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Abstract

Lower back pain (LBP) appears to be a common overuse injury in cycling. However, there are few scientific studies that report on the epidemiology and risk factors associated with LBP in cyclists. The prolonged flexed posture that a cyclist maintains may lead to increased mechanical strain of the lumbar spine, causing LBP. In this article, the epidemiology, pathomechanics and risk factors associated with LBP in cyclists will be critically reviewed. An extensive literature review was conducted using an evidence-based approach. Using selective keywords (lower back pain, cyclists, bicycle set-up, risk factors) a search was undertaken on the PubMed database to identify all research publications that relate to lower back pain in cyclists. Although epidemiological studies were limited, LBP was shown to be a common cycling overuse injury. The point prevalence of LBP in cyclists ranged from 10-60%. It has been suggested that LBP in cyclists may be prevented by adjusting certain bicycle parameters to match the anthropometric measurements of the cyclist. Pathomechanical hypotheses for the development of LBP in cyclists are poorly supported, and most studies were conducted over time periods shorter than one hour. Monitoring cyclists over a longer period of cycling may yield more accurate data. There is strong evidence supporting the incorrect saddle angle as an intrinsic risk factor is associated with LBP in cyclists. In conclusion, additional research on the epidemiology of LBP in cyclists is necessary. Further research studies, such as case control and intervention studies are necessary to study pathomechanics and risk factors associated with LBP in cyclists
Lower back pain in cyclists International SportMed Journal, Vol.11 No.1, 2010, pp.216-225.
Available at URL: http://www.ismj.com
216 Official Journal of FIMS (International Federation of Sports Medicine)
ISMJ
International SportMed Journal
Review article
Lower back pain in cyclists: A review of epidemiology,
pathomechanics and risk factors
Mrs Mandy Marsden, BSc (Physio), MPhil (Sports Physiotherapy),
Professor
Martin Schwellnus, MBBCh, MSc (Med), MD, FACSM
UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology,
Faculty of Health Sciences, University of Cape Town, South Africa
*Corresponding author. Address at the end of text.
Abstract
Lower back pain (LBP) appears to be a common overuse injury in cycling. However, there are few
scientific studies that report on the epidemiology and risk factors associated with LBP in cyclists. The
prolonged flexed posture that a cyclist maintains may lead to increased mechanical strain of the
lumbar spine, causing LBP. In this article, the epidemiology, pathomechanics and risk factors
associated with LBP in cyclists will be critically reviewed.
An extensive literature review was conducted using an evidence-based approach. Using selective
keywords (lower back pain, cyclists, bicycle set-up, risk factors) a search was undertaken on the
PubMed database to identify all research publications that relate to lower back pain in cyclists.
Although epidemiological studies were limited, LBP was shown to be a common cycling overuse
injury. The point prevalence of LBP in cyclists ranged from 10-60%. It has been suggested that LBP in
cyclists may be prevented by adjusting certain bicycle parameters to match the anthropometric
measurements of the cyclist. Pathomechanical hypotheses for the development of LBP in cyclists are
poorly supported, and most studies were conducted over time periods shorter than one hour.
Monitoring cyclists over a longer period of cycling may yield more accurate data. There is strong
evidence supporting the incorrect saddle angle as an intrinsic risk factor is associated with LBP in
cyclists.
In conclusion, additional research on the epidemiology of LBP in cyclists is necessary. Further
research studies, such as case control and intervention studies are necessary to study
pathomechanics and risk factors associated with LBP in cyclists.
Keywords: lower back pain,
cyclists, risk factors, bicycle set-up
Lower back pain in cyclists International SportMed Journal, Vol.11 No.1, 2010, pp.216-225.
Available at URL: http://www.ismj.com
217 Official Journal of FIMS (International Federation of Sports Medicine)
Introduction
Cycling is generally regarded as a sport with
great potential for fitness and rehabilitation
1
,
Additionally, cycling has the added value of not
being associated with repetitive joint impact
2-4
.
Despite this advantage, it has been shown that
there is still a risk for the development of
acute, traumatic injuries, as well as overuse
injuries in cycling
5-11
.
There are only a few studies that document
the incidence, and even fewer, the prevalence
of overuse injuries in cyclists. In addition, it is
difficult to draw comparisons between the
limited number of studies of overuse injuries,
as population samples and the time periods
over which studies were conducted
(exposure), vary between studies
3;12-14
. There
are no known studies that report the lifetime
prevalence of LBP in cyclists.
