UVA Center for Applied Biomechanics...•Video analysis •Cadaver experiments •Relate to NFL...

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Player Performance and Injury Studies on Various Types of Synthetic Turf with Various Cleat Types

Chris Sherwood, MSResearch Engineer, BioCore

Richard Kent, PhDJeff Crandall, PhD

Center for Applied Biomechanics, University of Virginia

Robert Anderson, MDMichael Coughlin, MD

Foot and Ankle Subcommittee, National Football League

UVA Center for Applied Biomechanics

• Mechanical and Aerospace Engineering• Founded 1989 with support from U.S. D.O.T.• Engineers, Epidemiologists, and M.D.’s• Staff of ~60

– Faculty from Schools of Medicine, Engineering– 15 Research staff– 40 Support staff and students

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CENTER for APPLIED BIOMECHANICS

Chaos

Distillation

Understanding

Prevention


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• Team games on infill artificial increasing

• Ankle and knee injury rate 22% higher than on grass– 10 years, 5,360 team games, 3,031 ankle or knee sprains

– Correlation vs. Causation

• Multi-tiered approach (fundamental and applied research, implementation)

Hershman et al. 2012

NFL Injury Distribution 2013 (Wall Street Journal)

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Lower Extremity Injury


Fundamental ResearchApplied Research

Characterize Shoe-Turf Interaction Mechanics (BEAST)

Measure mechanics of NFL players

during performance

Determine loads and toe angle that

cause turf toe

Determine loads and foot

deformations that cause Lisfranc

injuries

Determine mechanisms of

syndesmotic ankle sprains

Develop Recommended Practices (RPs)

for NFL Surfaces

•Gait laboratory study

•Literature review•Video analysis•Cadaver experiments•Relate to NFL players

•Literature review•Determine next steps

LiteratureExisting practicesNew research

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Fundamental Research – How do injuries happen?


Applied Research and Testing

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Technical: Richard Kent, PhD, University of Virginia; Andrew McNitt, PhD, Penn State University; Barry Myers, MD, PhD, Duke University; Don Follet, Baltimore Ravens; Tony Leonard, Philadelphia Eagles; Allen Johnson, Green Bay Packers; Steve Wightman, San Diego Chargers;

Implementation – Equipment Recommendations, Practices


Turf toe (Sprain of 1st metatarsophalangeal joint)

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Cadaver tests

9 Players

Run, cut (outside foot), cut (inside foot), jump, land, start, walk

Maximum big toe joint angle measured

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56° extension

99% of athletes

10% risk of injury

56

56° extension

99% of athletes

< 56°

56° extension

99% of athletes

10% risk of injury

56

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Flexion Tests with Football Cleats1. Shoe Request 2013

- Each shoe model being used by a NFL player

- Unmodified- Size 9, 12 (2), 15

2. Meetings - Review test

results and procedures


Flexion Testing

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Flexion Tests (21 cleats, 3 manufacturers)

0

2

4

6

8

10

12

14

16

18

20

30 40 50 60 70 80 90

Torq

ue (

Nm

)

Flex Angle (deg)

NK-ZCE-34-DST-12-1-3NK-ZCE-34-TD-12-1-3NK-AP-D-12-1-2NK-LSBP-TD-12-1-2NK-VP-L-D-12-1-2NK-ZCE-SS-12-1-3NK-VP-34-TD-12-1-2NK-VTE-L-12-1-2NK-LSBP-D-12-12NK-AP-TD-12-12NK-ZCED(W)-12-12NK-CJ81-E-TD-12-12UA-FH-MID-D-12-13UA-HL-MC-12-12UA-NI-MID-D-12-1-3UA-SFD-MID-MC-12-12UA-NI-LOW-MC-12-13UA-CH-MC-12-13AD-A-5-STAR-20-12-12AD-CQ-MID-12-14AD-FQ-MID-D-12-12

Region of shoe performance during regular play

Shoe Manufacturers can have whatever shoe response they want up to 56°

Player only gets into this region in “overload” or “injurious situations”

This is the region where we are going to rate shoes

Stiffness and Peak Moment Analysis

56°

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Moment

Angle

Peak Moment

Stiffer

Stiffness and Peak Moment Analysis

56°- We will not evaluateRegion - Doesn’t need to change for injury prevention

Softer

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90

Moment (Nm)

Angle (deg)

MTP Moment vs. Angle

PP01Mom

PP02Mom

PP03Ang

HP02Mom

HP03Mom

SP01Mom

SP02Mom

SP03Mom

Players

Shoes

Shoes

?

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BioCore Elite Athlete Shoe-turf Tester (B.E.A.S.T.)


