Summary
Objective: To compare the variability of symmetry indices within and between days when using
one and two force plates for data collection.
Animals: Seventeen healthy client-owned adult dogs.
Methods: Vertical ground reaction force data were collected in a crossover study design, with
four collection sessions on two consecutive days, and then two weeks apart (days 1,
2, 15, and 16) using both 1-plate and 2-plate collection methods. Symmetry indices
were calculated for limb pairs using two standard equations (SI1 and SI2). Repeated
measures analysis was used to compare symmetry indices data between plate systems
and days. Significance was set at p <0.05.
Results: There were no significant differences between plate systems for SI1 and SI2. There
were no significant differences between data collected on different days and no significant
interaction effects between variables. Symmetry indices were consistently larger for
ground reaction forces calculated from non-consecutive footfalls.
Conclusions: The use of two force plate systems will minimize variance caused by trial repetition
and paired limb variation. When comparing SI1 to SI2, results were not significantly
different. However, there were consistently higher mean values for SI1 compared with
SI2 and symmetry indices were consistently larger for 1-plate systems compared to
2-plate systems for both symmetry indices.
Keywords
Symmetry indices - force plate - dog - ground reaction forces
