New research from Coventry University and the Royal Horticultural Society reveals that bad digging technique leads to increased forces on joints and increased risk of musculoskeletal disorders[i].
The objective of the study was to determine whether measured biomechanical data correlated with a visual assessment of the digging technique to predict risk of injury. Participants were asked to dig and move to the side three spade-loads of soil. A method of three-dimensional motion capture was used, in which the participants’ movements were recorded with a 12-camera optical tracking system. The data was analysed by a computer programme that allows the loads of the joints to be calculated.
Fifteen participants each did two trials, and of the 30 trials, a team of horticulturalists and physiotherapists chose one exemplar of good technique and one example of bad technique, based on digging efficiency and risk of injury. A good technique was found to have minimal back bend and large knee bend, whereas a bad posture had large forward bending, stretching limbs and uncontrolled motion[ii].
Peak forces and torques were higher in both shoulders and the lumbar back in the trial assessed to be an example of bad technique. There was also greater variability in the force and torque patterns for the bad trial relative to the good trial. The researchers did not look for average forces, because factors such as age, horticultural experience and fitness could be significant.
Though ergonomic knowledge could already be used to suggest a good digging technique, this study provides quantitative evidence of a good digging style. The researchers conclude that their findings could be useful for home gardeners and professional horticulturists. The benefits for the latter include reducing economic loss through lost work time, worker injuries and compensation claims. In addition, the technique of using motion capture to calculate the loads on joints could be applied to other tasks.
[i] Shippen, J., Alexander, P. & May, B. A Novel Biomechanical Analysis of Horticultural Digging. HortTechnology 27, 746–753 (2017). http://horttech.ashspublications.org/content/27/6/746.full (Accessed 10 January 2018)
[ii] How gardeners can dig for health, not injury. ScienceDaily. 8 January 2018. https://www.sciencedaily.com/releases/2018/01/180108101349.htm (Accessed 10 January 2018)