• The influence of sprint spike bending stiffness on sprinting performance and metatarsophalangeal joint function

      Smith, Grace; Lake, Mark; Sterzing, Thorsten; Milani, Thomas; University of Chester; Liverpool John Moores University; Chemnitz University of Technology. (Taylor and Francis, 2016-06)
      There is evidence that increasing the longitudinal bending stiffness of sprinting footwear can lead to improved sprinting performance although this has not yet been established. This study examined the effect of four known shoe stiffness conditions on both sprinting performance and metatarsophalangeal joint (MTPJ) motion. Twelve trained sprinters performed 40 m maximal sprints along an indoor running track, two sprints in each stiffness condition, and high speed video (600 Hz) recorded two dimensional MTPJ motion during ground contact. To explore individual responses to the footwear manipulations, three dimensional (1000 Hz) kinematic and kinetic data was collected during maximal sprinting for two sprinters. At the group-level, increasing shoe bending stiffness elicited no significant differences in sprinting performance or MTPJ motion, with any changes between conditions being subject-specific. In-depth individual analyses revealed that increased shoe stiffness could restrict motion about the MTPJ and there appeared to be a preferred stiffness for best performance. This notion of individual optimal sprint shoe stiffness and what factors might contribute to the optimum requires further investigation.
    • Measurement procedures affect the interpretation of metatarsophalangeal joint function during accelerated sprinting

      Smith, Grace; Lake, Mark; Lees, Adrian; Worsfold, Paul R.; University of Chester ; Liverpool John Moores University ; Liverpool John Moores University ; University of Chester (Routledge, 2012-08)
      The metatarsophalangeal joint (MPJ) is a significant absorber of energy in sprinting. This study examined the influence of MPJ axis choice and filter cut-off frequency on kinetic variables describing MPJ function during accelerated sprinting. Eight trained sprinters performed maximal sprints along a runway. Three dimensional high-speed (1000 Hz) kinematic and kinetic data were collected at the 20 m point. Three axis definitions for the five MPJs were compared. MPJ moments, powers and energies were calculated using different filter cut-off frequencies. The more anatomically appropriate dual axis resulted in less energy absorbed at the MPJ compared to the oblique axis which also absorbed less energy compared to the perpendicular axis. Furthermore, a low cut-off frequency (8 Hz) substantially underestimated MPJ kinematics, kinetics and the energy absorbed at the joint and lowered the estimate of energy production during push-off. It is concluded that a better understanding of MPJ function during sprinting would be obtained by using an oblique or anatomically appropriate representation of the joint together with appropriate kinematic data sampling and filtering so that high frequency movement characteristics are retained.
    • Metatarsophalangeal joint function during sprinting: A comparison of barefoot and sprint spike shod foot conditions

      Smith, Grace; Lake, Mark; Lees, Adrian; University of Chester ; Liverpool John Moores University ; Liverpool John Moores University (13/09/2013)
      The metatarsophalangeal joint is an important contributor to lower limb energetics during sprint running. This study compared the kinematics, kinetics and energetics of the metatarsophalangeal joint during sprinting barefoot and wearing standardised sprint spikes. The aim of this investigation was to determine whether standard sprinting footwear alters the natural motion and function of the metatatarsophalangeal joint exhibited during barefoot sprint running. Eight trained sprinters performed maximal sprints along a runway, four sprints in each condition. Three dimensional high speed (1000 Hz) kinematic and kinetic data were collected at the 20 m point. Joint angle, angular velocity, moment, power and energy were calculated for the metatarsophalangeal joint. Sprint spikes significantly increase sprinting velocity (0.3 m/s average increase), yet limit the range of motion about the metatarsophalangeal joint (17.9 % average reduction) and reduce peak dorsiflexion velocity (25.5 % average reduction), thus exhibiting a controlling affect over the natural behaviour of the foot. However, sprint spikes improve metatarsophalangeal joint kinetics by significantly increasing the peak metatarsophalangeal joint moment (15 % average increase) and total energy generated during the important push-off phase (0.5 J to 1.4 J). The results demonstrate substantial changes in metatarsophalangeal function and potential improvements in performance-related parameters due to footwear.