The fact that

a runner can make an immediate alteration Selleck INK1197 in their footstrike pattern does not necessarily mean that this change is permanent. Adopting an FFS pattern places greater demands on the calf musculature.29 Thus, while patients were able to convert to an FFS pattern and significantly reduce their loading rates, additional training and conditioning of the lower leg and foot would be needed to maintain this pattern for longer duration runs. In addition, the increased load on the calf musculature, especially if it occurs suddenly, could put the runner at risk for muscle soreness or foot and ankle injuries resulting from overuse. This further supports the need for proper training, strengthening, and conditioning for a proper transition to an FFS pattern. Results of this study suggest that a runner who contacts the ground with less compliance,

or a higher vertical stiffness during IL, will exhibit a faster rise in VGRF, increasing Selleck HIF inhibitor the loading rate. We found strong correlations between the change in VILS and the changes in VALR and VILR. Both VALR and VILR, as well as VILS significantly decreased from shod running to instructed BF running (Table 2). This suggests that runners decreased their vertical stiffness in order to eliminate impact transients and reduce loading rates. The relationship between stiffness and loading rate is not always apparent in the literature due to the technique used to compute vertical stiffness. Most studies use a constant stiffness, which does not model the transient of the VGRF, thus ignoring the high stiffness during IL. For example, Shih et al.24 reported a significant increase in loading rates between an FFS and an RFS pattern that had an impact transient early in stance. However stiffness was similar between groups. Similarly, Divert et al.30 found no difference in vertical stiffness between the shod and BF runners despite reporting that only three of 12 BF runners demonstrated an impact peak. This is because, in both studies,

stiffness was assessed as an average value across the entire loading phase. The constant stiffness model misrepresents the actual vertical stiffness in cases where an impact transient exists. However, the method introduced by Hunter13 and employed in this study is an important tool that provides a more accurate computation of stiffness, particularly during initial loading. In the current study, we reported a significant reduction in VILS between the shod and BF conditions (mean (|shod| − |BF|) = 14.7 ± 9.8 kN/m, p < 0.00001). However, had the simple constant stiffness model been applied to all steps, ignoring the impact transient, the results would have actually indicated the opposite. We would have seen an increase in VILS from the shod to instructed BF condition (shod: 23.2 ± 3.9 kN/m, BF: 24.9 ± 4.1 kN/m; mean(|shod| − |BF|) = −1.7 ± 2.2 kN/m; p < 0.00001). This increase in VILS during the BF condition would greatly misrepresent what is actually occurring.