Physiological and subjective measures of workload when shovelling with a conventional and two-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 energy was consumed while shovelling a load of sand with this shovel compared to a conventional tool. Accordingly, an experiment was designed in which subjects (n = 10) shovelled 1815 kg sand under laboratory conditions using either a conventional or a levered shovel. Heart rate and oxygen consumption were measured continuously during the trial and subjective data on perceived exertion, general fatigue and body discomfort were recorded after the trial. Although total energy expenditure was similar under both conditions (120 +/- 20 and 125 +/- 25 kcal; conventional versus two-handled spade), average heart rate was 4% higher when the 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 conclusion, subjects used similar energy expenditure to shovel 1815 kg sand with the conventional shovel and the two-handled tool despite lower mass of sand per scoop with the latter. This can be explained by the fact that the increased mass of the additional handle compensated for the lower mass of sand per scoop. The higher average heart rate while shovelling with the two-handled shovel can be explained by the more erect posture.
Bridger
R S
RS
Department of Biomedical Engineering, University of Cape Town Medical School, South Africa.
Cabion
N
N
Goedecke
J
J
Rickard
S
S
Schabort
E
E
Westgarth-Taylor
C
C
Lambert
M I
MI
D000328:Adult; D000383:Agriculture / Q000295:instrumentation*; D004734:Energy Metabolism / Q000502:physiology*; D004867:Equipment Design; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010100:Oxygen / Q000097:blood; D016474:Weight-Bearing / Q000502:physiology*; D016526:Workload / Q000523:psychology*
D010100:Oxygen