The PoseRTM method : A biomechanical and physiological comparison with heel-toe running.

Research into endurance running performance (economy, optimal running biomechanics, and injury mechanisms) lacks a universal running technique; however, landing heel-toe identified eighty percent of runners. A new Gravitational hierarchical model of running was developed based upon a novel technique---Pose running---owing to deficiencies in the current hierarchical model (Hay and Reid, 1988) on the interaction of forces involved in running. A major deficiency in the current hierarchical model is viewing gravity as only active during flight. In contrast, the Gravitational hierarchical model defines a gravitational torque as the motive force in running. Ground reaction force is not a motive force but operates according to Newton's third law. The ground can only propel a runner forward via muscle activity, but leg and hip extensor muscles have consistently proven to be silent during leg extension. High Achilles tendon forces at terminal stance suggest the elastic recoil creates a re-bound effect in the vertical direction only, thus reducing work against gravity. Two experienced Pose runners were compared (study 1) with two experienced heel-toe runners using primary and secondary research variables derived from the Gravitational hierarchical model, which effectively distinguished the two techniques while establishing gravity as the motive force. For example, maximum horizontal acceleration of the centre of mass occurred before maximum horizontal ground reaction force, supporting the Gravitational hierarchical model that only a gravitational torque could create acceleration. Finally, sixteen male recreational endurance heel-toe runners (study 2 using the same primary variables as study 1) were randomly assigned into two groups where one group received a 7-hour Pose intervention over 7-days while the other group remained as heel-toe runners. A 2 x 2 mixed factorial ANOVA where group (control vs. treatment) and trial (pre to post changes) assessed the primary research variables. Significant interactions were explored using Tukey post hoc tests, which found significance (Pose runners pre-post test) for stance time (P= 0.001), centre of mass to support limb at 25 ms (P= 0.042), centre of mass displacement during stance (P = 0.001), knee flexion angular velocity during stance (P= 0.005) plus swing (P= 0.043) and stride frequency (P= 0.002). After 12-days the Pose group's posttest time-trial (2400 m) improved by a mean of 24.7 s compared with a 3 s decrease in the heel-toe group. No significant changes pre-post test, were found for an economy run (2400 m) at 3.35 m-s -1. A preliminary prospective 3-month injury report found no injury incidence in the Pose runners compared to six injuries in the heel-toe group. It was concluded, that the Pose technique is a valid biomechanical technique, which improved performance, while reducing injuries. Future work should further quantify gravity's role in accelerated running by ascertaining whether the horizontal acceleration of the centre of mass also occurs before maximal horizontal ground reaction force.