OBJECTIVETo investigate lifting-related musculoskeletal disorders in metal processing, to analyze the risk factors, and to study the validity and feasibility of using NIOSH lifting equation in China.

METHODSThe questionnaires of semi-structured interview, the Ovako Working Posture Analysing System (OWAS) postural analysis and variables of the NIOSH equation were applied to the study. The study population consisted of 69 workers mainly involved in manual materials handling (MMH), categorized as Job A; and 51 machinery workers, served as controls, that were less MMH task involved, as Job B.

RESULTSThe prevalence of low back pain (LBP), which was defined at least one episode lasting for more than 24 hours in the past 12 months, were 63.8% and 37.3% for Job A and Job B, respectively. However, the prevalence of LBP lasting for more than a week due to lifting were 26.09% and 5.88% for Job A and B, respectively. The proportion of awkward back postures were found higher in Job A than that of Job B (66% vs 63%, P < 0.05). The NIOSH Lifting Index (LI) was estimated to be 2.4 for Job A, and 0 < LI < 1 for Job B. The analysis of multiple regressions revealed that the repetitiveness of lifting and length of service had greatly attributed to the occurrence of LBP. The "composite load" (object weight x activity repetitiveness) had a significant adverse effect on lower back meaning that the objective weight remains an ingredient part of the risk.

CONCLUSIONThe occurrence of LBP is not only related to the force load, but the repetitiveness of lifting and awkward postures. The method of OWAS observation and US-NIOSH equation are important tools in assessing characteristics and risk factors of LBP for MMH tasks. Further study aimed at developing an integral scheme for the assessment system is needed.

Adult ; Back Injuries ; epidemiology ; etiology ; China ; epidemiology ; Female ; Humans ; Male ; Metallurgy ; Middle Aged ; Musculoskeletal Diseases ; epidemiology ; etiology ; Occupational Diseases ; epidemiology ; etiology ; Prevalence ; Risk Factors ; Surveys and Questionnaires ; Time Factors ; Weight Lifting ; injuries

OBJECTIVETo determine the anthropometric parameters and the isometric muscle strength in a working population sample in China, and to investigate the relationship between muscle strength and individual attributes, such as age, gender, height and weight.

METHODSThe study population consisted of 146 male and 47 female people including workers, administrators and college students. Four types of muscle strength, i.e., handgrip, arm lift, shoulder lift, and torso pull, were measured.

RESULTSLeft handgrip, right handgrip, arm lift, shoulder lift and torso pull of male workers were (42.07 +/- 7.20), (43.92 +/- 7.14), (26.79 +/- 4.64), (33.79 +/- 6.88), (88.56 +/- 17.98) kg, respectively while those of female workers were (21.29 +/- 5.09), (23.26 +/- 5.47), (13.29 +/- 3.37), (18.52 +/- 4.01), (41.06 +/- 12.04) kg, respectively. The female's strength was about 50% lower than the male's. The strength in the 40 approximately years old group was higher than that in other age groups. There were significant positive correlation between the gender and the isometric strength as well as between the body weight and the isometric strength. If the body weight served as the corrected parameter, there was no significant difference in the handgrip among the groups (P < 0.05), but the torso pull of male workers > college students > administrators. All relative muscle strengths except the torso pull were similar for all age groups.

CONCLUSIONThe body weight as the independent variable can be used for establishing the predictive equation of the muscle strength. Calculation of the relative muscle strength can relieve the interference of the body weight for the muscle strength.

Adolescent ; Adult ; Anthropometry ; Female ; Hand Strength ; physiology ; Humans ; Male ; Middle Aged ; Muscle Contraction ; physiology ; Muscle Strength ; physiology ; Muscle Strength Dynamometer ; Pilot Projects ; Transactional Analysis ; Work Capacity Evaluation