Comparing foot-strike patterns and kinetics during barefoot, two minimal shod and a cushioned shod running condition

taupeselectionΜηχανική

14 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

145 εμφανίσεις




Comparing foot
-
strike patterns and
kinetics during barefoot, two
minimal shod and
a
cushioned
shod running condition





110552686


1



Abstract


Background:

Barefoot running has been proposed as a method of preventing
overuse injuries due to modifications in gait,

leading to reduced impact forces.
Consequently, there has been a rise in the sales of minimal footwear which, it is
claimed, simulates barefoot running.

Objectives:

To compare foot
-
strike, impact peak, active peak, loading rate and
vertical impulse betwee
n running barefoot, in two minimal shod and a cushioned
shod condition (control).

Methods:

Nine long distance runners without barefoot/minimal shoe running
experience, who run 20km minimum a week with a rearfoot strike (RFS), each ran in
four conditions in

a random order: barefoot, Saucony Hattori, Nike Free 3.0 V4 and
Asics Cumulus 12 (control). Kinematics were recorded

using four CX1 Codamotion
units
.

Kinetics were measured by an
H/P/Cosmos Gaitway 1

instrumented

treadmill
.
Statistical analysis was perfor
med with Microsoft Excel and SPSS software.

Results:

Multivariate analysis revealed footwear had a significant effect on foot
-
strike angle (p=0.015) which correlated strongly with foot
-
strike pattern
(Pearson
correlation =
-
0.9; p<0.001). Specifically, bar
efoot and Saucony conditions had
6
66

.
% and
3
33

.
% less RFS than the control shoe respectively. Foot
-
strike angle did
not significantly differ between Nike and control. No significant difference was found
between running

conditions for all measured kinetic variables.

Submitted in part fulfilment of

the intercalated BSc in Sports and Exercise Medicine

110552686


2


Conclusion:

Habitually shod runners are less likely to land with a RFS whilst
barefoot or in shoes with minimal cushioning (Saucony Hattori), an adaptation which
may be responsible for the observed similariti
es in impact forces in all running
conditions. Minimal footwear may be a suitable tool for foot
-
strike modification.

Key terms: Barefoot running, shod running, kinetics, foot
-
strike, minimal shoe

1. Introduction


Recreational running continues to
grow in p
opularity
, with weekly athletic
participation in England increasing by approximately 17.5%

(
0.3 million
)

between
2008 and 2011.
[1]

Performing at least 150 minutes of moderate intensity e
xercise
,
such as running,

per week
is associated with a number of health benefits
,
[2]

including a 35% reduced risk of coronary heart disease and a 50% reduced risk of
type II diabetes
.
[3]

However,

running is

also

associated with a high incidence of
overuse injuries, reported between 1
9
-
78%
.
[4]

With increasing promotion of health
related physical activity,

the number of related musculoskeletal injuries is expected
to rise.
[2, 5]

Therefore, identifying risk factors contributing to running injuries and
effective interv
entions to prevent them is vital.

A number of kinetic and kinematic factors have been implicated in the development
of overuse running injuries.
High vertical loading rates and impact force magnitude
are associated with runners who have experienced overuse

injuries,
[6]

such as tibial
stress fractures
[7]

and plantar fasciitis.
[8]

Reviewing the evidence, Hreljac concluded
that it appears runners who achieve relatively low impact for
ces are at a reduced
risk of overuse injuries.
[9]

Additionally, foot
-
strike pattern has recently been
implicated in the development of lower limb injury, with an increased incidence of
110552686


3


overuse injury associated with rearfoot strikers (RFS) compared to for
efoot strikers
(FFS).
[10]

Barefoot running has recently experienced increasing popularity due to the p
roposed
benefits, primarily related to injury prevention. In fact, i
t has long been hypothesised
that running barefoot may be one wa
y of reducing running injuries.
[11]

