Barefoot vs. Shod Running: An Evidence-Based Review of

Ground Reaction Forces at Initial Contact

Ryan Johnson, MS, DPT(c) PT 209-910

Clinical Problem: • Currently there is a significant lack of

knowledge surrounding efficient running – What running patterns are most beneficial? – Is a heel strike really the best and most healthy

running pattern? – What are the effects of footwear? – How can physical therapy assist runners to reduce

injury and increase performance?

Significance of Problem: Growing Trend

Number of PEOPLE

interested in BF running

Number of PATIENTS

interested in BF running

(Fitzgerald M, 2010)

Physical Therapy Relevance:

Clinicians need Knowledge

Research provides clinicians with an

understanding of the biomechanics behind

different running patterns

Clinicians are able to make “evidence-

based” decisions for each patient

Physical Therapy Relevance:

Clinicians synthesize knowledge to make

clinical decisions

Pose questions to researchers to

stimulate future studies

Researchers need Inspiration

Purpose of Review Compare Shod vs. Barefoot (BF) Running

through analysis of Ground Reaction Forces (GRF)

http://www.youtube.com/watch?v=9itkEkcQ8WM&feature=related

Theoretical Constructs • Repetitive impact forces through the body may

be detrimental (landing hard after a jump or when stepping off curve, working all day with a jackhammer, FOOSH, etc.).

http://gallery.photo.net/photo/3069741-lg.jpg

http://c.photoshelter.com/img-get/I0000KnYFMTjp0dg/s

(Sangha et al. 2000; Hewett et al. 2005; Hreljac et al. 2004; Schamberger et al. 2002)

Theoretical Constructs • The ground reaction force (GRF) upon impact,

“is considered to be the most basic element which causes running related injuries.”

http://jpthermt.com/wp-content/uploads/2010/07/running-injury.jpg

(Robbins et al. 1987)

Theory behind BF Running • Current scientists, paleontologists, anatomists and

physiologists have been challenging “traditional” knowledge on running biomechanics

• Daniel E. Lieberman, PhD

• Irene Davis, PhD, PT, FACSM

• Madhusudhan Venkadesan, PhD

• Mark Bishop, PT, PhD, CSCS

• Craig Richards, PhD

• R. Squadrone

http://static.technorati.com/11/02/04/26399/woman-running221.jpg

Theory behind BF Running • Hypothesizing that landing on the mid-foot

rather than a heel-first strike may:

– Conserve energy

– Reduce impact transient forces (Liberman DE et al., 2010)

Anatomy and Theoretical Constructs

http://www.carifinonline.com/wp-content/uploads/2010/01/heel-strike-compare.jpg

http://www.ceessentials.net/images/critiqueLowerExtremity/image216.jpg

Proposed Benefits to BF Running The following have been postulated as possible

benefits to BF running: • Decreased VO2 consumption • Increasing the strength of the ligamentous and muscular

support of the arch • Increased proprioception • Decreased risk of lower extremity injury, including:

– Lateral Ankle Sprains – Plantar Fasciitis – Medial Tibial Stress Syndrome – Etc.

(Hanson et al. 2011; Squadrone et al. 2009; Jungers et al. 2010; Robbins et al. 1989; Divert C, 2005; Divert C, 1985; Warran et al. 1987)

And Lastly…. It has been proposed that BF running can decrease the transient ground reaction force experienced at initial contact (Liberman et al., 2010)

http://www.stgeorgerunningcenter.com/wp-content/uploads/2011/05/running-barefoot.jpg

Background • Have running shoes ever been proven to

reduce the risk of injury?

• Answer – No… There has never been a peer review article

published which showed a statistically significant reduction in injury rate for those individuals wearing shoes. (Richards et al., 2008)

Background • Are running related injuries a serious problem

in the medical community?

• Answer: – Yes… every year 65-80% of all runners suffer an

injury. (McDougall, 2009; Warran et al. 1987)

Terms Defined Passive Peak

(Impact Transient) Active Peak

Ground Reaction Forces (GRF)

GRF at initial contact (IC-GRF)

Terms Defined

http://4.bp.blogspot.com/_JadSUXnX75Q/S3aD2iNRnsI/AAAAAAAAAT8/sl8pbmfVQ70/s320/heelstrike.jpg

Heel Strike (HS) or

“Rear Foot Strike” (RFS)

Non-Heel Strike (NHS)

Mid-foot/ Forefoot Strike

(FFS)

Gap in the Literature • There has never been a systematic review or

meta-analysis addressing the relationship of IC-GRF to both shod/BF and location of first contact.

http://www.superstock.com/stock-photos-images/1598R-38363

QUESTIONS • Primary:

– While running, what are the differences in IC-GRF between BF and shod conditions?

• Secondary: – While running, what are the differences in IC-GRF

between HS vs NHS running patterns?

