Effects of Longitudinal Bending Stiffness of forefoot rocker profile shoes on ankle kinematics and kinetics

This study analysed the effects of increasing the longitudinal bending stiffness (LBS) of runners’ habitual shoes on the metabolic energetic demand, lower limb muscle activation and stride spatiotemporal parameters during a prolonged running session through classical group investigation, as well as a more individualised approach. Eleven recreational male participants ran overground for 40 min at 95% of their ventilatory anaerobic threshold with their own shoes or their shoes with higher LBS (stiff carbon plate inserted under insole). The net energetic cost of running, lower leg muscle activation and spatiotemporal parameters were measured during the prolonged running. The variables of interest were analysed for 1 min in seven time intervals. There were no main effects of LBS or interaction effects with running duration on the group averaged variables. Overall, the participant-specific metabolic effects induced by an increased shoe LBS were not beneficial. Beneficial metabolic effects were more likely to occur when the increased LBS induced a decrease or no change in the ground contact time relative to their habitual shoes, as well as for taller runners. Increasing the LBS in runners’ habitual shoes did not induce systematic metabolic effects for all the runners and may not be beneficial for performance purposes if the runners’ shoe habits were too disrupted.

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No effect of cycling shoe sole stiffness on sprint performance

10.31236/osf.io/k6bh8 ◽

2020 ◽

Author(s):

James Warren Hurt ◽

Rodger Kram

Keyword(s):

Carbon Fibre ◽

Metabolic Cost ◽

Bending Stiffness ◽

Sprint Performance ◽

Running Shoes ◽

Competitive Cyclists ◽

Longitudinal Bending ◽

Sprint Cycling ◽

Shoe Soles ◽

Power Outputs

Most competitive and recreational road cyclists use stiff-soled shoes designed for cycling and “clipless” pedals that firmly attach to the shoes. There are many unsubstantiated claims by cyclists and industry professionals about the advantages of cycling shoes and clipless pedals. Scientific research has shown that cycling shoes and clipless pedals have no significant effects on the metabolic cost of cycling during submaximal, steady-state efforts. However, a recent study demonstrated that, compared to running shoes, cycling shoes and clipless pedals do provide performance benefits relevant to sprint cycling. Here, we investigated if there was a positive relationship between longitudinal bending stiffness of cycling shoe soles and sprint performance. We measured the mechanical power outputs, velocities, and cadences of 19 healthy male recreational/competitive cyclists during maximal sprint cycling. Participants rode outdoors on a paved asphalt road with a steady, uphill grade of 4.9%. Each subject completed nine 50 m cycling sprints in three (single-blinded) shoe conditions: identical shoe uppers with injection moulded nylon soles, carbon fibre-fibreglass blend soles, and full carbon fibre soles. The same clipless pedals were used throughout all tests. No significant differences were detected between the three shoe soles for: 50 m average and peak 1-second power, average change and peak change in velocity, average and peak cadence, maximal sprint velocity, peak acceleration, and peak crank torque (all p > 0.31). Greater longitudinal bending stiffness of cycling shoe soles had no effect on sprint performance during short uphill sprints.

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Relativerigidity of twisted fishing gear

VESTNIK OF ASTRAKHAN STATE TECHNICAL UNIVERSITY SERIES FISHING INDUSTRY ◽

10.24143/2073-5529-2020-1-46-60 ◽

2020 ◽

Vol 0 (1) ◽

pp. 46-60

Author(s):

Alexander Alekseevich Nedostup ◽

Karina Konovalova ◽

Pavel Nasenkov ◽

Alexey Olegovich Razhev ◽

Boris Altschul ◽

...

Keyword(s):

Physical Modeling ◽

Bending Stiffness ◽

Full Scale ◽

Torsional Stiffness ◽

Dynamic Processes ◽

Fishing Gear ◽

Model Experiments ◽

Longitudinal Stiffness ◽

Longitudinal Bending ◽

Dimensionless Combination

The article touches upon the problem of physical modeling of fishing twisted filamentary materials, in particular, the justification of the rules of similarity of relative longitudinal, bending and torsional stiffness of filamentary parts. The formulation of the problem is associated with the difficulties of conducting full-scale experiments for designing new fishing gear, as well as with the lack of systematic experiments on measuring the stiffness of synthetic cordage. In connection with this, it becomes necessary to conduct model experiments related to physical modeling of dynamic processes occurring with the cordage under load. There has been calculated the coefficient of proportionality of bending stiffness that determines the ability of filamentary parts and cordage to resist bending. There have been given the formulas that determine the combination of the ratio of bending stiffness to longitudinal stiffness and the dimensionless combination of the ratio of bend-ing stiffness to torsional stiffness. The study allows to predict the behavior and basic properties (di-ameter, density, strength, elongation, etc.) of modern synthetic filamentous fishing gear at the stage of their creation (design).

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

Journal of Applied Biomechanics ◽

10.1123/jab.29.5.583 ◽

2013 ◽

Vol 29 (5) ◽

pp. 583-592 ◽

Cited By ~ 48

Author(s):

Steffen Willwacher ◽

Manuel König ◽

Wolfgang Potthast ◽

Gert-Peter Brüggemann

Keyword(s):

Carbon Fiber ◽

Reaction Force ◽

Metatarsophalangeal Joint ◽

Bending Stiffness ◽

Joint Mechanics ◽

Running Shoes ◽

Longitudinal Bending ◽

Bending Behavior ◽

Male Subjects ◽

Positive Work

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.

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