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Is your prescription of distance running shoes evidence

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Is your prescription of distance running shoes evidence
Review
Is your prescription of distance running shoes
evidence-based?
C E Richards,1,2 P J Magin,1 R Callister2
1
Discipline of General Practice,
School of Medicine and Public
Health, University of Newcastle,
Australia; 2 School of Biomedical
Sciences, University of
Newcastle, Australia
Correspondence to:
Dr C Richards, Discipline of
General Practice, Bowman
Building, School of Medicine and
Public Health, University of
Newcastle, University Drive,
Callaghan 2308, Australia;
[email protected]
Accepted 26 March 2008
Published Online First
18 April 2008
ABSTRACT
Objectives: To determine whether the current practice of
prescribing distance running shoes featuring elevated
cushioned heels and pronation control systems tailored to
the individual’s foot type is evidence-based.
Data sources: MEDLINE (1950–May 2007), CINAHL
(1982–May 2007), EMBASE (1980–May 2007), PsychInfo
(1806–May 2007), Cochrane Database of Systematic
Reviews (2nd Quarter 2007), Cochrane Central Register of
Controlled trials (2nd Quarter 2007), SPORTSDiscus
(1985–May 2007) and AMED (1985–May 2007).
Review methods: English language articles were
identified via keyword and medical subject headings
(MeSH) searches of the above electronic databases. With
these searches and the subsequent review process,
controlled trials or systematic reviews were sought in
which the study population included adult recreational or
competitive distance runners, the exposure was distance
running, the intervention evaluated was a running shoe
with an elevated cushioned heel and pronation control
systems individualised to the wearer’s foot type, and the
outcome measures included either running injury rates,
distance running performance, osteoarthritis risk, physical
activity levels, or overall health and wellbeing. The quality
of these studies and their findings were then evaluated.
Results: No original research that met the study criteria
was identified either directly or via the findings of the six
systematic reviews identified.
Conclusion: The prescription of this shoe type to
distance runners is not evidence-based.
Distance runners are notorious for their high rates
of minor musculoskeletal injury, with 37–56% of
average recreational runners becoming injured at
least once each year.1 In recreational and competitive runners alike, running injuries almost exclusively affect the leg and are primarily due to
chronic overloading rather than acute traumatic
events. Our capacity to prevent such injuries is
currently limited, with training advice and footwear prescription forming the mainstays.2 Thus,
the prescription of the correct running shoe, either
alone or in concert with an orthotic, is considered a
crucial and highly valued skill.
Since the 1980s, distance running shoes with
elevated, heavily cushioned heels and features to
control subtalar motion have been consistently
recommended to footwear prescribers as the gold
standard for injury prevention.2–6 Prescribed on the
basis of foot type, overpronators, mild pronators
and supinators are prescribed ‘‘motion control’’,
‘‘stability’’ and ‘‘cushion’’ shoes respectively.4 6 In
the absence of existing nomenclature to describe
these shoes as a group, we propose the term
Br J Sports Med 2009;43:159–162. doi:10.1136/bjsm.2008.046680
‘‘pronation control, elevated cushioned heel’’
(PCECH) running shoes.
Whether this approach to footwear prescription
is evidence-based has traditionally been tested by
examining the evidence supporting the use of each
of these key features of the PCECH design.
FEATURES OF THE PRONATION CONTROL,
ELEVATED CUSHIONED HEEL SHOE
Cushioning
The use of cushioning in running shoes is based on
the following assumptions: (1) that impact forces
while running are a significant cause of injury, (2)
that running on hard surfaces is a cause of high
impact forces, (3) that a cushioned shoe can reduce
impact forces to a less injurious level, and (4) that
the potential of the cushioning itself to cause
injury is minimal.
The evidence for these assumptions is mixed.
That excessive force will result in injury is selfevident.7 However, the evidence that running on
hard surfaces causes either an increase in impact
forces or an increase in injury rates is weak.8–10 The
capacity of cushioning to reduce either impact
forces or injury rates has also been called into
question.9 Furthermore, diminished proprioception
has been identified as a significant side effect of
heavily cushioned shoes.11 It has been argued that
this diminished capacity to precisely monitor
impact and foot position carries with it a significant risk of harm. The absence of data from
controlled clinical trials means that the overall
effect of cushioning on running injury rates
remains unknown.10
Elevated heel
It has been suggested that an elevated heel is
incorporated into the PCECH shoe to decrease
Achilles tendon strain and thus Achilles tendon
injury.3 12 It also allows placement of a substantive
heel cushioning system.
