Plantar loading during jumping while wearing a rigid carbon graphite footplate

- During the take-off phase of jumping the carbon graphite insert increases foot loading.
- The take-off and landing phases of jumping resulted in different loading patterns.
- Task selection is important during plantar loading testing.
- Carbon inserts would not be recommended to improve healing follow fifth metatarsal injury.

Fifth metatarsal stress fractures are common in sports and often result in delayed and non-union. The purpose of this study was to examine the effect of a rigid carbon graphite footplate (CGF) on plantar loading during take-off and landing from a jump. Nineteen recreational male athletes with no history of lower extremity injury in the past 6 months and no foot or ankle surgery in the past 3 years participated in this study. Subjects completed 7 jumping tasks while wearing a standard running shoe and then the shoe plus the CGF while plantar loading data was recorded. A series of paired t-tests were used to examine differences between the two footwear conditions independently for both takeoff and landing (α = 0.05). The contact area in the medial midfoot (p < .001) and forefoot (p = .010) statistically decreased when wearing the CGFP. The force-time integral was significantly greater when wearing the CGFP in the middle (p < .001) and lateral forefoot (p = .019). Maximum force was significantly greater beneath the middle (p < .001) and lateral forefoot (p < .001) when wearing the CGFP, while it was decreased beneath the medial midfoot (p < .001). During landing, the contact area beneath the medial (p = .017) and lateral midfoot (p = .004) were significantly decreased when wearing the CGFP. The force-time integral was significantly decrease beneath the medial midfoot (p < .001) when wearing the CGFP. The maximum force was significantly greater beneath the medial (p = .047) and middle forefoot (p = .001) when the subject was wearing the CGFP. The maximum force beneath the medial midfoot (p < .001) was significantly reduced when wearing the carbon graphite footplate. The results of the study indicate that the CGF is ineffective at reducing plantar loading during jumping and landing.