Experimental simulated study on the break for manual lifting task by surface electromyography and electrocardiogram / 中华劳动卫生职业病杂志
Chinese Journal of Industrial Hygiene and Occupational Diseases
;
(12): 167-170, 2011.
Article
in Chinese
| WPRIM
| ID: wpr-293746
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the recovery duration of manual lifting tasks.</p><p><b>METHODS</b>30 college student volunteers with gender equally distributed were involved in the simulated stoop-, squart- and semi squart-lifting tasks in the laboratory. Signals of electromyography (EMG) at the back muscles (left and right thorax m. erector spinae, LT(10) and RT(10); left and right lumbar m. erector spinae, LL(3) and RL(3)) and electrocardiography (ECG) were recorded during the rest intervals. The percentage of maximum voluntary electrical activation (MVE%), EMG median frequency (MF), and heart rate (HR) were analyzed to predict the recovery time required.</p><p><b>RESULTS</b>During the break, MVE% at 4 back muscles of all the male subjects were recovered to resting level within 5 minutes and 91.8% were within 2 minutes. Except for RL(3) after squat- and stoop-lifting task, the MVE% of female subjects went back to resting level within 3 minutes and 67.8% were within 2 minutes. The MF of male subjects were recovered in 10 minutes and 74.9% within 2 minutes, with the exception of RL(3) after stoop- and squat-lifting tasks. All the female MF were recovered in 8 minutes and 83.4% were within 2 minutes. However, during the last 20 minute break after the lifting tasks, the MVE% and MF of all male and female subjects were recovered, while HR came back to resting level within 14 and 5 minutes, respectively.</p><p><b>CONCLUSIONS</b>For the three manual lifting tasks with 25% MVC workload lasting for 4.5 min, a break of 15 minutes is sufficient for most erectors spinae to recover from local muscle load. However, in terms of the HR, a break of 15 minutes is enough for the recovery of systematic load.</p>
Full text:
Available
Index:
WPRIM (Western Pacific)
Main subject:
Physiology
/
Posture
/
Rest
/
Back
/
Weight-Bearing
/
Lifting
/
Muscle, Skeletal
/
Electrocardiography
/
Electromyography
/
Lumbosacral Region
Limits:
Adult
/
Female
/
Humans
/
Male
Language:
Chinese
Journal:
Chinese Journal of Industrial Hygiene and Occupational Diseases
Year:
2011
Type:
Article
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