Compared to
shod, barefoot running is associated with a more plantarflexed foot
-
strike, causing an
increased prevalence

of a

FFS or midfoot strike (MFS)

gait.
[12
-
14]

It is suggested
this is because this leads to

reduction
s

in

the rate and magnitude of

impact forces
compared to RFS,
[12, 15]

and limits local pressure under the heel
[16]

due to

controlled dorsiflexion

of the ankle at impact.
[17]

Research suggests
modern running
sh
oes reduce
loadin
g rates for shod RFS but do not a
ffect impact
force peaks
.
[12,
17]

It

is theorised
modern running shoes

ma
y

facilitate RFS

by

heel elevation
and
cushioning, which
may be one reason the incidence of injuries has remained high
despite advances in cushioni
ng and motion control footwear.
[18]


The proposed benefits of barefoot running have led to

the arrival of
numerou
s
“minimal” or “barefoot” shoes, accounting for 8% of total running shoe sales in
America in 2011.
[19]

Despite this, o
nly two commer
cially available minimal shoes
have been
tested

with barefoot or conventional shod conditions.
[13, 20]

The Nike
Free 5.0 was found to increase
cross
-
section
al areas
and

strength of plantar flexor
muscles after five months.
[20]

Squadrone and Gallozzi is the only study to
investigate kinetics and k
inematics of a minimal shoe, the

Vibram FiveFingers
.
[13]

In
a treadmill study involving experienced barefoot runners, it was suggested the thin
sole of the FiveFingers allowed plantar discomfort to be sensed

and therefore
moderated, resulting in the FiveFingers producing similar ankle joint angle and
impact forces to barefoot running.
[13]


110552686


4



1.1.
Aim

and hypotheses


The aim of this study wa
s to assess
the immedi
ate effect in

kinematic and kinetic
variables during running

in two different minimal shoes
(
Saucony Hattori and

Nike
Free

3.0 V4
)

compared to

barefoot

and

a control shoe:
conventional
neutral
cushioned trainers

(Asics Cumulus 12)
. The
kinematic variable

m
easured
was

foot
-
strike

(foot
-
strike
pattern

and foot
-
strike angle). The kinetic variables measured were

peak

vertical

impact

ground reaction force

(GRF) (impact peak), peak vertical GRF
(active peak), loading rate and vertical impulse (Figure 1). It was

h
ypothesis
ed that in
habitually shod long distance runners:

i) barefoot

a
nd Saucony Hattori would not differ significantly in the measured
variables, as this minimal shoe has very little cushioning and no heel elevation.

ii) Nike
F
ree

and
control shod

woul
d not differ significantly in the measured variables,
as both the Nike Free and control shoe have elevated cushioned heels, albeit to a
lesser degree in the Nike Free
.


It was further hypothesised that:

iii) the barefoot and Saucony conditions would be si
gnificantly
different
in foot
-
strike
and the measured kinetics to the Nike and control shod due to the highlighted
differences in cushioning and heel elevation
.

110552686


5



2. Materials and methods


2.1.
Subjects


Nine (three
male/
six
female
) long distance runners
w
ere

recruited from local running
clubs and specialised running shops via posters and email.
They ran on average a

minimum of 20 kilometres per week

and had not suffered from injury preventing them
running for more than four weeks in the previous six month
s. Their average
characteristics were:
age, 29.2
±
8.1

years; weight, 68.2
±
13.2
kg; height,

1.76
±
0.1m;
10km time, 44.47
±
4.93 minutes. All participants were
rearfoot strikers in
Impact Peak/ Peak
vertical impact GRF =
peak force at 70ms

Active peak/ Peak
vertical GRF

Loading rate
= force/time

Vertical impulse
= integral of a
force with
respect to time
(area bound by
its gra
ph)

Figure
1
:
A typical ground reaction force curve

of one shod running stride

with kinetic variables defined

(adapted from Lieberman et al)[12]


Time (seconds)


Force (body weights)


110552686


6


conventional
cushioned trainers

with no experience of running
barefoot or
in
minim
al
footwe
ar. Ethical approval was gained from
Queen Mary University

of London

ethic
s

committee
.
Participants were informed about the procedures and signed a written
consent.


