title: The effect of footwear and footfall pattern on running stride interval long-range correlations and distributional variability.
abstract: The presence of long-range correlations (self-similarity) in the stride-to-stride fluctuations in running stride interval has been used as an indicator of a healthy adaptable system. Changes to footfall patterns when running with minimalist shoes could cause a less adaptable running gait. The purpose of this study was to investigate stride interval variability and the degree of self-similarity of stride interval in runners wearing minimalist and conventional footwear. Twenty-six trained habitual rearfoot footfall runners, unaccustomed to running in minimalist footwear, performed 6-min sub-maximal treadmill running bouts at 11, 13 and 15 km·h(-1) in minimalist and conventional shoes. Force sensitive resistors were placed in the shoes to quantify stride interval (time between successive foot contacts). Footfall position, stride interval mean and coefficient of variation (CV), were used to assess performance as a function of shoe type. Long-range correlations of stride interval were assessed using detrended fluctuation analysis (α). Mean stride interval was 1-1.3% shorter (P=0.02) and 27% of runners adopted a midfoot footfall (MFF) in the minimalist shoe. There was a significant shoe effect on α and shoe*speed*footfall interaction effect on CV (P<0.05). Runners that adopted a MFF in minimalist shoes, displayed reduced long-range correlations (P<0.05) and CV (P<0.06) in their running stride interval at the 15 km·h(-1) speed. The reduced variability and self-similarity observed for runners that changed to a MFF in the minimalist shoe may be suggestive of a system that is less flexible and more prone to injury.
authors.affiliation: Alliance for Research in Exercise, Nutrition and Activity (ARENA), Sansom Institute for Health Research, University of South Australia, Adelaide, SA, 5001, Australia. Electronic address: joel.fuller@mymail.unisa.edu.au.
authors.forename: Joel T
authors.initials: JT
authors.lastname: Fuller
authors.affiliation: Department of Kinesiology, University of Massachusetts, Amherst, MA, 01003, United States.
authors.forename: Avelino
authors.initials: A
authors.lastname: Amado
authors.affiliation: Department of Kinesiology, University of Massachusetts, Amherst, MA, 01003, United States.
authors.forename: Richard E A van
authors.initials: RE
authors.lastname: Emmerik
authors.affiliation: Department of Kinesiology, University of Massachusetts, Amherst, MA, 01003, United States.
authors.forename: Joseph
authors.initials: J
authors.lastname: Hamill
authors.affiliation: Alliance for Research in Exercise, Nutrition and Activity (ARENA), Sansom Institute for Health Research, University of South Australia, Adelaide, SA, 5001, Australia.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Buckley
authors.affiliation: Alliance for Research in Exercise, Nutrition and Activity (ARENA), Sansom Institute for Health Research, University of South Australia, Adelaide, SA, 5001, Australia.
authors.forename: Margarita D
authors.initials: MD
authors.lastname: Tsiros
authors.affiliation: Alliance for Research in Exercise, Nutrition and Activity (ARENA), Sansom Institute for Health Research, University of South Australia, Adelaide, SA, 5001, Australia.
authors.forename: Dominic
authors.initials: D
authors.lastname: Thewlis
mesh_terms: D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D018592:Cross-Over Studies; D006801:Humans; D008297:Male; D011897:Random Allocation; D012420:Running / Q000502:physiology*; D012775:Shoes; D055815:Young Adult
keywords: DFA; Detrended fluctuation analysis; Dynamic systems theory; Long-range correlation; Minimalist