International Calgary Running Symposium
I was recently at the International Calgary Running Symposium where the most prominent scientists met to discuss sports footwear. Here are a few interesting quotes from the lecturers. Please note that I don't necessarily agree with all of them!
J. EA BERTRAM - Energy cost is strongly related to energy loss. Reducing collision forces and improving impact moderating behavior is very important.
V. D BOGERT - Posture of the foot and its velocity have more influence on impact peak than shoe cushioning.
G-P. BRÜGGEMANN - A prospective study suggests that running in minimal support footwear increases load on the intrinsic muscles that support the arch, thereby strengthening the foot.
P. CAVANAGH - Switching (from RFS) to FFS decreases tibial vertical acceleration but increases antero-posterior acceleration... and net acceleration.
I DAVIS - Footwear (chronic protective support) creates weakness. Gradual transition to less shoe is the key to success. - Children, two years of age, land with a slightly plantarflexed foot during shod running. By the time they are four, they are heelstriking with nearly 10 deg. of dorsiflexion.
R. FERBER - Researchers have very limited influence on clinicians.
E. C. FREDERICK - Certain shoe characteristics potentially represent a positive performance benefit. Running shoe's weight is critical (7x more costly on the foot than at the center of mass). Mass effect is 1% per 100gr in your feet. - Pronation control technologies and orthotics don't improve mechanical efficiency in long distance runners. - A certain amount of cushioning is another positive factor for performance in many runners, but even greater is the potential offered by customization and individualization of shoes.
J. HAMILL - Over the last 40 years, the major emphasis of research on running injuries has been related to athletic footwear development… aiming at impact attenuation and pronation control. Biomechanists have now come to the conclusion that the injuries may not be related to these two factors. - With regard to injuries, training errors and genetic factors are more important than shoes and biomechanics. - Freely chosen cadence is not the optimal cadence with regard to O2 consumption.
W. HERZOG - To perform you must be injury free. - Research on uninjured runners may be a better idea than research on injured runners. - One must not just look at how much he runs, but also at how much he rests.
R. KRAM - Running barefoot on relatively soft surfaces may provide the best conditions for better performance.
D. LIEBERMAN - There is more variability in foot strike during barefoot running than during shod running. - Modern life mismatch: even surfaces, irregular activity, less body skills and resilience, running shoes! - When they run barefoot, most tribes do it on hard surfaces… natural environment is not just sand and nice freshly mowed lawn).
G Y MILLET - Determinants of performance in ultramarathons that may be subjected to a compromise between energy cost and lower limb tissue damage.
E. MÜLLER - Modern motor learning theories consider movement variability as an essential factor for technique improvement. The inherent variability on a macroscopic level decreases as performance increases, the microscopic movement variability behaves the opposite. In order to achieve the ability to adapt to such changes, reactive phenomena should be increased in the training process. External perturbations (like trail running) might enable an increase of functional variability within the running movement pattern, and this might lead to more flexible, and to external perturbations, more adaptable movement patterns
R. O. NIELSEN - Training errors are widely accepted as the main cause of injuries but the evidence is non-existent
B. M. NIGG - It's not possible to make a conclusive statement about a difference in running injury rates over the last four to five decades (there has probably been no change) because studies used different definitions of injury and different populations. - Impact and excessive pronation have been shown to be weak predictors of running injuries - It seems that we use our comfort sensing system to protect ourselves from injuries.
This leads to the proposal of a new paradigm: The comfort filter paradigm.
Runners use their comfort assessment to select shoes that will cause a lower chance of injury.
C. B PAYNE - Different shoes and techniques load different tissues differently. Load management is the key!
N. ROMANOV - Shoe manufacturers have failed to decrease injury rates. - Taking off your shoes does not make you running well.
M. SHORTEN - 93% of mismatch between self reported strike type and reality. - Average angle between the foot and the ground in runners is 10 to 25 degrees of dorsiflexion (heel strike).
D. J. STEFANYSHYN - Greater longitudinal stiffness in running shoes increase the lever arm and can improve running economy. Excessively increasing the stiffness is detrimental to running economy.
Question to the PANEL INDUSTRY
- Are innovations in running shoes for 'function' or for 'business'?
Answer: business first! The key is core design (look... color...). We must be sure that consumers like and buy the product.
- Why industry keeps speaking about cushioning and motion control? Answer: because it’s easier to understand for everybody ... even if it's not true!
For live comments, follow my Twitter feed #ICRS.
Next blog article: What's wrong with Dr. Nigg's The Comfort Filter Paradigm?