2.2. Protocol


Preceding data collection, participants warmed up for five minute
s on the
instrumented treadmill in their own running shoes to allow them to accustom to the
equipment and select their speed for all trials, directed as a pace similar to an hour’s
training run. Each

participant then

r
an in four conditions on the instrumen
ted
treadmill:
barefoot,
Saucony Hattori,
Nike Free

3.0 and Asics Cumulus (control), in
an order determined by a random number generator. The characteristics of each
shoe are described in Table 1. Participants were given no instruction on foot
-
strike
patte
rn.

There was approximately two minutes break between each trial to change shoes and
prevent accumulating fatigue. For each condition, the participants ran continuously
for approximately four minutes whilst data were collected simultaneously by the
instrum
ented treadmill and motion analysis equipment over multiple periods of ten
seconds at approximately one minute intervals. This was done until at least two sets
of complete data were achieved for each running condition per subject, defined by
adequate motio
n analysis marker visibility and complete gait cycles recorded on the
treadmill.


110552686


7


Table
1
-

Shoe Characteristics

Shoe

Weight (g)

Heel elevation*
(mm)

Mid
-
sole materials

Outer
-
sole
materials

Saucony Hattori

125

0

Ethylene
-
vinyl aceta
te

(EVA)

Carbon rubber

Nike Free 3.0 V4

204

4

Phylite (EVA and
rubber)

Phylite, rubber

Asics Cumulus

12

340

14

Solyte, blown rubber,
plastic

Rubber

*The difference in height between the forefoot and heel sections of the shoe



2.3. Equipment and d
ata
c
ollection


D
ata
were

collected inside at the Human Performance Laboratory at Queen Mary,
University of London.

A
H/P/Cosmos Gaitway 1 treadmill (H/P/Cosmos Sports &
Medical GMBH, Nussdorf
-
Traunstein, Germany) containing two Kistler forceplates
sampling

at
100Hz (Kistler Group, Winterthur, Switzerland)

was used to measure
vertical GRF, from which the impact and active peaks, loading rate and impulse were
derived by Gaitway software. Impact peak was determined as the maximum force
occurring in the first 70ms
of each foot
-
strike. Results for the kinetic variables for
each foot
-
strike of each trial were averaged for each running condition per subject
and normalised to body mass (BW), before creating a group mean for each running
condition.

Intra
-
rater reliabilit
y was found to be good (Pearson correlation for active
force peak=1.0).

Motion capture
was
recorded at 200Hz

via an active system using four CX1
Codamotion units (Charmwood Dynamics, Rotheley, Leicestershire, UK) with infra
-
red markers placed

according to
a modified Helen Hayes gait protocol:

lateral aspect
of the base of the fifth metatarsal, lateral heel, lateral malleolus, proximal lateral
epicondyle of the tibia,
wand
-
sets

superior and inferior to the knees
,

anterior superior
110552686


8


iliac spine and posterior s
uperior iliac spine of both lower limbs.
In the shod
conditions
, the markers on the foot (base of fifth metatarsal and lateral heel)
were
placed directly on the shoe in the corresponding anatomical position
s.

Kinematic

results

of the last trial of each ru
nning condition for each participant were

analysed usi
ng Codamotion Analysis V6.9. Digital stick figures were examined
visually to classify foot
-
strike pattern as either rearfoot (heel contacts ground first),
midfoot (heel and forefoot contact ground simul
taneously) or forefoot (forefoot
contacts ground first).
[17]

In addition, the pitch of the foot was recorde
d for the first
three strides of the right and left leg of the trial being analysed, to give an average
foot
-
strike angle, with 0° indicating a level foot in relation to the treadmill.
[21]

Statistical analysis was carried out
with Excel (Microsoft, USA) and
SPSS
software
(IBM,
New York
,
U
SA). Data were checked for normality using
Kolmogorov
-
Smirn
ov
and Shapiro
-
Wilk tests.