Both are background questions

Hypothesis & Null Hypothesis H0: HA:

There is NO statistically significant difference in IC-GRF between:

There IS a statistically significant difference in IC-GRF between:

1) BF and Shod running conditions

2) HS and NHS running patterns

Search Procedures • Databases (number of results)

– PubMed (43) – CINAHL (17)

• Search Terms:

– “barefoot running” – “running barefoot” – “run barefoot” – “jog barefoot” – “barefoot runner(s)”

• Dates included in search: 1980 – 2011 – Last search performed: April 30th, 2011

All articles were reviewed against the following criteria

1. Must measure GRF with a force plate or 3D force transducer treadmill**

2. Must compare BF running to Shod running

3. Subjects were “normals” or “athletes” with no pathology present

4. IC-GRF data must be available

1. Articles written in languages other than English

2. Only abstract was available

3. Subjects were less than 16 years old

4. GRF data was not able to be correlated with body weight of subjects

Inclusion Criteria Exclusion Criteria

**(Low et al., 2010; Mainwald et al., 2008; Belli et al. 2001)

Secondary reviewer confirmed that the 7

studies met the inclusion criteria

Summary of Included Studies All studies: level of evidence 2b

Recalculated

Statistics BF vs. Shod running IC-GRF

Effect Size Calculated

High Q-Statistic

Random Effects Model Primary Question

Results Barefoot vs. Shod

Effect Size: -1.72 Large Effect Size

CI (-3.41, -0.04)

Significant

Q-Statistic 121.92

Random Effects Model

Secondary Question

Statistics HS vs. NHS running patterns IC-GRF

Evaluate for difference between HS and NHS means

z-test

Results

Study # of Subjects

HS Mean

HS SD

Hammill et al. 10 1.59 0.31

Lieberman et al. 26 1.74 0.45

Squadrone et al. 8 1.72 0.4

Divert et al. 35 1.70 0.03

Baur et al. 14 1.62 0.15

De Wit et al. 9 1.9 0.3

Dickinson et al. 6 1.39 0.67

Study # of Subjects

NHS Mean

NHS SD

Hammill et al. 10 1.40 0.31

Lieberman et al. 26 0.58 0.21

Squadrone et al. 8 1.62 0.4

BW IC-GRF Mean HS: 1.67

Mean NHS: 1.20

z-test comparing HS and NHS Heel Strike Non-Heel Strike

Results

Z-test: (95% CI) Upper CI: 0.85 Lower CI: 0.08

Statistically Significant Difference HS NHS

1.67 1.20

z-test comparing HS and NHS

Results: H0:

1) There is NO statistically significant difference in IC-GRF between BF and Shod running

conditions

2) There is NO statistically significant difference in IC-GRF between HS and NHS running

patterns

Discussion 1. Significant heterogeneity of data 2. Possible causes for reduced IC-GRF 3. Implications of reduced IC-GRF

http://www.runningnut.com/wp-content/uploads/2010/09/barefoot-runner.jpg

Discussion BF/Shod Comparison

- Number of Strides Measured

Discussion BF/Shod Comparison

Sample Size Difference This image cannot currently be displayed.

Experience of Barefoot Runners • Adaptations to BF running

could take several weeks

(Robbins et al. 1987, 1989 and 1993) http://100daysofmadness.com/wp-content/uploads/2010/11/Son-Running-Barefoot.jpg

http://farm5.static.flickr.com

/4012/4311804925_32cebc0631_o.png

Distance run during data analysis • 6.5 meters vs. 1.2 kilometers

Discussion BF/Shod Comparison Possible Explanations for Heterogeneity of Data

Discussion BF/Shod Comparison Possible Explanations for Heterogeneity of Data

– Experience of Barefoot Runners • De Wit et al. utilized only habitual shod runners in both BF

and Shod conditions – Smaller ES (-0.33)

http://communities.canada.com/calgaryherald/blogs/calgaryrunner/archive/2010/07/07/race-preview-canadian-mountain-running-championships.aspx

Discussion BF/Shod Comparison Possible Explanations for Heterogeneity of Data

– Experience of Barefoot Runners • Squadrone et al. utilized experienced BF runners in both shod

and barefoot conditions – Smaller ES (-0.25)

http://www.barefootrunning.fas.harvard.edu/3RunningBeforeTheModernShoe.html

Discussion BF/Shod Comparison – Experience of Barefoot Runners

• Lieberman et al. utilized habitually shod vs. habitually BF runners

– Larger ES (-3.44)

Possible Explanations for Heterogeneity of Data

http://www.healthynomics.com/wp-content/uploads/2009/08/barefoot-running1.jpg

Discussion The BF condition & FFS running pattern

decrease IC-GRF

Causes?

http://gearjunkie.com/images/1825.jpg http://barefootted.com/uploaded_images/Sportsllustrated

