Vol. 54 - No. 4 THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS 447 A recent surge in the popularity of minimalist and barefoot running has been founded on the concept that there is the potential for making im- provement in running economy compared to wear- ing cushioned shoes, 1 and for decreasing the risk of injury. 2 The study of barefoot running is challenging, because several factors may influence metabolic pa- rameters other than the presence of shoes. 1 What is known is that running barefoot is related to shorter stride length and increased cadence, 3, 4 both of which may help to minimize vertical excursion and de- crease ground reaction force. 5 Minimizing cyclical vertical displacement and braking forces may help reduce energy waste, reduce heart rates and oxygen use and make barefoot running more economical compared to shod running. These factors may impact the fuels used during the running in different shoe wear conditions. Several studies have attempted to address oxy- gen use and energy cost differences between bare- foot and shod running, with mixed results. Equivo- cal results may be due to the lack of control with shoe types used during testing, 6 a foot strike pattern switch from heel striking to mid-forefoot striking 1 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 2 Department of Family Medicine University of Florida, Gainesville, FL, USA J SPORTS MED PHYS FITNESS 2014;54:447-55 H. K. VINCENT 1 , C. MONTERO 1 , B. P. CONRAD 1 , A. SEAY 1 , K. EDENFIELD 2 , K. R. VINCENT 1 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 (VO 2 ), 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 correspond- ing to mean HR values of 146 bpm (shod) and 144 bpm (barefoot). Steady State VO 2 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 expend- ed 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). Conclusion. 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 par- ticipants were likely able to titrate kinematics to standard- ize energy output and fuel use for a given running distance and speed irrespective of shoe wear. Key words: Running - Oxygen - Shoes. Corresponding author: H. K. Vincent, PhD, Division of Research, College of Medicine, Department of Orthopedics and Rehabilitation, University of Florida, UF Orthopaedics and Sports Medicine Institute (OSMI), PO Box 112727, Gainesville, FL 32607, USA. E-mail: vincehk@ortho.ufl.edu MINERVA MEDICA COPYRIGHT® This document is protected by international copyright laws. No additional reproduction is authorized. It is permitted for personal use to download and save only one file and print only one copy of this Article. It is not permitted to make additional copies (either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo, or other proprietary information of the Publisher.