In addition to the limited research on the
epidemiology of LBP in cyclists, there are also
very few studies to determine the aetiology of
LBP in cyclists. The aim of the cyclist is to
produce maximal power at the pedals to propel
the bicycle forward
1
. To maximise speed the
cyclist must reduce aero-dynamic drag. This is
achieved by maintaining a position of flexion of
the hips and spine. This prolonged flexed
posture may be an important factor
contributing to the development of lower back
pain in cyclists as posterior active and passive
spinal structures may be subjected to
increased load and strain in this position
3;7;15;16
.
Therefore to optimise the cyclist’s position and
limit strain and injury to the lower back, while
maintaining efficient power output, specific
attention must be paid to the correct bicycle
“set-up”. The bicycle “set-up” refers to the
various adjustable parameters on the bicycle,
including, amongst others, reach distance from
seat to handle bars and saddle angle. These
parameters must be adjusted relative to the
cyclists unique anthropometric measurements
to ensure correct positioning of the cyclist on
the bicycle
1;6;17
. Although various researchers
and authors have documented advice for the
“optimal” bicycle set-up, much of the advice
appears to be anecdotal or concentrates on
performance (power output) rather than on
injury prevention and the comfort of the
cyclist
1;6;18-21
.
Lower back pain may be defined as pain in the
lower back or lumbar region, and it may be
intermittent or constant. For the purpose of this
article the discussion of LBP will be confined to
spondylogenic LBP, which is defined as pain
originating from the spine and its associated
structures.
A review of what is currently known about the
epidemiology of LBP in cycling will follow. The
bicycle set-up and related biomechanics will
then be briefly discussed. Proposed
hypotheses on the pathomechanics of LBP in
cyclists and risk factors associated with LBP in
cyclists will also be reviewed.
Epidemiology of lower back pain in
cyclists
The epidemiology of LBP in cyclists in this
review is defined by the prevalence and
incidence of this overuse injury. Prevalence
can be defined as the “overall proportion of a
population who suffer from an injury
22
. Two
Mrs Mandy Marsden, BSc (Physio), MPhil (Sports Physiotherapy)
Mandy Marsden is a BSc (Physio) graduate from the University of Cape Town. She recently completed a
Masters degree in Sports Physiotherapy in 2009. Her thesis was entitled “The epidemiology and risk
factors associated with lower back pain in cyclists. She currently runs a private physiotherapy practice.
Email:
mandym@cybersmart.co.za
*Professor Martin Schwellnus. MBBch, MSc (Med), MD, FACSM, FFIMS
Martin Schwellnus is a Professor of Sport and Exercise Medicine at the UCT/MRC Research Unit for
Exercise Science and Sports Medicine at the University of Cape Town, South Africa. He is responsible
for the administration of the postgraduate Sports Medicine programme (MPhil Sport and Exercise
Medicine degree) at the University of Cape Town, and undertakes clinical duties at the Sport and
Exercise Medicine Clinic at the Sports Science Institute of South Africa.
Lower back pain in cyclists International SportMed Journal, Vol.11 No.1, 2010, pp.216-225.
Available at URL: http://www.ismj.com
218 Official Journal of FIMS (International Federation of Sports Medicine)
types of prevalence are examined. Point
prevalence describes cyclists who experience
LBP at a particular point in time, and lifetime
prevalence refers to cyclists who have
experienced cycling related LBP at some point
in their entire cycling career. The incidence of
LBP is always linked to exposure over a
particular time period.
It appears that LBP is more common in some
athletes than in others.
In a prospective study
it was found that wrestlers
had the highest
point prevalence of severe low-back pain
(54%),
while rates were lower for tennis (32%),
and soccer players (37%) respectively
23
. In
another study, wrestlers were again found to
have a higher lifetime prevalence of lower
back pain
(59%) compared with
23% in
heavyweight lifters
24
. Competitive
male and
female rowers had a 15% and 25% point
prevalence of lower back pain respectively
25
.
In one study, with a small sample size, a high
incidence of LBP was reported in elite rhythmic
gymnasts (six out of seven), over a seven-
week period
26
. Therefore the prevalence and
incidence of LBP varies in different sports,
while interpretations of the data are difficult as
the same methodology and definitions for LBP
have not been consistently applied in all
studies.
