Objective: The purpose of this study is to examine the relationship of fatigue on plantar pressure distribution on subjects with chronic ankle instability after a jump-landing task. Setting: Two separate 2-within (condition, time), repeated measures ANOVAs were performed for the dependant variables of Forefoot Medial:Lateral pressure ratio, Midfoot Medial:Lateral pressure ratio, Rearfoot Medial:Lateral pressure ratio, and Total Foot Medial:Lateral pressure ratio. Significance was set at p<.05. All data was recorded within the research laboratory. Subjects: Twenty physically active subjects were recruited from the University of Toledo community voluntarily. The individuals consisted of both males and females between the ages of 18 and 30. Ten of the subjects were healthy subjects and had no previous lower extremity injuries. The other ten subjects had chronic ankle instability.
Measurements: Subjects participated in one testing session that consisted of a jump-landing task with the use of plantar pressure insoles before and after a fatigue protocol. Three trials of a jump-landing task were performed under each condition. The jump-landing task consisted of a single-leg landing from a jump height equivalent to 50% of the subjects maximum jump height. (50% Vertmax). The functional fatigue task consisted of three stations: Southeast Missouri (SEMO) agility drill, forward lunges and quick hops at 50% Vertmax. Subjects performed the fatigue task until the time to finish increased by 50% compared to their fastest time. Post-Testing took place immediately after fatigue. Results: There were no statistically significant findings for Group, Time and Group by Time interactions for each of the variables: Forefoot Medial:Lateral pressure ratio, Midfoot Medial:Lateral pressure ratio, Rearfoot Medial:Lateral pressure ratio, and Total Foot Medial:Lateral pressure ratio.
Conclusion: Previous work with plantar pressure systems demonstrated a pattern of increased lateral pressure during gait in CAI subjects that is theorized to contribute to increased risk of injury mechanism, plantar pressure distributions during a more dynamic task such as landing from a jump had not been conducted. Contradictory to previous studies and our hypotheses we did not find an increase in lateral plantar pressure distribution during a jump-landing task. Further research is needed with a larger sample size to make a better decision regarding the effects of fatigue and plantar pressure distribution within a jump-landing task.