Humans ; Lung ; physiology ; Posture ; physiology

Objective: To simulate and evaluate the scraping and grinding work of workers with different spinal anteversion angles, and to explore the effects of different anteversion angles on the erector spinae muscles of scrapers. Methods: In November 2019, 16 male college student volunteers were recruited to simulate workers' scraping and grinding work. The parameters were 25°, 15 times/min, 15°, 30 times/min, 5°, 60 times/min respectively. The surface electromyography (sEMG) was used to collect the electromyographic signals of the erector spinae muscles, and the surface electromyographic characteristics of the erector spinae muscles were evaluated with Borg Scale. Results: There were significant differences between the maximum voluntary contraction percentage (MVE%) of the left and right erector spinae muscles groups in the three groups with different spinal anteversion angles (F(left)=13.41, P(left)<0.001; F(right)=4.74, P(right)=0.005) , and the EMG amplitude was higher at 25°, 15 times/min. At 15°, 30 times/min, MVE% of the left side was significantly higher than that of the right side (t=2.58, P=0.021) . There was significant difference in the mean power frequency (MPF) of the right erector spinae muscle in the three groups (F=9.42, P<0.001) , but there was no significant difference in the MPF of the left erector spinae muscle (F=0.30, P=0.823) . The fitting line showed that the left erector spinae muscle showed a downward trend at 5°, 60 times/min (t=-5.39, P=0.012) . Conclusion: Scrapers are less likely to be fatigued when the posture is 15°, 30 times/min, but they are more likely to be fatigued when working at 5°, 60 times/min.
Electromyography ; Humans ; Male ; Muscle, Skeletal/physiology* ; Muscles/physiology* ; Posture/physiology*

AIMTo observe the difference of EMG features between junior athletes and general students of knee flexor and extensor in performing various jumps.

METHODS30 junior athletes and 30 middle school students took part in the test. EMG signal from knee flexor and extensor were measured, when subjects performed squatting jump, counter-movement jump and drop jump.

RESULTSThe results indicated that the agonists EMG activity related to sex. With the load of leg increasing, there were no significant changes in iEMG and Fmean for male. There was some increasing in iEMG but no change in Fmean for female. The antagonists EMG activity maybe related to training. With the load of leg increasing, the EMG activity of antagonists changed slightly for the junior athletes, however, increased obviously for the common students.

CONCLUSIONTo improve the performance of jump, male athletes should mostly improve efficiency, however female athletes can increase the recruiting of muscle fiber. Moreover the ability of antagonists coordinating for athlete in the course of jumping is higher than that of general students.

Adolescent ; Athletes ; Electromyography ; Female ; Humans ; Knee Joint ; physiology ; Male ; Movement ; physiology ; Muscle, Skeletal ; physiology ; Posture ; physiology

Adult ; Back ; physiology ; Electromyography ; Humans ; Lumbosacral Region ; physiology ; Male ; Muscle Fatigue ; Muscle, Skeletal ; physiology ; Posture ; physiology

In this paper, the respiration courses of human at different postures are reconstructed by electrical impedance tomography (EIT). Conjugate gradient least squares (CGLS) algorithm is applied to reconstruct the resistivity distribution during respiration courses, and the EIT images taken from human at flat lying, left lying, right lying, sitting and prone postures are reconstructed and compared. The relative changes of the resistivity in region of interest (ROI) are analyzed to evidence the influences caused by different postures. Results show that the changes in postures are the most influential factors for the reconstructions, and the EIT images vary with the postures. In human at flat-lying posture, the left and right lungs have larger pulmonary ventilation volume simultaneously, and the EIT-measured data are of lower variability.
Algorithms ; Electric Impedance ; Humans ; Lung ; physiology ; Posture ; Respiration ; Tomography ; methods

OBJECTIVE: To analyze the latency of posture evoked response of normal lower limb muscle in different stimulations and explore its influencing factors. METHODS: The normal lower limb was induced to produce postural evoked response by the dynamic posturography through two kinds of perturbations, the supporting surface rotation stimulation (Toes-up and Toes-down) and the horizontal perturbation stimulation (Forward and Backward). The latencies of tibialis anterior muscle and gastrocnemius muscle were recorded by surface electromyography acquisition system. The differences of the left and right limb, gender and height on the latency of postural evoked response were analyzed. RESULTS: (1) Under the Toes-up and Backward perturbation, the latency of tibialis anterior muscle was longer than gastrocnemius muscle; under the Toes-down and Forward perturbation, the latency of gastrocnemius muscle was longer than tibialis anterior muscle. (2) The latencies of left limb and right limb had no significant difference. (3) The latency in male was longer than that in female. (4) The latency gradually increased with the increase of height. CONCLUSION In the postural evoked response, different perturbations, gender and height have significant impacts on the latency of posture evoked response of lower limb muscle. However, the effect of height and gender should be not considered referring to the same individual.
Electromyography ; Female ; Humans ; Lower Extremity ; Male ; Muscle, Skeletal/physiology* ; Posture

OBJECTIVETo evaluate the intramuscular loads of the upper limb during static postures and repetitive work by surface electromyography.

