Influence of backpack load and gait speed on plantar forces during walking.

The purpose of this study is to examine the differences in plantar force associated with changes in backpack load and gait speed during walking. The F-scan tethered system was used to collect plantar pressure data. Subjects were asked to walk on a treadmill with varied levels of backpack load (0%, 10%, 20%, and 30% of body mass) and gait speed (4, 5, and 6 km/h). We found that an increase in gait speed and backpack load lead to increase in the magnitude of the first vertical ground reaction force (vGRF) peak. Greater magnitudes of the second vGRF peak were only associated with an increase when gait speeds were 4 km/h and 5 km/h. There was no speed-related change in the magnitudes of the second vGRF peak at the speed of 6 km/h. The results of this study may be important for the purpose of constituting a load-bearing walking program for protecting against osteoporosis.