amount of longitudinal bending stiffness to improve running economy which is

Amount of longitudinal bending stiffness to improve

This preview shows page 10 - 11 out of 12 pages.

amount of longitudinal bending stiffness to improve running economy, which is primarily dependent on athlete mass [ 32 ]. Similar results were found when investigating the inffuence of midsole longitudinal bending stiffness on running per- formance [ 37 ]. To our knowledge, this is the ff rst study to compare the Nike Vaporffy marathon shoe with a spike shoe traditionally worn during track racing. With regard to shoe type, materials and structure, the NZM spike would be considered a light- weight racing shoe featuring a thin Cushlon foam midsole with a ffexible horseshoe-shaped plastic plate and four pin spikes around the forefoot (Fig.  1 ). Running barefoot or in racing spikes that have a ffat midsole with little to no cush- ioning can cause runners to make acute, short-term changes in running gait from a rearfoot strike to a forefoot strike, increase cadence, and reduce vertical oscillation of the center of mass, which might contribute to improved running economy [ 38 , 39 ]. Indeed, in our study, subjects did have a faster cadence and shorter ground contact times while wear- ing the NZM spikes compared with that of other shoe mod- els (Table  5 ). However, running in shoes with minimal or no cushion also requires signiff cant muscular effort to cushion the impact of the foot with the ground [ 40 ]. Conversely, when running in cushioned shoes, the midsole material per- forms the task of cushioning, presumably with less muscular effort; however, all cushioning materials have mass, which in itself incurs a metabolic cost [ 10 ]. Frederick et al. [ 40 ] found that running barefoot and while wearing well-cushioned shoes with a mass of 290 g, each required the same rate of oxygen consumption. Similarly, Tung et al. [ 30 ] showed that running barefoot on 10 mm of surface cushioning improved running economy by 1.63% compared with barefoot running on a rigid running surface. These same subjects also ran in medium-weight shoes (230 g each) with ~ 10 mm of foam midsole cushioning, and the metabolic cost of running in those shoes was the same as running barefoot on the rigid surface [ 30 ]. Thus, the two factors appeared to counteract each other. Barefoot or minimalist shoe running involves lit- tle to no added mass but requires metabolic energy for cush- ioning. Running in cushioned shoes requires more energy for accelerating the shoe mass but provides the cushioning, with a reduced metabolic cost [ 10 ]. While running in the NVF shoes, subjects generally ran with longer contact times and stride lengths, and con- sequently slower stride rates, compared with NZM spike shoes (Table  5 ). Relative to the ADI shoes, contact times were generally shorter, stride lengths slightly longer, and differences in stride rate were trivial while wearing the NVF shoes. These changes are in opposition to Hoogkamer et al.
Image of page 10

Subscribe to view the full document.

Image of page 11
  • Fall '16
  • KaraCross

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Ask Expert Tutors You can ask You can ask ( soon) You can ask (will expire )
Answers in as fast as 15 minutes