Midsole Bending Stiffness Research Articles

The Relationship Between Foot Arch Stiffness, Midsole Bending Stiffness, And Running Economy

The Relationship Between Foot Arch Stiffness, Midsole Bending Stiffness, And Running Economy

Do Carbon-Plated Running Shoes with Different Characteristics Influence Physiological and Biomechanical Variables during a 10 km Treadmill Run?

Footwear properties can influence physiological and biomechanical variables, which may lead to positive changes in distance running performance. One innovative development in running shoe technology is adding carbon fiber plates to increase midsole bending stiffness. However, there are only a few studies investigating the influence of shoe conditions on both physiological and biomechanical variables, simultaneously, when running for longer than 5 min or for distances > 1 km. Hence, the purpose of the current study was to investigate the influence of different running shoe concepts with carbon fiber plates on physiological and biomechanical parameters during a 10 km treadmill run. Twenty-three athletes participated in the study, which comprised four measurement days for each subject. On the first day, subjects performed a treadmill exhaustion test to determine maximum oxygen uptake. On the second, third, and fourth days, each subject ran 10 km at 70% of their maximum oxygen uptake in one of three shoe models. Significant differences were found between the shoe conditions for the biomechanical parameters, but not for the physiological parameters. It seems that runners adjusted their running styles to the shoe conditions during the 10 km run to reduce the load on the lower extremities without compromising their endurance performance. These results may have practical implications for runners, coaches, and shoe manufacturers.

The 'Ride' Feeling during Running under Field Conditions-Objectified with a Single Inertial Measurement Unit.

Foot rollover and the ‘ride’ feeling that occurs during heel–toe transition during running have been investigated mostly in laboratory settings due to the technical requirements of ‘golden standard’ measurement devices. Hence, the purpose of the current study was to investigate ‘ride’ and rollover with a heel cap-mounted inertial measurement unit (IMU) when running under field conditions to get realistic results. Twenty athletes ran on a 1 km outdoor track with five different shoe conditions, only differing in their midsole bending stiffness. The peak angular velocity (PAV) in the sagittal plane of the shoe was analyzed. The subjective evaluation of the ‘ride’ perception during heel–toe transition was rated on a visual analogue scale. The results revealed that PAV and ‘ride’ varied for the different shoes. The regression analysis showed that PAV has a significant impact on the ‘ride’ rating (R2 = 0.952; p = 0.005). The shoe with a medium midsole bending stiffness had the lowest value for PAV (845.6 deg/s) and the best rating of perceived ‘ride’ on average. Our results show that IMU can be used as a low-cost method to investigate the heel–toe transition during field-running. In addition, we found that midsole bending stiffness influenced PAV and the subjective feeling of ‘ride’.

Effects of midsole bending stiffness and shape on lower extremity joint work per distance in level, incline and decline running

Midsole bending stiffness (MBS) and forefoot curvature are two essential footwear design features that can alter the joint work of the lower extremity in distance running (Cigoja et al., 2019; Fari...

Energetics and Biomechanics of Running Footwear with Increased Longitudinal Bending Stiffness: A Narrative Review

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.

Increasing the midsole bending stiffness of shoes alters gastrocnemius medialis muscle function during running

In recent years, increasing the midsole bending stiffness (MBS) of running shoes by embedding carbon fibre plates in the midsole resulted in many world records set during long-distance running competitions. Although several theories were introduced to unravel the mechanisms behind these performance benefits, no definitive explanation was provided so far. This study aimed to investigate how the function of the gastrocnemius medialis (GM) muscle and Achilles tendon is altered when running in shoes with increased MBS. Here, we provide the first direct evidence that the amount and velocity of GM muscle fascicle shortening is reduced when running with increased MBS. Compared to control, running in the stiffest condition at 90% of speed at lactate threshold resulted in less muscle fascicle shortening (p = 0.006, d = 0.87), slower average shortening velocity (p = 0.002, d = 0.93) and greater estimated Achilles tendon energy return (p ≤ 0.001, d = 0.96), without a significant change in GM fascicle work (p = 0.335, d = 0.40) or GM energy cost (p = 0.569, d = 0.30). The findings of this study suggest that running in stiff shoes allows the ankle plantarflexor muscle–tendon unit to continue to operate on a more favourable position of the muscle’s force–length–velocity relationship by lowering muscle shortening velocity and increasing tendon energy return.

Can changes in midsole bending stiffness of shoes affect the onset of joint work redistribution during a prolonged run?

