22/02/2026
Large individual variability was observed in both populations when using AFT compared with a traditional racing flat.
- World-class Kenyan runners showed responses ranging from a ~11.4% improvement to an ~11.3% worsening in running economy.
- Amateur European runners showed a narrower range, from a ~9.7% improvement to a ~1.1% worsening.
Despite similar mean trends, not all athletes benefited, and some performed worse in AFT despite its theoretically advantageous design.
Meta-analysis confirmed an overall statistically significant, moderate improvement in running economy with AFT compared to traditional racing flats (standardised effect size ≈ −0.58).
Speed-dependent effects were evident:
- Small effects at very low speeds
- Moderate effects at low–moderate speeds
- Large effects at high speeds, suggesting AFT mechanisms are more effective under higher mechanical and metabolic demands.
Importantly, the meta-analysis reinforced the presence of substantial individual variability, even when pooled effects were favourable.
The findings strongly challenge the assumption that AFT provides a uniform performance advantage, particularly in elite runners.
World-class Kenyan athletes, already highly economical may have less scope for improvement, or may respond differently due to anthropometrics, biomechanics, neuromuscular strategies, or prior shoe adaptation.
The results support a personalised approach to footwear selection, rather than blanket recommendations, especially for elite and highly trained athletes.
From a clinical and applied biomechanics perspective, the study highlights the importance of individual testing, familiarisation, and integration with gait mechanics, load tolerance, and performance goals.
Variability in Running Economy of Kenyan World-Class and European Amateur Male Runners with Advanced Footwear Running Technology: Experimental and Meta-analysis Results
Melanie Knopp et al. Sports Med. 2023
