Journal of Electromyography and Kinesiology最新文献

The study investigated the effects of unilateral and bilateral lower extremity fatigue on both postural stability and postural adjustments. Fourteen young male subjects performed unilateral and bilateral dynamic lower extremity pedaling exercises with 5 sets of 20 times at 50 % maximum voluntary contraction. Center of pressure (COP) signals were recorded before and after the fatigue exercise. Electromyography activities of six trunk and leg muscles were recorded and analyzed during the anticipatory (APAs) and compensatory (CPAs) postural adjustments. The results showed that both fatiguing exercises caused an increase in COP and larger APAs and CPAs in the rectus femoris and tibialis anterior during externally initiated perturbation. However, the observed indicators showed no clear difference between unilateral and bilateral fatigue. These results validated that when enlarged APAs were not sufficient to resist the external perturbation, the central nervous system increased the strength of CPAs to maintain the stability of the body. These findings provided a perspective on the association between APAs and CPAs, which may apply to the athletic training or rehabilitation on postural control.

Background

To better personalize treatment and monitor recovery of individuals with low back pain, objective tests of sensorimotor functions, such as lumbar proprioception, must be selected based on their reliability and validity. The primary objective of this study was to test the concurrent validity of three measures of lumbar proprioception.

Methods

Thirty-one participants performed three lumbar proprioception tests (motion perception threshold, active and passive joint positioning sense), a whole-body mobility and balance (time up-and-go) and two trunk-specific postural control (threshold of stability and sensor-based sway measures) tests.

Results

Only the motion perception threshold proprioception test showed some validity, correlating with the trunk-specific postural control tests [r range (positive values): 0.37 to 0.60]. The three lumbar proprioception measures were not correlated to each other. The threshold of stability measure was correlated with the time up-and-go (r = 0.37) and trunk-specific (sensor-based sway measures) postural control [r range (positive values): 0.48 to 0.77] tests.

Conclusion

The present study generated three original findings. Only the motion perception threshold proprioception test demonstrated its concurrent validity. In fact, the three lumbar proprioception tests performed in the present study were not correlated to each other, thus assessing different constructs. Finally, the threshold of stability protocol was validated against other tests. These findings will help in selecting the most appropriate lumbar proprioception measures to study the effects of exercise treatments in patients with back pain.

Objectives

People with low back pain (LBP) exhibit altered coordination, possibly indicating guarded movement. The connection between these changes and pain-related threat remains unclear. We aimed to determine if pain-related threat was related to spinal coordination and variability, during a lifting task, in people with chronic LBP.

Methods

Participants were adults with chronic LBP (n = 47). Upper lumbar, lower lumbar, and hip kinematics were measured during 10 crate lifting/lowering repetitions. Coordination and variability of the Hip-Lower Lumbar, and Lower Lumbar-Upper Lumbar joint pairs were calculated. Pain-related threat was measured using the Tampa Scale for Kinesiophobia, the Pain Catastrophizing Scale, and task-specific fear. Linear regression analyses tested the relationship between pain-related threat and coordination.

Results

Adding catastrophizing to our base model (sex) explained variance in Hip-Lower lumbar coordination (r² change = 0.125, p = 0.013). General and task specific measures of fear were unrelated to coordination and variability at both joint pairs (r² change < 0.064, p > 0.05). Exploratory t-tests revealed subgroups aligned with phenotypes of “tight” and “loose” control, where “tight” control was characterized by greater catastrophizing and disability.

Conclusion

Pain catastrophizing, but not measures of fear, was related to more in-phase (“tight”) Hip-Lower Lumbar coordination during lifting/lowering. Considering this relationship based on subgroups may add clarity.

