The Liberty Mutual manual materials handling (LM-MMH) equations

We summarise more than 40 years of Liberty Mutual psychophysical research on lifting, lowering, pushing, pulling and carrying, including the 7 studies used to develop 1991 Tables 12 subsequent studies. Predictive equations were developed based 612 mean maximum acceptable loads (MALs), representing 388 unique conditions from 123 female 149 male participants, starting with a reference load that is scaled frequency, height, distance (vertical for lift & lower, horizontal push, pull carry tasks) reach (for lower tasks). Representative coefficients variation are provided allow calculation MALs any percentile. Each equation performed well and, overall, they explained 90% variance in MAL values, RMS differences 6.7% 4.8% full range females males, respectively. propose these replace Tables. Practitioner summary: predictive 14 manual materials handling tables Snook Ciriello (1991). These publications, matched empirical data well, easier use both wider specific inputs tables.