Textured insoles reduce vertical loading rate and increase subjective plantar sensation in overground running

The effect of textured insoles on kinetics and kinematics of overground running was assessed. 16 male injury-free-recreational runners attended a single visit (age 23 ± 5 yrs; stature 1.78 ± 0.06 m; mass 72.6 ± 9.2 kg). Overground 15-m runs were completed in flat, canvas plimsolls both with and without textured insoles at self-selected velocity on an indoor track in an order that was balanced among participants. Average vertical loading rate and peak vertical force (Fpeak) were captured by force platforms. Video footage was digitised for sagittal plane hip, knee and ankle angles at foot strike and mid stance. Velocity, stride rate and length and contact and flight time were determined. Subjectively-rated plantar sensation was recorded by visual scale. 95% confidence intervals estimated mean differences. Smallest-worthwhile change in loading rate was defined as standardised reduction of 0.54 from a previous comparison of injured versus non-injured runners. Loading rate decreased (-25 to -9.3 BW·s-1; 60% likely beneficial reduction) and plantar sensation was increased (46 to 58 mm) with the insole. Fpeak (-0.1 to 0.14 BW) and velocity (-0.02 to 0.06 m·s-1) were similar. Stride length, flight and contact time were lower (-0.13 to -0.01 m; -0.02 to-0.01 s; -0.016 to -0.006 s) and stride rate was higher (0.01 to 0.07 steps·s-1) with insoles. Textured insoles elicited an acute, meaningful decrease in vertical loading rate in short-distance, overground running and were associated with subjectively-increased plantar sensation. Reduced vertical loading rate could be explained by altered stride characteristics.