Gymnastik- och idrottshögskolan, GIH

Advanced footwear technology (AFT) has reshaped distance running performance, but concerns remain regarding its potential biomechanical implications discussed in the injury literature. This study investigates whether the improved running economy provided by AFT occurs without systematic increases in biomechanical variables that have been discussed in the literature in relation to running-related injuries. Thirty recreational runners completed treadmill trials in three shoe conditions: Nike Vaporfly 3 (NV3; PEBA foam + carbon-fiber plate), Nike Invincible 3 (NI3; PEBA foam), and Brooks Levitate 5 (BL5; TPU foam). Running in each shoe was conducted at 10.8 and 12.6 km·h^-1. Oxygen uptake, heart rate (HR), and biomechanical variables related to injury risk (vertical average loading rate (VALR), vertical instantaneous loading rate (VILR), braking impulse, contact time, and contralateral pelvic drop) were analyzed using a two-way repeated measures ANOVA. Compared with both NI3 and BL5, NV3 significantly reduced oxygen uptake (mean difference: -1.749 ± 0.259 and -1.914 ± 0.215 mL·kg^-1·min^-1, respectively, p < 0.001) and HR (mean difference: -4.750 ± 0.637 and -5.433 ± 0.720 beats·min^-1, respectively, p < 0.001). The BL5 exhibited substantially higher VALR and VILR than both NV3 and NI3 (all p < 0.001) and NV3 exhibited significantly higher VALR values than NI3 (p = 0.006). Braking impulse was lowest in NI3, and no significant shoe condition effects were observed for contralateral pelvic drop or contact time. AFT shoes combining PEBA foam with a carbon-fiber plate improved running economy without increases in the biomechanical variables examined, which have been discussed in the literature in relation to running-related injuries. AFT shoes can enhance metabolic performance, while PEBA-only shoes may better suit sessions focused on cushioning and impact management.

Advanced footwear technology (AFT) has improved running economy in distance runners, yet individual responsiveness varies widely. Sex differences and anthropometric characteristics have been proposed as potential factors, but evidence remains limited. This study investigated whether sex-based differences exist in the response to running in an AFT shoe compared to a non-AFT control shoe. The response was measured by means of the change in energy cost (EC), ΔEC, and it was assessed whether isolated anthropometric characteristics could predict ΔEC in highly trained long-distance runners. Fifteen female and fifteen male runners completed treadmill running economy tests at 60%, 70%, and 80% of their VO_2peak speed in AFT and non-AFT shoes. Anthropometric measures investigated were height, body mass, foot length, femur and tibia length, and Achilles tendon length. Females showed significantly lower absolute EC than males across all speeds and shoe conditions (p < 0.05), but ΔEC did not differ between sexes (p = 0.5). Average individual ΔEC ranged from 1.1% to 6.4% in females and 0.2% to 8.7% in males. No anthropometric variable could significantly predict ΔEC in sex-stratified analyses. Highly trained runners exhibit large inter-individual variability in responsiveness to AFT shoes, but neither sex nor isolated anthropometric traits explained these differences in this study. These findings highlight the complexity of AFT individualization and suggest that personalization should not be based solely on sex or the anthropometric characteristics investigated in this study.