PurposeThis study aimed to investigate if changing the midsole bending stiffness of athletic footwear can affect the onset of lower limb joint work redistribution during a prolonged run. MethodsFifteen trained male runners (10-km time of <44 min) performed 10-km runs at 90% of their individual speed at lactate threshold (i.e., when change in lactate exceeded 1 mmol/L during an incremental running test) in a control and stiff shoe condition on 2 occasions. Lower limb joint kinematics and kinetics were measured using a motion capture system and a force-instrumented treadmill. Data were acquired every 500 m. ResultsProlonged running resulted in a redistribution of positive joint work from distal to proximal joints in both shoe conditions. Compared to the beginning of the run, less positive work was performed at the ankle (approximately 9%; p ≤ 0.001) and more positive work was performed at the knee joint (approximately 17%; p ≤ 0.001) at the end of the run. When running in the stiff shoe condition, the onset of joint work redistribution at the ankle and knee joints occurred at a later point during the run. ConclusionA delayed onset of joint work redistribution in the stiff condition may result in less activated muscle volume, because ankle plantar flexor muscles have shorter muscles fascicles and smaller cross-sectional areas compared to knee extensor muscles. Less active muscle volume could be related to previously reported decreases in metabolic cost when running in stiff footwear. These results contribute to the notion that footwear with increased stiffness likely results in reductions in metabolic cost by delaying joint work redistribution from distal to proximal joints.

The Effects of Increased Midsole Bending Stiffness of Sport Shoes on Muscle-Tendon Unit Shortening and Shortening Velocity: a Randomised Crossover Trial in Recreational Male Runners

BackgroundIndividual compliances of the foot-shoe interface have been suggested to store and release elastic strain energy via ligamentous and tendinous structures or by increased midsole bending stiffness (MBS), compression stiffness, and resilience of running shoes. It is unknown, however, how these compliances interact with each other when the MBS of a running shoe is increased. The purpose of this study was to investigate how structures of the foot-shoe interface are influenced during running by changes to the MBS of sport shoes.MethodsA randomised crossover trial was performed, where 13 male, recreational runners ran on an instrumented treadmill at 3.5 m·s−1 while motion capture was used to estimate foot arch, plantar muscle-tendon unit (pMTU), and shank muscle-tendon unit (sMTU) behaviour in two conditions: (1) control shoe and (2) the same shoe with carbon fibre plates inserted to increase the MBS.ResultsRunning in a shoe with increased MBS resulted in less deformation of the arch (mean ± SD; stiff, 7.26 ± 1.78°; control, 8.84 ± 2.87°; p ≤ 0.05), reduced pMTU shortening (stiff, 4.39 ± 1.59 mm; control, 6.46 ± 1.42 mm; p ≤ 0.01), and lower shortening velocities of the pMTU (stiff, − 0.21 ± 0.03 m·s−1; control, − 0.30 ± 0.05 m·s−1; p ≤ 0.01) and sMTU (stiff, − 0.35 ± 0.08 m·s−1; control, − 0.45 ± 0.11 m·s−1; p ≤ 0.001) compared to a control condition. The positive and net work performed at the arch and pMTU, and the net work at the sMTU were significantly lower in the stiff compared to the control condition.ConclusionThe findings of this study showed that if a compliance of the foot-shoe interface is altered during running (e.g. by increasing the MBS of a shoe), the mechanics of other structures change as well. This could potentially affect long-distance running performance.

Acute Effects of Midsole Bending Stiffness on Lower Extremity Biomechanics during Layup Jumps

Purpose: This study aims to investigate the acute effects of shoe midsole stiffness on the joint biomechanics of the lower extremities during specific basketball movements. Methods: Thirty participants wearing stiff midsole shoes (SS) and control shoes (CS) performed layup jumps (LJs) while the kinematics and ground reaction forces were simultaneously collected via the Vicon motion capture system and Kistler force plates. Furthermore, the joint angles, range of motion (ROM), joint power, joint energy, and jump height were calculated. Results: No significant differences were observed between SS and CS conditions for both jump height and the metatarsophalangeal (MTP) joint biomechanics except that the minimum angular velocity of the MTP joint was significantly lower in SS the condition. However, the ROM in the ankle joint was significantly greater in the SS condition than in the CS condition (p &lt; 0.05). Additionally, the maximum plantarflexion power, energy absorption (EA), and energy generation (EG) in the ankle joint were significantly greater in the SS condition than in the CS condition (p &lt; 0.05). Compared with the CS condition, jump height in the SS condition did not increase. Conclusion: During a single LJ, the longitudinal midsole stiffness did not influence the jump height and MTP joint biomechanical patterns but significantly increased the maximum power, EA, and EG during the push-off phase of the ankle joint. These preliminary results indicate that wearing SS could change the ankle joint mechanical patterns by modulating the lower extremity kinetic chain, and may enhance muscle strength in the ankle.

