An Isometric Predictor for Maximum Acceptable Weight of Lift for Chinese Men

Abstract

The aim of this study was to examine the practicality of the modified isometric strength tests to predict the maximum acceptable weight of lift (MAWL) of Chinese men. The modified strength tests allow the participant to pull on the load cell in front of the body and to apply force in a functional free posture. Both the modified and the standard strength data of each participant were used as predictors for the MAWLs. The prediction models were constructed and evaluated under task conditions of two lifting ranges, two box sizes, and three lifting frequencies. To realize the effect of modifications, testing posture was recorded and the joint angles were calculated. A stepwise multiple regression analysis indicated that modified composite strength (MCS), chest circumference, and acromial height accounted for 86% to 91% of the variance. Because the strength of the upper extremity body was also recruited in the test, the weak upper extremity strength of the Chinese participants would therefore be better reflected. Evidence for the existence of a close match between MAWL and MCS values, as well as the task conditions for its existence, suggest that a simple isometric strength measure is a good predictor for the MAWL.

Psychophysically determining the maximum acceptable weight of lift for polypropylene laminated bags

“…Among these significant factors, the chest circumference (CC) was the most preferentially selected predictor for all 9 lifting tasks, with the accounted variance ranging from 43.5% for the FSM task to 67.8% for the FK1 task. The significant relationship between the CC and MAWL observed in this study was in agreement with that reported by Lee and Chen12 ) .…”

“…Furthermore, the acromial height (AH) was determined to be a suitable predictor for KS tasks, as shown in Table 3. This result is in agreement with the regression model developed by Lee and Chen12 ) .…”

“…Because an effect of gloves on the MAWL was not found, the prediction models were developed without considering the glove condition. In this study, the body mass was added to the MAWL as a dependent variable to identify the significant predicting factors from previous studies7, 12 ) . Anthropometric data (cumulative R 2 ranged from 0.562 to 0.834) were considered to have superior predicting power compared with those reported in previous studies8, 12 ) in which boxes were equipped with well-designed handles.…”

“…The assumption of psychophysical stress as an integration of physiological and biomechanical stress has been studied by several researchers1, 5, 8, 12 ) . Specific instructions were given for the MAWL determination to adjust the weight of the bag by adding or subtracting sand to the maximum amount that they could lift comfortably (i.e., without straining themselves) for an 8-h workday in an assigned task combination.…”

Differences in lifting strength profiles between experienced workers and novices at various exertion heights

“…Lifting at an angle resulted in a decrease in moment at the upper arms and spinal L5/S1 joints and an increase in moment at the knees and ankles. Lee and Chen (1996) requested the participant to pull on the handle toward the body and found that the lifting strength can be a better predictor for the MAWL than other isometric strength. Therefore, identification of strength differences generated by different exertion directions deserves further investigation.…”