The
main factors that can be controlled in runners are technique,
equipment (footwear) and
overuse. All of
these factors can produce injuries independently but they can also
all be related to
each other. For
example over supportive cushioned running shoes can lead to incorrect
running
technique resulting
in excess stress (i.e. overuse) to the body, in particular the lower
extremities
(Lieberman,
2012; The
American College of Sports Medicine, (2014).
Running technique
is rarely addressed in all but the most elite of runners as it is
assumed
that running is a
natural activity for humans. In theory it should be but modern
lifestyles and
footwear have had a
negative effect on the way humans now move. Thus technique should be
the
focus of an injury
prevention programme, although overuse and footwear are also
intrinsically
linked.
In
a study of a group of middle and long distance college runners, it
was found that
injury
rates differed depending on technique, specifically foot-strike.
Daoud,
Geissler, Wang,
Saretsky,
Daoud, & Lieberman, (2012),
showed those that were rear-foot strikers (RFS) were
2.6
times more likely to have a mild injury and 2.4 times more likely to
have a moderate
injury,
than forefoot strikers (FFS).
This
was found to be due to the large impact peak in ground reaction force
(GRF)
associated
with RFS. Runners who FFS generate no such impact peak. High impact
peaks
apply
high loading forces to the body which in turn can lead to injury from
repeated stress.
High
impact peaks are useful predictors of injuries such as plantar
fasciitis, tibial stress
syndrome
and patellofemoral pain syndrome (Daoud, 2012).
Until the Daoud
study (2012), foot strike patterns and their effect on injuries had
not been
studied but the
results show that technique is very important in preventing injury.
However,
footwear is also
important as it has a direct effect on technique through reducing the
ability of the
body's
proprioceptive sensors to give adequate feedback regarding the ground
reaction forces acting
on
the body (Lieberman,
2012).
Foot-strike
also varies depending on the ability of the athlete. 936
recreational runners were
studied
while running in a marathon and observations made at the 10km mark
show that 88.9% of
them
were rear-foot strikers. Interestingly, by the 32km point this
percentage had increased even
higher,
presumably due to the effect of fatigue (Larson, Higgins, Kaminski,
Decker, Preble, Lyons,
&
Normile, A., 2011).
When
relating these results to the increased injury rates in RFS (Daoud,
2012), there is
obviously
huge potential for dramatically reducing injuries in recreational
runners by improving
their
technique. Those runners in the Larson et al (2011) study that
switched from a FFS
to
a RFS at 32km, lacked the level of conditioning to maintain their
technique through to the finish
line.
The FFS places a larger eccentric load on the calf, achilles and foot
architecture in the process
of
absorbing GRF naturally. When these structures fatigue, the natural
course of action would be to
slow
down to a walking pace which reduces GRF and allows a natural RFS
thus reducing stress on
the
overworked areas. In effect this is what the runners in the study
were doing by switching to a
RFS
and continuing to 'run' on their heels.
Dias
Lopes, (2012) describes most
of the injuries cited in his study
as being overuse
injuries,
due to, “overloading the musculoskeletal structures of the
runners”. He goes on to
say
that plantar fasciitis (PF) is “considered by healthcare
professionals to be one of the
most
common injuries of the foot”, explaining that the foot can only
absorb the increased
GRFs
when running if the plantar fascia is resilient. Ankle dorsiflexors
tendinopathy was
common
among the ultra marathoners studied, indicating overuse of the
dorsiflexors due to
heel-striking
or a potential lack of dorsiflexion in the ankle.
Poor
range of motion (ROM) in the toes, ankle, knees, hips and spine can
affect overall body
posture
and consequently running technique and potential for injury
(Lieberman 2012). All theses
factors
are controllable and once identified can be improved over time.
Overuse injuries, although traditionally thought of as simply
training too hard, can also be
related
back to musculoskeletal weaknesses. Simply put, if a structure is not
strong enough to
withstand
the force acting on it then it will fail. Modern lifestyles result in
reduced flexibility and
neuromuscular
skill and sophisticated shoes reduce proprioception and foot
strength. These factors
combine
to change running form which in turn introduce GRF impact peaks
causing elevated injury
figures
in runners with poor technique, particularly those that RFS
(Lieberman, 2012).
World
record holders and the majority of elite runners have techniques much
different to that
of
the majority of amateur runners and even some sub elites. Top
performers tend to run with a tall
and
upright stance and a high cadence resulting in a FFS where they land
lightly on their feet. They
also
wear minimal footwear (racing flats or spikes) or are barefoot (Adebe
Bikila and Zola Budd for
example
broke World records running in bare feet) (Lieberman,
2012).
There
are also implications for all sports that involve running either
during the event or for
training,
both from an injury prevention and a
performance perspective. Using the knee, ankle, hips
and
spine as shock absorbers creates potential energy which is released
in a spring like manner,
improving
running efficiency (Perl, Daoud, &
Lieberman, 2012).
In
fact, of the GRF acting on the body while running, 35% is absorbed by
the Achilles
tendon
and 17% by the plantar fascia (Alexander,
1991). This action protects the knee but cannot
occur
if the foot is encased in a shoe with an arch support (which prevents
the arch stretching) and a
heal
lift (which prevents the Achilles stretching). In this case,
particularly when heel striking, an
unnecessary amount of additional shock is taken by the knee joint, explaining the high rates of knee
injuries.
In
conclusion, technique is a risk factor that can be controlled, as is
the strength and
flexibility
of the body's lower limbs, particularly the foot and ankle.
References
The
American College of Sports Medicine, (2014). Retrieved April 10th
2014
from:
Alexander,
R. M. (1991). Energy-saving mechanisms in walking and running.
Journal of
Experimental
Biology, 160(1),
55-69.
Daoud,
A. I., Geissler, G. J., Wang, F., Saretsky, J., Daoud, Y. A., &
Lieberman, D. E. (2012). Foot
strike
and injury rates in endurance runners: a retrospective study. Med
Sci Sports Exerc,
44(7),
1325-34.
Dias
Lopes, A., Hespanhol Junior, L., Yeung, S. S., & Pena Costa, L.
(2012). What are the Main
Running-Related
Musculoskeletal Injuries? Sports
Medicine,
42(10),
891-905.
Larson,
P., Higgins, E., Kaminski, J., Decker, T., Preble, J., Lyons, D., ...
& Normile, A. (2011).
Foot
strike patterns of recreational and sub-elite runners in a
long-distance road race. Journal
of
sports sciences,
29(15),
1665-1673.
Lieberman
DE., (2012). What we can learn about running from barefoot running:
an evolutionary
medical
perspective. Exerc
Sport Sci Rev. 2012; 40 (2): 63-72.
Perl,
D. P., Daoud, A. I., & Lieberman, D. E. (2012). Effects of
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