Using musculoskeletal modelling to understand the energetic cost of running with different footwear

Introduction: A critical factor in long-distance running performance is the energy cost required to cover a specified distance. It has been suggested that the longitudinal midsole bending stiffness of a shoe can influence this cost. One limitation of current methods to assess energy cost is that it has to be measured well below a typical race pace, making it difficult to predict race performance. Estimating energy cost with a musculoskeletal model is a method to overcome this limitation. The purpose of this study was to determine the sensitivity of musculoskeletal modelling to detect changes in energy cost of running across speeds in different footwear.

Does increased midsole bending stiffness of sport shoes redistribute lower limb joint work during running?

ObjectivesTo investigate if lower limb joint work is redistributed when running in a shoe with increased midsole bending stiffness compared to a control shoe. DesignWithin-subject with two conditions: (1) commercially available running shoe and (2) the same shoe with carbon fibre inserts to increase midsole bending stiffness. MethodsThirteen male, recreational runners ran on an instrumented treadmill at 3.5m/s in each of the two shoe conditions while motion capture and force platform data were collected. Positive and negative metatarsophalangeal (MTP), ankle, knee, and hip joint work were calculated and statistically compared between conditions. ResultsRunning in the stiff condition (with carbon fibre inserts) resulted in significantly more positive work and less negative work at the MTP joint, and less positive work at the knee joint. ConclusionsIncreased midsole bending stiffness resulted in a redistribution of positive lower limb joint work from the knee to the MTP joint. A larger MTP joint plantarflexor moment due to increased vGRF at the instant of peak positive power and an earlier onset of MTP joint plantarflexion velocity were identified as the reasons for lower limb joint work redistribution.

Effects of midsole bending stiffness on arch deformation of the human foot during running

It has been postulated that the arch of the human foot stores and releases elastic strain energy during locomotion via ligamentous and tendinous structures (Ker, Bennett, Bibby, Kester, & Alexander...

The effects of midsole bending stiffness on ball speed during maximum effort soccer kicks

The soccer kick is the most prominent movement in soccer. Kicking performance depends on two major factors: kicking accuracy and ball speed. During the soccer kick, momentum is transferred from the foot/cleat to the ball. This interplay between the foot/cleat and the ball can be modelled as a mixture of ‘impulse-like’ and ‘throwing-like’ components. While kicking the ball, the metatarsophalangeal (MTP) joint and the cleat experience deformation. This deformation can be reduced by increasing the bending stiffness of the cleat’s midsole. Therefore, the purpose of this study was to investigate experimentally the influence of midsole bending stiffness on ball speed during maximum effort soccer kicks. Twenty male subjects (mean ± SD; age: 29.5 ± 5.6 years, height: 175.5 ± 6.4 cm, mass: 74.3 ± 8.4 kg) performed six maximum effort soccer kicks in five stiffness conditions. Kinematic data were collected using an optical motion capture system consisting of eight high-speed cameras, and ball speed was recorded using a radar gun. There was no significant difference in the average ball speed between the five stiffness conditions when all subjects were pooled. Further, there was no significant difference in the change of the MTP joint angle from before ball contact to after ball contact between the stiffness configurations. Thirteen (of the 20) subjects showed the highest ball speed in the two stiffest cleats. The differences between the best and the worst performing stiffness configurations across all subjects ranged from 2.2 km/h to 9.2 km/h. The optimal stiffness condition that resulted in highest ball speed was subject specific, and therefore soccer cleats need to be tuned to individual players.

