ecco biom study

G.-P. Brüggemann and S. Willwacher

23.09.2010

Prospective Intervention Study on the BIOM Natural Motion Footwear

ECCO NATURAL MOTION – Munich 23.09.2010

BASIC CONSIDERATIONS - BACKGROUND

FOOTWEAR – THE THREE AIMS

• Protection, injury prevention

• Performance enhancement

• Training of biological structures

FOOTWEAR – PROTECTION


Decrease loading of biological tissue

- Cushioning (impact)- Motion Control (excessive joint motion)- Joint Moment Control (excessive joint moments)

….. no changes in injury frequency and location in 30 years

FOOTWEAR - PERFORMANCE



Increase of performance

- Minimum loss of energy (e.g. additional mass)- Energy storage and return (e.g. midsoles)- Optimize muscle function (e.g. optimum muscle length,

optimum contraction velocity)

FOOTWEAR - TRAINING



• Training of biological structures

Increase of loading of biological tissue

- Lever of ground reaction forces (moments): LEV- Range of joint motion (muscle work): ROM

Strategy ROM: Increased range of joint motion

– increase of muscle work

angle of metatarsal-phalangeal joint

Time

dorsiflexion

plantarflexion

BENEFITS OF ROM or BAREFOOT TRAINING

• Barefoot Training (BT) improves strength of overall muscular system: Coaches “experience” and recommendation

• Wobble board training decreases injury frequency (Emery et al. 2005)

• 5 months training in flexible shoe increases - ACSA of small foot muscles and - MPJ flexor strength by 20% (Potthast et al. 2005)

• Flexible shoe training decreased injury frequency by 29% in a 9 months follow up (Brüggemann et al. 2008)

Strategy LEV: BENEFITS OF US TRAININGUS - unstable shoes

• Increase of muscle activity during standing to remain balance (Nigg et al. 2005)

• 100% increase in balance time after 3-months using US (Nigg et al. 2006)

• 25% decrease in joint pain in OA patients in 3 months with US(Nigg et al. 2006)

• 44% decrease of back pain in golfers after US application for 6 weeks

(Nigg 2009)

NATURAL JOINT MOTION

• No mechanical perturbation to a joint

• No protection

• Preferred joint’s movement path (with minimum friction)

• … for a given motor task

• on an adequate surface

“barefoot running” on grass

BAREFOOT vs SHOD RUNNING

• Increase of vertical loading rate (de Wit et al. 2000)

• Earlier impact peak for barefoot running (de Wit et al. 2000)

• Higher tibial acceleration for barefoot (McNair & Marshall 1994)


• Flatter foot placement at initial contact for barefoot (Herzog 1978, de Wit et al. 2000, Bishop et al. 2006)

• Larger minimal knee angle for barefoot (de Wit & de Clercq 2000)

• Higher ankle joint stiffness and lower knee joint stiffness for barefoot

(Coyles et al 2001)

• Small but non systematic differences in foot eversionand tibial rotation

(Stacoff et al. 2000)


• Earlier maximal EMG intensity for M. tibialis ant. for barefoot (van Tscharner et al 2003, Wissemann 2006)

• Less inverted foot placement in barefoot

(Brüggemann et al. 2006) shod

barefoot

Wissemann 2006

heel-toe running; 3,5 ms-1

Komi 1991

Experimental conditions:

(a) Minimum sagittal lever of GRF at HS (barefoot on soft surface, EVA)

(b) Increased sagittal lever arm of GRF at HS (modified running shoe)

(a)

(b)

Brüggemann et al. 2009

GRF: ground reaction forceHS: heel strike

0,28

0,285

0,29

0,295

0,3

0,305

0,31

c

Soleus MTU length [m]

Time norm. [% of stance]

heel-toe running: n=18, k=5

Mean, SE(a)

(b)

shorten lengthen shorten


• Footwear has the potential to modify the lever of GRF to AJ in the sagittal plane (SP).

• The increased initial shortening de-couples the AJ in the SP.

• The higher lever in SP is related to rearfoot eversion and the frontal plane moment at AJ.

• Frontal plane joint instability is strongly related to sagittal plane kinematics and kinetics.


ASSUMPTION

A more natural movement of MPJ and AJ (and KJ) leads to a re-definition of neuromuscular loading at MPJ, foot, AJ, KJ

• Might decrease the risk of overuse

• Might enhance performance

• Might “train” the foot structures

MPJ: metatarsal-phalangeal jointAJ: ankle jointKJ: knee joint

Flatter and less supinated foot placement at foot strike

Less eversion velocity

Higher inversion at push off

Smaller lever arm of GRF in sagittal and frontal plane at foot placement and during stance

Less de-coupling of TS and AT

Better use of energy storage potential of MTUs

….