For the purpose of testing shoulder joint proprioception while controlling for axioscapular muscle recruitment, a novel shoulder thoracohumeral (TH) rotation joint position sense (JPS) measurement device was designed. This device was intended to measure shoulder TH rotation, while also implicitly constraining other upper limb degrees of freedom (DOF) and minimizing cutaneous sensation. The purpose of this study was to determine whether joint motion aside from shoulder TH rotation is being captured by the shoulder JPS measurement device. Upper limb kinematics were collected from 32 participants during joint angle matching trials using the shoulder JPS measurement device. Step wise multiple regression revealed that shoulder TH rotation (β-Humeral Rotation = 0.409, p < 0.001), and wrist deviation (β-Wrist Deviation = 0.104, p = 0.008) both contributed a significant unique variance in the prediction of shoulder JPS measurement device rotation. Findings suggest that seated, unconstrained shoulder TH rotation JPS testing protocols in literature may be confounded by contributions from joints both proximal and distal to the shoulder. Researchers should be aware of the limitations of both constrained and unconstrained shoulder TH rotation JPS testing protocols.

Background

Chronic low back pain (LBP) is a leading cause of disability, which is exacerbated in some by repeated lifting. Electromyography (EMG) assessments of isolated erector spinae (ES) regions during lifting identified conflicting results. Here, high-density EMG comprehensively assesses the lumbar and thoracolumbar ES activity in people with and without LBP performing a multiplanar lifting task.

Methods

Four high-density EMG grids (two bilaterally) and reflective markers were affixed over the ES and trunk to record muscle activity and trunk kinematics respectively. The task involved cyclical lifting of a 5 kg box for ∼7 min from a central shelf to five peripheral shelves, returning to the first between movements, while monitoring perceived exertion.

Results

Fourteen LBP (26.9 ± 11.1 years) and 15 control participants (32.1 ± 14.6 years) completed the study. LBP participants used a strategy characterised by less diffuse and more cranially-focussed ES activity (P < 0.05). LBP participants also exhibited less variation in ES activity distribution between sides during movements distal to the central shelf (P < 0.05). There were few consistent differences in kinematics, but LBP participants reported greater exertion (P < 0.05).

Conclusion

In the presence of mild LBP, participants used a less variable motor strategy, with less diffuse and more cranially-focussed ES activity; this motor strategy occurred concomitantly with increased exertion while completing this dynamic task.

Walking without falling requires stabilization of the trajectory of the body center of mass relative to the base of support. Model studies suggest that this requires active, feedback control, i.e., the nervous system must process sensory information on the state of the body to generate descending motor commands to the muscles to stabilize walking, especially in the mediolateral direction. Stabilization of bipedal gait is challenging and can be impaired in older and diseased individuals. In this tutorial, we illustrate how gait analysis can be used to assess the stabilizing feedback control of gait. We present methods ranging from those that require limited input data (e.g. position data of markers placed on the feet and pelvis only) to those that require full-body kinematics and electromyography. Analyses range from simple kinematics analyses to inverse dynamics. These methods assess stabilizing feedback control of human walking at three levels: 1) the level of center of mass movement and horizontal ground reaction forces, 2) the level of center of mass movement and foot placement and 3) the level of center of mass movement and the joint moments or muscle activity. We show how these can be calculated and provide a GitHub repository (https://github.com/VU-HMS/Tutorial-stabilizing-walking) which contains open access Matlab and Python code to calculate these. Finally, we discuss what information on feedback control can be learned from each of these.

This study aimed to develop an insertion technique for intramuscular EMG recording of the oblique head of adductor hallucis (AddH) and first dorsal interosseous (FDI) muscles in humans via the dorsum of the foot, and report feasibility of intramuscular EMG data acquisition during walking in shoes. In eight individuals without musculoskeletal pain or injury (5 males; 32 ± 8 years), intramuscular electrodes were inserted into AddH (oblique head) and FDI through the right foot’s dorsum (between metatarsals I-II) with ultrasound guidance. The ultrasound transducer was positioned on the plantar surface. Intramuscular EMG was also recorded from abductor hallucis, tibialis posterior, flexor digitorum longus and peroneus longus. Participants performed six overground walking trials wearing modified shoes, and rated pain associated with the intramuscular electrodes during walking (numerical rating scale, 0–10). High-quality EMG recordings were obtained from intrinsic and extrinsic foot muscles. Analyses of power spectral densities indicated that movement artefacts commonly observed during gait were removed by filtering. Pain associated with AddH/FDI electrodes during walking was low (median[IQR] 1[2]; range 0–4) and similar to other sites. Findings demonstrate that intramuscular EMG recording from AddH (oblique head) and FDI using this insertion technique is feasible and associated with minimal pain when walking in shoes.

