It may be that the results have been influenced by typically homogeneous test subject groups, which were mostly young sporty male university students. However, the results of many initial studies have shown that this is not the case. This result is surprising because it was assumed that one could easily reduce the impact force peaks with soft shoe midsoles. However, this strategy was associated with the surprising result that in many studies, shoe midsole hardness had little to no effect on impact force peaks during landing. One of the most popular approaches was to change the hardness of the shoe midsole. Several strategies have been proposed to reduce impact loading. As a result, the development of shoe cushioning guidelines evolved as repetitive loading became a concern for injury risk during running. Some have argued that increased impact forces are associated with the development of specific running injuries. Impact forces during heel-toe running have been discussed in the scientific literature for many years. They did not have a role in the data analysis, decision to publish, or preparation of this manuscript.Д¬ompeting interests: The authors have declared that no competing interests exist. The funders had a role in the study design. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedДata Availability: All relevant data are within the paper and its Supporting Information files.ДЇunding: This study was part of a project sponsored by Decathlon (now Oxylane Group, France). Received: DecemAccepted: MaPublished: April 21, 2015Д¬opyright: В© 2015 Baltich et al. PLoS ONE 10(4):ДЄcademic Editor: Jose Manuel Garcia Aznar, University of Zaragoza, SPAIN The results from this study may provide useful information regarding the development of cushioning guidelines for running shoes.Д¬itation: Baltich J, Maurer C, Nigg BM (2015) Increased Vertical Impact Forces and Altered Running Mechanics with Softer Midsole Shoes. The results from this study confirm that shoe midsole hardness can have an effect on vertical impact force peaks and that this may be connected to the hardness of the landing. Apparent knee joint stiffness increased for soft (1.06BWm/Вє x 100 (0.04)) midsole compared to the medium (0.95BWm/Вє x 100 (0.04)) and hard (0.96BWm/Вє x 100 (0.04)) midsoles for female participants.

Similar results were found for the apparent ankle joint stiffness where apparent stiffness increased as the shoe midsole hardness decreased (soft: 2.08BWm/Вє x 100 (0.05), medium: 1.92 BWm/Вє x 100 (0.05), hard: 1.85 BWm/Вє x 100 (0.05)). The vertical impact peak increased as the shoe midsole hardness decreased (mean(SE) soft: 1.70BW(0.03), medium: 1.64BW(0.03), hard: 1.54BW(0.03)). 93 runners (male and female) aged 16-75 years ran at 3.33 В± 0.15 m/s on a 30 m-long runway with soft, medium and hard midsole shoes. The purpose of this study was to quantify the effect of shoe midsole hardness on apparent ankle and knee joint stiffness and the associated vertical ground reaction force for age and sex subgroups during heel-toe running. An increase in apparent joint stiffness could result in a harder landing, which should result in increased vertical impact peaks during running.

However, it is currently unknown how apparent joint stiffness is affected by shoe midsole hardness. This conclusion is based partially on results from experimental data using homogeneous samples of participants that found no difference in vertical impact peaks when running in shoes with different midsole properties. To date it has been thought that shoe midsole hardness does not affect vertical impact peak forces during running.

H force shoes