Does Midsole Foam Energy Return Influence Fatigue, Muscle Soreness, And Training Load During Running Training?

“Super-shoes” appear to contribute to improvements in marathon running performance from reduced energetic costs but their construct, especially their compliant midsole foam with high energy return, may also help reduce muscle soreness following heavy training periods. Lower soreness and fatigue may allow runners to handle higher training loads to further improve marathon performance. PURPOSE: To compare self-reported muscle soreness, fatigue, and perceived effort during a heavy training period between footwear with midsole foam of low and high energy return in distance runners. METHODS: 87 trained runners (47 women) were provided two pairs of running shoes with low (LOW) and higher (HIGH) midsole foam energy return and an individualized 48-day running program based on prior reported training. Training consisted of two identical 24-day plans including 14 days of de-loading followed by 10 days of intense training to elicit muscle soreness and fatigue. The two 24-day periods were randomized and followed a cross-over design in both shoes. Training data were recorded from personal watches and muscle soreness (/100), general fatigue (/100), and session rate of perceived exertion (sRPE; /100) were obtained from surveys each day. Wilcoxon signed rank tests were used to compare soreness and fatigue, and paired sample t-tests were used to compare training load data. RESULTS: Plantarflexor soreness during the intense training period was (~19%) lower in the HIGH compared to LOW shoe (Table 1). It is important to note that the reported calf soreness values were generally low (i.e., below 20 out of 100). Soreness of other muscles, fatigue or training load variables were not different between shoes. CONCLUSIONS: Findings from the study suggest that midsole foam with higher energy return slightly reduces calf soreness during intense training but does not influence self-reported fatigue, soreness of other muscles, or training load.This project was funded with support from New Balance