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"Super-shoes" are designed to improve endurance running performance by reducing the metabolic demands of running. Although the research on "super-shoes" is still developing and has mostly been studied in male runners, it is not clear how possible mediating factors, such as foot strike pattern, influence the metabolic cost and joint mechanics in competitive female runners. Purpose: The objective of this study is to assess the influence of "super-shoes" on metabolic cost and joint mechanics in competitive female runners and to understand how foot strike patter may influence the footwear effects. Methods: Eighteen competitive female runners ran four 5-min bouts on a force instrumented treadmill at 12.9 km⋅h-1 in 1) Nike Vaporfly Next% 2™(SUPER) and 2) Nike Pegasus 38™(CON) in a randomized and mirrored order. Results: Metabolic power was improved by 4.2% (P < 0.001; d = 0.43) and metatarsophalangeal (MTP) negative work (P < 0.001; d = 1.22), ankle negative work (P = 0.001; d = 0.67), and ankle positive work (P < 0.001; d = 0.97) were all smaller when running in SUPER compared with CON. There was no correlation between foot strike pattern and the between-shoe (CON to SUPER) percentage change for metabolic power (r = 0.093, P = 0.715). Conclusions: Metabolic power improved by 4.2% in "super-shoes" (but only by ~3.2% if controlling for shoe mass differences) in this cohort of competitive female runners, which is a smaller improvement than previously observed in men. The reduced mechanical demand at the MTP and ankle in "super-shoes" are consistent with previous literature and may explain or contribute to the metabolic improvements observed in "super-shoes"; however, foot strike pattern was not a moderating factor for the metabolic improvements of "super-shoes." Future studies should directly compare the metabolic response among different types of "super-shoes" between men and women. [ABSTRACT FROM AUTHOR]

Introduction/Purpose: Shoe longitudinal bending stiffness (LBS) is often considered to influence running economy (RE) and thus, running performance. However, previous results are mixed and LBS levels have not been studied in advanced footwear technology (AFT). The purpose of this study was to evaluate the effects of increased LBS from curved carbon fiber plates embedded within an AFT midsole compared to a traditional running shoe on RE and spatiotemporal parameters. Methods: Twenty‐one male trained runners completed three times 4 min at 13 km/h with two experimental shoe models with a curved carbon fiber plate embedded in an AFT midsole with different LBS values (Stiff: 35.5 N/mm and Stiffest: 43.1 N/mm), and a Control condition (no carbon fiber plate: 20.1 N/mm). We measured energy cost of running (W/kg) and spatiotemporal parameters in one visit. Results: RE improved for the Stiff shoe condition (15.71 ± 0.95 W/kg; p < 0.001; n2 = 0.374) compared to the Control condition (16.13 ± 1.08 W/kg; 2.56%) and Stiffest condition (16.03 ± 1.19 W/kg; 1.98%). However, we found no significant differences between the Stiffest and Control conditions. Moreover, there were no spatiotemporal differences between shoe conditions. Conclusion: Changes in LBS in AFT influences RE suggesting that moderately stiff shoes have the most effective LBS to improve RE in AFT compared to very stiff shoes and traditional, flexible shoe conditions while running at 13 km/h. [ABSTRACT FROM AUTHOR]

In the quest to uncover the underlying mechanisms responsible for the performance-enhancing benefits imparted by advanced footwear technology (AFT), footwear researchers are employing an individual-level approach. In doing so, they hope to unveil individual-specific responses to AFT otherwise masked by a group-level approach. Classifying an individual's response on the basis of running economy (RE) is a logical strategy given that the intended purpose of AFT is to enhance performance; however, caution should be taken when doing so. Metabolic measurement devices are far from perfect, and given the known errors associated with metabolic measurements we would like to reiterate a suggestion first made 40 years ago: when seeking to quantify the interindividual variability of improvement in RE associated with running in AFT, the best practice is to rely on a minimum of two same-day measurements of RE. [ABSTRACT FROM AUTHOR]

Background: Ethylene and vinyl acetate (EVA) and polyether block amide (PEBA) are recently the most widely used materials for advanced footwear technology (AFT) that has been shown to improve running economy (RE). This study investigated the effects of these midsole materials on RE and biomechanics, in both fresh and worn state (after 450 km). Methods: Twenty‐two male trained runners participated in this study. Subjects ran four 4‐min trials at 13 km‧h−1 with both fresh EVA and PEBA AFT and with the same models with 450 km of wear using a randomized crossover experimental design. We measured energy cost of running (W/kg), spatiotemporal, and neuromuscular parameters. Results: There were significant differences in RE between conditions (p = 0.01; n2 = 0.17). There was a significant increase in energy cost in the worn PEBA condition compared with new (15.21 ± 1.01 and 14.87 ± 0.99 W/kg; p < 0.05; ES = 0.54), without differences between worn EVA (15.13 ± 1.14 W/kg; p > 0.05), and new EVA (15.15 ± 1.13 w/kg; ES = 0.02). The increase in energy cost between new and worn was significantly higher for the PEBA shoes (0.32 ± 0.38 W/kg) but without significant increase for the EVA shoes (0.06 ± 0.58 W/kg) (p < 0.01; ES = 0.51) with changes in step frequency and step length. The new PEBA shoes had lower energy cost than the new EVA shoes (p < 0.05; ES = 0.27) with significant differences between conditions in contact time. Conclusion: There is a clear RE advantage of incorporating PEBA versus EVA in an AFT when the models are new. However, after 450 km of use, the PEBA and EVA shoes had similar RE. [ABSTRACT FROM AUTHOR]

