Gender differences in exerted forces and physiological load during pushing and pulling of wheeled cages by postal workers.

The aim was to determine gender differences regarding exerted forces and physiological load during push/pull tasks simulating the daily working practice of postal workers. Eight female and four male workers handled four-wheeled cages under eight conditions corresponding to the cage weight (130, 250, 400, 550 kg) and the direction of force exertion (pushing, pulling). For each of the five dependent variables, average force, initial force, ending force, oxygen uptake and heart rate, two analyses of variance with repeated measurements were performed, i.e. with and without correction for the worker's body weight, body height and maximum capacity regarding the dependent variable. Exerted forces and physiological load were high for the cages weighing 400 and 550 kg. Gender differences were significant for all dependent variables (p = 0.030-0.000). When the personal factors were included in the model, male workers exerted significantly higher average forces and ending forces than their females, while differences regarding initial forces and physiological load were not significant. However, none of the personal factors were significantly related to any of the dependent variables. It is concluded that gender differences in exerted forces were not caused by differences in anthropometry and maximum capacity, but due to application of different work methods by women in order to balance work demands and work ability.