Metabolic responses of running shod and barefoot in mid-forefoot runners.
BACKGROUND
The purposes of this study were to compare the oxygen cost, metabolic parameters and temporalspatial variables between barefoot and shod running in trained mid-forefoot runners.


METHODS
Experienced runners (N.=21; 30±10.9 years; 16 men) performed two separate 20 minute treadmill running bouts at ~77% of estimated maximal heart rate. Rate of oxygen consumption (VO2), energy cost, fuel use and heart rate (HR) were collected continuously using a portable gas analyzer. Three-dimensional motion capture was used to measure temporalspatial parameters.


RESULTS
Participants ran at a mean self-selected speed of 3.1±0.3 m/s for both conditions, at intensities corresponding to mean HR values of 146 bpm (shod) and 144 bpm (barefoot). Steady State VO2 was not different between the shod and barefoot conditions (39.4± 4.7 mL/kg*min vs. 40±5.2 mL/kg*min, respectively). The total energy expended in the shod and barefoot conditions was 974±134 kJ and 979±142 kJ. The average non-protein respiratory exchange ratios, proportions and amount of fat and carbohydrate used were not different between conditions. Cadence was 2.5% higher and center of gravity vertical displacement was 0.5 cm less for the barefoot condition (P<0.05).


CONCLUSIONS
In trained mid-forefoot runners experienced with barefoot running, there are not significant metabolic differences between shod and barefoot running conditions. Barefoot running increases cadence and decreases foot contact time and vertical displacement. Experienced participants were likely able to titrate kinematics to standardize energy output and fuel use for a given running distance and speed irrespective of shoe wear.
Department of Orthopedics and Rehabilitation Interdisciplinary Center for Musculoskeletal Training and Research Divisions of Research Physical Medicine and Rehabilitation and Sports Medicine, Gainesville, FL, USA - vincehk@ortho.ufl.edu.
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D000328:Adult; D001696:Biomechanical Phenomena; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D005528:Foot / Q000502:physiology*; D005684:Gait / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012044:Regression Analysis; D012420:Running / Q000502:physiology*; D012775:Shoes; D055815:Young Adult