Risk Factor Assessment Using Surface Electromyography and Electrogoniometer among Automobile Part Manufacturers / 대한산업의학회지

OBJECTIVES: As automobile part manufacturing is characterized by high speed and high repetition, observation methods which are usually utilized for static posture are inappropriate to evaluate musculoskeleatal risk factors. This study quantified the risk factors of musculoskeletal disorders on the forearm and suggested exposure limits by estimating the risk factors using surface electromyography (EMG) and electrogoniometer. METHODS: Ten percent of the total workers at 3 automobile part manufacturing factories were randomly selected, and 99 male workers were recruited as study subjects. The study was conducted during May 2003 to September 2004. The workers were equipped with electrogoniometers on the wrist and the elbow, surface EMGs on the skin of the flexor digitorum superficialis (FDS) and extensor carpi radialis (ECR) muscles, and the heart beat recorder during work as indicators of joint movement, local muscle tension and physical work load, respectively. RESULTS: After controlling for age, body mass index and job stress, wrist flexion maximum angle, FDS relative activity (RA) and ECR RA were significantly associated with forearm musculoskeletal symptoms. The odds ratios of the forearm were 5.0(95% CI: 1.1-22.7), 14.0(95% CI: 1.5-128.8) and 7.3(95% CI: 1.1-49.4) for wrist flexion maximum angle more than 76 degrees, FDS RA more than 2.8%, and ECR RA more than 3.5%, respectively. CONCLUSIONS: Joint angle and focal muscle activity were associated with forearm musculoskeletal symptoms. To reduce forearm musculoskeletal symptoms among automobile part manufacturers, the wrist flexion angle, and FDS and ECR activity need to be reduced below the guidelines recommended in this study.

Validity of the Energy Expenditure Prediction Program to Evaluate Energy Expenditure During Work / 대한산업의학회지

OBJECTIVES: The Energy Expenditure Prediction ProgramTM (EEPP) has been considered as a simple and quantitative method to evaluate physical work load. However, the adoption of EEPP directly to Korean workers is problematic because it was developed in a laboratory setting for Caucasians. Therefore, this study was conducted to validate EEPP for Korean workers. METHODS: The study subjects consisted of 60 workers from two factories. Cycle ergometer test was conducted to calculate physical work capacity, and heart rate monitoring was conducted to check heart rate during work. After observing the task, energy expenditure was estimated by EEPP. RESULTS: EEPP underestimated energy expenditure less than EEHR (energy expenditure checked by heart rate) did(p<0.0001). The factors effecting EEHR were EEPP and task type. After dividing the task into regular and irregular tasks, the irregular task had a larger difference between the values from the two methods. We provided task specific regression models between EEHR and EEPP. CONCLUSIONS: Because EEPP underestimated energy expenditure, it needs to be adjusted before use with Korean workers. It is suggested that different adjusting equations are formulated for regular and irregular tasks. Further study to develop a specific energy estimation model appropriate for Koreans is needed to obtain more precise estimation.