Are super shoes a super placebo? A randomised crossover trial in female recreational runners

We examined the potential placebo effect of advanced footwear technology (AFT) on running economy (RE) and perceptual measures while monitoring biomechanics. Twenty-four female recreational runners completed 4 × 6-minute RE trials in two pairs of women’s Nike ZoomX Vaporfly Next% 2. One pair was described as performance-enhancing super shoes with AFT worn by elite athletes, and the other pair was spray-painted black and described as ‘knock-off’ AFT shoes. Oxygen consumption (difference: −0.05 ± 0.47 mL·kg⁻¹·min⁻¹, <i>d</i> = −0.02), energy cost (difference: −0.02 ± 0.17 W·kg⁻¹, <i>d</i> = −0.03), and discrete biomechanical variables were not significantly different between conditions. There were no significant differences between shoes in lower-extremity angular and angular velocity curves based on statistical parametric mapping. Overall comfort (100-mm visual analogue scale) was significantly greater (14.6 ± 15.0 mm, <i>d</i> = 0.94) in the performance-enhancing than ‘knock-off’ condition, with most runners (87.5%) preferring the former. Runners perceived running as more enjoyable and less difficult and perceived an improved running performance and lower injury risk in the performance-enhancing shoe (<i>d</i> = 0.72–1.16). While no significant physiological or biomechanical differences were observed, a significant placebo effect was apparent for both perceived comfort and perceived performance based on shoe description alone.