Influence of brick laying height on biomechanical load in masons: Cross-sectional field study with technical measurements.
Mikkel Brandt, Rúni Bláfoss, Markus Due Jakobsen and 4 others
PMID 38517831WHAT IT FOUND
In 12 masons, bricklaying at shoulder or above shoulder height increased upper trapezius load, while knee-height work produced the most forward trunk bending.
Hip height had lower trapezius load than shoulder or above-shoulder work and less trunk bending than knee-height work.
Key findings
01Dominant erector spinae activity, as a percentage of maximal contraction, was 26.6% at hip height, 29.6% at shoulder height and 18.9% at knee height.
02Dominant trapezius activity, as a percentage of maximal contraction, was 13.9% at hip height, 19.7% at shoulder height, 24.0% above shoulder height and 11.5% at knee height.
03Forward trunk bending was 34.5° at knee height, 27.9° at hip height, 17.6° at shoulder height and 12.5° above shoulder height.
STILL TO COME
How it was doneWhat they foundWhat it means for OTs
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What it does not show
Participants were men with mean age 36 years, so results may not apply to women or older workers. Only 12 masons were analysed. Six of 80 working days were excluded for poor data quality. The study measured muscle activity and trunk bending, not pain, injury or work disability. Only erector spinae and upper trapezius muscles were measured, and patterns over the working day were not analysed. The analysis was cross-sectional and did not test a workplace intervention.
The easy way to misread this
Do not read the muscle load differences as proof that changing bricklaying height prevents low back or neck-shoulder pain. The study measured muscle activity and trunk bending in 12 male masons and did not test a workplace intervention or follow patients for pain outcomes.