|Barefoot vs Light-weight Footwear vs Conventional Running Footwear
This paper will briefly discuss:
Ground reaction forces in running
Impact and sensory perception
Running footwear has changed significantly over the past 40 years. Footwear has changed from being thin-soled and streamlined, to be thicker, wider and mostly softer. More recently runners now have thin flexible footwear available.
Fig 1. Older thin-soled shoe Fig 2. Thicker, softer shoe
Fig 3. Lighter, flexible shoe
Ground reaction Forces
The problem with modern conventional running shoes are that thicker softer midsoles contribute to a loss of sensory perception of the surface and therefore contribute to a more passive foot-strike. The result being greater heel strike and greater initial impact.
Fig 4. Ground reaction force curve showing initial impact peak and propulsive phase peak.
There is an enormous body of research from two decades of research reporting that footwear:
reduces sensory perception of the surface
reduces sensory stimulus to the muscular system
contributes to greater passive impact
contributes to greater muscle vibration
contributes to greater motion of the foot
Clarke et al 1983, Nigg et al 1995, Nigg 2009, Robbins & Hanna 1987, Robbins & Gouw 1991, Stacoff et al 1996, Stacoff et al 2001
With less sensory perception of the surface a runner will passively heel strike in running shoes. This will contribute to greater initial impact forces at heel/footstrike (Fig 4). Less stimulus contributes to slower and less recruitment of muscular action and therefore greater forces through the lower limb, greater muscle vibration and greater motion (Nigg, 2009).
Using thin lightweight footwear or running barefooted, a runner can ‘feel’ the surface, and with heightened sensory perception, natural protective mechanisms will contribute to a more mid-foot strike and activate muscular control. This means less rate of impact and less motion (Fig 5.) Robbins & Hanna 1987, Robbins & Gouw 1991.
Fig 5. Passive heel strike vs midfoot strike
The use of conventional footwear reduces sensory perception and reduces the stimulus to the foot and lower limb. Therefore there is slower activation and less muscular activity at footstrike. It has been reported that due to less muscular activity, there is in turn, greater motion of the foot. Studies of barefoot running have repeatedly shown greater muscular activity and less motion of the foot during running. Robbins and Gouw 1991, Robbins et al 1989, Stacoff et al 1996, Stacoff et al 2001.
Using thin-soled flexible footwear is to promote similar benefits to barefoot running and assist in recruiting muscular control and strengthening.
Studies of foot motion have continually reported increased motion of the foot while running in conventional footwear while there is less motion of the foot while running barefoot. Studies have repeatedly reported the above for more than 20 years. Frederick 1986, Nigg and Bahlsen 1988.
Shoe companies have developed shoes to be bigger heavier and more rigidly supported in attempt to support and reduce the motion of the foot. But, the motion of the foot is accentuated from using conventional running initially. The leverage around the foot from using shoes promotes greater pronation during running. Shoe companies have designed and promoted footwear that in no doubt has been detrimental to a runners in that shoes promote greater motion and limit natural impact attenuation.
There is no doubt that there are benefits associated with barefoot running including less impact, less motion and strengthening benefits. But for most runners, running barefoot is too far from what most have adapted to wearing.
Similar benefits can be gained from thin-soled flexible footwear. For most runners, using thin, lightweight and low-profile shoes are enough to provide benefits.
But, not all runners are likely to be able to easily re-adapt ‘back’ to lightweight and low-profile shoes and/or barefoot running. For most distance runners, at the age 38 years +/- 2 years is the time of highest rate of onset of overuse injuries and degenerative changes.
Most runners who are older, or have been running for at least 2 decades have acquired degenerative stiffness of the calves and deep posterior compartments of the lower leg. This is why there is a significant number of older runners who develop a history of calf, Achilles and plantar fascia pain of the foot.
Often the older runner who begins to run in low-profile lightweight footwear, or barefooted, often encounters tightness and injury of this ‘extensor loop’ of calf-Achilles-plantar fascia structure. This is due to the need for greater extension of the leg over the foot when the heel height is lower as compared to conventional footwear. Conventional footwear usually has greater heel height and therefore lessens the need for extension at the ankle.
As with any change, particularly with distance runners, a change of footwear to using low-profile and lightweight footwear should be done gradually starting with walking and few short runs.
Nike have designed Free footwear for more than 10 years now that allow a more natural running gait. Footwear that is low-profile and lightweight is probably the single most effective injury-preventative tool a runner could introduce to their running. Research independant of Nike, reports that runners who use Free footwear for 3 runs per week for 30 mins and for 6 months will gain 4-5 % increase in calf girth, demonstrated on cross sectional MRI. Runners using Free have also been shown to gain greater calf power output (Bruggemann et al 2004).
Prospective studies on distance runners have shown that those with larger and stronger calves have much less lower limb history including calf, Achilles, shin pain and tibial stress fractures (Bennell et al 1996). The benefits of strengthening from using footwear that is lightweight and low-profile are preventative for any runner.
Runners who have attempted to increase running barefoot are prone to calf, Achilles and plantar fascia problems. Anterior ankle joint pain has also been observed in runners shifting from footwear to barefoot running.
Natural surfaces, which are what the foot and lower limb have evolved to be suited to, provide the best environment for runners. There is less ground reaction force applied to the lower limb and less repetition of movement. Natural surfaces are therefore the ideal environment for runners and best for wearing thin-soled lightweight footwear
Conclusion and suggestions
Recently there has been the release of several lightweight and low-profile shoes to enhance more natural motion in the runner.
Adidas have released the CC Ride. Asics will their own lightweight shoe as yet to be named.release. Brooks have designed ‘Flow’. New Balance have ‘Minimus’. Saucony have ‘Kinvara’ and ‘Mirage’. All flexible low profile designed footwear.
Runners who use conventional footwear, should use lighter streamlined shoes and not large, heavy and thick footwear. Runners should use thin flexible footwear for some amount of time of weekly running for strengthening benefits.
Younger runners will be suited and more easily adaptable to low-profile and lightweight footwear as compared to older athletes.
In consideration of current trends, it is unreasonable to suggest that runners should be running barefoot. Most of us have adapted to footwear, and it takes an incredibly long time to adapt ‘back’ to a simple barefoot state. Using low-profile lightweight footwear has enormous benefits for runners and provide positive benefits of injury prevention and more natural motion.
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