nike free 3.0

the430miler wrote:

i disagree. how have you gotten to be so mis-informed?

....i suppose you have also conformed to the "free" mentallity? do you think that they make you have "perfect" pronation and heal all of your perdiatric ailments??

pronation is bad, it just needs to be corrected sometimes so it doesnt cause further injuries to your lower extremities.

"The softness of the midsole has no marked effect on landing forces during running (T.E. Clarke et al,1983b; Frederick,1986; Nigg et al., 1987). It seems that runners alter their gaits and muscle activation patterns (Komi et al., 1987) when running in harder shoes or when running barefoot. Thus, the degree of pronation is reduced when one runs barefoot (Frederick, 1986; L.S. Smith et al., 1986), a reduction due to changes in running patterns...."

"One problem with cushioning properties of the shoe is that the tendons and ligaments of the foot are designed to absorb shock when one runs barefoot (R.M. Alexander, 1987). Furthermore, these structures in the foot act act as highly efficient springs, converting as much as 93% of the energy they absorb on landing into elastic recoil at toe-off. Compared to these structures, the midsoles and outer soles of running shoes are relatively inefficient, because they convert only 40 to 50% of this energy back into elastic recoil (Alexander, 1987; Alexander & Bennett, 1989); the remainder of the energy heats up in the midsole."

Int J Sports Med. 2005 Sep;26(7):593-8. Related Articles, Links

Mechanical comparison of barefoot and shod running.

Divert C, Mornieux G, Baur H, Mayer F, Belli A.

Laboratory of Physiology, GIP Exercice-Sport-Sante, University of Saint-Etienne, France.

caroline.divert@univ-st-etienne.fr

In order to further compare shod versus barefoot running, 35 subjects ran two bouts of 4 minutes at 3.33 m x s(-1) on a treadmill dynamometer. Parameters were measured on about 60 consecutive steps. Barefoot showed mainly lower contact and flight time (p < 0.05), lower passive peak (1.48 versus 1.70 body weight, p < 0.05), higher braking and pushing impulses (p < 0.05), and higher pre-activation of triceps surae muscles (p < 0.05) than shod. It was concluded that when performed on a sufficient number of steps, barefoot running leads to a reduction of impact peak in order to reduce the high mechanical stress occurring during repetitive steps. This neural-mechanical adaptation could also enhance the storage and restitution of elastic energy at ankle extensors level.

The torsion of the foot in running. / (La torsion du pied lors de la course.)

Author(s): Stacoff, A.; Kaelin, X.; Stuessi, E.; Segesser, B. Source: International journal of sport biomechanics (Champaign, Ill.), Nov 1989: 5 (4). p. 375-389

Abstract: In the research of running shoes, excessive pronation is often related to various running injuries. Anatomically, pronation is a movement that occurs in more than one joint. Previous investigations that evaluated the pronation in running studied the movements of the lower leg and the rearfoot only. However, pronation could also be influenced by the movement of the forefoot and therefore depend on the torsional stiffness of the foot and of the shoe sole. This study investigated the relationship between the torsion and the pronation in running with a rearfoot touchdown and with a forefoot touchdown. The results show that, compared to running barefoot, running with a shoe decreases torsion and thereby increases pronation significantly for the forefoot and rearfoot touchdown conditions. Thus the reduction of torsional movement due to stiff shoe soles could well be a reason for running injuries caused by excessive pronation. It is concluded that modern running shoes could be designedto allow a certain torsional movement of the foot.