S. Reynolds1, L. Hastert1, I. Matthews1, N. Nodland1, A.D. Gidley2, & B.W. Wilkins1

1Gonzaga University, Spokane, WA

2Western Oregon University, Monmouth, OR

Running shoes with midsole carbon fiber (CF) plates are often worn by long-distance runners, which has resulted in measurable improvements in running performance in elite athletes. PURPOSE: This study aims to explore the effect of midsole CF plates on the performance of non-elite runners by evaluating variables such as foot stiffness, leg stiffness, and ground reaction forces (GRF). METHODS: 30 runners were recruited: 12 males (20.75 ± 0.62 years) and 18 females (22.94 ± 5.06 years). Foot arch height, a proxy for foot stiffness, was determined by performing a wet test. Following a warmup (400m) in their own shoes at their preferred pace, runners ran 800m twice, each in one of two shoes: Pegasus or Next% (with CF plates). The order was randomized to reduce the potential effects of fatigue. Step frequency was controlled to match preferred rate via a metronome. Wearable gait analysis pods were worn to collect biomechanical data during all trials. RESULTS: Stride length was greater (p < 0.001) in Next% (2.99 ± 0.50 m) than the Pegasus (2.87 ± 0.48 m). Foot strike pattern while wearing Pegasus was on average more midfoot (9.20 ± 3.44) whereas in Next% foot strike pattern was more forefoot (9.96 ± 3.35) (p < 0.05). Pronation excursion angle was more negative (p<0.001) in the Next% shoes (-19.89 ± 6.18°) than the Pegasus (-13.45 ± 5.35°). Peak GRF was significantly greater (p = 0.028) in the Next% shoes (3.76 ± 0.71 BW) than the Pegasus (3.63 ± 0.63 BW). Leg stiffness was not significantly different between Next% shoes (7.47 ± 1.98 kN/m) and Pegasus shoes (7.49 ± 1.67 kN/m). CONCLUSIONS: While wearing shoes with CF plates, ground reaction forces were greater, regardless of sex or arch height. Subjects also transitioned to a forefoot foot strike pattern while wearing CF plates (regardless of sex or arch type), which has been found to be associated with faster running. Interestingly, runners with low arches landed with more of a forefoot pattern. Across all comparisons, leg stiffness was not found to be significantly different, indicating the adaptability of the body to different running shoes. Ultimately, CF plates were found to improve running performance in non-elite runners.

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