Several studies have investigated the effect of
progressive heel elevation on loading of the Achilles
tendon, but with mixed results.13 14 Furthermore, it
has been observed that since the introduction of
the PCECH design there has actually been an
increase, not a decrease in Achilles tendon injuries.15 Others have shown that heel elevation
during stance places the ankle joint in a position
where proprioception is inherently poor.16 The
capacity of existing levels of heel elevation to
increase pronation has also been noted.17
Unfortunately, the overall effect on injury rates
of running in a shoe with an elevated heel remains
untested in clinical trials.10
159
Review
Pronation control systems
The protective effect of normalising subtalar joint motion is
built on the following assumptions: (1) that overpronation and
supination are causally linked to overuse injuries, (2) that
promoting limited pronation reduces this risk, and (3) that
PCECH shoes are an effective means of reducing injuries via this
approach.
Subtalar motion and foot type have not been consistently
associated with injury rates in runners.7 10 18 19 Furthermore,
PCECH shoes are themselves a relatively ineffective and
unreliable means of altering subtalar motion, causing small
and inconsistent changes in alignment.20 The clinical efficacy of
pronation control systems remains untested, with no longitudinal trials having been reported that compare injury rates in
runners wearing shoes with and without pronation control
systems.10
RATIONALE
It is apparent that the ongoing use of pronation control systems
and elevated cushioned heels in running shoes is being
challenged. We have identified several studies suggesting that
these features either fail to achieve their desired purpose, or
worse still, have the potential to cause harm. Also apparent is
the absence of clinical data, which are required to rigorously
evaluate the direct effect of each of these features on injury
rates.
That this uncertainty coexists with both strong professional
and consumer belief in the PCECH design means that it is more
important than ever that clinicians rely on evidence rather than
dogma or conjecture when making decisions for patients.
Rather than examining the features of the PCECH shoe in
isolation, the most definitive evidence of its effect on injury
rates will come from clinical trials comparing injury rates in
runners wearing PCECH shoes with those running in bare feet
or in other shoe types.
Several authors have commented on the paucity of this highlevel clinical evidence to support the ongoing use of PCECH
running shoes,17 20 but none has reported a specific systematic
review of this literature, nor broadly considered other possible
effects of wearing PCECH shoes on runner’s health and
performance.
METHODS
A series of clinical questions pertinent to the health and
performance of competitive and recreational runners was
formulated. These questions focussed on distance running
performance, injury rates, osteoarthritis risk, physical activity
levels, and overall health and wellbeing (table 1). The search
terms used to identify evidence pertinent to each question are
also shown.
These search terms were used to interrogate the following
electronic databases: MEDLINE (1950–May 2007), CINAHL
(1982–May 2007), EMBASE (1980–May 2007), PsychInfo (1806–
May 2007), Cochrane Database of Systematic Reviews (2nd
Quarter 2007), Cochrane Central Register of Controlled trials
(2nd Quarter 2007), SPORTSDiscus (1985–May 2007) and
AMED (1985–May 2007). Keyword and medical subject heading
(MeSH) searches were performed.
Articles were included in our review if they were published in
English and reported original research or a systematic review in
which the study population included adult recreational or
competitive runners, the exposure was distance running, the
intervention being assessed was a PCECH running shoe and at
160
least one of the outcomes listed in table 1 was measured
directly. A control group who ran in non-PCECH shoes or bare
feet was also required. Studies that only measured surrogate
outcomes such as impact forces, rather than injury rates
directly, were excluded.
The sorting of search results was undertaken by a single
reviewer. During this process, articles clearly irrelevant on the
basis of title and abstract were immediately excluded. Articles
clearly relevant or of uncertain relevance were retained. The full
texts of these articles were then retrieved and both their
findings and methodology reviewed.
RESULTS
No articles were identified that reported original research
addressing the capacity of PCECH shoes to prevent injury. Six
systematic reviews were identified whose scope included
interventions to prevent injuries in runners, or injuries common
in runners.21–26 Two were outdated systematic reviews for which
updated versions were identified.21 26 The details of the
remaining four systematic reviews are presented in table 2.
No controlled trials were identified by these systematic
reviews in which a PCECH running shoe was the intervention
tested. No systematic reviews or reports of original research
were found which assessed the effect of the PCECH running
shoe on the enjoyment of running, on physical activity levels or
on the wearer’s uptake of prescribed physical activity. No
articles were found which evaluated the effectiveness of PCECH
running shoes as a means of preventing the development of
osteoarthritis of the leg, nor were any articles found which
attempted to assess the effect of the modern athletic shoe on
overall mortality, morbidity or quality of life. No studies were
identified which evaluated the effect of PCECH running shoes
on distance running performance.
