Kinematic and perceptual responses in heavy lifting and pulling: Are there differences between males and females?

Quantifying how functional and structural personal factors influence biomechanical exposures in paramedic lifting tasks

It is unknown how structural (sex, stature, body mass) and functional (strength, flexibility) personal factors influence lifting strategy in paramedic work. We explored whether variance in peak low back forces and kinematic coordination patterns could be explained by structural and functional personal factors in paramedic lifting tasks. Seventy-two participants performed backboard and stretcher lifts. Peak low back forces normalised to body mass, as well as kinematic coordination patterns, were calculated as dependent variables. Being female, stronger, shorter, having higher body mass, and/or having greater lower body range of motion (ROM) were all independently associated with lower normalised low back forces across backboard and stretcher lifting. Females and stronger individuals seemed to define a movement objective to consistently minimise compressive forces, while individuals with greater hip ROM consistently minimised anteroposterior shear forces. The efficacy of improving strength and hip ROM to reduce low back forces in paramedic lifting should be investigated.Practitioner summary: Females, stronger individuals, and individuals with greater hip range of motion consistently exhibited lower normalised low back forces in paramedic lifting. Improving strength and hip range of motion via training is a potential proactive ergonomics approach to reduce peak low back forces in paramedic lifting tasks.

Revised NIOSH lifting equation: a critical evaluation

The revised NIOSH lifting equation (RNLE) aims to manage lifting-related lower back pain (LBP), by determining safe load limits. Many researchers have studied the multiplier development criteria, the universal applicability of the equation and its ability to identify an increased risk of LBP in lifting tasks. Although a number of strengths of the equation have been highlighted, many limitations have also been identified. The need for new multipliers, such as worker and environmental characteristics, was highlighted in order to make the equation more adaptable. The RNLE was designed to protect 75% of female workers and is therefore inherently conservative. Additionally, as all multipliers have values less than or equal to 1, the recommended weight limits (RWLs) can be further reduced. Thus, new multipliers may be defined, by combining two or more existing multipliers, to make the RWLs more realistic.

Predicting load constant of RNLE based on demographics

Manual material handling (MMH) and lifting activities have been identified as risk factors for low back pain (LBP). Of the many tools available to analyse and design lifting tasks, the Revised NIOSH Lifting Equation (RNLE) is perhaps the most widely used. However, the equation is based on data primarily from the west. To make it universally applicable, the effect of worker characteristics like age, gender, weight, and anthropometry on MAWL was studied. A psychophysical methodology was adopted to arrive at the maximum acceptable weight limits (MAWLs). 58 industrial workers (30 men and 28 women) participated in the study. Based on the observations of the study, an equation was developed that would allow the RNLE load constant to be modified for different populations based on simple anthropometric data. The load constant for the Indian population was found to be comparable to the RNLE recommendations.