Nike Air Zoom Vapor JetDetachable cleat

Molded cleat

Nike Air Zoom Merciless Destroyer

Turf shoe

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• SELECTED RESULTS: Start from Stop TestComparison Across 5 Turfs

-50

0

50

100

150

200

250

0.0 0.2 0.4 0.6 0.8 1.0

Time (s)

Hor

izon

tal D

ispl

acem

ent (

mm

)

BEAST33: Baltimore Ravens, Shoe VJTD2BEAST45: NY Giants Grass, Shoe VJTD3BEAST62: NY Giants Turf, Shoe VJTD3BEAST74: Atlanta Falcons, Shoe VJTD3BEAST90: Carolina Panthers, Shoe VJTD3

Cleat “snags”

Cleat moves

Cleat catches, then releases

Displacement


• SELECTED RESULTS : Start from StopComparison Across 5 Turfs

-50

0

50

100

150

200

250

0.0 0.2 0.4 0.6 0.8 1.0

Time (s)

Hor

izon

tal D

ispl

acem

ent (

mm

)

BEAST33: Baltimore Ravens, Shoe VJTD2BEAST45: NY Giants Grass, Shoe VJTD3BEAST62: NY Giants Turf, Shoe VJTD3BEAST74: Atlanta Falcons, Shoe VJTD3BEAST90: Carolina Panthers, Shoe VJTD3

Infill manuf 2

Infill manuf 2

Old Bermuda GrassNew Bluegrass

Infill manuf 1

Displacement

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Interaction Between Shoe and Turf

Nike Air Zoom Vapor JetNike Air Zoom Merciless Destroyer


• RESULTS: Start from Stop (Translation)

Displacement

-50

0

50

100

150

200

250

0.0 0.1 0.2 0.3 0.4 0.5 0.6Time (s)

Hor

izon

tal D

ispl

acem

ent (

mm

)

Molded on GrassMolded on FieldturfTurf shoe on FieldturfTurf shoe on Momentum turf

Artificial TurfArtificial TurfArtificial Turf

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• Evaluation Rubric for Cleat Recommendations

Rotation Test

Rotation

-20

0

20

40

60

80

100

120

140

160

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Foot

Rot

atio

n (d

eg)

Time (s)

CAF-0913UAF-0811

UAB-0803-1CASO-1092

VCTDMPSMNAT2

RBMP2-11RBSD4-11RBD4-11

-20

0

20

40

60

80

100

120

140

160

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Foo

t Rot

atio

n (d

eg)

Time (s)


• Evaluation Rubric for Cleat Recommendations

Rotation Test

MN RBSD4-11

VCF-D

AT

UAF-0606

VJTD

VJTDAT

UAF-0811

AT

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Cleat Evaluation RubricBroke Away Held

Full Power Translation

Force Desired Undesired

Horizontal Disp. Desired Undesired

Full Power Rotation

Torque Desired Undesired

Rotation Angle Desired Undesired

Half Power Translation

Force Undesired Desired

Horizontal Disp. Undesired Desired

Half Power Rotation

Torque Desired Undesired

Rotation Angle Desired Undesired

3/4 Power Translation

Force Undesired Desired

Horizontal Disp. Undesired Desired

Total Score = Probability of desired outcome occurring in all tests on turf

100% = Desired outcome always occurred , 0% = Desired outcome never occurred


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RESULTS: Score of all cleat patterns on TURF

83 83 83

75 75

67 67 67 67

50 5046

3833 33 33 33

0

10

20

30

40

50

60

70

80

90

RB

D4-

11

UA

B-0

803-

1

AT

2

CA

F-0

913

VC

TD

RB

MP

2-11

CA

SO

-109

2

MP

S

MN

RB

SD

4-11

UA

F-0

811

AT

VJT

D

RB

M4

UA

F-0

606

UA

F-0

626

VC

F-D

Sco

re

2015 Season Composite Rating System

Traction Evaluation

Flexion Evaluation

Shoe Model

Composite Rating

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Update on NFL Field Certification Program“Recommended Practices”

• Artificial Turf: Roll‐out 2011‐12 season• 3 seasons of data • Impact hardness, infill depth and evenness, visual inspection

• Natural Turf: Roll‐out 2012‐13 season• 2 seasons of data • Impact hardness, visual inspection

• Research project (turf replacement timing)

How it Works:

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Example Success Story – Artificial Surface• Week 4,5: Hardness approaching 100g at seams

• Field manager contacted

• Independent tests conducted

• Turf manufacturer visited

• Infill depth and constituency remediated

• Hardness dropped to mid‐80s and remained there for the rest of the season

Example Success Story – Natural Surface

• High temps 20F with high winds (dry, frozen field)

• Heavy snow (field covered, numerous passes with snow removal equipment, not able to water as usual)

• With Field Manager, developed a proactive strategy to limit hardness

Week 1 Week 3 Week 7 Week 10 Week 11 Week 14 Week 15 Week 17

88 94 86 88 93 97 110 81

86 95 94 91 91 96 98 80

81 94 79 86 94 93 96 87

87 94 81 78 88 98 99 88

89 89 85 86 92 97 103 94

94 93 74 84 87 96 101 94

88 90 87 94 98 93 96 93

98 93 76 96 95 93 118 97

84 88 77 88 91 87 102 89

88 94 90 90 84 96 110 92

83 92 77 89 94 94 101 86

76 96 81 93 91 96 105 94

86 88 82 87 87 93 118 81

84 91 86 93 93 89 94 87

82 86 78 91 88 93 98 85

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Team Data, 2013‐14

Natural Surfaces

RP1 – Impact Hardness

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Team Data, 2013‐14

Artificial Surfaces

Manuf A

Man

ufB

Manuf C Man

ufD

Man

ufE

Man

ufE

RP1 – Impact Hardness

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Manuf A

Man

ufB

Manuf C Man

ufD

Man

ufE

Man

ufE

RP2 – Infill Depth

Manuf A

Man

ufB

Manuf C Man

ufD

Man

ufE

Man

ufE

RP2 – Infill Evenness

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Positive Changes Motivated by RPs• NFL maintenance practices have changed substantially

