An individually moulded insole with 5-mm medial arch support reduces peak impact and loading at the heel after a one-hour treadmill run

Background: Foot pain experienced by long-distance runners could be relieved by functional insoles which aim at evenly distributing the plantar pressure. Research question: We hypothesised that an individually moulded insole with medial arch support would reduce the impact and loading under the heel and metatarsal regions. Methods: Twelve male recreational runners ran on a treadmill at 10 km/h for 1 hour with flat insoles and medial arch supported insoles. A pressure insole system (Novel Pedar, Germany) was used to obtain the peak pressure, peak force, time normalised pressure-time integrals, and the percentage of the total force-time integrals under 10 regions. Results: Medial arch supported insoles reduced the peak force under the heel (medial: -15.3%, p = 0.001; lateral: -19.2%, p = 0.037) during the initial run, and reduced peak pressure under the heel (medial: -13.3%, p = 0.005; lateral: -9.9%, p = 0.006), and peak force under the medial heel (-17.8%, p = 0.006) after the run. The percentage of the total force-time integrals under the heel was reduced (medial: -23.8%, p = 0.004; lateral: -13.6%, p = 0.022) after the run. No significant difference was found under the metatarsal regions. There is shift of load from the metatarsal regions to the medial mid-foot as indicated by the change of the percentage of total force-time integrals. Significance: Medial arch supported insoles were effective in reducing the impact and loading under the heel region in prolonged running on a treadmill. Level of evidence: Controlled laboratory study, Level V