Introduction/purpose: Previous results about shoe longitudinal bending stiffness (LBS) and running economy (RE) show high variability. This study aimed to assess the effects of shoes with increased LBS on RE and performance in trained and national runners. Methods: Twenty-eight male runners were divided into two groups according to their 10-km performance times (trained, 38-45 min and national runners, <34 min). Subjects ran 2 - 3 min (at 9 and 13 km·h-1 for trained, and 13 and 17 km·h-1 for national runners) with an experimental shoe with carbon fiber plate to increase the LBS (Increased LBS) and a control shoe (without carbon fiber plate). We measured energy cost of running (W·kg-1) and spatiotemporal parameters in visit one and participants performed a 3000 m time trial (TT) in two successive visits. Results: Increased LBS improved RE in the trained group at slow (11.41 ± 0.93 W·kg-1 vs 11.86 ± 0.93 W·kg-1) and fast velocity (15.89 ± 1.24 W·kg--1 vs 16.39 ± 1.24 W·kg-1) and only at the fast velocity in the national group (20.35 ± 1.45 W·kg-1 vs 20.78 ± 1.18 W·kg-1). The improvements in RE were accompanied by different changes in biomechanical variables between groups. There were a similar improvement in the 3000 m TT test in Increased LBS for trained (639 ± 59 vs 644 ± 61 s in control shoes) and national runners (569 ± 21 vs 574 ± 21 s in control shoes)withmore constant pace in increased LBS compared with control shoes in both groups. Conclusions: Increasing shoe LBS improved RE at slow and fast velocities in trained runners and only at fast velocity in national runners. However, the 3000m TT test improved similarly in both levels of runners with increased LBS. The improvements in RE are accompanied by small modifications in running kinematics that could explain the difference between the different levels of runners. [ABSTRACT FROM AUTHOR]

The recent and rapid developments in track spike innovation have been followed by a wave of record-breaking times and top performances. This has led many to question what role "super spikes" play in improving running performance. To date, the specific contributions of new innovations in footwear, including lightweight, resilient, and compliant midsole foam, altered geometry, and increased longitudinal bending stiffness, to track running performance are unknown. Based on current literature, we speculate about what advantages these features provide. Importantly, the effects of super spikes will vary based on several factors including the event (e.g., 100 m vs. 10,000 m) and the characteristics of the athlete wearing them. Further confounding our understanding of super spikes is the difficulty of testing them. Unlike marathon shoes, testing track spikes comes with a unique challenge of quantifying the metabolic energy demands of middle-distance running events, which are partly anaerobic. Quantifying the exact benefits from super spikes is difficult and we may need to rely on comparison of track performances pre- and post- the introduction of super spikes. [ABSTRACT FROM AUTHOR]

In the wake of the quest to break the 2-h marathon barrier, carbon-fiber plates have become commonplace in marathon racing shoes. Despite the controversy surrounding this shoe technology, studies on the effects of increased longitudinal bending stiffness on running economy report mixed results. Here, we provide a comprehensive review of the current literature on midsole bending stiffness and carbon-fiber plates in distance running shoes, focusing on how longitudinal bending stiffness affects running energetics and lower limb mechanics. The current literature reports changes in running economy with increased longitudinal bending stiffness ranging from ~ 3% deterioration to ~ 3% improvement. In some studies, larger improvements have been observed, but often those shoes varied in many aspects, not just longitudinal bending stiffness. Biomechanically, increased longitudinal bending stiffness has the largest impact on metatarsal–phalangeal (MTP) and ankle joint mechanics. Plate location [top loaded (an insole), embedded (in between midsole foam), and bottom loaded (along the bottom of the shoe)] and geometry (flat/curved) affect joint moments and angular velocities at the MTP and ankle joint differently, which partly explains the mixed running economy results. Further research investigating how carbon-fiber plates interact with other footwear features (such as foam and midsole geometry), scaling of those with shoe size, body mass, and strike pattern, and comparing various plate placements is needed to better understand how longitudinal bending stiffness affects running economy. [ABSTRACT FROM AUTHOR]

