The Influence of Footwear Midsole Thickness on Running Economy and Frontal Plane Ankle Stability

A Review of the Potential Effects of the World Athletics Stack Height Regulation on the Footwear Function and Running Performance

“…According to the 1% rule per 100 g added [20,21], Bertschy et al [18] reported that the running economy deteriorated by 0.5% per 10 mm for the EVA midsole material tested and by 0.34% per 10 mm for the NITRO midsole material. Likewise, the conditions tested by Barrons et al [17] impaired 0.33% per 10 mm added. Therefore, according to the largest stack height limitation established (i.e., 20 mm), running on an illegal shoe of 40 mm would result in a 0.7 to 1.0% detriment in running economy from the shoe mass standpoint.…”

“…Despite being a highly debated topic [10][11][12][13], the effect of stack height on running performance has been scarily analyzed. The results provided by Barrons et al [17] and Bertschy et al [18] are the unique published data regarding this topic (See references for further details). On the one hand, Barrons et al [17] compared four identical models differing only in the midsole thickness (i.e., 35, 40, 45, 50 mm).…”

“…The results provided by Barrons et al [17] and Bertschy et al [18] are the unique published data regarding this topic (See references for further details). On the one hand, Barrons et al [17] compared four identical models differing only in the midsole thickness (i.e., 35, 40, 45, 50 mm). After matching shoe weights, no significant differences in running economy were observed.…”

“…This was performed by adding lead beads to the same footwear model [19,21] or to the feet [20]. In order to illustrate the effects of reducing the stack height on shoe mass, a linear regression analysis was traced to the shoe mass and stack heights reported by Barrons et al [17] in Figure 2. In addition, the midsole thickness and shoe mass of 15 common racing footwear models were searched on a specialized running footwear website [22] and reported in Figure 2.…”

“…Four studies were identified that analyze the effect of the midsole properties on a running performance outcome while maintaining the rest of the footwear features similarly [17,18,23,24]. This was performed by using the same footwear prototype with different midsole stack heights [17,18] or materials [24] and by running barefoot on a standard and cushioned surface [23].…”