The focus of this review is on cycling, but there
are no known published data on the lifetime
prevalence of lower back pain in cyclists. A
number of surveys have investigated overuse
injuries among recreational cyclists and elite
cyclists
3;13;14
. The incidence of LBP in two
separate staged multi-day cycling events
varied from 2.7 - 15%. The details of these
studies indicate that: (1) only 2.7% of the
participants (n=113) in a bicycle tour (805km
over 8 days) reported significant LBP
3
, and (2)
15% of the participants (n= 89) in a long
distance cycle tour (4500 7242km over 80
days) experienced LBP
13
. Point prevalence
statistics of LBP in cycling ranged from 10 -
60% and details of the studies indicate that: (1)
10% of cyclists (n=20) who responded to a
research questionnaire suffered from LBP (it is
not clear what the actual prevalence of LBP
was in the larger group of which the 20
respondents were a subset
12
) (2) 30% of
cyclists (n=518) who responded to a mailed
questionnaire experienced LBP
14
, (3) and 60%
of cyclists reported suffering from LBP in a
squad medical questionnaire of 424 elite
cyclists. This made LBP the most common
injury that the riders encountered.
It is clear that there are limited studies on the
epidemiology of LBP. Furthermore, the
methodology employed by researchers in
studies that have been conducted varies
considerably, and this makes interpretation of
the data difficult. The position of the cyclist on
the bicycle relative to the development of LBP
will now be discussed.
Cyclist’s position and bicycle set-up
An important consideration is that although an
“optimal” posture may be adopted by the
cyclist, cycling still places the upper body in an
unnatural position.
In the seated position during cycling the
optimal position is one of hip flexion, anterior
pelvic tilt and a reduced spinal flexion. This
position would minimise wind
resistance
1;15;27;28
and this could improve
cycling speed
27
, and may also reduce the risk
of spinal injury. However, very few cyclists,
often only elite cyclists, maintain this ideal
position. Most cyclists maintain a position in
which there is a varying degree of spinal
flexion, as well as varying angles of anterior
and posterior pelvic tilt
29;30
.
The key bicycle set-up parameters which most
affect the upper body position of the cyclist will
be discussed, namely, reach and saddle
angle. These will be discussed separately.
Reach distance
The reach distance is defined as the
measurement from the centre of the seat
tube/post to the transverse position of the
middle of the handle bars
1;17
. It has been
suggested that LBP in cyclists may be related
to an incorrect reach distance
6;7;20
.
However, opinions differ regarding the correct
reach distance from the saddle to the handle
bars. One opinion is that, in order to prevent
back pain in cycling, the reach should be
decreased so that the cyclist can adopt a
posterior pelvic tilt position
1;7;12;18
. A directly
opposing opinion is that most often the cyclist
experiences problems in the lower back due to
insufficient reach, and that the reach distance
should in fact be increased
20
.
The explanation that motivates the suggestion
that reach distance should be longer rather
than shorter is based on anatomical
principles
20
. However, further research would
Lower back pain in cyclists International SportMed Journal, Vol.11 No.1, 2010, pp.216-225.
Available at URL: http://www.ismj.com
219 Official Journal of FIMS (International Federation of Sports Medicine)
be required for adequate validation of this
explanation. These researchers suggest that if
the reach is too short the lumbar spine is
placed in a position of increased flexion, and
the cervical spine may often assume an
increased lordotic position relative to the
thoracic kyphosis. This exaggerated unnatural
position of the spine may lead to neck and
back pain. A shortened reach distance and the
resultant increase in lumbar flexion may result
in a posterior tilt of the pelvis. This position of
the pelvis, coupled with excessive flexion of
the lumbar spine, may place increased
mechanical strain on the posterior spinal
structures
20
. By increasing the reach distance
and allowing the pelvis to adopt an anterior
pelvic tilt, the cyclist can maintain a more
neutral position of the vertebral column,
thereby creating a more stable posture closer
to the rear of the saddle
19;20
. The reach
distance may be altered by adjusting the stem
length, saddle set-back and handle bar height.
Saddle angle
The saddle angle is an important factor that
can influence the position of the pelvis. An
increased anterior pelvic tilt and a resultant
decreased tensile stress to the longitudinal
ligaments of the lumbar spine have been
reported with a downward tilting saddle
30
.
The discussion of the bicycle set-up provides
background for the discussion of the different
hypotheses for the development of lower back
pain in cyclists.
Pathomechanics of lower back pain in
cyclists
There are limited research data to determine
the possible pathomechanical mechanisms
responsible for the development of LBP in
cyclists. Furthermore, existing research is
often limited by sub-optimal study designs and
sample sizes. In this section, the data in
support of the different hypotheses for the
pathomechanics of LBP in cyclists will be
reviewed.
