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Do you get value for money when you buy an
1
ORIGINAL ARTICLE
Do you get value for money when you buy an expensive pair
of running shoes?
Richard Clinghan, Graham P Arnold, Tim S Drew, Lynda A Cochrane, Rami J Abboud
...................................................................................................................................
Br J Sports Med 2007;0:1–5. doi: 10.1136/bjsm.2007.038844
See end of article for
authors’ affiliations
........................
Correspondence to:
R J Abboud, Institute of
Motion Analysis and
Research (IMAR), Division of
Surgery & Oncology, TORT
Centre, Ninewells Hospital
and Medical School, Dundee
DD1 9SY, Scotland, UK;
[email protected]
Accepted 9 August 2007
........................
Objective: This investigation aims to determine if more expensive running shoes provide better cushioning of
plantar pressure and are more comfortable than low-cost alternatives from the same brand.
Methods: Three pairs of running shoes were purchased from three different manufacturers at three different
price ranges: low (£40–45), medium (£60–65) and high (£70–75). Plantar pressure was recorded with the
PedarH in-shoe pressure measurement system. Comfort was assessed with a 100 mm visual analogue scale.
A follow-on study was conducted to ascertain if shoe cushioning and comfort were comparable to walking
while running on a treadmill. Forty-three and 9 male subjects participated in the main and follow-on studies,
respectively. The main outcome measure was the evaluation of plantar pressure and comfort.
Results: Plantar pressure measurements were recorded from under the heel, across the forefoot and under the
great toe. Differences in plantar pressure were recorded between models and between brands in relation to
cost. Shoe performance was comparable between walking and running trials on a treadmill. No significant
difference was observed between shoes and test occasions in terms of comfort.
Conclusions: Low- and medium-cost running shoes in each of the three brands tested provided the same (if
not better) cushioning of plantar pressure as high-cost running shoes. Cushioning was comparable when
walking and running on a treadmill. Comfort is a subjective sensation based on individual preferences and
was not related to either the distribution of plantar pressure or cost.
R
unning is a high-impact activity. Middle-distance runners
experience impact forces (ground reaction force) upwards
of 2.5 times bodyweight with each footfall.1 Impact force
increases with speed2 and fatigue.3 The latter also reduces the
stabilising capacity of the musculoskeletal structures surrounding the ankle.4 The ground reaction force produces vibrations
(shock waves) that are transmitted by the bones of the foot to
the rest of the body.5 The intensity of this shock wave has been
linked to the development of running-related injuries.6
Running has been associated with the occurrence of knee pain,
shin splints, plantar fasciitis, stress fractures,7 and the development of degenerative conditions (primary osteoarthrosis,
achilles tendonitis) and muscle tears.8 It has been suggested
that running injuries are the result of training error, anatomical
factors (such as excessive pronation), accumulated impact
loading and chronic overuse.7 Impact force is substantially
reduced by appropriate joint alignment.9 The viscoelastic
properties of the heel tissues provide significant shock absorption.10 11 Athletic footwear reduces impact force peaks and
shock wave intensity by approximately 33% and 36%, respectively, compared with measurements recorded walking barefoot. Shoes with a more elastic mid-sole offer better cushioning,
thus providing improved impact force attenuation.12
Better cushioning materials, found in more expensive
running shoes, have been reported to attenuate impact force
to a greater extent than less expensive alternatives.3 However, it
has been suggested that the advertising of advanced safety
features and protective devices of these more expensive running
shoes is deceptive; runners subconsciously subject themselves
to greater impact forces, thereby increasing the risk of injury.
This accounted for a 123% greater injury frequency observed
amongst runners who trained in expensive running shoes
compared with those running in less expensive models or
brands.13
Comfort is becoming an increasingly important aspect of
running shoe design as it may be related to fatigue, injury
development and athletic performance.14 It has been suggested
that perceptions of comfort are based on previous stimuli.15
Many factors, including plantar pressure distribution, foot
accommodation and skeletal alignment, may influence the
perception of comfort.14 Other influencing factors include
whether an individual is walking or running, and the flexibility
and hardness of the mid-sole.16 Ultimately, comfort relates to a
multitude of mechanical, neuro-physiological and psychological attributes, unique to the individual.14
This investigation aims to determine whether more expensive
running shoes provide better cushioning of plantar pressure
(and therefore improve pressure attenuation) and whether
these are more comfortable than less expensive alternatives
from the same brand.
