This study evaluated spinal loads associated with lifting and hanging heavy mining cable in a variety of postures. This electrical cable can weigh up to 10 kg per metre and is often lifted in ...restricted spaces in underground coal mines. Seven male subjects performed eight cable lifting and hanging tasks, while trunk kinematic data and trunk muscle electromyograms (EMGs) were obtained. The eight tasks were combinations of four postures (standing, stooping, kneeling on one knee, or kneeling on both knees) and two levels of cable load (0 N or 100 N load added to the existing cable weight). An EMG-assisted model was used to calculate forces and moments acting on the lumbar spine. A two-way split-plot ANOVA showed that increased load (p<0.05) and changes in lifting posture (p<0.05) independently affected trunk muscle recruitment and spinal loading. The increase in cable load resulted in higher EMG activity of all trunk muscles and increased axial and lateral bending moments on the spine (p<0.05). Changes in posture caused more selective adjustments in muscle recruitment and affected the sagittal plane moment (p<0.05). Despite the more selective nature of trunk EMG changes due to posture, the magnitude of changes in spinal loading was often quite dramatic. However, average compression values exceeded 3400 N for all cable lifting tasks.
Consideration for Driving a Car TAKASAKI, Kyosuke; YONEDA, Hirohisa; YAMAGUCHI, Takeshi ...
Journal of Kansai Physical Therapy,
2008, Volume:
8
Journal Article
Open access
Patients with cerebrovascular disease are often drive a car. It is necessary for these patients to assess driving a car as Activities Parallel to Daily Living (APDL). The driver is affected by ...inertial forces of acceleration, deceleration, taking a curve and others. Especially, it is impossible for the trunk to resist the inertial forces. Accordingly, it is indispensable to assess the function of the trunk for a patient with cerebrovascular disease who drives a car. The analysis of the driving motion and the assessment of the physical function on the driving are difficult in a clinical setting. Moreover, there has been little research in the field of rehabilitation related to driving a car. To contribute to therapy of patients who drive a car, the function of the trunk of a driver were investigated in this report. The subject of this research was a healthy person. Electromyography (EMG) of the trunk muscles of the driver was recorded, and digital video tape recordings were synchronized with the EMG. The characteristic results were: 1) When the car cornered sharply, the muscle activity of the trunk muscles on the side contralateral to turning increased. 2) When the driver braked hard, the muscle activity of the internal oblique abdominus on the brake side increased. The results suggest that the trunk muscles and the internal oblique abdominus resist the centrifugal force and the shear force on the sacro-iliac joint.
At a certain position of trunk flexion, there is a sudden onset of electrical silence in back muscles. This is called "flexion-relaxation (F-R) phenomenon." The goals of this study were (1) to ...evaluate the relationship between flexion angle and activity of back muscles during flexion movement and (2) to determine what the difference is between healthy subjects and patients with chronic low back pain (CLBP). Twenty-five healthy subjects (13 males and 12 females; average age, 28.3 yr) and 20 patients with CLBP (12 males and 8 females; average age, 34.1 yr) volunteered for this study. The subjects were asked to flex forward maximally from the erect position and to maintain full flexion, followed by returning to the initial upright position. Flexion angle of trunk and hip was measured during the examination. Electromyographic activity of erector spinae was also monitored simultaneously. F-R phenomenon was observed in all healthy subjects before reaching the maximum flexion. Electrical silence continued even after extending the trunk began. In contrast, no patients with CLBP demonstrated F-R phenomenon. A significant difference in muscular activities of erector spinae between the groups was obtained when returning to the erect position from the maximum flexion. Moreover, time lag between trunk and hip movement was much greater in patients than in healthy subjects. This study demonstrated that neuromuscular coordination between trunk and hip could be abnormal in patients with CLBP.
Surface electromyographic signals were collected from 14 lower torso muscles while participants resisted high-magnitude static trunk moments applied in a variety of directions.
To obtain a ...description of muscle activations in response to large moment magnitudes and axial twisting, including levels of agonistic and antagonistic muscle cocontraction. To assess differences in lower torso muscle activation patterns associated with gender and trial repetition.
Back pain is associated with mechanical loads in the back. Biomechanical modeling of these loads is facilitated by knowledge of typical muscle activation patterns. Previous efforts in obtaining such data have often limited their scope to low-magnitude exertions or relatively simple scenarios.
Eight male and eight female participants, matched by height and mass, performed static exertions in an apparatus that immobilized their lower body while the activation levels of seven bilateral torso muscles were measured using surface electromyography. Activation patterns were analyzed to assess differences resulting from a variety of factors.
No significant differences in activation patterns were found between genders or repetitions, but moment magnitude and direction elicited substantial differential responses. Good repeatability was found between trial repetitions, as indicated by intraclass correlation coefficients (>0.65). Significant synergistic muscle coactivation, large intersubject variability (mean coefficient of variation 82.2%), and consistent levels of antagonism ranging from 10% to 30% maximum voluntary exertions were observed.
Individuals of different genders, but similar anthropometry, have comparable muscular reactions to complex torso loads, suggesting similar motor control strategies. Future spine models should consider that the variability in muscle recruitment patterns is larger between subjects than within subjects. High-magnitude exertions, especially those with moment loads in more than one plane, require most muscles to be active (>5%) and moderate levels of antagonism.
