Comparison of experimental results between using auxetic shoe, conventional shoe and barefoot on the kinematics of vertebral column during drop vertical jump

Footwear condition has been found to change kinematics of body especially in high-demanding activities. The present study compared the kinematics of healthy individuals when different footwear conditions were used. Two types of shoes, i.e., auxetic and conventional, were compared with each other and also with barefoot condition during gait and drop vertical jump (DVJ) activities using in vivo experimentation. A number of 11 male individuals were asked to do the experiments. Three trials for each footwear condition were completed for every participant, i.e., total of nine trials for each person. All methods were performed in conformity with relevant procedures and protocols. Their motion and force-plate data as well as electromyographic (EMG) activities of some trunk muscles were recorded during abovementioned actions. Two main stages of first landing (FL) and second landing (SL) were considered in the DVJ activity. Statistical analysis, using ANOVA and Tukey’s honestly significant difference, was carried out to investigate effects of footwear conditions on the kinematics. Results showed that biomechanical changes between the the three footwear conditions were insignificant in gait and the SL phase of DVJ. However, significant differences were detected during the FL stage of DVJ; using the auxetic shoes resulted in smaller EMG activities in longissimus and iliocostalis muscles, smaller anterior-posterior distance between the center of pressure of ground reaction force and heel, and also larger maximal hip, knee, and ankle flexion angles (p