3. Results


The average participant selected speed of the trials was 11.1
±
1.9kmph. Cadence
was found to be significantly higher (p<0.001) barefoot compared to control shod
(170
±14spm

(mean ± standard deviation, steps per minute)
versus
164±11spm).

Cadence was 168
±10spm

in the Saucony and 165±12spm in the Nike.

Contact time
was not found to be significantly different between footwear conditions.





110552686


9


3.1. Foot
-
strike


Footwear had a significant effect on foot
-
strike angle (p=0.015).

Tukey post
-
hoc
analysis revealed barefoot running was associated with a flatter foot placement at
initial contact compared to all shod conditions and the Saucony was associated with
a flatter foot placement compared to the Nike and control. The Nike and c
ontrol were
not significantly different in foot
-
strike angle.

Foot
-
strike angle correlated strongly with foot
-
strike pattern
(Pearson correlation =
-
0.9; p<0.001)
. The flatter foot
-
strike angle whilst barefoot resulted in a
6
66

.
%
reductio
n in RFS prevalence when compared to control shod (Table 2).


Table
2
-

Mean foot
-
strike angle and correlating foot
-
strike pattern


3.2. Kinetic variables


Data were reported as normally distributed. Impact peak was found to be 1.63
±0.31
BW

(mean ± standard deviation, bodyweights)
for barefoot, 1.54
±0.25

BW

for
Sa
ucony, 1.50±0.29
BW

for Nike and 1.49±0.28

BW

for control shod (Figure 2).
Active peak was found to be 2.33
±0.28BW
for barefoot, 2.34
±0.29

BW
for Saucony,
2.33±0.27
BW

for Nike and 2.32±0.26

BW

for control shod (Figure 3).

Footwear

Mean foot
-
strike
angle (
degrees)

Foot
-
strike pattern (%)

RFS

MFS

FFS

Barefoot

2.0

3
33

.

2
22.


4
44

.

Saucony Hattori

6.3

6
66

.

0.0

3
33

.

Nike Free 3.0

11.0

9
88

.

0.0

1
11

.

Control (Asics Cumulus)

11.5

100.0

0.0

0.0

Abbrevia
tions: RFS, rearfoot strike; MFS, midfoot strike; FFS, forefoot strike

110552686


10


Loading rate was found to be 28.
18
±7.74 BWs
-
1

(bodyweights per second)
for
barefoot, 27.08
±6.48

BW
s
-
1

for Saucony, 26.43±6.48
BW
s
-
1

for Nike and 26.12±6.96

BW
s
-
1

for control shod (Figure 4).

Impulse was found to be 0.347
±0.026 BW∙s
(bodyweights x seconds)
for barefoot, 0.357
±0.022

BW
∙s

f
or Saucony, 0.365±0.028
BW
∙s for Nike and 0.370±0.027

BW
∙s

for control shod (Figure 5).
Multivariate
analysis demonstrated that footwear had no significant effect on impact peak, active
peak, loading rate or impulse.



Figure 2:

Mean impact peaks with standard deviations compared betwee
n multiple
running conditions.


110552686


11



Figure 3:

Mean active peaks with standard deviations compared between multiple
running conditions.


Figure 4:

Mean loading rates and standard deviations compared between multiple
running conditions.


110552686


12


4. Discussion


This study aimed t
o examine whether there were any differences in
foot
-
strike
,
impact peak, active peak, loading rate and vertical impulse between running barefoot
and three varying shod conditions. Footwear was not found to have a significant
effect on running kinetics, bu
t did significantly influence foot
-
strike. Therefore, the
hypothesis that barefoot and Saucony conditions will be similar in the measured
variables (i) is only partially accepted as foot
-
strike pattern

significantly differed
between the two conditions.
The

hypothesis that the Nike and control shod
conditions will be similar in the measured variables (ii) is accepted. Hypothesis ‘iii’ is
partially accepted because although kinetic variables were not significantly different
between footwear, foot
-
strike patte
rn was.