It has been documented by various
researchers that there is an association
between LBP and frequent forward
bending
31;32
and prolonged sitting with the
lumbar spine in a flexed position
31;33-35
. Spinal
flexion is also associated with increased discal
pressures
36
. These mechanisms for the
development of LBP could possibly be applied
to cyclists who spend extended periods in a
flexed position. However, the main difference
in cycling is that a portion of the cyclist’s mass
is supported on the handlebars, unlike the
open chain positions that are encountered in
occupational and other settings. Furthermore,
cyclists are not stationary, and the lumbar
spine also has to absorb intersegmental joint
reaction forces and moments that are
generated by the lower limbs during pedalling.
These forces and moments are transferred
through the thoracolumbar spine while the
trunk is in a flexed and sometimes rotated
position.
A number of hypotheses to explain the
pathomechanics of cycling related lower back
pain have been suggested
3;7;15;37
. These
hypotheses can be classified as: 1) the flexion
relaxation hypothesis, 2) the muscle fatigue
hypothesis, 3) over-activation of the spinal
extensors hypothesis, 4) the mechanical creep
hypothesis and 5) the disc ischaemic
hypothesis. These hypotheses for the
development of LBP in cyclists will now be
reviewed.
The flexion-relaxation hypothesis
The flexion-relaxation (FR) hypothesis for the
development of LBP in cyclists suggests that a
deactivation of the erector spinae and/or the
multifidus muscles occurs as the spine
maintains a flexed position during cycling. As
muscles relax, load is then shifted to the
passive structures, such as the ligaments, and
possibly the deeper muscles
10;38-41
. This
results in structures, such as the ligaments
and intervertebral discs, being placed at higher
risk, as has been shown to occur when muscle
forces are reduced during lifting
42
.
A review of studies to identify if the FR
response occurred in the seated cycling
position revealed only one study in which FR
of the erector spinae occurred in the flexed
racing position. However, this study was
limited by a small sample size
43
.
Muscle fatigue hypothesis
The muscle fatigue hypothesis suggests that
the deactivation of spinal extensors is a sign of
muscle fatigue rather than a manifestation of
the flexion relaxation response. Evidence
supporting the muscle fatigue hypothesis is
limited to one case-control study with a small
Lower back pain in cyclists International SportMed Journal, Vol.11 No.1, 2010, pp.216-225.
Available at URL: http://www.ismj.com
220 Official Journal of FIMS (International Federation of Sports Medicine)
sample size. Additional research is necessary
to validate this hypothesis
44
.
Over-activation of spinal extensors
hypothesis
Another hypothesis for the development of
LBP in cyclists suggests that over-activation of
the spinal extensor muscles may cause
muscle contracture and increased tissue strain
across the lumbar spine in cyclists
3;7;15;16;45
.
The results from a small case series study
indicated over-activation of the spinal
extensors, leading to muscle contracture, and
this may result in tissue strain of the lumbar
extensors resulting in LBP in cyclists. Activity
levels of the lumbar extensors increased
proportionally relative to cycling intensity
15
.This
hypothesis, however, requires more research.
Mechanical creep hypothesis
Mechanical creep is a biomechanical
characteristic which refers to a deformation or
a change in strain of the ligament tissue which
can occur over time if a constant load is
applied to these structures
46-48
. Researchers
suggest that mechanical creep may occur in
the lumbar spine ligaments during prolonged
sitting in a flexed position on a bicycle
37
.
Data from two animal studies showed the
negative effects of creep on the visco-elastic
tissues of the spine, as well as the associated
muscle spasms in the multifidus muscles that
are caused by sustained static flexion
49;50
.
However, in a single human study, short
duration static lumbar flexion showed that
creep resulted in a loss of tension in the
lumbar visco-elastic tissues which was
associated with muscle spasm that could
indicate micro-damage to the visco-elastic
tissues. In one study investigating spinal
kinematics in cyclists, no evidence of creep
was demonstrated. This hypothesis also
requires further research.
Disc ischemia hypothesis
It is well established that up to the age of 8
years the intervertebral discs of a human have
a blood supply, but thereafter discs are
dependent for their nutrition on diffusion of
tissue fluids
51
. Movement of the spine is
thought to aid this fluid transfer in and out of
the disc
51;52
. The stretched static position that
the lumbar spine remains in during cycling
may reduce the normal mechanism for
nutrients to enter the disc and metabolic waste
to move out, and thus result in ischemic pain.
Intermittent cyclical loading of the disc may
possibly aid fluid movement in and out of the
disc, thus reducing pain
51
.