MTU: muscle tendon unitTS: triceps suraeAT: Achilles tendon

NATURAL MOTION - FOOTWEAR DESIGN

PROSPECTIVE INTERVENTION STUDY BIOM NATURAL MOTION FOOTWEAR

RESULTS

PROSPECTIVE INTERVENTION STUDY

Subjects: 120 (male, female)

Pre-Test: Conventional shoes (CO)

6-weeks intervention: running NM shoes

Post-Test: Natural Motion Shoes (NM)

Pre- and Post-Test: 3D gait analysis

flex stiffness

CO NM

MassFlexibilityStiffnessLever armsArea of support

NM

CO: conventional shoe

Study time line: January (pre_CO) to March (post_NM) 2010

Subjects: n=120, male and female

Experimental conditions: (a) own (used) running shoe (initial)(b) BIOM running shoe (after 6 weeks)

Running: (a) 3,5 m/s, (b) self selected speed

Methods (applied initially and after 6 weeks):

: 3D motion analysis (12 cameras, 250 fps)force plates (2 Kistler plates)

Running style analysis (high speed video)VO2 uptake at given speed (2,5 m/s)

PROSPECTIVE INTERVENTION STUDY - neuromuscular adaptation to footwear

Initial analysis Final analysis6 weeks adaptation to footwear (BIOM)

No changes of training program/load

STUDY FACTS

• 120 subjects entered the study• 18 subjects dropped out because of sickness, accidents, etc.

no relation to footwear (BIOM)• 6 subjects dropped out because of problems with the BIOM

problems were different in each subject• 47 of 108 subjects reported problems (similar to normal running population)• Most of the problems were of low intensity or disappeared immediately• Some of the reported problems can be related to the adaptation process

RUNNING PATTERNS

No changes in stride length

No changes in preferred running speed

Decreased gait width – more narrow(foot falls more in a straight line)

Decrease ml-ground reaction forces

Increased DUTY factor (more time on ground)

Decrease vertical CM’ lift (ROM)

Medio-lateral ground rection forces

CONVENTIONAL(CO) vs NM

k_KJ [Nm/°] k_AJ [Nm/°] CO NM CO NM

Male 6,7 6,5 4,7 5,0

Female 5,2 5,0 4,1 4,3

Flight time

Stance time

CO NM

CO NM

**

**

k_KJ: Stiffness knee jointk_AJ: Stiffness ankle joint

Men -

ConventionalNatural Motion

Vertical ground reaction force

BIOM footwear

• Decreased peak vertical GRF• Decreased joint axial loading• Higher loading rate • Lower energy at impact




Ankle angle

plantarflexion

Ankle angle

inversion

eversion


Ankle angular velocity

flexion abduction

Ankle angular velocity



Plantar-dorsi-flexion Eversion-inversion


Ankle power (Watt/kg) (sagittal plane)

• Elastic behavior results in more energy absorbed (or stored) e.g. in the Achilles tendon and visco-elastic tissues of foot and ankle in the first part of stance and reutilized in the second half

CONM


Knee angle Knee angle

flexion adduction

abduction




External knee joint moment External knee joint moment

flexion adduction ConventionalNatural Motion



More general …

NM or BIOM FOOTWEAR has the potential to define neuromuscular loading in normal locomotion and running

NM FOOTWARE can increase instability and/or increase neuromuscular loading

NM FOOTWEAR has the capacity to re-define neuromuscular loading during running

The impact of BIOM FOOTWARE to neuromusculat loading has to be acknowledged

NATURAL JOINT MOTION might provide the proper orientation how to re-define loading

In summary …Some variables describing running movement and neuromuscular loading changed during the BIOM 6 weeks intervention,

The BIOM footwear seems to facilitate are more „elastic“ behavior in the sagittal plane and reduces initial eversion velocity by improving the neuromuscular joint coupling. Initial eversion moments at the ankle joints have been decreased through minimizing levers arms.

BIOM footwear leads to a reduction in step width which might be aresponse to the lower and smaller base of support of the BIOM compared to conventional running shoes.

This change in running style leads to a shift of the GRF vector which is related to a decrease in knee adduction moments in approx. 70 % of the subjects.

There is some evidence that the increased adduction moments at the knee of the remaining 30% of the subjects might still be in a physiological windowand do not indicate a higher risk of knee joint’s medial compartment overuse.

Changes in leg configuration lead to a more outward orientated position of the leg during stance which might be a compensation mechanism to improve stability One can speculate on an advantage to the hip joint kinematics and kinetics.

• BIOM offers a smaller base of support

• … which is closer to barefoot condition

• BIOM has a lower torsional stiffnesscompared to conventional running shoes

• This two factors might lead to lower stepwidth to avoid instability

• BIOM offers the potential to moreneuromuscular control of the ankle(eventually of knee and hip joints)and opens the potential of a more efficientuse of the elastics properties of the human machinery.

• The natural motion technology is related to anincreased neuromechanical loading.

• Modification of overall running style

• Changes in ground reaction force characteristics

• Adaptation of lower extremity joints‘ kinematics and kinetics

• A general re-definition of neuromuscular loading

Take home: Natural Motion Footwear is related to

ecco biom study

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