METHODS
Test shoes
Nine pairs of neutral running shoes (male fittings) UK sizes 8
and 10 were purchased in the UK. These sizes were considered
to be the most common male shoe sizes, and would thus allow
the optimum number of subjects to participate. As no
standardisation of shoe size exists amongst manufacturers,
shoes were bought based on their actual size, rather than their
marked size. The size of the shoe was determined with a
calibrated shoe size ruler, which correlates length of shoe to its
size. Three pairs of shoes were bought from three different
manufacturers (Brands A, B, C). The price ranges were low
(£40–45), medium (£60–65) and high (£70–75) as shown in
table 1. No manufacturer involvement was established during
the trials, ensuring that testing was completely independent.
All manufacturer-specific features and company logos were
concealed with adhesive tape to ensure blinding. One pair in
each size were chosen from a leisure brand to act as controls.
Abbreviation: VAS, visual analogue scale
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Clinghan, Arnold, Drew, et al
Table 1 Shoes tested
Manufacturer
Price (£)
Price range
Shoe code
Brand A
40
60
70
40
60
70
40
65
75
Low
Medium
High
Low
Medium
High
Low
Medium
High
Al
Am
Ah
Bl
Bm
Bh
Cl
Cm
Ch
X1
X2
Brand B
Brand C
Control first trial
Control last trial
Subjects
This study was conducted in the Institute of Motion Analysis
and Research, Ninewells Hospital and Medical School, Dundee,
UK, and was approved by the Tayside Committee on Medical
Research Ethics. Subjects were selected provided they had size 8
or 10 feet, and had no gait abnormality or previous or current
history of lower limb pathology, no foot or leg length
discrepancy, or any other disability that might in some way
affect their gait (eg, visual impairment, walking aid).
PedarH System
Plantar pressure was recorded with the PedarH in-shoe pressure
measurement system (Novelgmbh, Munich, Germany). This
consists of a synchronisation box that is attached by a set of
cables to a pair of specially made insoles placed in the test
shoes. Each lightweight insole is composed of a matrix of 99
capacitive sensors with an effective area of about 2 cm2. These
sensors detect changes in pressure application and send
electrical signals to the synchronisation box, which in turn
relays them via a Bluetooth wireless radio link to an electronic
database. Prior to testing, the insoles were calibrated in
accordance with the manufacturer’s instructions. This ensures
accurate readings are recorded.17 A rucksack was constructed to
house the synchronisation box on the subject’s back (fig 1). The
PedarH system was shown to have good repeatability in a
concurrent study.18
Assessment of comfort
Comfort was assessed with a visual analogue scale (VAS). A
100 mm scale was adapted where the left-hand side was
labelled ‘‘least comfortable imaginable’’, and the opposite end
‘‘most comfortable imaginable’’. This method of assessing
comfort has been shown to be reliable15 when used in this
context.
Test protocol
The study was explained to each subject, and consent for
participation was gained. Height, weight, foot dimensions and
lower limb length were recorded prior to the PedarH equipment
being attached. Each subject was then shown a pair of shoes
and asked to provide a score on the VAS for expected comfort. A
second score (immediate comfort) was recorded when standing
in the shoes. To investigate the possibility that shearing forces
between the PedarH insole, the mid-sole and the foot altered
plantar pressure measurements, a pilot study was conducted to
determine whether insoles would conform to a position where
they would no longer slip. This was achieved within a few steps
by asking each subject to walk to the start of the walkway.
Plantar pressure was recorded over approximately 15 steps
along a 20 m walkway. Nine steps or more ensured reliable
results were recorded.19 The final VAS was recorded for each
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shoe after walking. The control shoes were always worn as the
first and last trials. The order of the shoes was randomised.
Each subject was asked to estimate the cost of the shoes
(low/medium/high) based on their perception of comfort alone.
Subjects walked barefoot between each trial. This acted as a
standard condition between trials, and was done in an attempt
to reduce any confounding effect of the perception of comfort
between shoes.15
Follow-on study
Subjects with previous running and treadmill experience were
selected to take part in a follow-on study. This was intended
primarily to compare the pressure distribution patterns under the
foot while walking and running. In addition, it provided
information on variability needed for a power calculation in a
further study. Each subject walked at his natural speed and ran
(3.13 ms–1) on a treadmill. Comfort scores were collected as
before for each walking and running trial, for each pair of shoes.