Summary: Pathomechanics of lower back
pain in cyclists
In summary, a number of hypotheses have
been suggested to explain the
pathomechanics of the development of low
back pain in cyclists. In general, there is very
little scientific evidence to support any of these
hypotheses, and in many instances these
hypotheses seem contradictory. However, it is
also possible that these hypotheses represent
a continuum of the development of LBP in
cyclists, but do not explain this in isolation. It
is important to note that in all the studies that
investigate possible pathomechanics of LBP in
cyclists, the behaviour of muscles and spinal
kinematics in cyclists with LBP were monitored
for a short time period (less than an
hour)
15;37;44
. It is possible that by beginning to
record motor patterns after a time period
exceeding one hour, and thereafter, by
continuing to record over a longer period, more
accurate information on the pathomechanics of
LBP in cyclists will be obtained. In most
instances, cycling sessions and races far
exceed one hour.
A review of the possible intrinsic and extrinsic
risk factors that have been associated with
LBP in cyclists may provide information to
determine the possible causes of LBP in
cyclists.
Risk factors associated with lower back
pain in cyclists
Although the aetiology of LBP in cyclists is still
unclear, a few studies have reported possible
associated risk factors. Scientific evidence to
support each of these risk factors is, however,
limited. In Table 1, postulated extrinsic and
intrinsic risk factors that may be associated
with the development of LBP in cyclists are
listed. In addition, the evidence from studies to
support each risk factor is listed. The evidence
is depicted as ranging from Level 1 (strong
evidence), to Level IV (very weak or no
evidence), and is based on evaluating the
studies using well- established evidence-
based medicine criteria
53
.
Lower back pain in cyclists International SportMed Journal, Vol.11 No.1, 2010, pp.216-225.
Available at URL: http://www.ismj.com
221 Official Journal of FIMS (International Federation of Sports Medicine)
Table 1: Extrinsic and Intrinsic Risk Factors for LBP in cyclists (level of evidence according to
evidence based medicine (EBM) criteria)
53
Risk factors
Study details and
reference
Level of
evidence
(I-IV)
53
Extrinsic risk
factors
Training and racing factors:
Distance cycled
Positive association: Cross
sectional survey
14
III
Low gear usage
Positive association: Cross
sectional survey
14
III
Intrinsic risk
factors
Muscle dysfunction:
Asymmetrical spinal muscle firing
patterns
Positive association: case
control
37, 44
III
Imbalance of trunk muscles
No association: case series
15
IV
Weak hip flexors and abductors
Positive association: case
series
56
IV
Flexibility:
Lumbo-pelvic inflexibility
No association: case control
57
III
Anthropometry :
Cyclist / bicycle fit (pelvic tilt /
saddle angle)
Positive association:
prospective cohort
30
I
Based on the findings of this analysis, it is
apparent that there is very little evidence
supporting extrinsic risk factors associated
with LBP in cyclists. Only distance cycled, low
gear usage and less years of cycling showed
any association in a single questionnaire
survey.
Additionally, there are few studies which
present strong evidence for intrinsic factors
which have a positive association with LBP in
cyclists. Two intrinsic factors which are worthy
of discussion are the “Pelvic tilt/ saddle angle”
and “Asymmetrical spinal muscle firing
patterns”. These will be discussed separately.
Lower back pain in cyclists International SportMed Journal, Vol.11 No.1, 2010, pp.216-225.
Available at URL: http://www.ismj.com
222 Official Journal of FIMS (International Federation of Sports Medicine)
Pelvic tilt/saddle angle
The pelvic tilt/saddle angle has the strongest
evidence for a possible risk factor associated
with LBP in cyclists.
It has been suggested that a forward or
anterior pelvic tilt (APT) of the cyclist’s pelvis is
favourable for cycling as it may reduce the
tensile forces on the lumbo-sacral spine,
thereby reducing the risk of LBP in cyclists
20;30
.
An APT and forward position of the trunk may
help distribute a greater percentage of the
body weight over the handlebars, thereby
reducing the load on the seat and lumbar
vertebrae of the spine
20
.
In one controlled clinical trial
30
the pelvic/spine
angles at different seat angles on different
bicycles (10 asymptomatic subjects per
bicycle) was measured by serial fluoroscopic
investigations. The results of this study
showed that there was a tendency towards
hyperextension of the pelvic/spine angle, and
this resulted in an increase in tensile forces at
the promontorium. It was shown that these
forces could be reduced by adjusting the seat
angle to create an anterior inclining angle. The
findings were then applied to a group of 80
cyclists who suffered from l