Journal of biomechanics
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Journal of biomechanics · Apr 2020
What is the best way to collect maximum forward lumbar spine flexion values for normalizing posture to range of motion?
Spine angles are an important measure in biomechanics research and are commonly normalized to a percentage of range of motion. However, standardized methods to collect the reference posture trials for this normalization do not exist. The purpose of this study was to determine posture (seated or standing) and number of trials that should be collected and how to calculate the angle that best represents the maximum range. ⋯ The maximum angle of all 10 flexion trials was significantly greater than the angle of the first standing or seated trial only but not significantly greater than the maximum of all seated or standing flexion trials respectively. Secondarily, no differences in the maximum lumbar angle were found between sexes. This study suggests that 6 flexion trials, involving both standing and seated flexion, should be collected to best represent the maximum end range of spine flexion.
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Journal of biomechanics · Apr 2020
Adversarial autoencoder for visualization and classification of human activity: Application to a low-cost commercial force plate.
The ability to visualize and interpret high dimensional time-series data will be critical as wearable and other sensors are adopted in rehabilitation protocols. This study proposes a latent space representation of high dimensional time-series data for data visualization. For that purpose, a deep learning model called Adversarial AutoEncoder (AAE) is proposed to perform efficient data dimensionality reduction by considering unsupervised and semi-supervised adversarial training. ⋯ Data dimensionality reduction with conventional Machine Learning (ML) and supervised Deep Learning (DL) classification are also performed to compare the efficiency of AAE approaches. The results showed that AAE can outperform conventional ML approaches while providing close results to DL supervised classification. AAE approaches for data visualization are a promising approach to monitor the subject's movements and detect adverse events or similarity with previous data, providing an intuitive way to monitor the patient's progress and provide potential information for rehabilitation tracking.
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Journal of biomechanics · Mar 2020
A prospective study of lumbo-pelvic coordination in patients with non-chronic low back pain.
Despite the current knowledge about abnormalities in the lumbo-pelvic coordination of patients with non-specific low back pain (LBP), it is unclear how such abnormalities change with time. Timing and magnitude aspects of lumbo-pelvic coordination during a trunk forward bending and backward return task along with subjective measures of pain and disability were collected at three-time points over a six-month period from 29 patients who had non-chronic LBP at the time of enrollment in the study. To enable investigation of abnormalities in lumbo-pelvic coordination of patients, we also included lumbo-pelvic coordination data of age and gender-matched back healthy individuals from an earlier study of our group. ⋯ The abnormal lumbo-pelvic coordination of patients with non-specific LBP, observed at baseline, persisted (F < 1.96, P > 0.156) or worsen (F > 3.48, P < 0.04) over the course of study period despite significant improvement in their pain (18% decrease; F = 12.10, P < 0.001) and disability (10% decrease; F = 4.39, P = 0.017). Distinct but lingering abnormalities in lumbo-pelvic coordination, observed in patients with low-moderate and moderate-severe LBP, might have a role in persistence and/or relapse of symptoms in patients with non-specific LBP. Such inferences, however, should further be studied in future via investigation of the relationship between abnormalities in lumbo-pelvic coordination and clinical presentation of LBP.
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Journal of biomechanics · Mar 2020
Sudden gait perturbations elicit sex-specific neuromuscular trunk responses in persons with low back pain.
Persons with low back pain (LBP) exhibit delayed trunk muscle onset and increased co-contractions as a response to quasi-static and dynamic sudden trunk loading in comparison to back-healthy controls. Although LBP is more prevalent in females, sex-specific responses have not been well documented. Therefore, the purpose was to explore sex-specific neuromuscular differences, to gait perturbation, in LBP patients. ⋯ In this LBP population, abdominal muscle activation discriminated females from males. Specifically, females had higher activity of the rectus abdominis muscles and lower activation of the externus oblique muscles. These different activation strategies might be relevant to the development of sex-specific intervention strategies.
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Journal of biomechanics · Feb 2020
A braced arm-to-thigh (BATT) lifting technique reduces lumbar spine loads in healthy and low back pain participants.
Despite the common use of one-handed lifting techniques for activities of daily living, these techniques have received little attention in the biomechanics literature. The braced arm-to-thigh technique (BATT) is a one-handed lifting method in which the dominant hand picks up objects, while the free hand braces the trunk on the ipsilateral thigh. The aim of this study was to compare the BATT to two-handed or unsupported one-handed lifting techniques with loads of 2 and 10 kg, by evaluating trunk motion and spine loading at L4/L5. ⋯ However, the BATT also increased asymmetric trunk kinematics and moments at L4/L5. The BATT produced significantly lower moments (28-38%), and compressive (25-32%) and antero-posterior shear (25-45%) forces at L4/L5, compared to unsupported lifting techniques. Bracing the hand on the thigh to support the trunk can substantially reduce low back loading during lifting tasks of 2 to 10 kg.