Background: We have shown that a prototype marathon racing shoe reduced the metabolic cost of running for all 18 participants in our sample by an average of 4%, compared to two well-established racing shoes. Gross measures of biomechanics showed minor differences and could not explain the metabolic savings.Objective: To explain the metabolic savings by comparing the mechanics of the shoes, leg, and foot joints during the stance phase of running.Methods: Ten male competitive runners, who habitually rearfoot strike ran three 5-min trials in prototype shoes (NP) and two established marathon shoes, the Nike Zoom Streak 6 (NS) and the adidas adizero Adios BOOST 2 (AB), at 16 km/h. We measured ground reaction forces and 3D kinematics of the lower limbs.Results: Hip and knee joint mechanics were similar between the shoes, but peak ankle extensor moment was smaller in NP versus AB shoes. Negative and positive work rates at the ankle were lower in NP shoes versus the other shoes. Dorsiflexion and negative work at the metatarsophalangeal (MTP) joint were reduced in the NP shoes versus the other shoes. Substantial mechanical energy was stored/returned in compressing the NP midsole foam, but not in bending the carbon-fiber plate.Conclusion: The metabolic savings of the NP shoes appear to be due to: (1) superior energy storage in the midsole foam, (2) the clever lever effects of the carbon-fiber plate on the ankle joint mechanics, and (3) the stiffening effects of the plate on the MTP joint. [ABSTRACT FROM AUTHOR]

Background: Reducing the energetic cost of running seems the most feasible path to a sub-2-hour marathon. Footwear mass, cushioning, and bending stiffness each affect the energetic cost of running. Recently, prototype running shoes were developed that combine a new highly compliant and resilient midsole material with a stiff embedded plate.Objective: The aim of this study was to determine if, and to what extent, these newly developed running shoes reduce the energetic cost of running compared with established marathon racing shoes.Methods: 18 high-caliber athletes ran six 5-min trials (three shoes × two replicates) in prototype shoes (NP), and two established marathon shoes (NS and AB) during three separate sessions: 14, 16, and 18 km/h. We measured submaximal oxygen uptake and carbon dioxide production during minutes 3-5 and averaged energetic cost (W/kg) for the two trials in each shoe model.Results: Compared with the established racing shoes, the new shoes reduced the energetic cost of running in all 18 subjects tested. Averaged across all three velocities, the energetic cost for running in the NP shoes (16.45 ± 0.89 W/kg; mean ± SD) was 4.16 and 4.01% lower than in the NS and AB shoes, when shoe mass was matched (17.16 ± 0.92 and 17.14 ± 0.97 W/kg, respectively, both p < 0.001). The observed percent changes were independent of running velocity (14-18 km/h).Conclusion: The prototype shoes lowered the energetic cost of running by 4% on average. We predict that with these shoes, top athletes could run substantially faster and achieve the first sub-2-hour marathon. [ABSTRACT FROM AUTHOR]

A sub-2-hour marathon requires an average velocity (5.86 m/s) that is 2.5% faster than the current world record of 02:02:57 (5.72 m/s) and could be accomplished with a 2.7% reduction in the metabolic cost of running. Although supporting body weight comprises the majority of the metabolic cost of running, targeting the costs of forward propulsion and leg swing are the most promising strategies for reducing the metabolic cost of running and thus improving marathon running performance. Here, we calculate how much time could be saved by taking advantage of unconventional drafting strategies, a consistent tailwind, a downhill course, and specific running shoe design features while staying within the current International Association of Athletic Federations regulations for record purposes. Specifically, running in shoes that are 100 g lighter along with second-half scenarios of four runners alternately leading and drafting, or a tailwind of 6.0 m/s, combined with a 42-m elevation drop could result in a time well below the 2-hour marathon barrier. [ABSTRACT FROM AUTHOR]

Purpose: Our goal was to quantify if small (1%-3%) changes in running economy quantitatively affect distance-running performance. Based on the linear relationship between metabolic rate and running velocity and on earlier observations that added shoe mass increases metabolic rate by ~1% per 100 g per shoe, we hypothesized that adding 100 and 300 g per shoe would slow 3000-m time-trial performance by 1% and 3%, respectively. Methods: Eighteen male sub-20-min 5-km runners completed treadmill testing, and three 3000-m time trials wearing control shoes and identical shoes with 100 and 300 g of discreetly added mass. We measured rates of oxygen consumption and carbon dioxide production and calculated metabolic rates for the treadmill tests, and we recorded overall running time for the time trials. Results: Adding mass to the shoes significantly increased metabolic rate at 3.5 m⋅s-1 by 1.11% per 100 g per shoe (95% confidence interval = 0.88%-1.35%). While wearing the control shoes, participants ran the 3000-m time trial in 626.1 ± 55.6 s. Times averaged 0.65% ± 1.36% and 2.37% ± 2.09% slower for the +100-g and +300-g shoes, respectively (P < 0.001). On the basis of a linear fit of all the data, 3000-m time increased 0.78% per added 100 g per shoe (95% confidence interval = 0.52%-1.04%). Conclusion: Adding shoe mass predictably degrades running economy and slows 3000-m time-trial performance proportionally. Our data demonstrate that laboratory-based running economy measurements can accurately predict changes in distance-running race performance due to shoe modifications. [ABSTRACT FROM AUTHOR]

An Online First version of this article was made available online at https://link.springer.com/article/10.1007/s40279-017-0811-2 on 16 November 2017. An error was subsequently identified in the article, and the following correction should be noted: [ABSTRACT FROM AUTHOR]