Data validation
Erroneous readings were removed with the Novel step analysis
programme. Masks were constructed (with the Novel creation
of any masks program) to analyse plantar pressure measurements under eight areas of the foot including medial, and
lateral heel (M1–M2), 1st–5th metatarsals (M3–M7) and great
toe (M8) (fig 2). These are the main regions of load-bearing
areas under the foot.20 Pressure recorded under the lesser toes
was incorporated into the follow-on study, as this area tends to
bear more weight whilst running.2
Statistical analysis
A power study suggested that 39 subjects would be required to
enable a difference of 80 kPa to be detected between groups.
Power was set at 80% and significance at 5%. The estimate of
standard deviation was obtained from a pilot study conducted
within the department. General linear model, repeated measures analysis of variance was applied to investigate relationships between models and the effects of brand and cost on
plantar pressure and comfort. Brand and cost were withinsubjects factors. The Bonferroni correction for multiple comparisons was applied to means post hoc and the Huynh–Feldt
adjustment for non-sphericity made when appropriate. In an
attempt to standardise comfort scores between subjects the
average comfort rating for each subject across all shoes and
occasions was calculated. Individual comfort scores (for three
occasions and 11 shoes) were divided by this average. Cohen’s
kappa statistic was used to assess agreement between actual
and estimated costs (low, medium, high in each shoe). The
relationship between comfort score and plantar pressure
readings was investigated using scatter plots and Pearson’s
product moment correlation coefficient.
RESULTS
Forty-three male subjects (mean age 28.9 years, SD 9.3)
participated in this investigation. The results are presented as
Venn diagrams (fig 3). Mean plantar pressures recorded under
each foot region were arranged in increasing order of plantar
pressure. Shoes within the same ring were not significantly
different (p.0.05). For example (fig 3: left medial heel), mean
plantar pressures between shoes Am, Ah, Bh and Cl were not
significantly different. Likewise, mean plantar pressures
between shoes Cl and Bm were not significantly different.
Shoe Bm provided significantly poorer cushioning under the left
medial heel than shoes Am, Ah and Bh.
Similar plantar pressure measurements were recorded under
the heel in both left and right feet. Brands A and B provided
better cushioning under the heel in the medium- and high-cost
Are expensive running shoes value for money?
3
Figure 1 PedarH Mobile system and one tested shoe. Informed consent
was obtained for publication of this figure.
shoes rather than in the low-cost models. Overall, poorer
under-heel cushioning was recorded in Brand C. Under-heel
cushioning decreased with increasing cost in Brand C. Few
significantly different values were observed under the 1st
metatarsal between brands in relation to cost. Improved
cushioning was recorded under the 2nd/3rd metatarsals with
increasing cost from Brand A. The moderately priced models
from Brands B and C provided better cushioning of plantar
pressure than their low- and high-cost alternatives. The
medium- and high-cost models from Brand C recorded
significantly better cushioning under the 4th/5th metatarsals
than all of the other shoes. However, this could have been the
result of off-loading pressure from over this area by the medial
forefoot. Cushioning from under the medial forefoot in the
medium- and high-cost models from Brand C was poorer than the
remaining shoes. Brand A provided relatively better cushioning
under the 4th/5th metatarsals than Brand B. Enhanced cushioning under the great toe was observed in Brands A and B with
rising cost. The opposite was found for in Brand C.
When plantar pressure was analysed under all the masked
regions studied, there was no significant difference between shoes
with regard to brand or cost. Mean plantar pressure was lower
overall in low- and medium-cost shoes but not significantly so.
Standardised comfort ratings proved to be highly variable
across all shoes investigated. No significant differences between
shoes and test occasions were observed. There was negligible
agreement between perceived comfort and predicted cost
(0.081). No relationship was found between comfort score
and plantar pressure recordings.
Nine subjects (mean age 24.8 years, SD 5.2) participated in
the follow-on investigation. Similar pressure distribution
patterns for each area under the foot were seen in the walking
and running phases. As the study group was small, it was not
possible to reliably detect differences between pressure in shoes
from different brands and cost ranges.
DISCUSSION
Pressure attenuation under the heel reduces the potency of the
shock wave experienced by the body. It has been suggested that
increasing shock wave intensity perpetuates damage of the
Figure 2 Study mask.
micro-composition of the musculoskeletal structures surrounding the foot and ankle. If the magnitude of accumulated impact
force and the rate of impact loading exceed the tensile limit for
a particular musculoskeletal component with increasing cycles,
then the structure will fail (fig 4).6 This will either result in, or
increase the risk of, a disabling injury. Regular rest intervals
should be incorporated into any running regimen to allow
positive remodelling and strengthening of micro-composition
of the musculoskeletal structure; this, in turn will reduce the
likelihood of sustaining a chronic overuse running injury.6 No
evidence currently exists to suggest whether an infrequently
high and sudden impact force is more likely to cause an injury
than several sustained lesser impact forces. It has, however,
been confirmed that runners who exhibit relatively high and
rapid impact forces are at an increased risk of sustaining a
chronic overuse injury.6
Different models of shoes performed better in terms of
cushioning capacity under different areas of the foot. The
brands investigated performed differently in relation to cost.