Figure 5:

Mean vertic
al impulses with standard deviations compared between
multiple running conditions.


110552686


13


4.1. Shod versus barefoot


There was a significant mean difference (MD) in foot
-
strike angle between control
shod and barefoot (MD, 9.5
°
; 95% C.I: 6.5
°,
12.7
°; p<0.001) which correlated
strongly with the difference in foot
-
strike pattern. Specifica
lly, 100% of participants
ran RFS in the control shod versus only 33% whilst barefoot. As demonstrated by
Lieberman et al, foot
-
strike pattern is an important confounding factor to GRFs, with
a FFS being associated with a significant reduction in impact pe
ak and loading rate
compared to a RFS whilst barefoot.
[12]

As previous studies have found FFS to be associated with a reduced impact peak
compared to RFS,
[12, 13]

it could be expected that barefoot r
unning would be
associated with a reduced impact peak in the current study due to the increased FFS
prevalence. However, neither impact peak nor active peak values were found to be
significantly different between control shod and barefoot. The small sample

size and
large spread of data may contribute to this. Additionally, differences in calculating
impact peak may be responsible. Specifically, impact peak was determined as the
peak value in the first 70ms of stance, whereas previous studies have determined

this value by measuring the impact transient on GRF curves.
[12, 13]


Previous research by Squadrone and Gallozzi
[13]

and De Wit et al,
[16]

also found
no difference in active peaks between running barefoot or a neutral cushioned shoe.
However, Squadrone and Gallozzi did find barefoot running to be associated with a
significant reduction in impact peak, as did
Divert et al.
[15]

It has been suggested
that the repetition of impacts over four minutes of treadmill running in Divert et al’s
study led to a switch from RFS to FFS whilst barefoot.
[15]

It was further suggested
110552686


14


that this adjustment may not occur over a limited number of steps,
[15]

as in studies
using a forceplate on short runways such as De Wit et al.
[16]


Loading rate was also found not to be significantly different whilst barefoot compared
to control shod, in co
ntrast to De Wit et al whom reported reduced loading rates
whilst shod.
[16]

However, all of the participants in De Wit et al ran RFS whilst
barefoot and shod, whereas only 33% of participants ran R
FS whilst barefoot in the
current study. Lieberman et al found RFS barefoot associated with higher loading
rates, in contrast to FFS barefoot which produced loading rates similar to shod
running.
[12]

Therefore, the higher prevalence of FFS w
hilst barefoot may be
responsible for the observed similarity between barefoot and shod loading rates in
the current study. Considering injury prevention, it appears barefoot runners who do
not adopt a FFS technique may experience higher loading rates comp
ared to shod
runners, which may put them at increased injury risk.
[6]

Vertical impulse was higher shod compared to barefoot. However, the observed
difference was not significant, agreeing with findings of Divert et al.
[15]

Impulse is
related to a change in momentum
[22]

and it has been shown that running RFS is
associated with a higher effective mass (percentage o
f mass which exchanges
momentum with the ground at impact) than FFS.
[12]

Therefore, impulse may be
higher during shod running because of the higher RFS prevalence.

