The Acute and Chronic Effects of Highly Cushioned Shoes on Loading Characteristics in Recreational Runners

Abstract

Highly cushioned shoes (HCS) are a popular choice for road and trail runners. Manufacturers suggested extra cushioning potentially reduces injury rates through superior shock absorption, implying less impact upon foot strike versus standard cushioned shoes (SCS). PURPOSE: To examine the effects of a 4-week HCS intervention on running- related impact forces in adult recreational runners. METHODS: Twenty-nine healthy runners (18-60 yrs of age) who had never worn HCS were randomized to either HCS intervention (INV) or SCS control (CON) groups, and wore HCS or SCS a majority of each training week. During pre and post-tests in a lab, all participants wore SCS first, followed by HCS, while running overground at a self-selected, monitored pace and striking embedded force plates in up to 30 total trials/session, at least 10 trials/shoe, to obtain impact peak (PK1) and active peak (PK2) forces, instantaneous loading rate (ILR), average loading rate (ALR), and contact time (CT). Runners recorded daily training data for 4-weeks. A repeated measures, mixed ANOVA was utilized to detect differences between shoes and groups. RESULTS: At pretesting, when comparing pooled data in SCS to HCS, no significant differences were found and all effect sizes were small. The acute (i.e., at baseline testing) response to the shoes yielded no statistically significant difference between shoe types. Additionally, there was no statistically significant difference between shoes over time (p >0.05) or between the groups over time (p>0.05). ILR was the variable closest to significance (p=0.066) with a small effect size (0.120). CONCLUSION: HCS do not cause alterations in ground reaction forces over a short-term (4-week) habituation period in recreational runners. Interestingly, there was a high drop-out rate in the HCS group of 18% due to self-reported adverse reactions (e.g., numbness, bruising, pain), but results indicated no differences in loading characteristics between shoe types. Still, transitioning to HCS should be a gradual process; however, more research is warranted in long-term HCS usage.