# Foot Insole Pressure Distribution during the Golf Swing in Professionals and Amateur Players
## 4 Discussion  
The pressure data from sensors between the foot and the shoe were analyzed during the golf swing using an instrumented insole. We consider pressure of the seven anatomical areas normalized with respect to the total pressure of each foot. It is known that the swing performance depends primarily on the velocity vector and the orientation of the cubface at the ball contact, as well as the forces applied during the impact. To perform a good swing, players move their body parts sequentially, starting with lower limbs, which are furthest from club head to move the club in a plane during downswing [24]. Hence, the player must generate the necessary reaction forces between his feet and the ground during the whole swing [9]. Four hypotheses with respect to the plantar pressure during the swing were formulated at the beginning of this work. In the following, we discuss these hypotheses in detail regarding our obtained results and statistical analysis. Hypothesis # 1 was confirmed. The pressure distribution pattern of the rear foot (right in right-handed player) is significantly different from that of the lead foot (left in right-handed player). The pair comparisons of the pressure in the seven anatomical areas between the left and the right feet throughout the swing show significant differences in 54 out of the 70 cases (Figure 5). At the top of the backswing, in the lateral parts of the metatarsal (METlat), arch (ARClat), and heel (HEELlat), we have observed that pressure reaches a maximum on the right foot, whereas the same areas show a minimum on the left foot. However, pressure patterns at the lateral areas (METlat, ARClat, and HEELlat) inversely evolve during the downswing, the phase between top of backswing and impact instants. During the downswing phase, the pressure at the right foot decreases in these three lateral areas, while it increases at the left foot, reaching their maximum at the impact (Figure 5). Interestingly, in comparison with the lateral regions, our results show a reverse behavior in the toes and medial metatarats (TOES and METmed) areas. Figure 5 shows that in TOES and METmed areas, pressure reaches a maximum during the backswing in the left foot (lead), while in the right foot (rear), pressure maximum occurs during the downswing. In the medial arch area (ARCmed), we observed insignificant differences between pressures of the left and the right feet. In both feet, medial arch areas (ARCmed) show the same pattern of pressure distribution, contributing to less than 8% of the total pressure. In the medial part of the heel (HEELmed), both feet behave also in a similar way, albeit the contribution of this area to the total pressure is higher in the left foot. In addition, HEELmed areas of both feet reach a maximum at the middle backswing instant and a minimum at the impact moment. The former results agree with those obtained by the other authors who have analyzed the plantar pressures [15; 16; 18; 19]. According to [15] the loads are different for each foot, so that greater pressure is produced first on the rear foot before the top of the swing, and then on the lead foot just before impact.