The observed differences between running shod and barefoot do not suggest a
basis
for a difference in risk of injuries related to ground reaction force. However, it must
be stressed that these are only immediate effects. The change towards a FFS whilst
barefoot may put the runners at an increased risk of other potential sources of

injury
such as gastrocnemius
-
soleus muscle soreness and strain, Achilles
110552686


15


tendinopathies
[17]

and metatarsal

stress fractures
[23]

as habitually shod runners
may not have the required calf strength to deal with the increased plantarflexor
moments associated wit
h a FFS.
[24]


4.2. Shod versus minimal shod


Foot
-
strike angle was significantly larger in the control shod compared to the
Saucony (MD, 5.2
°
; 95% C.I: 2.1
°, 8.3°; p<0.001) but not compared to the Nike
(MD,
0.5
°
; 95% C.I:
-
2.6
°, 3
.6
°; p=0.98). This is fur
ther demonstrated by noting that three
participants utilised a FFS technique whilst in the Saucony compared to none in the
control shod, with just one FFS participant in the Nike. It seems probable that the
cushioning or elevation of the Nike’s heel is res
ponsible for its higher RFS
prevalence. It is likely that more of the participants switched to a FFS in the Saucony
due to the reduced amount of cushioning in the heel causing plantar discomfort, a
similar mechanism to that suggested for the Vibram FiveFin
gers.
[13]

Even so, most
participants persisted with a RFS in the Saucony, warranting further investigation.

No significant difference was found in the kinetic variables between the control shod
and either mi
nimal shod condition. This suggests that in the short term, the degree of
cushioning in a shoe does not significantly influence GRFs experienced by habitually
shod runners. However, further investigation must be carried out considering the
long term effect
s of transitioning to a minimal shoe. Recent case series have
demonstrated potential benefits of re
-
training symptomatic individuals with
patellofemoral pain and chronic exertional compartment syndrome to run with a non
-
RFS technique.
[25, 26]

A minimal shoe with little cushioning at the heel, such as the
Saucony Hattori, may aid in training landing pattern modification as habitually shod
110552686


16


RFS runners seem more likely to switch to non
-
RFS in this shoe compared to a
co
nventional shoe, without any instruction to do so.


4.3. Limitations


The major limitation in this study is the small sample size, so conclusions must be
drawn with caution. The investigation should be extended to see if trends can be
projected. Another li
mitation is that this study only considers the immediate effects of
changing the footwear condition, which may be different to the effects of habituation.
Two studies consider habituated barefoot runners
[12, 13]

bu
t there are yet to be
prospective studies examining the effects of habituating to barefoot or minimal shoe
use.

This study is also limited by the number of biomechanical variables measured. Other
variables such as joint moments,
[27, 28]

braking and pushing impulse,
[15]

knee
kinematics,
[14, 16, 29]

leg stiffness
[14, 30]

and muscle activation
[15, 31]

have been
shown to differ between barefoot an
d shod running. How these variables are related
to running injuries needs further investigation. Also, how minimal footwear affects
these variables should be considered.

Additionally, as previous research suggests, foot
-
strike could be a confounding factor

on the kinetic results.
[12, 15]

The low sample size did not allow for robust statistical
analysis of foot
-
strike as a sub
-
group but the results merit further study with a larger
sample size (Appendix, Table 1A). T
he difficulty of identifying a MFS has been
previously described, which may lead to the incorrect classification of FFS or
RFS.
[21]

Furthermore, it has been found that faster runners are more likely to land
110552686


17


with a MFS or FFS compared to slower runners,
[32]

reflected in the current study
(Appendix, Figure 1A), which may further confound results as an increased velocity
is associated with increased gro
und reaction forces.
[16]


4.4 Conclusion


This study shows that when speed is kept constant, habitual shod runners are more
likely to switch to a FFS whilst barefoot

compared to shod. This pattern
is also more
likely in a shoe with minimal cushioning and no heel elevation (Saucony Hattori)
compared to a shoe with more cushioning and heel elevation (Nike Free 3.0 or Asics
Cumulus). Impact peak, active peak, loading rate and impulse were found to be n
ot
significantly different across barefoot and three varying shod conditions, which may
be due to the changes in foot
-
strike pattern. Consequently, a minimal shoe such as
the Saucony Hattori may be a suitable aid to those attempting to modify their foot
-
st
rike pattern, although it will not have an immediate effect on impact rates and
magnitudes.

110552686


18



References


1.