Barefoot01-719926.jpg

Discussion Causes of Decreased IC-GRF

• Superior neurosensory feedback preparing musculature for next stride (Kurz and Stergiou, 2004)

http://www.ransacker.co.uk/wp-content/uploads/2010/08/A-barefoot-runner-in-Hyde-001.jpg

Discussion Causes of Decreased IC-GRF

BF condition tends to equal NHS running pattern (Lieberman et al. 2010; Squadrone et al. 2009; Divert et al. 2005)

http://4.bp.blogspot.com/_JadSUXnX75Q/S3aD2iNRnsI/AAAAAAAAAT8/sl8pbmfVQ70/s320/heelstrike.jpg

Discussion Causes of Decreased IC-GRF

Stretching of arch • first half of FFS • second half of RFS

No energy return and no dampening of forces (Lieberman et al.

2010)

http://www.youtube.com/watch?v=r6YhVN_YIUk

Change in stride length (Lieberman et al. 2010; Squadrone et al,

2009; Divert et al, 2005; De Wit, 2000; Edwards et al. 2009, etc.)

Greater vertical compliance, leading to lower rate of loading (Lieberman et al. 2010)

Discussion Causes of Decreased IC-GRF

Discussion Reduced IC-GRF

http://signaturestyleblog.com/wp-content/uploads/2011/03/girl_running_on_beach.jpg

Implications?

http://signaturestyleblog.com/wp-content/uploads/2011/03/girl_running_on_beach.jpg

Harm and Cost Effects • Not examined in any primary

article – BF running reduces IC-GRF,

theoretically there could be a reduction in stress-induced injuries

– If stress induced injuries are reduced, theoretically health care costs could be reduced

http://ravenessences.files.wordpress.com/2011/03/barefoot_tefe_dancing.jpg?w=218&h=247

Possible Precautions/Contraindications

• Osteoporosis/Osteopenia • Peripheral Neuropathy • Peripheral Arterial Disease • Rigid midfoot • Cold/Hot Temperatures • Obstacles on ground

– Broken glass – Nails – Needles

http://shodless.com/wp-content/uploads/2010/01/michael_sadler_barefoot_winter.jpg

(Squadrone et al. 2009; Jenkins and Ross, 2011)

Shoes for forefoot strike? • Vibram Fivefingers

• Tarra Plana Evo

• Merrell Trail Glove

• New Balance Minimus

• Kigo Edge

• Nike Free

http://www.vibramget.com/images/729013%5B1%5D.jpg

http://www.nikefreerunshop.com/images/nike_free_run_men_black_red.jpg

http://www.treehugger.com/Terra-plana-evo-barefoot-running-shoe-photo.jpg

http://runningtimes.com/rt/images/201012/TrailShoe_Merrell-Trail-Glove-.jpg

http://kayakshed.blogspot.com/2010/07/kigo-improves-its-minimalist-shoes.html

http://www.shopnewbalance.com/products/MT10GY_lg.jpg

Implications for Practice • Educate patients on

evidence available at this point

• Decreased IC-GRF with BF running – Effect size -1.72 = 41% BW

• NHS also reduces IC-GRF

• PT interventions?

http://www.voxy.co.nz/userfiles/running%20barefoot%20shoes.jpg

Limitations

• Heterogeneous studies – Heterogeneous subjects – Inconsistent distance run in experiment – Small sample sizes

• Developing area of research – HS vs NHS required

• Only included articles in English • Not enough data to determine interaction

effect between BF and NHS

Directions for Further Research • Define normative values for specific sub-groups

of runners

• Further examine differences between habitually shod and barefoot runners

• Investigate whether minimalist shoes mimic the positive aspects of BF running

• Investigate BF vs Shod running patterns at longer distances

Directions for Further Research • Investigate injury rates in both BF and shod

running populations • Investigate which body types and structures

are most successful for both shod and barefoot running

• Role of BF/NHS running in injury prevention

Conclusions • Statistically Significant

difference in IC-GRF between BF/Shod and HS/NHS

• Further research needs to be completed before making large clinical decisions

• This literature review is just one step towards understanding the vast differences between running barefoot and running shod

http://www.goodhousekeeping.com/cm/goodhousekeeping/images/qZ/ghk-canyon-spotting-lg.jpg

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Thank You

• Diane Allen, PT, PhD • Arlene McCarthy, PT, DPT, MS, NCS • Ali Legakis, MS, DPT(c) • Emily Hellmuth, MS, DPT(c) • Pete Rumford, MS, DPT(c), CSCS • Sara Tanza, MS, DPT(c) • Naomi Hosking, MS, DPT(c) • Janeen Gray, MS, DPT(c) • UCSF/SFSU, DPT Class of 2011

Videos if Time Allows • Barefoot Kenyan runner • http://www.youtube.com/watch?v=pgkWhca

pWLU