Impact accelerations during a prolonged run using a microwavable self-customised foot orthosis.

The use of custom-made foot orthoses has been associated with numerous benefits, such as decreased impact accelerations. However, it is not known whether this effect could be due to better customisation. The present study analysed the effects of the first generation of  a microwavable prefabricated self-customised foot orthosis vs. a prefabricated standard one on impact accelerations throughout a prolonged run. Thirty runners performed two tests of 30-min running on a treadmill, each one with an orthosis condition. Impact acceleration variables of tibia and head were recorded every 5 min. Microwavable self-customised foot orthosis increased the following variables in the first instants compared to the prefabricated standard one: tibial peak (min1: 6.5 (1.8) vs. 6.0 (1.7) g, = .009, min5: 6.6 (1.7) vs. 6.2 (1.7) g, = .035), tibial magnitude (min1: 8.3 (2.6) vs. 7.7 (2.4) g, = .030, min5: 8.5 (2.6) vs. 7.9 (2.5) g, = .026) and shock attenuation (min1: 61.4 (16.8) vs. 56.3 (16.3)%, = .014, min5: 62.0 (15.5) vs. 57.2 (15.3)%, = .040), and tibial rate throughout the entire run (504.3 (229.7) vs. 422.7 (212.9) g/s, = .006). However, it was more stable throughout 30-min running ( < .05). These results show that the shape customisation entailed by the thermoformable material does not provide impact acceleration improvements.