Plantar Pressure Differences Between Genders When Comparing Racing Flats and Traditional Training Shoes

Abstract

With the increasing popularity of running around the world available shoe types have been increasing. Racing flats have begun to be used not only as a racing shoe, but also for daily training. It has been suggested that decreased cushioning in racing flats could lead to increased plantar loading, which has been linked to an increased risk of lower leg injuries. Previous reports have indicated that lower leg injury risk is gender dependent. PURPOSE: To determine differences in plantar pressure distributions between men and women when running in training shoes and racing flats. METHODS: Each subject was asked to run over-ground at a self-selected speed 7 times in each shoe while in-shoe plantar pressure data were collected at 50 Hz. Contact area (CA), maximum force (MF), and contact time under the entire foot as well as beneath the medial midfoot (MMF), lateral midfoot (LMF), medial forefoot (MFF), middle forefoot (MiFF), and lateral forefoot (LFF) were obtained. CA was normalized to total insole contact area and MF was normalized to body weight. Shoe testing order was randomized to avoid fatigue effects. No significant running speed differences existed, therefore, each variable was analyzed using a 2×2 (shoe x gender) repeated measures ANOVA (a=0.05). RESULTS: In men, MF was increased in the racing flats (p=0.016) in the MMF, yet was increased at the MFF in the training shoe (p=0.018). Independent of gender, CA was decreased in the racing flats beneath the entire foot (p=0.029) and in the MMF (p=0.013) and MFF (p=0.030), and increased in the LFF (p=0.023). In the racing flats MF was increased beneath the entire foot (p<0.001) and the LFF (p<0.001). Independent of the shoe, CA was decreased in men beneath the MFF (p=0.007) and MiFF (p<0.001), while MF was increased in the LFF (p=0.002). CONCLUSIONS: These results indicate that racing flats increase loading beneath the total foot and in the LFF. The LFF is an area of increased stress fracture risk specifically in men, who also demonstrated an increase in MF in this region. Based on the gender differences in loading, it appears that running shoe design and cushioning should be gender specific in an attempt to prevent injuries. It is possible that wearing racing flats for high mileage running coupled with the observed increases in loading could be a factor in lower limb injuries.