Study of the Effect of Worker Characteristics on Maximum Acceptable Weight of Lift

Manual material handling (MMH) and lifting activities have been identified as risk factors for low back pain (LBP). Statistical findings suggest that about 50% of all back pains are related to manual lifting. Of the many tools available for analyzing and designing lifting tasks, the revised NIOSH lifting equation (RNLE) is perhaps the most widely used. An inherent limitation of the equation is that it addresses task demands only. However, load lifting task is dependent not just on the characteristics of lift but on worker characteristics like age, gender, weight, anthropometry and ethnicity. Thus, the present study investigates the role of worker characteristics like age, gender, BMI and anthropometric variables in a manual lifting task. A psychophysical methodology was adopted to arrive at the maximum acceptable weight limits (MAWLs). 44 industrial workers (22 males and 22 females) participated in the study. ANCOVA for gender using age, height, acromial height and BMI as covariates showed that BMI, gender and age had statistically significant effect on MAWL while the effect of height and acromial height was statistically non-significant. Further, it was observed that the recommended weight limit (RWL) as obtained by the RNLE was 17.2 kg. However, using the psychophysical criteria of 75th percentile women (as per the RNLE guideline), in the present study a MAWL of 19.3 kg was found.