New Running Shoe Reduces the Energetic Cost of Running

Running shoe features (low mass, cushioning, midsole bending stiffness) have been shown to individually reduce the energetic cost of running. Recently, energetic cost has been directly linked to time-trial performance. PURPOSE: To quantify the energetic cost of running in three marathon racing shoes: a prototype and two shoes currently available to runners. METHODS: 18 sub-elite runners (sub-31 min 10km at altitude or equivalent; altitude VO2max: 72.1±3.4 ml O2/kg/min) ran six 5 min trials (3 shoes × 2 replicates) in: a prototype shoe (NP), and two established marathon shoes (NS6) and (AB2), all equilibrated to 250g/shoe (the mass of AB2, size 10) during three separate sessions - 14, 16 and 18 km/hr. The order of the shoe conditions within a session and the session speed order were pseudo-randomized, mirrored and counterbalanced. The NP shoe has a novel, lightweight and highly resilient midsole and a carbon fiber plate that stiffens the shoe in longitudinal bending. We measured submaximal VO2 and VCO2 during min 3-5 and averaged metabolic rate (W/kg) for the 2 trials in each shoe model. Blood [La] measured after the last trial of each session and RER indicated running energetics were at steady-state (<3.0 mmol/L and <0.91, respectively). We compared the 3 shoes over 3 speeds using a two-way ANOVA with repeated measures. RESULTS: A significant main effect for shoe (P<0.0001) indicated the NP shoes required 4.0±1.3% (mean±SD) less energy than the NS6 and AB2 shoes (NP vs. NS6: P<0.0001; NP vs. AB2: P<0.0001), which had similar metabolic costs (NS6 vs. AB2: P=0.34): NP 16.45±0.89, NS6 17.16±0.92 and AB2 17.14±0.97 W/kg averaged across 3 speeds. Although the shoe × speed interaction effect was significant (P=0.0005), post-hoc analyses suggest that relative percent differences between shoes were similar at the 3 running speeds (all P>0.56). CONCLUSIONS: The new shoe reduces the cost of running by 4.0% as compared to two other established marathon racing shoes. This study was supported by Nike Inc. EF and GL are employees of Nike Inc., RK is a paid consultant to Nike Inc.

Does Specific Footwear Facilitate Energy Storage and Return at the Metatarsophalangeal Joint in Running?

Longitudinal midsole bending stiffness and elasticity are two critical features in the construction of running shoes. Stiff elastic materials (eg, carbon fiber) can be used to alter the midsole bending behavior. The purpose of this study was to investigate the effects of midsole stiffness and elasticity manipulation on metatarsophalangeal (MTP) joint mechanics during running in 19 male subjects at 3.5 m/s. Midsole bending stiffness and elasticity were modified by means of carbon fiber insoles of varying thickness. Stiffening the shoe structures around the MTP joint caused a shift of the point of force application toward the front edge of the shoe-ground interface. Negative work was significantly reduced for the stiffest shoe condition and at the same time a significant increase of positive work at the MTP joint was found. It seems plausible that the increase in positive work originates from the reutilization of elastic energy that was stored inside the passive elastic structures of the shoe and toe flexing muscle tendon units. Further, an increase in midsole longitudinal bending stiffness seems to alter the working conditions and mechanical power generation capacities of the MTP plantar flexing muscle tendon units by changing ground reaction force leverage and MTP angular velocity.

B18 ソール曲げ剛性が走動作における支持脚関節機能に及ぼす影響(シューズIII・アダプテッド用器具)

The purposes of this study are 1) to propose an evaluation index for the function of support leg joints during running under the conditions of wearing shoes with different sole properties and 2) to determine the influence of increasing sole bending stiffness on the function of support leg joints. We discussed about the methodology to select the optimal sole bending stiffness distribution for each runner. Four male runners participated and 4 types of shoes, which have different midsole bending stiffness, were used in this study. The contribution of joint axial torques to the acceleration of body CG (center of gravity) was derived from dynamics analysis. We defined a contribution index as the ratio of total torque contribution to the sum of leg joint torque contributions to the generation of the horizontal acceleration. Increasing midsole bending stiffness led to increasing the contribution of ankle planter/dorsal flexion torque to horizontal acceleration and MP joint planter/dorsal flexion torque to horizontal deceleration. Furthermore, the results indicate that the optimal bending stiffness of midsole, which improves the contribution index, may exist for each runner.

Influence of midsole bending stiffness on joint energy and jump height performance.

A substantial amount of rotational energy is lost at the metatarsophalangeal joint during running and jumping. We hypothesized that the lost energy could be decreased by increasing the bending stiffness of shoe midsoles. The purposes of this investigation were to determine the influence of stiff shoe midsoles on changes in lower extremity joint power during running and jumping and to determine the influence of stiff shoe midsoles on vertical jump performance. Carbon fiber plates were inserted into shoe midsoles and data were collected on five subjects during running and vertical jumping. The data showed that energy generation and absorption at each of the ankle, knee, and hip joints was not influenced by the stiffness of the shoe midsole. The stiff shoes with the carbon fiber plates did not increase the amount of energy stored and reused at the metatarsophalangeal joint; however, they reduced the amount of energy lost at this joint during both running and jumping. Vertical jump height was significantly higher (average, 1.7 cm for a group of 25 subjects) while wearing the stiff shoes. Increasing the bending stiffness of the metatarsophalangeal joint reduced the amount of energy lost at that joint and resulted in a corresponding improvement of performance.