CAJ | 학술논문

目的研究手工搬举作业的工间休息时间.方法 30名大学生志愿者从事模拟的蹲举、背举和半蹲举手工搬举作业,分别测定他们在工间休息时左、右侧胸10(LT10、RT10)和腰3(LL3、RL3)竖脊肌的肌电及其心电,分析最大随意收缩肌电百分比(percentage of maximum voluntary electrical activation,MVE%)、中位频率(median frequency,MF)及心率(heart rate,HR),评价负荷恢复状况.结果 15 min工间休息内,男性被测试者4个部位竖脊肌肌电MVE%均在5 min内恢复至静息水平,且91.8%在2 min内恢复;而女性被测试者除RL3和LL3 MVE%在半蹲举活动后未恢复外,其余肌肉MVE%均在3 min内恢复,且67.8%在2 min内恢复.男性被测试者除RL3竖脊肌肌电MF在蹲举和背举后未恢复外,其余MF均在10 min内恢复,且74.9%在2 min内恢复.女性被测试者竖脊肌肌电MF均在8 min内恢复,且83.4%在2 min内恢复.在3种搬举活动结束后20 min休息时段内,男、女被测试者各部位竖脊肌MVE%和MF均恢复到静息水平;男、女被测试者心率分别在14、5 min恢复到静息水平.结论在负荷为25%MVC,持续时间为4.5 min的3种搬举活动中,就局部肌肉负荷的恢复而言,15 min休息仅保证绝大多数竖脊肌恢复;就全身负荷恢复而言,15 min休息可保证心率完全恢复到静息水平.
목적 연구수공반거작업적공간휴식시간.방법 30명대학생지원자종사모의적준거、배거화반준거수공반거작업,분별측정타문재공간휴식시좌、우측흉10(LT10、RT10)화요3(LL3、RL3)수척기적기전급기심전,분석최대수의수축기전백분비(percentage of maximum voluntary electrical activation,MVE%)、중위빈솔(median frequency,MF)급심솔(heart rate,HR),평개부하회복상황.결과 15 min공간휴식내,남성피측시자4개부위수척기기전MVE%균재5 min내회복지정식수평,차91.8%재2 min내회복;이녀성피측시자제RL3화LL3 MVE%재반준거활동후미회복외,기여기육MVE%균재3 min내회복,차67.8%재2 min내회복.남성피측시자제RL3수척기기전MF재준거화배거후미회복외,기여MF균재10 min내회복,차74.9%재2 min내회복.녀성피측시자수척기기전MF균재8 min내회복,차83.4%재2 min내회복.재3충반거활동결속후20 min휴식시단내,남、녀피측시자각부위수척기MVE%화MF균회복도정식수평;남、녀피측시자심솔분별재14、5 min회복도정식수평.결론 재부하위25%MVC,지속시간위4.5 min적3충반거활동중,취국부기육부하적회복이언,15 min휴식부보증절대다수수척기회복;취전신부하회복이언,15 min휴식가보증심솔완전회복도정식수평.
Objective To investigate the recovery duration of manual lifting tasks. Methods 30 college student volunteers with gender equally distributed were involved in the simulated stoop-, squart- and semisquart-lifting tasks in the laboratory. Signals of electromyography ( EMG ) at the back muscles ( left and right thorax m. erector spinae, LT10 and RT10; left and right lumbar m. erector spinae, LL3 and RL3) 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. Results 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 Rt3 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 RL3 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. Conclusions 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.