Sport England
. Active People Survey 5 Q2
-

Athletics. 2011.

2.

Department of Health PA, Health Improvement and Protection. Start

Active,
Stay Active. 2011.

3.

NHS. Benefits of Exercise. 2011 [cited 2011 6th December]; Available from:
http://www.nhs.uk/livewell/fitness/pages/whybeactive.aspx
.

4.

van Gent RN, Siem D, van Middelkoop M, van Os AG, Bierma
-
Zeinstra SMA,
Koes BW, et al. I
ncidence and determinants of lower extremity running injuries
in long distance runners: a systematic review. British Journal of Sports
Medicine. 2007;41(8):469
-
80.

5.

Seah R, Radford D, Tillett E, Creaney L. NHS Consultants in Sport & Exercise
Medicine: a
new medical specialty to facilitate a physically active population.
The Faculty of Sports and Exercise Medicine (UK), 2009.

6.

Hreljac A, Marshall RN, Hume PA. Evaluation of lower extremity overuse injury
potential in runners. Medicine and Science in Sport
s and Exercise.
2000;32(9):1635
-
41.

7.

Zadpoor AA, Nikooyan AA. The relationship between lower
-
extremity stress
fractures and the ground reaction force: A systematic review. Clinical
Biomechanics. 2011;26(1):23
-
8.

8.

Pohl MB, Hamill J, Davis IS. Biomechani
cal and Anatomic Factors Associated
with a History of Plantar Fasciitis in Female Runners. Clinical Journal of Sport
Medicine. 2009;19(5):372
-
6.

9.

Hreljac A. Impact and Overuse Injuries in Runners. Medicine & Science in
Sports & Exercise. 2004;36(5):845
-
9
.

10.

Daoud AI, Geissler GJ, Wang F, Saretsky J, Daoud YA, Lieberman DE. Foot
Strike and Injury Rates in Endurance Runners: a retrospective study. Med Sci
Sports Exerc. 2012. Epub 2012/01/06.

11.

Robbins SE, Hanna AM. Running
-
related injury prevention thro
ugh barefoot
adaptations. Medicine and Science in Sports and Exercise. 1987;19(2):148
-
56.

12.

Lieberman DE, Venkadesan M, Werbel WA, Daoud AI, D'Andrea S, Davis IS,
et al. Foot strike patterns and collision forces in habitually barefoot versus shod
runners
. Nature. 2010;463(7280):531
-
U149.

13.

Squadrone R, Gallozzi C. Biomechanical and physiological comparison of
barefoot and two shod conditions in experienced barefoot runners. Journal of
Sports Medicine and Physical Fitness. 2009;49(1):6
-
13.

14.

Bishop M,
Fiolkowski P, Conrad B, Brunt D, Horodyski M. Athletic footwear, leg
stiffness, and running kinematics. Journal of Athletic Training. 2006;41(4):387
-
92.

15.

Divert C, Mornieux G, Baur H, Mayer F, Belli A. Mechanical comparison of
barefoot and shod running.

International Journal of Sports Medicine.
2005;26(7):593
-
8.

16.

De Wit B, De Clercq D, Aerts P. Biomechanical analysis of the stance phase
during barefoot and shod running. Journal of Biomechanics. 2000;33(3):269
-
78.

110552686


19


17.

Lieberman DE. What we can learn ab
out running from barefoot running: an
evolutionary medical perspective. Exercise and sport sciences reviews.
2012;40(2):63
-
72.

18.

Jenkins DW, Cauthon DJ. Barefoot Running Claims and Controversies A
Review of the Literature. Journal of the American Podiatr
ic Medical Association.
2011;101(3):231
-
46.

19.

Insight F. Less Shoe, More Sales. Footwear Insight. 2011:40
-
1.

20.

Brüggemann G
-
P, Potthast W, Braunstein B, Niehoff A, editors. Effect of
Increased Mechanical Stimuli on Foot Muscles Functional Capacity.
Int
ernational Society of Biomechanics' Symposium; 2005; Cleveland, Ohio,
USA.

