Introduction: Excessive pronation is discussed to be the cause of various overuse injuries in distance running which makes stability features of running shoes a huge research interest. Several authors have shown the reduction of pronation range and velocity induced by shoes with extreme varus angles (VA) of 8-10 . However, a reduction of cushioning properties was also observed in those shoes. Therefore, this study is aimed to investigate if shoes with moderate VA, usable for everyday running, are suited to reduce pronation parameters while maintaining cushioning properties. Methods: In two laboratory studies (n ¼ 11, n ¼ 10) the effects of gradually (1 steps) increasing VA between 0 and 4 were investigated with two different samples of running shoes. Additionally, a field study (n ¼ 17) determined subjects' perception of the different VA conditions. Results and discussion: Linear reductions of pronation excursion ( p50.01) and pronation velocity ( p50.01) were observed with increasing VA between shoes, whereas cushioning parameters remained unaltered. Runners did not perceive changes in shoe properties due to different VA nor did they favour any condition. Conclusion: In running shoe designs, small varus perturbations can be implemented to fine tune the pronation parameters and thereby create the runner specific pronation control.

TPR (dotted) and MPV (solid) at different VA (study A squares, study B circles) Figure 1 TPR (dotted) and MPV (solid) at different VA (study A squares, study B circles).Publish with Bio Med Central and every scientist can read your work free of charge "BioMed Central will be the most significant development for disseminating the results of biomedical researc h in our lifetime.

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Progression of the difficulty of agility exercises in sport is often achieved by changing the stability of the support surface via graded sensorimotor training devices. However, little is known about the challenge imposed to postural equilibrium by these graded devices. This study quantified the instability provided by four sensorimotor training devices typically used to enhance athletic performance; three progressively unstable balance pads (ST1–3) and an oscillatory platform (PM). Twenty-five (13 female, 12 male) young adults (age, 26 ± 3 yr; height, 1.76 ± 0.10 m; and weight, 69 ± 12 kg), completed seven unipedal balance conditions involving stable and progressively unstable surfaces that involved four sensorimotor training devices (ST1-3, PM) and their combination (PM-ST1, PM-ST2). An inertial sensor, mounted over the lumbar spine, was used to monitor Centre of Mass (COM) displacement in each condition. Potential differences in COM displacement between conditions were assessed using a mixed-model analysis of variance. COM displacement differed between training devices; with a progressive, though non-linear, increase in COM displacement from the most (ST1) to the least (ST3) stable balance pad. However, there was no significant difference in COM displacement between the least stable balance pad (ST3) and the oscillatory platform used in isolation (PM) or in combination with balance pads (PM-ST1, PM-ST2). These novel findings have important practical implications for the design of progressive sensorimotor training programs in sport.

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