Therefore, before any definitive conclusions concerning the
relationship between cushioning and cost can be made, more
models and more brands should be investigated. It would
appear from the shoes studied that performance, in terms of
cushioning, is not related to cost. In fact, plantar pressure was
lower overall in low- and medium-cost shoes than in high-cost
shoes. Even though this difference is small, it may be
significant over time with repetitive impact loading. This may
suggest that less expensive running shoes not only provide as
much protection from impact force as expensive running shoes,
but that in actual fact they may also provide more. However, it
should be acknowledged that this study concentrated on only
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4
Clinghan, Arnold, Drew, et al
Figure 4 Injury threshold curve.
tested. It should also be acknowledged that pressure measurements were recorded whilst walking rather than running, and
that joint forces were not considered.
Consistent plantar pressure distribution patterns in walking
and running phases suggested that running shoes performed
comparably while walking and running on a treadmill. Caution
should be exercised when interpreting these results as only a
small number of subjects participated. Running shoe performance on a treadmill was found to differ from that in an overground situation.20 However, this finding is questionable
because the kinematics of running were compared between a
set of control shoes and the subjects’ own personal shoes,
which would be more familiar to the subjects. Also, the footstrike region was not accounted for.21 Further research at our
Institute is currently being conducted in this area of shoe
performance testing, and walking/running versus brands/cost.
What is already known on this topic
N
N
N
N
Advertising of advanced safety features and protective
devices of more expensive running shoes is deceptive.
Athletic footwear reduces impact force peaks and shock
wave intensity by up to 36%.
Running shoes with a more elastic mid-sole offer better
cushioning.
A 123% greater injury frequency was observed amongst
runners who trained in expensive running shoes compared with those running in less expensive models or
brands.
What this study adds
N
Figure 3 Venn diagrams representing differences in plantar pressure
recorded under each area of the foot (refer to table 1 for shoe codes).
two aspects of running shoe design: cushioning and comfort.
Before any definitive conclusions can be made between brands,
the durability of the mid-soles and in-soles should also be
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N
N
N
In the three brands tested, expensive running shoes did
not provide better cushioning than the cheaper shoes
within the same brand.
Plantar pressure was lower overall in low- and mediumcost running shoes than in high-cost shoes.
Comfort was not related to either the distribution of
plantar pressure or the cost of running shoes.
More models and more brands are currently being
tested.
Are expensive running shoes value for money?
The broad between-subject variability of comfort scores
suggests that comfort is highly subjective. Comfort ratings for
both control shoe trials were similar. This may suggest that
subjects can be consistent in assessing comfort. It has been
suggested that lower plantar pressure distribution under the
medial forefoot and the great toe influences the perception of
comfort. However, no relationship between comfort and plantar
pressure could be observed under these or any other areas of the
foot in this study. The agreement between actual and estimated
cost of shoe was found to be 0.081. The most common value
selected was the intermediate price. This would suggest most of
the subjects chose the ‘‘common ground’’ value. The low value of
agreement calculated would suggest that the subjects were poor at
estimating the cost of shoes based on comfort.
ACKNOWLEDGEMENTS
R Clinghan conducted the study, collected data, contributed to data
analysis and wrote the report. RJ Abboud supervised the study, being
the originator of the project, provided the funding and laboratory
equipment needed to complete it, coordinated completion of the report
and decided to submit the article for publication. L Cochrane devised
the statistical analysis. T Drew and GP Arnold provided technical
assistance.
.......................
Authors’ affiliations
Richard Clinghan, Graham P Arnold, Tim S Drew, Lynda A Cochrane,
Rami J Abboud, Institute of Motion Analysis and Research (IMAR), Division
of Surgery & Oncology, TORT Centre, Ninewells Hospital and Medical
School, Dundee, Scotland, UK
Funding: Funding was provided internally by the Institute of Motion
Analysis & Research (IMAR). No funding was provided by any of the shoe
manufacturers.
Competing interests: No shoe manufacturer involvement was established.
All authors declare that they have no competing interests.
Informed consent was obtained for publication of figure 1.
5
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