respectively, in orthopaedic nurses, and 58% and 25%, respectively, in the intensive care nurses. The mean weight handled was reported to be 47 +/- 30 kg by the orthopaedic nurses and 26 +/- 10 kg by the intensive care nurses. The low back scored highest for body-part discomfort - 4.6 and 4.0, respectively, on a 10-point scale. The rate of perceived job exertion was 6.7 +/- 1.8 (very strong), and 5.8 +/- 1.9 (strong) on Borg's 10-point scale. The total effort required by the job, rated on Visual Analogue Scales, was 67 +/- 14% and 68 +/- 15% of the maximum, respectively. The Borg scores and the total effort according to the Visual Analogue Scale, and the Borg scores and force effort on the Visual Analogue Scale were moderately correlated (r = 0.53, P < 0.01 for both comparisons). Conclusion. The methodology proposed here is practical for job evaluation and to design a participatory ergonomic intervention aiming at reducing low back injuries in nursing jobs. There are workload differences between nursing jobs. Lifting devices, biomechanical training, bigger rooms, adequate set-up and additional staff are suggested improvements.

Objective: The objective of this Study was to determine the effect of a standard 3-point lap-and-shoulder seat belt and car seat oil the electromyogram (EMG) response of the cervical muscles to increasing low-velocity impacts in comparison with that of a rigid seat and 5-point restraint.Methods: Seventeen healthy Volunteers were Subjected to rear, frontal, right and left lateral and bilateral anterolateral, and posterolateral impacts with an acceleration varying from 4.4 to 16.8 m/s(2) while in a car seat with lap-and-shoulder seat belt.Results: For rear-end impacts, whether straight oil, right posterolateral, or left posterolateral, all Muscles generated 50% or less of the maximal voluntary contraction (MVC) EMG. In straight-on real impacts, the sternocleidomastoid was symmetrically file most active; however, in posterolateral impacts, the sternocleidomastoid contralateral to impact direction was more active than its counterpart. For a tight lateral impact, at the highest acceleration, file left splenius capitis generated 47% of its MVC and the left trapezius did 46% of its MVC. In a left lateral impact, the right splenius capitis generated 48% of its MVC and the right trapezius did 57% of its MVC. In a straight-on frontal impact, the left trapezius generated 35% of its MVC and the right trapezius did 48% of its MVC. In a left anterolateral impact, the right splenius generated 60% of its MVC and the right trapezius did 66% of its MVC. Similarly, in a tight anterolateral impact, the contralateral splenius muscle increased its activity to 52% of its MVC and the left trapezius was at 52% of its MVC.Conclusions: Compared with previously reported impact Studies with a rigid seat and 5-point harness, the use of a 3-point lap-and-shoulder seat belt with a standard car seat did not appear to adversely affect cervical muscle response. In very-tow-velocity and low-velocity impact experiments, scat bell and scat type may not significantly alter cervical EMG and kinematics.

Background The cervical muscles are considered a potential site of whiplash injury, and there is a need to understand the cervical muscle response under non-conventional whiplash impact scenarios, including variable body position and impact direction. There is no data, however, on the effect of occupant position on the muscle response to frontal impacts. Therefore, the objective of the study was to measure cervical muscle response to graded right anterolateral impacts. Methods Twenty volunteers were subjected to right anterolateral impacts of 4.3, 7.8, 10.6, and 12.8 m/s 2 acceleration with their trunk flexed forward 45 degrees and laterally flexed right or left by 45 degrees. Bilateral EMG of the sternocleidomastoids, trapezii, and splenii capitis and acceleration of the sled, torso, and head were measured. Results and discussion With either direction of trunk flexion at impact, the trapezius EMGs increased with increasing acceleration ( p < 0.05). Time to onset of the electromyogram and time to peak electromyogram for most muscles showed a trend towards decreasing with increasing acceleration. With trunk flexion to the left, the left trapezius generated 38% of its maximal voluntary contraction (MVC) EMG, while the right trapezius generated 28% of its MVC EMG. All other muscles generated 25% or less of this measure (25% for the left splenius capitis, 8% for the right splenius capitis, 6% for the left sternocleidomastoid, and 2% for the left sterncleidomastoid). Conversely, with the trunk flexed to the right, the right trapezius generated 44% of its MVC EMG, while the left trapezius generated 31% of this value, and all other muscles generated 20% or less of their MVC EMG (20% for the left splenius capitis, 14% for the right splenius capitis, 4% for both the left and right sternocleidomastoids). Conclusion When the subject sits with trunk flexed out of neutral posture at the time of anterolateral impact, the cervical muscle response is dramatically reduced compared to frontal impacts with the trunk in neutral posture. In the absence of bodily impact, the flexed trunk posture appears to produce a biomechanical response that would decrease the likelihood of cervical muscle injury in low velocity impacts.