21.

Altman AR, Davis IS. A kinematic method for footstrike pattern detection in
barefoot and shod runners. Gait &amp; Posture. 2012;35(2):298
-
300.

22.

Bobbert MF, Schamhardt HC, Nig
g BM. Calculation of vertical ground reaction
force estimates during running from positional data. Journal of Biomechanics.
1991;24(12):1095
-
105.

23.

Giuliani J, Masini B, Alitz C, Owens BD. Barefoot
-
simulating footwear
associated with metatarsal stress in
jury in 2 runners. Orthopedics.
2011;34(7):e320
-
3.

24.

Williams DS, McClay IS, Manal KT. Lower extremity mechanics in runners with
a converted forefoot strike pattern. Journal of Applied Biomechanics.
2000;16(2):210
-
8.

25.

Cheung RTH, Davis IS. Landing Pat
tern Modification to Improve Patellofemoral
Pain in Runners: A Case Series. Journal of Orthopaedic & Sports Physical
Therapy. 2011;41(12):914
-
9.

26.

Diebal AR, Gregory R, Alitz C, Gerber JP. Forefoot running improves pain and
disability associated with chr
onic exertional compartment syndrome. Am J
Sports Med. United States2012. p. 1060
-
7.

27.

Kerrigan DC, Franz JR, Keenan GS, Dicharry J, Della Croce U, Wilder RP. The
effect of running shoes on lower extremity joint torques. PM & R : the journal of
injury,
function, and rehabilitation. 2009;1(12):1058
-
63.

28.

Braunstein B, Arampatzis A, Eysel P, Brueggemann G
-
P. Footwear affects the
gearing at the ankle and knee joints during running. Journal of Biomechanics.
2010;43(11):2120
-
5.

29.

McNair PJ, Marshall RN. K
inematic and kinetic
-
parameters associated with
running in different shoes. British Journal of Sports Medicine. 1994;28(4):256
-
60.

30.

Divert C, Baur H, Mornieux G, Mayer F, Belli A. Stiffness adaptations in shod
running. Journal of Applied Biomechanics. 2
005;21(4):311
-
21.

31.

von Tscharner V, Goepfert B, Nigg BM. Changes in EMG signals for the muscle
tibialis anterior while running barefoot or with shoes resolved by non
-
linearly
scaled wavelets. Journal of Biomechanics. 2003;36(8):1169
-
76.

32.

Hasegawa H
,
Y
amauchi
T
,
K
raemer
WJ
. Foot Strike Patterns of Runners At the
15
-
Km Point During An Elite
-
Level Half Marathon. The Journal of Strength &
Conditioning Research. 2007;21(3):888
-
93.



110552686


20



Appendix
-

Additional analysis of potential confounding factors


Table
1A:
Descriptive statistics and
Mann
-
Whitney test

to assess the difference in impact
peaks between FFS and RFS whilst barefoot
.







Variable

Observations

Minimum

Maximum

Mean

Std.
deviation

FFS

4

1.494

2.042

1.851

0.247

RFS

3

1.342

1.435

1.374

0.053







Mann
-
Whitney test / Two
-
tailed test:









U

12.000





Expected value

6.000





Variance (U)

8.000





p
-
value (Two
-
tailed)

0.057





alpha

0.05





Test interpretation:

As the p
-
value is greater
than the
α
-
level of 0.05, one cannot reject the
null hypothesis (that there is no difference
between the impact peaks of FFS

and RFS
running). However the p
-
value of 0.57 was
only just outside the significance level and with
a greater sample size is likely to be significant.

110552686


21



Figure A1:

Mean selected running speeds between differing foot
-
strike patterns
observed whilst barefoo
t. Note that those running MFS and FFS chose a faster
velocity than those who ran RFS. Faster running velocities are associated with
greater ground reaction forces.[16]