DISCUSSION
The findings of this systematic review suggest that the true
effects of PCECH running shoes on the health and performance
of distance runners remain unknown. Unless convincing highlevel evidence emerges to support their use, the prescription of
PCECH running shoes has no place in evidence-based practice.
What weight can we give to this finding? The broad scope
and the systematic manner in which this review was undertaken give us significant confidence that there are indeed no
studies of relevance in the mainstream English literature. Given
Table 1
Review questions and search strategies used
Review question
Search terms
Does wearing PCECH running shoes improve Running + shoes + (performance or
distance running performance?
speed or acceleration or endurance or
time or distance)
Running + shoes + injury + (prevention
Does wearing PCECH running shoes
or aetiology)
decrease musculoskeletal injury rates in
runners?
Running + shoes + osteoarthritis +
Does wearing PCECH running shoes
decrease osteoarthritis rates in runners and prevention
ex-runners?
Does wearing PCECH running shoes affect Running + shoes + enjoyment
the enjoyment of running?
Does wearing PCECH running shoes improve Running + shoes + (exercise prescription
compliance with prescribed physical activity? or exercise therapy)
Does wearing PCECH running shoes improve Running + shoes + (physical activity or
total physical activity levels?
physical fitness or motor activity)
What is the overall effect of wearing PCECH Running + shoes + (quality of life or
shoes during running on health & wellbeing? mortality or morbidity)
Br J Sports Med 2009;43:159–162. doi:10.1136/bjsm.2008.046680
Review
Table 2 Systematic reviews of interventions to prevent running injury
Reference
Study subjects
Study factor
Outcome factor
Result
Limitations
Verhagen et al,
200022
No restriction
Preventative
interventions
Ankle sprain
No trials examining running
shoes
Thacker et al,
200223
Rome et al, 200724
No restriction
Exertional shin pain
Adults with normal
bone density
Preventative
interventions
Preventative
interventions
No trials examining running
shoes
No trials examining running
shoes
‘‘High quality’’ interventional studies published
between 1980 and 1998. Language restriction
undefined
Searches performed in 2000. Non-English
language articles may have been excluded
Searches performed in 2004. Randomised and
quasirandomised studies only
Yeung & Yeung,
200725
Adolescent & adult
runners
Preventative
interventions
Stress fractures of bone,
stress reactions of bone (not
medial tibial stress syndrome)
Soft-tissue injury
No trials examining running
shoes
that our findings are consistent with those of other high-quality
systematic reviews performed without our language restrictions, we believe that the cumulative weight of these findings
cannot be ignored.10 24 25
If we accept this finding, we are then faced with the
realisation that we have been prescribing a treatment without
proven benefit for .20 years. Worse still, these footwear
prescription practices have not gone uncontested in the
literature. Despite the absence of a systematic review specifically addressing the capacity of PCECH shoes to prevent injury,
the lack of evidence for their use and their potential to cause
injury has been raised by several authors, including leading
authorities in the field.9 17 27 28
In spite of these findings, footwear prescription guidelines
that unequivocally recommend the PCECH design continue to
be published.4 6 That practitioners are being encouraged to base
their practice on expert opinion is not inappropriate given the
lack of high-level evidence, but that such recommendations are
being published without explicitly acknowledging both the lack
of supporting clinical evidence and the existence of conflicting
expert opinion is of concern.
Individual readers may not have the time or the training to
themselves assess the quality of such recommendations and
thus rely on editorial and peer review to ensure that they are
evidence-based. That the peer review process has failed in these
circumstances suggests that a significant subgroup of footwear
researchers either remain uncommitted to genuine evidencebased practice, lack understanding of the requirements for
assessing the efficacy and safety of a therapeutic intervention,
or are unduly influenced by conflicts of interest such as receipt
of funding from shoe manufacturers.
This suboptimal approach to evidence is mirrored by the
behaviour of some of the most prominent organisations
representing sports medicine professionals. It is difficult to
identify a PCECH running shoe in the range by the runningshoe manufacturer ASICS that is not recommended by one or
more of the International Federation of Sports Medicine (FIMS),
Sports Medicine Australia (SMA) or the New Zealand Society of
Podiatrists (PNZ).29 If such influential organisations are
genuinely committed to evidence-based practice, then in light
of our findings such recommendations cannot be credibly made.