Objective: To examine the effect of forward and lateral trunk flexion on the cervical electromyogram and head kinematic response to whiplash-type frontal impacts.Design: Observational study of sled impacts.Setting: Laboratory.Participants: Twenty healthy volunteers.Intervention: Twenty volunteers were subjected to increasing low-velocity (< 8km/h) frontal impacts of 4.4, 7.6, 10.3, and 13.3m/s(2) acceleration with trunk forward flexed by 45 degrees and laterally flexed to the right and left by 45 degrees.Main Outcome Measures: Bilateral electromyography of the stemocleidomastoids, trapezii, and splenii capitis and acceleration of the sled, torso, and head were recorded.Results: With either direction of lateral trunk flexion at impact, the trapezii electromyographic activity increased with increasing acceleration (P <.05). With the trunk flexed to the left, the left trapezius generated 39% of its maximal voluntary contraction (MVC) electromyographic activity, while the right trapezius generated 31% of its MVC electromyographic activity. The left splenius (ipsilateral to leftward trunk flexion) generated 24% of its MVC electromyographic activity, with all other muscles generating 15% or less of this measure. With the trunk flexed to the right, the right trapezius generated 38% of its MVC electromyographic activity, while the left trapezius generated 32% of this value. Again, the ipsilateral (to trunk flexion) splenius capitis generated 27% of its MVC electromyographic activity, and all other muscles generating 15% or less of this measure.Conclusions: When subjects sit with trunk flexed out of neutral posture at the time of frontal impact, the cervical muscle response is low and unlikely to be injurious.

The objective of this study was to determine the best variable, if any, to indicate the level of localized muscle fatigue. Six male and six female subjects were studied while they exerted their maximal voluntary contraction and 40% of maximal voluntary contraction of spinal extensors in an isometric lifting activity. The electromyography (EMG) of erectores spinae at thoracic and lumbar levels was measured bilaterally. Also, the muscle bed blood volume, level of blood oxygenation to erector spinae at L3 level and heart rate were measured. The initial and final values of subjective feelings of fatigue through visual analogue score, rate of perceived exertions and body part discomfort rating were recorded. The mean maximal voluntary contraction forces for males and females were 899 (238) N and 431 (135) N respectively. The mean durations of hold in maximal voluntary fatiguing contraction were 68.1 (39.9) s and 72.3 (37.0) s for men and women respectively. By the end of the hold the force declined to 52% for males and 62% for females. The EMG amplitudes and median frequencies also progressively declined (p < 0.01). ANOVA revealed that the task percentile values of all variables were significantly different (p < 0.01). Gender had a significant main effect (p < 0.01). The correlation coefficients between force and other individual variables were weak to modest, but significant (p < 0.001). None of the single variables predicted fatigue reliably for either gender and levels of contraction. The regression equations developed were highly significant (p < 0.01) and they explained 96 to 98% of variance in both genders and contractions.

Background. Back injury is a common place in our society. Up to two-thirds of back injuries have been associated with trunk rotation. However, the torque production ability with a rotated spine and electromyographic activity of trunk muscles in such efforts is poorly understood. Therefore, the objectives of this study are to study torque production capacity of variously rotated and flexed trunk and to measure the EMG of selected trunk muscles in these activities.Methods. Nineteen normal young subjects (7 males and 12 females) were recruited. Subjects were stabilized on a posture-stabilizing platform and were instructed to assume a flexed and right rotated posture (20 degrees, 40 degrees and 60 degrees of rotation and 20 degrees, 40 degrees and 60 degrees of flexion) in a random order. The subjects were asked to exert their maximal voluntary contraction in the asymmetric plane of rotation-extension for a period of 5 s. The surface EMG of the external and internal obliques, rectus abdominis, latissimus dorsi, erector spinae at the 10th thoracic and 3rd lumbar vertebral levels was recorded bilaterally along with the torque generated.Findings. Whereas the torque generated was significantly affected by both rotation and extension in both genders (P < 0.001), the EMG was independent of rotation but affected by flexion in females only (P < 0.01). The torques produced by both genders in each of the nine postures was significantly different from each other (P < 0.001). The EMG demonstrated a trend of increase with increasing rotation and flexion. The response surfaces of normalized peak EMG of the right external oblique and internal oblique was somewhat similar, indicating a rotator torque and a stabilizing effect. The left latissimus dorsi and right external oblique provided the rotational torque and the right erector spinae provided the extensor effort. Since the rotation-extension was performed in the plane of asymmetry, the effort required the recruitment of muscles involved in left rotation, stability of rotated spine and an extensor effort.Interpretation. The torque production capacity of the human trunk is posture dependent and declines with increasing rotation. However, with increasing rotation and flexion, the magnitude of EMG increases. This implies that with increasing asymmetry, it requires more muscle effort (thus tissue stress) to generate less torque. Increasing asymmetry tends to weaken the system and may enhance chances of injury. (c) 2006 Elsevier Ltd. All rights reserved.

Objective: To determine the effect of occupant positioning on the response of the cervical muscles to whiplash-type posterolateral impacts.Methods: Twenty healthy volunteers underwent left posterolateral whiplash-type impacts with the volunteers seated "out-of-position". Electromyograms of the cervical muscles were recorded.Results: Whether having the trunk flexed to the left or right at the time of impact, the muscle responses were low in magnitude, showing a trend to increasing EMG responses with increasing acceleration (P > 0.05). The time to onset and time to peak electromyogram for most muscles showed a trend to progressively decrease with increasing levels of acceleration. With the subject flexed to the left, all muscles generated 31% or less of the maximal voluntary contraction electromyogram. With the subject flexed to the right, all muscles generated 27% or less of their maximal electromyogram. In both positions, the trapezii were the most active (P < 0.05). Thus, having the trunk flexed Out of neutral posture at the time of impact produces a very low magnitude cervical muscle response compared to impacts with the trunk in neutral posture.Conclusions: In the absence of bodily impact, the flexed trunk posture appears to produce a biomechanical response that would probably decrease the likelihood of cervical muscle injury in low velocity posterolateral impacts. (c) 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.