SLR - December 2017 - Stacey Helland
Reference: Tam N, Darragh IAJ, Divekar NV, Lamberts RP. Habitual Minimalist Shod Running Biomechanics and the Acute Response to Running Barefoot. Int J Sports Med. 2017 Sep; 38(10):770–775.Scientific Literature Review
Reviewed By: Stacey Helland, DPM
Residency Program: Southern Arizona Veterans Affairs Health Care System, Tucson, AZ
Podiatric Relevance: Podiatrists are increasingly confronted by runner enthusiasts about the advantages of barefoot running. Initially, technological advances created the traditional, cushioned running shoe to fight rearfoot pronation. However, recent public interest in barefoot running has created a shift from a cushioned shoe to a more “minimalist” style. Minimalist shoes are marketed to mimic barefoot running for a more natural mid/forefoot strike pattern leading to a reduction in injuries. Current studies evaluating barefoot running in those who habitually wear cushioned running shoes have inconsistent results. The goals of this study were to evaluate the running gait and the response of acute exposure to barefoot running in traditional shoe runners and minimalist shoe runners.
Methods: Thirty-four runners were recruited for this study. Eighteen runners had run over a year in only minimalist shoe gear (MIN), and sixteen were traditional, cushioned shod runners (TRAD). All runners had no barefoot running experience, ran at least four hours per week and could run ten kilometers in under 50 minutes. The gaits of the runners were evaluated on a 40-meter indoor track in both barefoot and shod conditions at 3.33 m/s-1. An eight-camera motion analysis system recorded 3D marker trajectories. Ground reaction forces were collected from a force platform. Initial rate of loading (LR), foot strike angle (FSA) and sagittal plane joint stiffness of the knees and ankles were measured.
Results: When both groups ran in their preferred shoe gear, there was no difference between their LRs. Both MIN and TRAD runners had greater LRs when barefoot running compared to shod running. The MIN and TRAD groups had no differences in ankle stiffness between each other, but both groups displayed decreased ankle stiffness when barefoot running (large effect in TRAD and moderate effect in MIN). There was significantly greater knee stiffness in TRAD runners than MIN runners when shod, but this interaction effect did not exist when both groups ran barefoot. Lastly, TRAD runners had a greater FSA when shod compared to MIN shod, but FSA significantly decreased for both groups when barefoot running.
Conclusions: The significant decrease in FSA and increase in LR when both groups transitioned from shod to barefoot running suggest that a minimalist shoe may not offer the same gait-related benefits as barefoot running. However, when removing footwear, the TRAD runner experienced a greater change in ankle stiffness than MIN runners proposing that minimalist runners may reactively adjust better to ankle stiffness. This may proximally affect the kinetic chain since TRAD runners also displayed significantly greater knee stiffness than MIN runners while shod. Greater knee stiffness may lead to coactivation of muscles, increase metabolic cost and put the TRAD runners at an increased risk of knee injury. Shoe construction affects biomechanics and risk of injury. Thus, minimalist shoes may decrease injury risk, but minimalist and cushioned shoe runners alike may require similar training to develop the desirable changes seen in barefoot runners.