Controlling Injury Risk in Running

          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 10^th 2014 from:

          http://www.acsm.org/docs/brochures/running-shoes.pdf

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 footwear and strike type on running

          economy. Med Sci Sports Exerc, 44(7), 1335-43.