1 / 18

Introduction

lincoln-hatcher
Download Presentation

Introduction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Effects of different shoe-lacing patterns on the biomechanics of running shoesJournal of Sports Sciences Feb2009, Vol. 27 Issue 3, p267 9p.Authors: Marco Hagen & Ewald M. Hennig Sport and Movement Sciences, Biomechanics Laboratory, University of Duisburg Essen, Essen GermanyPresented by: Kelly Gartland

  2. Introduction • Sport shoe research has been a major interest for 30+ years • Lots of studies have been conducted that influence the design of running shoes (varus wedges, varying amounts of padding) • Some purposes of running shoes include reduce impact shocks reduce excessive pronation pronation: rotation of the subtalar joint that involves more weight being supported on the inside sole of the foot

  3. Other Research Studies • Few studies have looked at mechanical coupling between foot and shoe • One study found that from the mathematical point of view, the most frequently used X-lacing is the best and strongest way (Polster 2002) • Another study found that a soccer shoe with a special anti-pronation lacing technique was more effective in controlling rearfoot motion (Sandrey et. al 2001) • GOAL: To Study the effect of shoe-lacing on the biomechanics of heel-toe running

  4. Methods • 20 Male Rearfoot Runners -experienced -symptom free - chosen based on fit to a US 10.5 experimental shoe • Shoe: NIKE Air Pegasus - manufacturer emphasizes that it is built with a lateral crash pad that acts as cushion and anti-pronation element • Used X-lacing, or “zig-zag-lacing”

  5. Lacing Conditions Varied in Number of pairs of eyelets used (1,2,3,6,7) Tightness of the lace (weak, regular, or tight) Figure 1. Lacing conditions: (a) 6-eyelet cross-lacing of conditions REG6, WEAK6, TIGHT6; (b) EYE12; (c) EYE135; (d) ALL7

  6. Kinetic and Kinematic Measurements • Ran each laced condition at a speed of 3.3m/s across a piezoelectric force platform (3.3m/s = 7.38mph) • Running speed had to be within ±3% of target • 5 successful trials per laced condition • Factors evaluated -ground reaction forces -in-shoe pressure distribution -tibial acceleration -rearfoot motion measurements

  7. Ground Reaction Force • Newton’s Law of Reaction- Every action has an equal and opposite reaction • Piezoelectric force platform • Measures the vertical component of the force in the geometric centre of the platform • Calculated the force rate by taking highest differential quotient of vertical ground reaction force by time resolution of 1 ms

  8. Peak Pressures • Piezoceramic transducers placed on 7 anatomical locations of the foot • Fastened under the foot with adhesive tape P=F/A • ↑Area over which force is applied=↓Pressure

  9. Tibial Acceleration • Acceleration= ∆V/∆t • Accelerometer fastened by an elastic strap to the tibia between medial malleolus and tibial plateau • This study did not find any significant differences in peak tibial accelerations for the different shoe lacing conditions

  10. Maximum Pronation & Maximum Velocity of Pronation • Used a goniometer • Determined a neutral angle by placing participants in an upright sitting position • Neutral angle used as a reference point for all pronation and supination measurements to be based off of • Used the angular values to calculate maximum pronation and maximum velocity of pronation

  11. Perception Tests • Comfort/Stability Compared against the left foot which wore the reference (REG6) shoe • Evaluate on “anchored” 7 point scale with 1 being low, 7 being high, and 4 being the reference shoe • Rank from 1 through 6 Perception Results • Comfort -Each condition= more comfortable than the Tight6 - Most favored for comfort= Weak6 and EYE135 • Stability -ALL7 and Tight6= the most stable conditions

  12. The top graph displays peak vertical forces. It demonstrates that the lowest peak vertical forces were observed with the lowest lacing condition. Does it not make sense to recommend the lowest lacing? Shock Attenuation The lower graph displays maximum vertical force rates. It demonstrates that the lowest vertical force rates were observed with the tightest and highest lacing conditions. Does this contradict the top graph?

  13. Why the difference in peak vertical force and maximum vertical force rate? • Lacing Condition EYE12 - Weak foot-shoe coupling could result in the foot and the shoe contacting the ground at different times - Participants may have changed running style to accommodate loose fit by increasing plantar flexion and curling toes; this would result in decreased angle of impact of the foot - Weak foot-shoe coupling could result in foot slippage; if foot slides forward within the shoe, less volume of cushion can be used

  14. Why the difference in peak vertical force and maximum vertical force rate? • ALL7 - better foot-shoe coupling could result in the foot being able to directly use the air cushion at impact

  15. Peak Pressure Distribution P=F/A ALL7- ↑ foot-shoe coupling, heel can go deeper into the cushioning material of shoe and can distribute the force more evenly over a greater area EYE12- ↑ loading rates even though ↓ peak vertical forces; therefore, will have ↑ peak pressures under the heel

  16. Pronation and Pronation Velocities • Pronation Data should be treated with caution… the goniometer was attached to the heel counter of the shoe, in the lower and softer laced conditions with weak foot-shoe coupling, the goniometer would not be able to account for sliding of the foot within the shoe. • Maximum pronation (⁰)= NO DIFFERENCE • Pronation velocity (rad/s)= decreased for the REG6, TIGHT6, and ALL7 in comparison to the WEAK6, EYE135, and EYE12 • WHY? -Mechanical Coupling and the Lateral Crash Pad The foot goes deeper into the crash pad, becoming closer to the ground, this reduces the pronation lever arm

  17. What about the REG6 compared to the ALL7?

  18. CONCLUSIONS • Shoe lacing must be considered when making biomechanical comparisons of running shoes because it does make a difference • Under these circumstances, the ALL7 lacing condition resulted in reduced pronation velocity and shock • Further research should be conducted. Research recommendations include should there be special lacing techniques for different foot types, or different running types

More Related