This scenario is reminiscent of the controversy surrounding
the safety of hydration guidelines endorsed by the American
College of Sports Medicine while it was engaged in a
commercial arrangement with Gatorade.30 It is surprising, given
this recent history and the open acknowledgement by FIMS,
SMA and PNZ that their footwear recommendations are made
as part of sponsorship arrangements with ASICS, that these
recommendations have not been questioned previously. Clearly,
the fields of running-shoe research and footwear prescription
Br J Sports Med 2009;43:159–162. doi:10.1136/bjsm.2008.046680
Searches performed in 2000. Randomised and
quasirandomised studies only
have not yet matured to the point where the evidence base for
such recommendations are routinely examined.
Although these broader issues regarding the use of evidence
must also be addressed, the core issue remains a lack of data
derived from quality clinical trials. Randomised controlled trials
measuring clinically relevant outcomes such as running performance and injury rates must be used. Head-to-head trials of
existing shoe constructions are urgently required to identify a
gold standard distance running shoe design. Once identified,
this will be the shoe against which all new designs should be
evaluated until a superior alternative is confirmed. For this to
occur, a systematic nomenclature for describing the structure of
running shoes needs to be developed, with its use insisted upon
when papers are reviewed for publication.
Once these steps have been achieved, footwear prescription
guidelines can then be developed based on high-level evidence,
replacing the current uncertainty as to what shoe type
represents optimal care. Complementary evidence-based industry standards should also be developed and implemented in a
manner similar to that of other sports protective equipment.31
This will ensure that only running shoes with proven benefit
can be marketed and sold as therapeutic devices, with the
remainder being clearly identifiable as fashion items.
Until these steps are achieved, clinicians will not know
whether the distance running shoes they are prescribing are
beneficial, harmless or harmful. Given this uncertainty, a
What is already known on this topic
The prescription of PCECH running shoes (shoes with elevated
cushioned heels and pronation control features tailored to foot
type) is considered best practice when prescribing shoes to
distance runners.
However, the findings of biomechanical and epidemiological
studies continue to call into question the efficacy and safety of
this approach.
What this study adds
This systematic review found that PCECH running shoes have
never been tested in controlled clinical trials.
Their effect on running injury rates, enjoyment, performance,
osteoarthritis risk, physical activity levels and overall athlete
health and wellbeing remain unknown.
The prescription of this shoe type to distance runners is not
evidence-based.
161
Review
pragmatic interim approach is required. We suggest the
following: (1) that all distance runners should be advised that
the ideal shoe type is unknown, (2) that no change should be
made to the shoe prescriptions of distance runners currently
wearing PCECH shoes and experiencing no ill effects, and (3)
that discontinuing the use of PCECH shoes should be
considered in runners suffering repeated injuries in spite of
structurally normal feet or appropriately prescribed orthotics.
When the prescription of a PCECH shoe is ceased, clinicians
must then identify an alternative, again in the absence of
evidence from controlled clinical trials. Evolution would suggest
that a return to running in bare feet should be the first choice.32
However in those cases where this is considered either
impractical or undesirable, prescription of a non-PCECH
alternative is required. In both cases it will be essential that
conservative training advice is also provided to protect the
athlete from injury while adapting to the marked changes in the
biomechanics involved.28
CONCLUSION
Biomechanical and epidemiological studies have raised significant questions about the capacity of running shoes incorporating either cushioning, heel elevation or subtalar control systems
to prevent injury and have identified their potential to cause
harm. We identified no clinical trials that assessed the effect of
the PCECH design, which incorporates all three of these
features, on either running injury rates, running performance,
or runners’ global health and wellbeing. Until such evidence
becomes available, PCECH running shoes must be considered
unproven technology with the potential to cause harm, and
thus the prescription of PCECH shoes to distance runners is not
evidence-based. As clinicians, researchers and footwear
designers, we must now adjust our existing practice accordingly
and define our future path via a renewed commitment to
evidence-based practice.
Acknowledgements: We wish to acknowledge the support and encouragement
provided by all members of the Discipline of General Practice, University of Newcastle,
with special thanks owed to Ms Susan Goode.
Funding: Funding for this paper was provided in the form of income support for the
first author by the Australian Government, via the Primary Health Care Research
Evaluation Development Program
Competing interests: CER is a partner in the footwear design company Barefoot on
Grass. PJM and RC have no competing financial interests.
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REFERENCES
1.
2.
162
Van Mechelen W. Running injuries. A review of the epidemiological literature.
Sports Med 1992;14:320–35.
Johnston CAM, Taunton JE, Lloyd-Smith DR, et al. Preventing running injuries.
Practical approach for family doctors. Can Fam Physician 2003;49:1101–9.
31.
32.
Heil B. Running shoe design and selection related to lower limb biomechanics.
