effects of different shoe-lacing patterns on the biomechanics of running shoes journal of sports...

Effects of different shoe-lacing patterns on the biomechanics of

running shoes

Journal 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 Germany

Presented by: Kelly Gartland

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

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

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”

Lacing ConditionsVaried in 1.Number of pairs of eyelets used (1,2,3,6,7)2.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

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

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 forceby time resolution of 1 ms

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

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

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

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

Shock Attenuation 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?

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?

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

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

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 areaEYE12- ↑ loading rates even though ↓ peak vertical forces; therefore, will have ↑ peak pressures under the heel

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

What about the REG6 compared to the ALL7?

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