The electromyography (EMG) signal provides insight into neuromuscular activity which is used in medical and technological fields. Traditional needle electrodes and surface electrodes have several drawbacks making them less suitable for portable and long-term use. In contrast, emerging capacitive electrodes offer promising features over the existing electrodes. Yet, the full potential of capacitive electrodes remains untapped due to the lack of comprehensive design optimization for consistently reliable signal quality. This study highlights the complex interplay of factors influencing correlation in capacitive EMG (cEMG) and wet surface EMG (wet sEMG) signals. The study emphasizes the importance of the surface area of capacitive electrodes, muscle force, preprocessing, and sampling frequency in understanding and improving the correlation between cEMG and wet sEMG signals, providing valuable insights for future research and applications in the field. The study reveals that the electrode area has no significant effect on the correlation. However, the correlation significantly depends on the muscle force. In addition, removing artifacts from the cEMG signal increases the correlation, especially for lower force where artifacts are significant. Again, oversampling the EMG signal above 800 Hz does not have any impact on increasing the correlation but the correlation decreases with higher inter-electrode distance (IED). In this research, the highest correlation of 82.89% (normalized-91.62%) between cEMG and sEMG has been achieved for high muscle force with a plate area of 4 cm². Therefore, the capacitive electrode can be an alternative for EMG signal acquisition.

The neurogenic oropharyngeal dysphagia is a prevalent functional swallowing disorder resulting from neurological causes. The conventional diagnosis involves ionizing radiation in Videofluoroscopy Swallowing Studies (VFSS). Surface electromyography (sEMG) offers a non-invasive alternative by recording muscle activity. This research compares bolus passage timing through anatomical structures using VFSS and sEMG-related activation times. Fifty confirmed oropharyngeal dysphagia patients underwent synchronized VFSS and sEMG, evaluating muscle groups during cracker and fluid ingestion. sEMG revealed activation patterns in masseters, suprahyoid, and infrahyoid muscles, occurring before bolus passage through the mandibular line and concluding near the upper esophageal sphincter complex. sEMG identified differences in dysphagia severity (EAT-10 score), age, and diagnosis, contrasting VFSS results. Results indicate potential complementarity between sEMG and VFSS for dysphagia screening, diagnosis, and monitoring.

We explore the effect of stress-recovery schedule on the cumulative creep response of lumbar tissues. Twelve participants performed a 48-minute protocol that consisted of 12 min of full trunk flexion and 36 min of upright standing. Two stress-recovery (work-rest) schedules were considered: a) three minutes of full trunk flexion followed by twelve minutes of upright standing (3:12), and b) one minute of full trunk flexion followed by four minutes of upright standing (1:4). Lumbar kinematics and EMG activity of erector spinae muscles were collected. Cumulative creep deformation was explored by considering the changes in peak lumbar flexion angles during full flexion and changes in the angles of flexion-relaxation (EMG-off) of the lumbar extensor musculature after the 48-minute protocol. The results of time-dependent lumbar flexion angle during full flexion revealed a noticeable creep response in both work-rest schedules, but the cumulative creep response was significantly greater in the 3:12 schedule (Δ3.5°) than in the 1:4 schedule (Δ1.6°). Similarly, the change in the EMG-off lumbar flexion angle in the 3:12 schedule was significantly greater than in the 1:4 schedule (Δ2.5° vs −Δ0.2°, respectively). These results indicate that the passive lumbar tissues recover their force producing capability more rapidly with shorter cycle times.