METHODSTwenty-six male college student volunteers were recruited for the experiment. The surface electromyography (SEMG) singal were recorded from the brachioradialis, biceps brachii, deltoid and trapezius of right arm during static postures including forward elevating, abducting, extending and a repetitive performance at different height of the bench, and root mean square (RMS) values were educed from the singal.

RESULTSThe SEMG amplitudes from forward elevating and abducting were in direct proportion to the angle of the elevating and abducting (r > 0.9, P < 0.01). The maximal voluntary electrical activation (MVE) of the deltoid were 6.4%, 10.1%, 12.6%, 16.2% and 20.8% while the arm elevated forward at an angle of 0 degrees , 45 degrees , 90 degrees , 135 degrees and 180 degrees respectively. The repetitive work showed that the height of the bench and the duration had more effects on deltoid and trapezius than the other muscles. The MVE% of the deltoid were 13.0%, 14.4% and 15.6% while the bench was 74, 79 and 84 cm in height respectively (P < 0.01).

CONCLUSIONSEMG which is suitable for determining and reflecting the muscle strain during static postures and repetitive work may be a reasonable indicator for the assessment of manual workload and the ergonomic design.

Arm ; physiology ; Electromyography ; Humans ; Male ; Muscle, Skeletal ; physiology ; Posture ; physiology ; Young Adult

OBJECTIVE: To analyze the balance function of injured lower limb by dynamic posturography. METHODS: Using the dynamic posturography instrument, the postural evoked responses of sixty-two normal people and two hundred and fifty-eight people with injured lower limb bones and joints were detected. The test was included sensory organization test (SOT) and adaption test (ADT). The results of two groups were compared by t test. RESULTS: Compared with the normal people, the impaired people had significant statistical differences in balance scores of SOT3-SOT6 and proportion score of dynamic proprioception (P < 0.05). There was no obvious decrease in ADT. CONCLUSION The balance function of injured lower limb significantly decreases.
Case-Control Studies ; Humans ; Lower Extremity/physiopathology* ; Postural Balance/physiology* ; Posture/physiology* ; Proprioception/physiology*

With an un-calibrated camera a new method is proposed in this paper to measure dynamically the bending angle of knee-joint based on cross ratio invariability. Firstly, by video image processing technique, we detected 25 circular objectives distributed in the aided measurement tool and determined their geometric centers in the video frame respectively. Then we further computed the extending direction of thigh and shank by detecting position of two rectangular targets tied on them. Finally, using of the principle of cross ratio invariability in Projection Geometry, we could realize real-time dynamic measurement of the bending angle of knee-joint based on the method. Experiments have proved that the measurement precision of the introduced approach could satisfy basic requirements of clinical applications.
Algorithms ; Biomechanical Phenomena ; Humans ; Knee Joint ; anatomy & histology ; physiology ; Movement ; physiology ; Posture ; physiology ; Range of Motion, Articular ; physiology ; Video Recording

OBJECTIVETo study neck and shoulder work-related muscle fatigue of female sewing machine operators.

METHODS18 health female sewing machine operators without musculoskeletal disorders work in Beijing garment industry factory as volunteers in participate of this study. The maximal voluntary contraction (MVC) and 20% MVC of bilateral upper trapezium and cervical erectors spinae was tested before sewing operations, then the whole 20 time windows (1 time window = 10 min) sewing machine operations was monitored and the surface electromyography (sEMG) signals simultaneously was recorded after monitoring the 20%MVC was tested. Use amplitude analysis method to reduction recorded EMG signals.

RESULTSDuring work, the median load for the left cervical erector spinae (LCES), right cervical erector spinae (RCES), left upper trapezium (LUT) and right upper trapezium (RUT) respectively was 6.78 ± 1.05, 6.94 ± 1.12, 5.68 ± 2.56 and 6.47 ± 3.22, work load of right is higher than the left; static load analysis indicated the value of RMS(20%MVC) before work was higher than that value after work, the increase of right CES and UT RMS(20%MVC) was more; the largest 20%MVE of bilateral CES occurred at 20th time window, and that of bilateral UT happened at 16th.

CONCLUSIONSThe work load of female sewing machine operators is sustained "static" load, and work load of right neck-shoulder is higher than left, right neck-shoulder muscle is more fatigable and much serious once fatigued.

Adult ; Electromyography ; Female ; Humans ; Muscle Fatigue ; physiology ; Posture ; Shoulder ; physiology ; Textile Industry ; Work ; Young Adult