PHYSIOLOGICAL AND SUBJECTIVE MEASURES OF WORKLOAD WHEN SHOVELING WITHA CONVENTIONAL AND 2-HANDLED (LEVERED) SHOVEL

Previous studies have suggested that the two-handled (levered) shovel is advantageous over the conventional spade from a biomechanical point of view. The aim of this experiment was to determine whether less ene rgy was consumed while shovelling a load of sand with this shovel comp ared to a conventional tool. Accordingly, an experiment was designed i n which subjects (n = 10) shovelled 1815 kg sand under laboratory cond itions using either a conventional or a levered shovel. Heart rate and oxygen consumption were measured continuously during the trial and su bjective data on perceived exertion, general fatigue and body discomfo rt were recorded after the trial. Although total energy expenditure wa s similar under both conditions (120+/-20 and 125+/-25 kcal; conventio nal versus two-handled spade), average heart rate was 4% higher when t he two-handled shovel was used (p<0.05). In addition, the mass of sand per scoop was 4% less with the two-handled shovel (p<0.05). In conclu sion, subjects used similar energy expenditure to shovel 1815 kg sand with the conventional shovel and the two-handled tool despite lower ma ss of sand per scoop with the latter. This can be explained by the fac t that the increased mass of the additional handle compensated for the lower mass of sand per scoop. The higher average heart rate while sho velling with the two-handled shovel can be explained by the more erect posture.