Abstract:
Objective To observe the rule of plantar dynamics in Chinese parachutists at landing.
Methods The maximum stress, maximum pressure, contact area, pressure-time integration value of 12 active duty parachutists from“ August 1st” Skydiving Team were measured using the German Pedar-X system when they jumped off from a 1.5-meter high platform. The left and right plantars were divided into 10 regions according to the conventional criteria and their dynamics parameters were recorded. The rule of dynamics change in each region was observed. The dynamics values in different regions of the left and right plantars were compared.
Results The distribution of the maximum pressure in left plantar was as follows: the maximum pressure in left plantar of medial heel in region 9>that of lateral heel in region 10>that of middle foot in region 8>that of the first toe in region 1>that of the first metatarsal area in region 3>that of the second metatarsal area in region 4>that of the third metatarsal area in region 5>that of 2-4 toes in region 2>that of the fourth metatarsal area in region 6>that of the fifth metatarsal area in region 7 (7.86±1.68 kPa
vs 7.47±1.88 kPa
vs 4.68±0.71 kPa
vs 3.96±1.56 kPa
vs 3.72±1.43 kPa
vs 2.87±1.05 kPa
vs 2.13±0.87 kPa). The distribution of maximum stress and maximum pressure-time integration value was consistent with that of the maximum pressure in left plantar. The distribution of maximum stress, maximum pressure and maximum pressure-time integration value in the right plantar was consistent with that of those in the left plantar.
Conclusion The pressure of left and right feet is similar at half-squat landing. The pressure of plantar and heel is the highest. The pressure of medial plantar is greater than that of the lateral plantar, thus easy leading to fracture of medial and lateral ankles.