• Tractor sweepers phasing out, hand‐raking phasing in (lowers compaction)

• Routine top‐dressing occurred on one field pre‐2011, is now common practice

• Field managers now tracking hardness year round and earlier in the week during season, learning how to manage proactively.

• Cultivating in‐season to control hardness on natural turf

• Field managers tracking hardness on practice fields (rare pre‐2011)

• Improved heating systems in use so that they can meet hardness RP late in the season

• Teams purchased magnets for sweeping debris from field (not pre‐2011)

Positive Changes Motivated by RPs• Industry has responded

• Turf companies now provide top‐dressing with a new field and instruct that top‐dressing is part of standard maintenance

• Clegg Hammers now calibrated to tighter specification if being sold for turf testing

• We have regular dialogue with turf industries, other sports, other governing bodies (STC, ASTM, FIFA, IRB, etc.)

• Industry provides quantitative, documentable targets• Allowable ranges in infill depth defined, Coefficient of Variation now a common term, etc.

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Positive Changes Motivated by RPs• Painting practices have changed substantially

• Paint is applied less heavily to prevent build‐up• Paint removal technology/methods now have a market; companies investing in R&D, new devices coming to market

• Paint companies report dramatic change in attitude and practice

• NFL Management/Executives have responded• 7 artificial NFL fields have been replaced since RPs introduced• Some teams have gone with higher‐quality sod suppliers• Resodding reduced surface hardness on 8 natural NFL fields in 2013

• One NFL Owner:• “I believe that the work on the turf fields has led to more consistency, better appearances without split seems, fewer hard fields, fewer slick painted fields, and probably other things that can or cannot be measured. I am not sure that the same can be said regarding grass fields.”

• “The turf manufacturers and the grounds crews at the Clubs all know that the League is paying attention to quantitative and qualitative measurements of fields. This leads to greater emphasis on consistency and standards.”

How Have Fields Changed Since RP Rollout?

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Clegg Hardness (All Locations, All Artificial NFL Fields)

• Hardness has dropped average of 0.05g/week

• Range has dropped from 68g in first three weeks of rollout to 44g over last three (55% reduction)

Range in Infill Depth (mm) over a Field (Artificial NFL Fields)

• Ranges as high as 17mm when RPs rolled out.

• Ranges now less than 8 mm.

• Average range over an NFL field is now less than 4.3 mm.

• Coefficient of Variation has dropped by 44%

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Conclusions and Recommendations

•Conclusions• Industry and NFL have changed in several positive ways since RP rollout

• NFL fields are slightly softer, but much more consistent

• Maintenance practices have improved

•Recommendations• Improve administrative structure

• Narrow time window for independent testing (should occur between certification and game time)

• Continue to track state of the science to ensure continued technical relevance of RPs

Research Focus – High Ankle Sprains

18 21

114 147

338

435

587

1143

1349

1920

2408

Ankle Posterior

Tibio‐Fibular Sprain 2 Deg

Ankle Posterior

Tibio‐Fibular Sprain

Ankle Posterior

Tibio‐Fibular Sprain 1 Deg

Tibia Interosseous Membrane Sprain 3 Deg


Tibia Interosseous Membrane Sprain


Ankle Anterior Tibio‐Fibular Sprain 1 Deg


Ankle Anterior Tibio‐Fibular

Sprain


= 8,480 player‐days

lost over 5 years

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Research Focus – High Ankle Sprains

Dissemination and Outreach• Subcommittee Meets Quarterly

• Athletic Trainers, Field Managers, Equipment Managers, NFL

• Update Injury and Safety Panel Biannually• Update Competition Committee Annually

• Present to Equipment Managers Annually

• Meet with Field Managers Annually

• Meet with Nike, UnderArmour, Adidas Regularly

• Meet with Field Manufacturers Annually

• Scientific Publication/Presentations

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Player Performance and Injury Studies on Various Types of Synthetic Turf with Various Cleat Types

Chris Sherwood, MSResearch Engineer, BioCore

Richard Kent, PhDJeff Crandall, PhD

Center for Applied Biomechanics, University of Virginia

Robert Anderson, MDMichael Coughlin, MD

Foot and Ankle Subcommittee, National Football League

UVA Center for Applied Biomechanics...•Video analysis •Cadaver experiments •Relate to NFL...

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Transcript of UVA Center for Applied Biomechanics...•Video analysis •Cadaver experiments •Relate to NFL...