Physiotherapy 1992;78:406–12.
Yamashita MH. Evaluation and selection of shoe wear and orthoses for the runner.
Phys Med Rehabil Clin N Am 2005;16:801–29.
Cook SD, Kester MA, Brunet ME, et al. Biomechanics of running shoe performance.
Clin Sports Med 1985;4:619–26.
Asplund CABDL. The Running shoe prescription: fit for performance. Phys
Sportsmed 2005;33:17–24.
Hreljac A. Impact and overuse injuries in runners. Med Sci Sports Exerc
2004;36:845–9.
Feehery FJ. The biomechanics of running on different surfaces. Clin Podiatr Med
Surg 1986;3:649–59.
Nigg B, Wakeling J. Impact forces and muscle tuning: a new paradigm. Exerc Sport
Sci Rev 2001;29:37–41.
Van Gent RN, Siem D, Van Middelkoop M, et al. Incidence and determinants of
lower extremity running injuries in long distance runners: A systematic review. BrJ
Sports Med 2007;41:469–80.
Robbins S, Waked E. Foot position awareness: the effect of footwear on instability,
excessive impact, and ankle spraining. Crit Rev Phys Rehabil Med 1997;9:53–74.
Clement DB, Taunton JE. A guide to the prevention of running injuries. Aust Fam
Physician 1981;10:156–64.
Reinschmidt C, Nigg BM. Influence of heel height on ankle joint moments in running.
Med Sci Sports Exerc 1995;27:410–16.
Dixon SJ, Kerwin DG. The influence of heel lift manipulation on sagittal plane
kinematics in running. J Appl Biomech 1999;15:139–51.
Jarvinen T, Kannus P, Maffulli N, et al. Achilles tendon disorders: etiology and
epidemiology. Foot Ankle Clin 2005;10:255–66.
Sekizawa K, Sandrey MA, Ingersoll CD, et al. Effects of shoe sole thickness on joint
position sense. Gait Posture 2001;13:221–8.
Baycroft CM, Culp V. Running shoes - Design facts and functional fantasies. Chiropr
Sports Med 1993;7:6–8.
Wen DY, Puffer JC, Schmalzried TP. Lower extremity alignment and risk of overuse
injuries in runners. Med Sci Sports Exerc 1997;29:1291–8.
Taunton JE, Ryan MB, Clement DB, et al. A prospective study of running injuries:
The Vancouver Sun Run ‘‘In Training’’ clinics. Br J Sports Med 2003;37:239–44.
Nigg B. The role of impact forces and foot pronation: a new paradigm. Clin J Sport
Med 2001;11:2–9.
Gillespie WJ, Grant I. Interventions for preventing and treating stress fractures and
stress reactions of bone of the lower limbs in young adults. Cochrane Database Syst
Rev 2000;(2):CD000450.
Verhagen EALM, Mechelen Wv, Vente Wd. The effect of preventive measures on
the incidence of ankle sprains. Clin J Sport Med 2000;10:291–6.
Thacker SB, Gilchrist J, Stroup DF, et al. The prevention of shin splints in sports: a
systematic review of literature. Med Sci Sports Exerc 2002;34:32–40.
Rome K, Handoll HHG, Ashford R. Interventions for preventing and treating stress
fractures and stress reactions of bone of the lower limbs in young adults. Cochrane
Database Syst Rev 2005;(2):CD000450.
Yeung EW, Yeung SS. Interventions for preventing lower limb soft-tissue injuries in
runners. Cochrane Database Syst Rev 2001;(3):CD001256.
Yeung EW, Yeung SS. A systematic review of interventions to prevent lower limb
soft tissue running injuries. Br J Sports Med 2001;35:383–9.
Robbins SE, Gouw GJ. Athletic footwear and chronic overloading: a brief review.
Sports Med 1990;9:76–85.
Robbins SE, Hanna AM. Running-related injury prevention through barefoot
adaptations. Med Sci Sports Exerc 1987;19:148–56.
ASICS. Technical footwear profiles. January–June 2007:8–17.
Noakes T. Drinking guidelines for exercise: what evidence is there that athletes
should drink ‘‘as much as tolerable’’, ‘‘to replace the weight lost during exercise’’ or
‘‘ad libitum’’? J Sports Sci 2007;25:781–96.
McIntosh A, McCrory P. Preventing head and neck injury. Br J Sports Med
2005;39:314–18.
Bramble D, Lieberman D. Endurance running and the evolution of Homo. Nature
2004;432:345–52.
Br J Sports Med 2009;43:159–162. doi:10.1136/bjsm.2008.046680
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