BACKGROUND: Various parameters related to pushing/pulling tasks
have been examined yet the effects of changing the load position in
one-wheeled wheelbarrow task has not been examined.
OBJECTIVE: To explore the effects of load position and force
direction on muscle activity during wheelbarrow tasks.
PARTICIPANTS: Nine participants were recruited to take part in the
experiment.
METHODS: Each participant performed 18 trials consisting of 2 force
directions (push and pull) and 9 load positions. The dependent variables
were EMG of erector spinae and gripping force. ANOVA was used to identify
significant differences between force direction and load position in EMG and
gripping force data.
RESULTS: Results showed that peak EMG was lowest for the left and
right erector spinae when the load was positioned farther from the
participant. Peak EMG of the bilateral erector spinae increased when the
weight was near the participant and on the ipsilateral hand.
CONCLUSIONS: Based on the EMG results, we suggest that loads be
arranged in the anterior part of the bin in order to reduce muscle activity
on the spine during the wheelbarrow task. This finding also provides some
directions in the improvement and ergonomic redesign of the one-wheeled
wheelbarrow.
