By Rob Shaul
Overview
Two new studies—Kobayashi et al. (2026) in Frontiers in Sports and Active Living and Jaboulay & Giandolini (2025) in Footwear Science—together redefine what we know about the role of carbon plates and longitudinal stiffness in running footwear.
The first study, a large meta-analysis of 14 trials, confirmed that carbon-plated shoes improve running economy by 2–3% on flat, consistent terrain—an effect that translates to a ~1% improvement in marathon performance.
The second, a controlled lab study funded by shoe-makerSalomon, showed that those same carbon plates provide no benefit on trails or uphill terrain and may actually increase energy cost by 2%.
The Road Running Data: 2-3% Efficiency Gains
The 2026 Frontiers meta-analysis by Kobayashi and colleagues analyzed 271 runners across 14 crossover studies comparing carbon-plated and traditional shoes. The findings confirmed claims from Nike and other “super” shoe makers that carbon-plated footwear reduces metabolic cost, improves oxygen efficiency, and enhances running economy on smooth surfaces.
The results showed an average 2.5–3% improvement in running economy—a measurable, real-world advantage translating to about 1–2 minutes faster in a marathon. All on the research was conducted on a level surface, and most on treadmills.
Key Findings:
- Running economy: +2.9% improvement
- Metabolic cost: −2.6%
- Oxygen consumption: −2.8%
- Energetic cost of transport: −2.6%
These benefits stem from how carbon plates increase longitudinal bending stiffness, allowing the shoe to act as a rigid lever that improves propulsion efficiency at toe-off. Combined with PEBA-based foam midsoles—like Nike’s ZoomX or Saucony’s PWRRUN PB—this creates a spring-lever system that stores and returns energy efficiently.
However, the study included two caveats: the carbon plate’s contribution cannot be isolated from the foam and rocker, and body mass affects the benefit. Heavier runners (>165 lb) often compress the foam more deeply, diminishing its rebound and effectively neutralizing the plate’s advantage.
Also, it’s unclear how much of the increase in performance comes from the carbon plate, the foam, or the shoe rocker profile. All three components work as a “system” to improve efficiency.
The authors suggested the next generation of footwear might feature mass-specific plate stiffness and foam density, designed to optimize performance for different body weight ranges.
The Trail Running Data: Carbon Plates Hurt Efficiency the Uphills
In contrast, the 2025 Footwear Science study by Jaboulay and Giandolini—conducted with Salomon’s Research & Development team—found that adding a carbon plate to trail shoes offered no metabolic benefit on level ground and actually increased energy cost by ~2% during uphill running.
Ten trained trail runners completed treadmill trials under two conditions—plated and non-plated—on both flat (11.6 km/h) and uphill (7.8 km/h) grades, as well as on unstable terrain simulating technical trail conditions. Findings:
- Level terrain: No difference in running economy.
- Uphill terrain: Metabolic cost increased 2% in plated shoes.
- Unstable terrain: No improvement in joint stability, control, or proprioception.
- Runners reported no increase in comfort or ground feel.
Biomechanically, the carbon plate neither stabilized the ankle nor improved joint control. In fact, the increased stiffness may have limited the foot’s ability to conform to uneven terrain, forcing runners to expend additional energy to stabilize their gait.
The authors concluded that while increased stiffness aids propulsion on level, uniform surfaces, it becomes a liability in technical, low-speed conditions—precisely the environments where trail and mountain runners operate.
Citations:
Kobayashi, E. N., de Toledo, R. R. F., de Almeida, M. O., Sprey, J. W. C., & Jorge, P. B. (2026). Metabolic effects of carbon-plated running shoes: A systematic review and meta-analysis. Frontiers in Sports and Active Living, 7, 1710224.
Jaboulay, C., & Giandolini, M. (2025). Effect of increased bending stiffness on running economy and joint biomechanics in uphill running and running on unstable terrain. Footwear Science, 17(1), 19–27.