Enhanced shoe cushioning : are they more comfortable and better in impact attenuation during level and downhill running?

Rationale/Objectives: A relatively new type of footwear, known as the maximalist (MAXI), features an extra thick layer of ethyl vinyl acetate midsole for comfort enhancement and impact attenuation. The scientific evidence on the effectiveness of such cushioning, however, was inconsistent. Furthermore, previous studies only tested MAXI during level ground running but it was designed for trail runners. The function of MAXI might be better reflected during downhill running. Hence, this study compared the subjective comfort and impact loading between MAXI and standard running shoes (STAN) in both level and downhill running. Methods: Twenty-five runners (14 males and 11 females) completed running trials in the two footwear conditions on a level and a 10%-declined instrumented treadmill (AMTI, Watertown, MA, USA) in a randomized order. Using a validated visual-analog scale, runners rated the footwear comfort immediately after each trial. Average (ALR) and instantaneous loading rates (ILR) were calculated and averaged across all footfalls in the last minute of each running trial. Results: There were significant interactions between footwear and running conditions on comfort (p=0.043), ALR (p=0.031) and ILR (p=0.033). Simple main effects of footwear were found in comfort (p=0.001, Cohen's d=0.78) and ILR (p=0.043, Cohen's d=0.49) under the downhill running condition. Yet, comfort and loading rates (p>0.328, Cohen's d=0.05-0.26) were comparable between footwear conditions during level running. Conclusions: The effect of MAXI on comfort and impact loading differed between level and downhill running. The additional cushioning in MAXI could enhance comfort during downhill running but did not appear to provide extra loading protection.