It will depend on te type of shin splints i.e. surface related or structurally related. If its Tib Ant then rolling and stretching that area and lots of ice (plunging lower limbs into ice water, ice massage etc). You need to get the inflammation down. Once you have done this different exercises including heel walks and toe walks wil help strengthen this area. However, you may need to find alternative surfaces or better shoes. Maybe just do one session a week on the testing surface to familiarise yourself with the timing, bounce etc. If its more Tib Post then usually high arch individuals or over pronaters put this area under stress causing it to inflam. Again you need to rid yourself of the inflammation however you may find you need to tap your ankles to reduce the amount of overpronation when you aren’t wearing shoes that support your feet and reduce it. Good luck and remember you have a short time period, are very fit and need to run only 70m so it probably best to concentrate on the key aspects you can heavily influence it that period that will impact on your performance.