To evaluate whether there is an association between facial morphology on cephalometrics and surface electromyographic (sEMG) recordings of head, neck and trunk muscles.
31 Caucasian adult females, ...average age 26 years (range 21-29) underwent lateral skull radiographs in natural head position (mirror position) and the sEMG recordings for the following muscles: masseter, anterior temporal, digastric, posterior cervicals, sternocleidomastoid, and upper and lower trapezius. All muscles were monitored in the mandibular rest position, and during maximal voluntary clenching (MVC).
Spearman's correlation coefficient revealed significant correlations (P<0.01): (i) between the variables controlling mandibular position, and the inclination of the lower incisors, and the sEMG activity of the trapezius; (ii) between the sEMG activity of sternocleidomastoid and the variables indicating the height of the mandibular ramus; (iii) between the sEMG activity of anterior temporal and the incisive angle, the inclination of the upper incisors and the maxillary base length, and (iv) between the sEMG activity of cervical muscles and the anterior cranial base length.
Some associations between cephalometric variables and sEMG of the neck and trunk muscles were observed. However, in view of the cross-sectional nature of the study and the limited sample, no conclusion was possible about the mechanism concerning these results. Future longitudinal studies are required to investigate the "mechanism at work".
The aim of the present study was to test the assumption that asymmetric trunk loading requires a higher total muscle force and consequently entails a higher compression forces on the spine as ...compared to symmetric loading. When the trunk musculature is modelled in sufficient detail, optimisation shows that there is no mechanical necessity for an increase in total muscle force (or compression force) with task asymmetry. A physiologically based optimisation does also not predict an increase in total muscle force or spinal loading with asymmetry. EMG data on 14 trunk muscles collected in eight subjects showed antagonistic coactivity to be present in both conditions. However, estimates of total muscle force based on the EMG were lower when producing an asymmetric moment. In conclusion, producing an asymmetric moment appears to cause slightly lower forces on the lumbosacral joint as compared to a symmetric moment. Only lateral shear forces increase with asymmetry but these remain well below failure levels.
Currently available musculoskeletal inverse-dynamics thoracolumbar spine models are entirely based on data from adults and might therefore not be applicable for simulations in children and ...adolescents. In addition, these models lack lower extremities, which are required for comprehensive evaluations of functional activities or therapeutic exercises. We therefore created OpenSim-based musculoskeletal full-body models including a detailed thoracolumbar spine for children and adolescents aged 6-18 years and validated by comparing model predictions to in vivo data. After combining our recently developed adult thoracolumbar spine model with a lower extremity model, children and adolescent models were created for each year of age by adjusting segmental length and mass distribution, center of mass positions and moments of inertia of the major body segments as well as sagittal pelvis and spine alignment based on literature data. Similarly, muscle strength properties were adjusted based on CT-derived cross-sectional area measurements. Simulations were conducted from in vivo studies reported in the literature involving children and adolescents evaluating maximum trunk muscle strength (MTMS), lumbar disc compressibility (LDC), intradiscal pressure (IDP) and trunk muscle activity (MA). Model predictions correlated highly with in vivo data (MTMS: r>=0.82, p<=0.03; LDC: r=0.77, p<0.001; IDP: r>=0.78, p<0.001; MA: r>=0.90, p<0.001), indicating suitability for the reasonably accurate prediction of maximal trunk muscle strength, segmental loading and trunk muscle activity in children and adolescents. When aiming at investigating children or adolescents with pathologies such as idiopathic scoliosis, our models can serve as a basis for the creation of deformed spine models and for comparative purposes.
Low Back Pain (LBP) affects the vast majority of the population at some point in their lives. People with LBP show altered trunk muscle activity and enhanced fatigability of trunk muscles is ...associated with the development and future risk of LBP. Therefore, a system that can forecast trunk muscle activity and detect fatigue can help subjects, practitioners and physiotherapists in the diagnosis, monitoring and recovery of LBP. In this paper, we present a novel approach in order to determine whether subjects are fatigued, or transitioning to fatigue, 25 seconds ahead of time using surface Electromyography (sEMG) from 14 trunk muscles. This is achieved using a three-step approach: A) extracting features related to fatigue from sEMG, B) forecasting the features using a real-time adaptive filter and C) performing dimensionality reduction (from 70 to 2 features) and then classifying subjects using a supervised machine learning algorithm. The forecasting classification accuracy across 13 patients is 99.1% ± 0.004 and the area under the micro and macro ROC curve is 0.935 ± 0.036 and 0.940 ±0.034 as determined by 10-fold cross validation. The proposed approach enables a computationally efficient solution which could be implemented in a wearable device for preventing muscle injury.
Flexed postural tasks are frequently involved in daily activities, this paper evaluated a wide range of trunk muscle electromyogram (EMG) features to find the best feature spaces that discriminate ...among different trunk flexion angles. Using Davies-Bouldin index (DBI) and Calinski-Harabasz index (CHI) it was found that zero crossings, mean power frequency, median power frequency, and second order cumulants of extensor muscles' EMG, independent of holding load level and electrode location (right or left side of muscle) are the most sensitive features to trunk flexion angle variation.
