Insole effects on impact loading during walking

Abstract

Impact loading during walking has been associated with overuse related musculoskeletal disorders, such as osteoarthritis. This study was designed to determine the effect of two shoe insole designs on impact-related loading during walking. In total, 22 healthy adults walked along a 10-m walkway in three different insole conditions: (i) no insole; (ii) flat material insole; (iii) heel-cup insole. Impact forces at the ground were determined and estimated at the knee in a subset of participants (n = 14). Repeated measures ANOVA revealed a significant reduction in peak vertical ground reaction force (vGRF) with the flat material insole compared with the no insole and heel-cup conditions (p = 0.001). No differences between conditions were observed in vGRF loading rate (p > 0.05). Peak impact force at the knee was reduced with flat material insoles and heel-cup insoles (p < 0.05). These data indicate that reductions in impact forces during walking are dependent upon insole design.

Statement of Relevance: This study provides new evidence that impact loads are reduced with shoe insoles during walking. High impact loads are implicated in the development and progression of knee pathologies, including osteoarthritis. Thus, these findings indicate that insole use may be beneficial for various musculoskeletal disorders, including key public health problems such as osteoarthritis.

Keywords:

• biomechanics
• gait
• ground reaction force
• orthotics
• overuse injury

Acknowledgements

The authors would like to acknowledge Milena Simic for her assistance with data collection, Ben Metcalf and Tim Wrigley for their technical assistance (all University of Melbourne, Australia), and Dan Low (University of Exeter, UK) for providing the Shore A hardness ratings.